JET Manual 10 - Amusement 21 and Sound System … Folder/EOT-EO1 … · 5.4 Inventory control 33 ... This JET manual introduces the storage, handling, mixing, and transportation of

JET Manual 10Acid Storage, Handling,

Transportation, and Mixing

Version 1.0

JET Manual 10 Acid Storage, Handling, Transportation, and Mixing

InTouch Content ID#: 4221679 Version: 1.0 Release Date: January 31, 2007 Owner: Well Services Training and Development, IPC

Schlumberger private

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Copyright © 2007 Schlumberger, Unpublished Work. All Rights Reserved.This work contains the confidential and proprietary trade secrets of Schlumberger and may not be copied or stored in an information retrieval system, transferred, used, distributed, translated or retransmitted in any form or by any means, electronic or mechanical, in whole or in part, without the express written permission of the copyright owner.

Trademarks & Service Marks“Schlumberger,” the Schlumberger logotype, and other words or symbols used to identify the products and services described herein are either trademarks, trade names, or service marks of Schlumberger and its licensors, or are the property of their respective owners. These marks may not be copied, imitated or used, in whole or in part, without the express prior written permission of Schlumberger. In addition, covers, page headers, custom graphics, icons, and other design elements may be service marks, trademarks, and/or trade dress of Schlumberger, and may not be copied, imitated, or used, in whole or in part, without the express prior written permission of Schlumberger.

An asterisk (*) is used throughout this document to designate a mark of Schlumberger.

A complete list of Schlumberger marks may be viewed at the Schlumberger Oilfield Services Marks page: http://www.hub.slb.com/index.cfm?id=id32083

iiiJET 10 - Acid Storage, Handling, Transportation, and Mixing |

Table of Contents

1.0 Introduction 71.1 Learning objectives 81.2 Safety warning 8

2.0 Acid Properties and Hazards 92.1 Definition of an acid 92.2 Applications 92.3 Acid properties 9

2.3.1 HClacidstrength 92.3.2 pHscale 10

3.0 Use of Acids in the Oilfield 133.1 Current oilfield acid applications 133.2 Historical background 133.3 Acid system selection 143.4 Description of acids used in the oilfield 15

3.4.1 Hydrochloricacid(HCl) 153.4.2 Hydrofluoricacid(HF) 153.4.3 Mudacid 173.4.4 Clayacid 173.4.5 Aceticacid 173.4.6 Formicacid(L036) 173.4.7 Otheracidsystems 17

3.5 Acid additives 173.5.1 Inhibitorsandinhibitoraids 183.5.2 Surfactants 183.5.3 Foamingagents 183.5.4 Mutualsolvents 193.5.5 Antisludgeagents 193.5.6 Nonemulsifyingagents 193.5.7 Iron-controlagents 193.5.8 Specialtyadditives 19

4.0 Safety Considerations 214.1 Safety standards 214.2 Responsibilities 21

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4.3 PPE 224.3.1 Eyeandfaceprotection: 224.3.2 Handprotection 224.3.3 Skinandbodyprotection 224.3.4 Respiratoryprotection 234.3.5 TreatingHFacidexposure 24

4.4 Hazard communication documents 244.4.1 Materialsafetydatasheets(MSDSs) 244.4.2 Chemicallabels 254.4.3 Dangerousgoodswarning 25

4.5 Transportation 294.5.1 Hazardousmaterialstransportationplacards 294.5.2 EUTREMcards 29

5.0 Acid Supply 315.1 Acid supply packaging 315.2 Material specifications 325.3 Procedure to receive acid at the district 325.4 Inventory control 33

6.0 Acid Storage 356.1 Safety equipment 48

6.1.1 Acidbulkplantarea 486.1.2 Liningforacidstoragearea 486.1.3 Loadingslab 496.1.4 Signage 496.1.5 Chemicalstorage 496.1.6 Safetyshowerandeyewashstations 506.1.7 Spillkit 516.1.8 Oxidizerstorageandtransport 526.1.9 Fireextinguisher 52

6.2 Acid storage tanks 526.2.1 Polyethylenetanks 526.2.2 Steeltankswithlining 536.2.3 Tankliningsandcoatings 536.2.4 Pipeworkandvalves 55

6.3 Fume scrubber 556.3.1 Absorber 56

6.4 Water storage 576.5 Acid mix/transfer tank 57

vJET 10 - Acid Storage, Handling, Transportation, and Mixing |

6.6 Liquid additive system 586.7 Dry additive system 586.8 Pipe work, valves, and fittings 596.9 Acid transfer 59

6.9.1 Pressuretransfer 596.9.2 Transferpumps 596.9.3 Standalonecentrifugalpumps 63

6.10 Liquid additive pumps 646.11 Transfer hoses and connections 64

7.0 Acid Transport Equipment 677.1 Mobile acid transporter 677.2 Acid transport tanks 69

7.2.1 SSS-111/SSS-121acidtransporttank 697.2.2 Containerizedtransporttanks 707.2.3 Safetydevicesontransporttanks 70

8.0 Acid Tank and Transport Equipment Maintenance 738.1 Tank maintenance 73

8.1.1 Externalvessel 748.1.2 Pipeworkandacidhosefittings 748.1.3 Instrumentation 758.1.4 Testsandinspections 758.1.5 Tankliningsandinterior 758.1.6 Crashframe,skid,andliftpoints 76

8.2 Trailer and tractor 768.3 Additional testing and inspection 778.4 Acid plant housekeeping and maintenance 78

9.0 Acid Mixing Procedures and Calculations 819.1 HCl-specific calculations 819.2 Acetic acid 829.3 Mud acid (HF + HCl) 829.4 Clay acid 839.5 Other acids 839.6 AcidMIX Formulator 83

10.0 Operating Procedures 8710.1 Nine requirements 8710.2 Transferring acid from supply transporter to bulk plant 8810.3 Loading transporter or tank with concentrated acid from bulk plant 9010.4 Preparing acid mixtures for transport 92

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10.4.1 Specialnote:mixingmudacidscontainingHF 9510.5 Transporting acid to job site 96

10.5.1 Equipmentcondition 9610.5.2 Journeymanagement 9610.5.3 Drivercompetency 9610.5.4 Arrivalatlocation 97

10.6 Transferring acid to or from a vessel or offshore rig 9810.7 Field mixing of acids 98

10.7.1 MixingHClonsite 9910.7.2 Mixingaceticacid 10010.7.3 MixingHFwithY1 10110.7.4 Mixingclayacid 10210.7.5 MixingSXEacidsystems 10310.7.6 Mixingotheracidsystems 105

11.0 Acid Spills and Disposal 10711.1 Reporting 10711.2 Spill prevention and control plan 10811.3 MSDSs 10811.4 Spill kits 10811.5 Disposal 108

12.0 Appendix 11113.0 Check Your Understanding 113

7JET 10 - Acid Storage, Handling, Transportation, and Mixing |

This JET manual introduces the storage, handling, mixing, and transportation of the acids used by Schlumberger Well Services in matrix and acid-fracturing treatments and other acid-pumping services provided to clients.

This manual discusses how acid mixing and storage systems work, describes the major components used, reviews their proper operation, and addresses important safety and maintenance issues.

Note:Hydrochloric acid is by far the most common acid used by Schlumberger, and unless otherwise stated, will be the acid of reference throughout the JET manual.

Other acids used are hydrofluoric acid (HF), acetic acid, or mixtures of acids.

Because Schlumberger has locations all over the world, acid storage tanks and related equipment, transfer pumps, and transport tankers are procured from a variety of sources. For this reason, operating and maintenance procedures are different depending on the location.

However, some basic facts do not change. It is important for the equipment operator (EO) to understand the following:

Acid and acid materials are hazardous products and should be handled with extreme caution.

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The correct personal protective equipment (PPE) should be available and worn at all times by those handling acid and acid materials.

All personnel must be up-to-date on the required safety training and certification in standards and procedures.

Review all material safety data sheets (MSDSs) for all materials before handling.

A risk assessment should be performed before any operation.

All equipment associated with the handling, storage, transport, transfer, mixing, and pumping of any acid or acid materials must be well maintained and in good operating condition. The Standard Equipment Maintenance (STEM) program must be well documented and followed.

Document all procedures for the operation of any equipment and processes relating to the storage, handling, mixing, transportation, and pumping of acids. All personnel must be competent.

Note:The EO has a significant impact on the profitability of the operation through the application of best practices related to the storage, handling, and transportation of acids.

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1.0 Introduction

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1.1 Learning objectives Upon completion of this manual, you will be able to

describe the safe working practices required when working with acids

explain the principles of acid storage

identify the various types of bulk storage tanks, transfer pumps, fume scrubbers and transport tanks.

describe the operational guidelines for district acid plants and acid plant equipment on location

describe maintenance and procedures for acid storage and transport tanks.

1.2 Safety warningProper supervision is required during hands-on training. Request assistance from your supervisor if you are unfamiliar with or uncomfortable with the proper operation of any equipment or chemical.

All personnel involved with the operation of acid equipment and transfer units must understand the dangers involved when dealing with the materials and equipment, along with all applicable Well Services (WS) and Oilfield Services (OFS) safety standards. Follow proper procedures before working with equipment, acids, and acid additives (e.g., job safety analyses (JSAs) and Hazards Assessment and Risk Controls (HARCs).

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2.0 Acid Properties and Hazards

This section describes the properties and dangers of acids.

2.1 Definition of an acidAn acid is any chemical compound that, when dissolved in water, contributes hydrogen ions (H+) to a solution, resulting in a pH of less than seven.

For example: HCl in water ionizes to hydrogen and chloride ions:

HCl = > H+ + Cl–

Hence an aqueous solution of HCl is acidic.

The word acid comes from the Latin acidus meaning sour. Acids have the following chemical and physical properties:

taste: Acids generally are sour when dissolved in water.

touch: Acids produce a stinging feeling, particularly strong acids.

reactivity: Acids react with metals, oxides, hydroxides, or carbonates to form salts and other products.

electrical conductivity: Acids are electrolytes.

Warning:Acids are hazardous materials capable of doing harm. The handling, storage, transportation, and mixing of all acids must be done with extreme care.

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2.2 Applications The wide range of properties of acids makes them very useful in many different industrial applications. Acids are used in the steel processing, water treatment, paper, leather, brewing, cosmetics, pharmaceutical, chemical manufacturing (production of inorganic salts, pesticides, catalysts, and plastics), metal extraction and producing, and food-producing industries.

The demand for acids is increasing worldwide. In the USA in 1999 the demand for hydrochloric acid (also known as muriatic acid) exceeded 6,500,000 metric tons. One percent of this demand was for use in oil well stimulation. Schlumberger spends approximately $18 million per year globally on 33 to 36% HCl, obtained from about 80 suppliers around the world.

In the oilfield, hydrochloric acid (HCL), organic acids (e.g. acetic, formic, and citric acid) and hydrofluoric acids are used for a variety of purposes. Their properties, reactivity, and reactions with various compounds is controlled with additives.

2.3 Acid propertiesAcid has specific properties, which are important to understand to be able to handle it safely.

2.3.1 HCl acid strengthHCl is a solution of hydrogen chloride (HCl) gas in water. The strength of the acid depends on how much HCl gas is dissolved in a given quantity of water. Maximum concentration of commercial grade HCl is about 36% by weight.

10 | Acid Properties and Hazards

This is then diluted to lower concentrations (in the 5 to 28% HCl range) by the addition of water.

The most common method of measuring the concentration of dissolved gas is by determining the specific gravity of the acid solution. The lower the specific gravity is, the lower the concentration of acid is. The specific gravity reading is then converted into a percentage HCl by weight.

A hydrometer is used to measure the specific gravity (and thus the strength) of HCl solutions. A sample of the HCl is placed in a graduated cylinder so that it floats freely (see Fig. 2-1). Any floating oil must be removed from the surface of the acid and the hydrometer must be cleaned. The point on the hydrometer scale at the surface of the liquid indicates the specific gravity.

Figure 2-1. Measuring SG with a Hydrometer

Meniscus

Horizontal plane surface of liquid

Read scale at this point

See detail

Liquid

Horizontal plane surface of liquid

Bottom of meniscus

Acid strength is also measured using the Baume scale, where 1.0 Baume units = 1.0069 specific gravity.

The specific gravity is affected by temperature; therefore, it is also necessary to measure the temperature of the acid at the same time. Corrections are then made to convert the readings back to the reference temperature of 60 degF (16 degC).

Refer to Appendix 2.1.3 of the Matrix Materials Manual for the method, conversion tables from percent HCl to specific gravity and Baume units, and the temperature correction factors.

2.3.2 pH scaleThe pH scale (Fig. 2-2) is a measure of the relative acidity or alkalinity of a solution. A change of one pH unit means a 10x change in the acidity or alkalinity of the solution. For example, a change from pH 5 to pH 2 means an increase in acidity of 1,000x.

Figure 2-2. pH Scale

Water is a neutral liquid with a pH of 7 (green). Acidic solutions have a pH of less than 7, and the lower the number, the stronger the acid. The opposite of an acid is a base. Base, or alkaline solutions have a pH of over 7. The higher the pH is, the stronger the alkali is.

Testing the pH helps to quickly identify fluids and to check if an acid has been neutralized. The pH of a fluid can be measured using

red litmus paper: the paper turns red when touched by an acid

electronic pH meter (see Fig. 2-3): a probe containing an acidic aqueous solution encased in a special glass membrane

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allows migration of hydrogen ions (H+). If the water has a pH different from that of the solution within the probe, an electric potential results that registers on the meter

Figure 2-3. pH Meter

chemical indicators: color changes in chemicals such as cobalt chloride, Congo red, methyl orange, phenolphthalein, and turmeric are used to measure different ranges of pH.

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3.0 Use of Acids in the Oilfield

The choice of different acids used in the oil industry is based on

their reactivity with different reservoir rocks and damage type

by-products formed when they react

properties of the reservoir, reservoir fluids, and well tubulars.

3.1 Current oilfield acid applications Acids are used in the oilfield to

stimulate wells to improve well production

wellbore cleanup: The wellbore is filled, washed, and allowed to soak with acid to remove inorganic and organic deposits from the tubulars and the formation face.

acid fracturing: Acid is injected into low-permeability carbonate formations at pressures greater than the formation fracturing pressure.

matrix acidizing: Acid is injected radially into the matrix structure of the formation below the fracturing pressure. The acid reacts with rock and plugging materials, removing damage and restoring permeability to the near-wellbore reservoir rock.

remove scale and buildup of compounds on the inner walls of pipes used in oil and gas wells

clean equipment such as boilers, pipe work, and heat exchangers in chemical plants and refineries

help free stuck pipe

provide miscellaneous other uses.

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3.2 Historical backgroundThe use of acids in oil wells began over 100 years ago (Fig. 3-1). The following significant dates and events mark the development of well stimulation.

1895: Ohio Oil Company used hydrochloric acid to acidize wells. It was reported that oil wells increased production three times and gas wells four times.

March 1896: A patent for using hydrochloric acid (HCl) for acidizing limestone was issued to Herman Frasch, a chief chemist with Standard Oil Company.

Unfortunately, the use of corrosion inhibitors was not considered and the acid severely corroded the well casing. The technique declined in popularity and was dormant for about 30 years.

Figure 3-1. Pumping Acid in the Old Days

1931: Dr. John Grebe of the Dow Chemical Company discovered that arsenic inhibited the action of HCl on metal. The Gypsy

14 | Use of Acids in the Oilfield

Oil Company performed a number of well treatments in sandstone formations, in which inhibited HCl was used in an attempt to remove “gyp” deposits (calcium sulfate). The treatment results were mostly unimpressive, and no patents were filed on the process.

February 1932: The first use of an inhibited acid on a limestone formation was by Dow Chemical Company, which siphoned 500 galUS of HCl containing 2 galUS of an arsenic inhibitor through a garden hose into a well owned by the Pure Oil Company. The acid was then displaced with an oil flush and the previously dead well began producing 16 bbl/d.

November 1932: Dow Well Service Group was renamed Dowell in November 1932 to provide acidizing services.

1933: A patent for the use of hydrofluoric acid (HF) in sandstone formations was issued to J. R. Wilson of the Standard Oil Company. Wilson’s patent suggested in-situ generation of HF in HCl by using sodium fluoride (NaF). It was not known that NaF, in the presence of HCl, produces the insoluble compound Na3SiF6.

1933: Halliburton Services performed the first treatment using HF blended with HCl in a 1,500-ft well. The results were disappointing and observers stated, “The reaction products of the acid seemed to have a plugging effect on the permeability of the formation.” As a result, Halliburton discontinued the use of HF blends until the 1950s.

1935: Halliburton Oil Well Cementing Co. started providing a commercial acidizing service in Kansas.

1940: Schlumberger accomplished the first commercially successful use of mixtures of HCl and HF in the Gulf Coast area by using mud acid. The HF was generated in a solution of HCl by using ammonium bifluoride (NH4HF2).

Mud acid dissolved the drilling mud deposited as a filter cake during the drilling process.

1949: Halliburton performed the first hydraulic fracturing treatment. The first treatments were probably performed with acid, although they were not recognized as such at the time. Wells in tight carbonate formations usually will not accept acid until a critical pressure is reached. Once this pressure is reached, acid can easily be injected at high rates. It was later recognized that these wells had been hydraulically fractured.

3.3 Acid system selectionThe two main acid systems used in the oil industry are designed to treat either carbonate (limestone, dolomite, and oolite) or sandstone (silica, quartz, feldspar, clay) reservoirs. For the two formation types, the following acids used are:

Carbonates (e.g., limestone; see Fig. 3-2 for an example): HCl is the most common acid used in carbonate acidizing because of its low cost, availability, and soluble reaction products. Organic acids such as acetic and formic acids are used for high-temperature applications because of their low corrosiveness, ease of inhibition, and retarded reaction characteristics. Blends of HCl with either formic or acetic acids are also used because of cost efficiency and the reduced corrosivity provided by the organic acids.

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Figure 3-2. Limestone

Sandstones: Sandstone formations (see Fig. 3-3 for an example) are typically treated with a mixture of hydrochloric acid (HCl) and HF, commonly called mud acid. The acid and other fluids used in sandstone formations depend very much on the mineralogy of the rock as well as on the damage type. Other acids used in sandstone formations include lower concentrations of HCl and HF with fluoboric acid (HBF4) added. These mixtures are called clay acids and are designed specifically for acidizing sensitive sandstone formations and providing stabilization of clays and other fines.

Figure 3-3. Sandstone

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3.4 Description of acids used in the oilfield

The properties of these acids are shown in Table 3-1.

Additives, such as inhibitor, iron stabilizers, surfactants, demulsifying agents, and mutual solvents can be added as required depending on the fluid design for the particular job.

3.4.1 Hydrochloric acid (HCl)Hydrochloric acid (HCI) is a solution of hydrogen chloride (HCl) gas in water. The strength of the acid depends on how much HCl gas is dissolved in a given quantity of water. The maximum concentration of commercial grade HCl is about 36% by weight. Concentrations of HCl up to 28% by weight are generally used in oilfield treatment. In Well Services, the chemical code for hydrochloric acid includes H005, H015, and H028, with the last three digits representing the concentration of HCl in percent (for example, H028 is 28% hydrochloric acid).

3.4.2 Hydrofluoric acid (HF)HF is the second most frequently used acid in the oil field and is always used with another acid, usually HCl. The most common form of HF is mud acid (see Section 3.4.3). The HF reacts with and dissolves all materials that are soluble in HCl. HF also reacts with, dissolves, or partially dissolves bentonite, naturally occurring formation clays, and other siliceous materials.


Table 3-1. Properties of Common Acids Used by Schlumberger

Chemical Code Product Name Form

SG @ 60 degF

Flash Point degF

pH

H005 Hydrochloricacid(HCI)5% Colorlessliquid 1.068 >200 <2

H075 Hydrochloricacid7.5% Liquid 1.068 >200 <2

H010 Hydrochloricacid10% Liquid 1.068 >200 <2

H015 Hydrochloricacid15% Colorless-lightyellowliquid 1.068 >200 <2

H020 Hydrochloricacid20% Liquid 1.068 >200 <2



H152 HCI/HFacid25/20 Colorlesstoyellowliquid 1.20 >200 <1

H200 Hydrofluoric(HF)acid20% Colorlessliquid 1.20 >200

H700 Hydrofluoricacid70% UsedbySchlumbergervendortoprepare20%HFinourstoragetanks

Y001 IntensiferY1ammoniumbifluoride Whitecrystals 1.50 >200 2

H948 DilutemudacidAnysolutionwithupto7.5%HCIand1.5%HF

Colorlessliquid >200 <1

H949 RegularmudacidAnysolutionwith7.6%to12%HCIand1.6to3.0%HF

Colorlessliquid 1.10 >200 <1

H950 SupermudacidAnysolutionwith12.1%to16%HCIand3.1%to6%HF


Y006 IntensifierY6 Whitegranularpowder 1.40 >200 5.1@1%

H813 Fullstrengthclayacid7.8%HBF4+0.6%HF+0.3%HCI


H814 FullstrengthclayacidLT7.8%HBF4+0.6%HF+5.5%HCI


H913 Half-strengthclayacid4.1%HBF4+0.3%HF+0.15%HCI


H914 Half-strengthclayacid4.0%HBF4+0.3%HF+2.9%HCI

Colorlessliquid 1.1 >200

L400 Glacialaceticacid(100%aceticacid) Colorlessliquid 1.05 109

L401 Aceticacidsolution Colorlessliquid 1.00to1.05

90 1.0

L036 Formicacid Colorlessliquid 1.20 64degC(147

degF)

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Warning:Concentrated HF is dangerous to handle. Schlumberger employees are not permitted to handle HF concentrations greater than 20% by weight. Higher concentrations must be transported and mixed by vendors.

3.4.3 Mud acidMud acid is a mixture of inhibited HCl and HF. There are three main classifications: dilute, regular, and super mud acid. These acids can be prepared in one of three ways:

by blending a 20% solution of HF with HCl

by diluting a storage mixture of 25% HCl + 20% HF solution with water and HCl

by dissolving Intensifier Y001 in HCl acid to obtain the desired concentration.

3.4.4 Clay acidClay acid is a mixture of HCl, intensifier Y001 (ammonium bifluoride), and intensifier Y006, which contains boron. Clay acids slowly release HF from the hydrolysis of HBF4. There are four clay acid formulations:

full strength clay acid, used for 130 to 300 degF [54 to 149 degC]

full strength clay acid LT, used for 100 to 130 degF [38 to 54 degC]

half-strength clay acid

half-strength clay acid LT.

3.4.5 Acetic acidAcetic acid (HC2H3O2) can be prepared using either glacial acetic acid (using stabilizing agent L400, 100% acetic acid) or a low freezing point

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acetic acid solution (using stabilizing agent L401). The big advantage of acetic acid is that concentrations of up to 12% acetic acid can be adequately inhibited from causing steel corrosion at temperatures up to 350 degF for extended periods of time. In most cases, acetic acid is used in conjunction with HCl.

3.4.6 Formic acid (L036)Formic acid (HCOOH) is a mixture of 9% L036 and water. It is much stronger than acetic acid, but it is also more difficult to inhibit. It can be used at temperatures as high as 400 degF [204 degC].

3.4.7 Other acid systemsThere are many other acid systems that are mixtures of the acids discussed in the previous sections with alcohols, oils, gelling agents, and surfactants.

Other acids, such as citric acid, are used in some industrial cleaning applications.

Refer to the Matrix Materials Manual for details, InTouch Content ID# 4013354.

3.5 Acid additivesAcid solutions are mixed with one or more additives to allow them to be used effectively in oilfield applications. Schlumberger stimulation acids always contain water, concentrated acid, and a corrosion inhibitor.

Note:Clean, rust-free tanks must be used when preparing all acid mixtures.


Other additives commonly used include

a nonemulsifier

a surfactant to reduce surface tension, suspend fines, or create foam

a mutual solvent

an iron ion stabilizer

an acid diverter.

Note:All the additives used in a specific acid solution must be compatible with the carrier fluid, with each other, and with the formation and reaction products. Compatibility tests must be performed in a laboratory.

3.5.1 Inhibitors and inhibitor aidsAn acid corrosion inhibitor is added to acid to decrease the destructive reaction of acid with metals. The inhibitor eliminates more than 99% of the metal losses that would occur if the inhibitor were not present.

Inhibitor type and concentration depends on the acid system and the temperature. Inhibitor aids are used to extend the performance range of acid inhibitors. Corrosion testing is performed to determine the concentrations of inhibitor and inhibitor aid required to give the desired protection time.

Inhibitor examples include A261, A2262, A270, and A272. The most common inhibitor aid is A201.

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Warning:Inhibitors and inhibitor aids are hazardous materials. Extreme care should be taken when handling these products (see MSDSs).

For more details, refer to the Corrosion Inhibitor Reference Page, InTouch Content ID# 3300760.

3.5.2 SurfactantsA surfactant is a chemical that alters liquid-liquid or gas-liquid interfacial properties. Surfactants reduce the interfacial tension and change the contact angle at the interface between liquid and solid. Surfactants are used to

reduce surface or interfacial tension and capillary force

control or change rock wettability

prevent or break water blocks and emulsions

disperse and suspend fines.

Common surfactants include F78, F103, and F105.

3.5.3 Foaming agentsFoams are used in stimulation treatments as a diverter and to improve cleanup. To ensure that the foam is stable (that is, that the gas is well dispersed in the liquid), a foaming agent is added. Foaming agents are surfactants.

Antifoams and alcohol tend to neutralize the actions of these foaming agents. Common foaming agents include F78, F100, F105, and F107.

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3.5.4 Mutual solventsMutual solvents are multifunctional, nonionic agents soluble in oil, water, acid, and brines. The mutual solvents act as wetting agents, nonemulsifiers and surface/interfacial tension reducers. They dissolve oil on the rock surface and off fines generated during acidizing, leaving them water wet. Water-wet fines do not tend to stabilize emulsions.

Mutual solvents are used in large quantities of 5% to 80%. They tend to penetrate deep into the formation, aid in the injection of the treating fluid into the rock matrix, and help cleaning up the treatment quicker.

U66 and U100 are common mutual solvents.

3.5.5 Antisludge agentsAcid sludges are precipitates comprising asphaltenes, resins, asphaltogenic acids, and/or other high-molecular hydrocarbons. These sludges are formed when acid contacts the crude oil.

Antisludge additives stabilize the colloidal asphaltic materials found in crudes and prevent the formation of sludge.

W60 and W54 are common antisludge agents.

3.5.6 Nonemulsifying agentsMost crudes contain emulsifying agents capable of generating very stable emulsions downhole, resulting in formation damage. When a treating fluid comes in contact with crude oil, varying degrees of emulsion takes place.

Nonemulsifiers are added to the treating fluid. They help prevent the formation of emulsions and also break existing emulsions.

W53 and W54 are common nonemulsifying agents.

3.5.7 Iron-control agentsWhen iron is dissolved during matrix treatments, iron precipitation and formation damage may occur. Iron precipitation can be prevented by adding complexing agents and reducing agents.

Common iron control agents include L1, L41, U42, and L58.

3.5.8 Specialty additivesSpecialty additives can be added to the acid or pre- and postflushes to help improve the effectiveness of a stimulation treatment. These include

clay stabilizers

alcohols

antifoam agents

formation cleaners

emulsifiers

scale inhibitors

bactericides.

More information about these and all the other additives can be found in the Matrix Materials Manual, InTouch Content ID# 4013354, or in the SWBT Matrix Acidizing Additives, InTouch Content ID# 4135038.

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4.0 Safety Considerations

Acids and acid additives are hazardous materials because they can cause injury, a health hazard, or damage to property and equipment. To minimize the risks while working with acids and acid additives, appropriate precautions should be taken. For example, water should never be added to the concentrated acid because the solution could boil and splash into your face or on your body. Always add acid to water.

4.1 Safety standardsPersonnel involved in handling and using any acid or acid additive must review and be certified in the following standards:

Well Services Safety Standard 18: Material Handling and Chemical Hazard Communication (HAZCOM): details specific rules and procedures that must be followed at all locations at which hazardous materials are handled and used in operations; refer to InTouch Content ID# 3313694 and also the TBT at InTouch Content ID# 3348663.

Schlumberger Environmental Standard: SLB-QHSE S008: details the requirements and procedures designed to protect the environment, prevent pollution, minimize environmental impact, and comply with environmental laws and regulatory requirements; InTouch Content ID# 3605373.

OFS QHSE Safety Std 003: Personal Protective Equipment (PPE): InTouch Content ID# 3260259.

WS Safety Standard 5: Pressure Pumping and Location Safety: InTouch Content

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ID# 3313681 and TBT at InTouch Content ID# 3318425.

WS Safety Standard 17: Storage and Handling of Oxidizers: InTouch Content ID# 3313693 and the TBT at InTouch Content ID# 3334298.

Well Services Safety Standard 4: Facilities and Workshops: InTouch Content ID# 3313678.

Well Services Safety Standard 25: Confined Space Entry, InTouch Content ID# 3313705, because the tanks used to store acids and acid chemicals are considered confined spaces and personnel must meet all the confined space requirements before entering them.

4.2 ResponsibilitiesManagement is responsible for

complying with these standards; supplying the necessary personal protective equipment (PPE)

providing the training for personnel

applying for exemptions when compliance is not possible.

Job supervisors are responsible for

ensuring that all Schlumberger employees and contractors at the work site comply with these standards

recognizing the risks associated with the operation and reducing these risks to the greatest extent possible

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ensuring that all Schlumberger personnel on site are competent to drive and/or operate their assigned equipment

taking the appropriate action, up to and including terminating the job, if unacceptable risks exist.

All employees are responsible for complying with these standards and recognizing and reducing (to the extent possible), the risks associated with the operation.

4.3 PPEPPE must be worn while working as mandated in OFS QHSE Safety Standard 003. When handling acids and acid additives, any additional PPE required is listed in the MSDS for each product (see http://slb-chemicals.sugar-land.oilfield.slb.com/Msds.cfm ). See Table 4-1 for a list of the minimum PPE required for each type of acid.

4.3.1 Eye and face protection:Wear close-fitting chemical splash goggles (indirect-vented chemical goggles), at a minimum. Where splash hazard to face is present, also wear a full-length transparent face shield (see Figs. 4-1 and 4-2). Protection should meet ANSI standard Z87.1 - 1989 or European Standard 166.

Note:Contact lenses should not be worn; they could contribute to severe eye damage.

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Figure 4-1. Goggles

Figure 4-2. Faceshield

4.3.2 Hand protectionImpervious gloves (Butyl, Neoprene, Nitrile, PVC, or Viton) must be worn (see Table 4-1).

4.3.3 Skin and body protection You must wear a chemical-resistant apron and chemical-resistant boots, such as neoprene or polyvinyl chloride (PVC) (see Figs. 4-3 and 4-4). Ensure all potentially affected body parts are covered, using such precautions as taping sleeves and pant legs to gloves and boots and buttoning clothing to the neck.

Note:A safety shower and eyewash station should be located in the immediate work area.

22 | Safety Considerations


Table 4-1. PPE Required for Handling Different Acid Types

AcidHand Protection: Gloves (Impervious) Eye & Face

Protection Respirator Skin & Body ProtectionButyl Neoprene Nitrite PVC Viton

Hydrochloricacids(HCl) X X X - X

Tightlyfittingsafety

goggles.Faceshield.

NIOSH-approvedrespirator

withorganicvapor/acid

gasprotection(colorcoded

yellow).Chemical-

resistantsuit,boots.

Hydrofluoricacids(HF) - X X X X

Aceticacid(L400,L401) - X - - -

Formicacid(L036) - X - - -

Mudacids(HCI+HF) - X X X -

Clayacids(HBF4+HF+HCl) - X X X -

Y001intensifier - - X - - NIOSH-approved

respiratorwithdustandmist

protection(3M8210).

Y006intensifier X - - - -

Figure 4-3. Protective Suit

Figure 4-4. Protective Apron

4.3.4 Respiratory protectionWhen exposure levels could exceed 5 ppm, a NIOSH-approved air-purifying respirator with an acid-gas cartridge (color-coded yellow) in combination with a high-efficiency particulate air filter (HEPA) is recommended (see Fig. 4-5).

When exposure levels could exceed 50 ppm, a self-contained breathing apparatus with a full face piece is recommended (see Fig. 4-6).

Figure 4-5. Respirator


Figure 4-6. Breathing Mask

4.3.5 Treating HF acid exposureHF will cause excruciatingly painful, deep-seated skin burns that are slow to heal. The effects of dilute solutions (<20%) do not usually become apparent until several hours after exposure.

If skin comes in contact with HF, rinse thoroughly with water and massage calcium gluconate gel or benzalkonium chloride solution into the burn site. This gel is not PPE, but it is a special requirement when handling or mixing hydrofluoric acid (HF). Apply the gel every 15 minutes and massage until pain/redness resolves or until medical care is available. The first aid provider should wear gloves when applying the gel to prevent contact with the acid.

4.4 Hazard communication documentsSeveral documents identify the hazardous nature of acids and acid additives. The documents state the nature of the materials, PPE and safety precautions and requirements, potential hazards, and what to do in the case of an incident. The documents are

MSDSs

product labels

shipping pages

EU – ADR Trem Cards

US – Shipping Papers

Canada – Shipping Manifests.

These documents are available at the following Web site, which is also a useful source of information: http://slb-chemicals.sugar-land.oilfield.slb.com/.

4.4.1 Material safety data sheets (MSDSs)

The MSDS is the reference document for all material hazard, safety, and handling information for each acid or acid additive.

A complete list of MSDSs can be found at http://www.hub.slb.com/display/index.do?id=id84363

The following requirements include all Well Services chemicals, purchased products, and purchased maintenance materials, which are hazardous items:

The identity of the material on the container label must be the same as that on the MSDS. This identity enables the correct MSDS to be found using the material name or code.

For locally purchased products, a copy of the vendor MSDS must be kept on file.

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The local manager is responsible for making sure that a current MSDS is on file for any material or product from other companies.

Current MSDSs must be available to any person in the workplace who works with or has exposure to hazardous materials.

MSDSs must be in the work areas where they are easy to find.

MSDSs must be supplied for any materials purchased from Well Services (WS) and to customers upon request.

4.4.2 Chemical labelsAll chemical materials that cause a physical, health, or environmental hazard must comply with the Well Services policy for labels. This includes chemicals supplied by WS, repackaged chemicals, laboratory chemicals, raw materials, and common chemicals such as solvents, coolants, and fuels.

Each material package or container must be clearly marked with the following information:

chemical name or code of the chemical. This identity must show the alphanumeric Well Services code and the trade name and must be the same as the description of the material in the MSDS (e.g., H015 hydrochloric acid 15%).

hazard warnings

name and address of the manufacturer, the company packaging the product, distributor, and so on.

Other requirements include the following:

Missing or worn labels must be replaced immediately.

Labels on purchased products must not be removed or damaged.

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Old labels may be replaced with new labels that meet Well Services requirements.

4.4.3 Dangerous goods warningAll containers for materials must be marked with a warning that defines the possible hazards of the product. The design of this label can change in different locations, but it is normally included with the product label.

HMIS Label (see Fig 4-7): All products from the USA must have the HMIS label, which contains three boxes:

health hazard

flammability hazard

reactivity hazard.

Each of the boxes contains a number from 0 to 4 indicating the hazard level: 0 = no risk; 4 = high risk.

EU Label (see Fig. 4-8): Products from Europe must have the EU label, which shows a series of symbols to define physical, health, and environmental hazards. These symbols do NOT indicate the potential hazards.

Canadian WHMIS label (see Fig. 4-9): Products from Canada must have the Canadian WHMIS label, which has symbols that define physical, health, and environmental hazards.

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Figure 4-7. US Chemical Label for 15% HCI


Figure 4-8. EU Chemical Label for 33% HCl


Figure 4-9. Canada Chemical Label for 15% HCl


NFPA 704 is a standard maintained by the U.S. National Fire Protection Association. It defines the fire diamond used by emergency personnel to quickly and easily identify the risks posed by hazardous materials. This helps determine if any specialty equipment should be used, procedures followed, or precautions taken during the first moments of an emergency response. For example, Figure 4-10 shows the diamond for hydrochloric acid; each color represents a hazard type and each number rates the hazard. The higher the number, the greater the hazard. COR means it is corrosive.

Figure 4-10. Fire Diamond NFPA 704

0

03

COR

4.5 TransportationTransporting acid presents several issues and concerns.

4.5.1 Hazardous materials transportation placards

Transportation regulations in the majority of countries require hazardous materials (or dangerous goods) placards when shipping hazardous materials or dangerous goods.

Acids are classified as Class 8: corrosive fluids, so they will likely have a HAZMAT placard, depending on the country. These placards should be placed in the placard holders on acid transport trailers and tanks (Fig. 4-11).

Figure 4-11. Transport Placards

4.5.2 EU TREM cardsIn Europe, the ADR (L’accord européen relatif au transport international des marchandises dangereuses par route, or the European agreement for the international transport of dangerous goods by road) controls the road transport of hazardous materials such as acids. In addition to driver training and certification, TREM (transport emergency cards) must accompany the driver and truck. The TREM cards (see Fig. 4-12) detail the hazardous material being transported and safety information and instructions.


Figure 4-12. ADR TREM Card for 15% HCI


5.0 Acid Supply

Schlumberger uses approximately 80 acid suppliers around the world, with 60% of the supply coming from five suppliers. The locations in which the largest use of acid occur are US land, Canada, and the Arabian Gulf.

5.1 Acid supply packagingAcid is purchased and supplied in four ways (in descending order of volumes):

Bulk acid in road transporters: conventional acid transporters (Fig. 5-1) provided by the acid supplier or Schlumberger. Various capacities are used depending on availability. The transporters are usually rubber lined.

Figure 5-1. Commerical Acid Transporter

bulk acid in rail cars: Large volumes of bulk acid can be supplied in rubber-lined, 22,000 to 23,500 gallon acid railcars (Fig. 5-2) if the district is close to a rail system. In technologically-advanced countries, most acid cars are fitted with loading and unloading devices on a single nozzle, thus protecting workers and the environment. In other locations, it is

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necessary to unload the acid with an acid transfer pump and hoses.

Figure 5-2. Acid Railcar in Kazakhstan

intermediate bulk containers (IBCs): IBCs are 1000-liter or 250-galUS tote tanks (Fig. 5-3) made of a steel-tube cage with an inner container made out of high-density polyethylene. When containing fluids of SG = 1.30, they can be stacked in threes. IBCs have a fill port equipped with a 2-in sealed screw cap, and discharge through a 2-in butterfly valve at the bottom. The dimensions are: 1,200 mm x 1,000 mm x 1,163 mm H with a tare weight of 59 kg.

Figure 5-3. Acid Tote Tank (IBC)

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32 | Acid Supply

Polyethylene drums (220 L): the drums are blow molded in one operation together with the top and bottom out of high-molecular weight-high density polyethylene (HMW-HDPE), and have an integrated L-ring on the top (Fig. 5-4). The drums are optimally drainable and can be stacked three to four high on pallets.

Figure 5-4. 220-Liter Acid Drums

5.2 Material specifications Each product that Schlumberger buys must meet purchasing specifications. All shipments must comply with these specifications.

Note:Product specifications are confidential!

The specifications list the following:

product code and name, e.g., H036, HCl 36% uninhibited H36

nominal composition information (chemical composition)

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quality control test criteria (type of test, acceptable limits, and test method)

acknowledgements.

Acid delivered by suppliers generally contains <180 ppm iron content.

Note:The acid must not be transferred to dirty storage tanks.

5.3 Procedure to receive acid at the district

Acid is delivered to the Schlumberger facility and typically is transferred to bulk acid storage tanks. If the district does not have bulk acid storage, the acid is stored in a chemical warehouse and then either mixed at the district and sent to the job site in acid transport tanks, or the concentrated acid is sent in its containers to the job site to be mixed on location.

Bulk plant personnel should follow these guidelines:

Ensure all necessary PPE is available and worn by personnel. Spill equipment should be available. The eye wash station and emergency shower must be functional. Current MSDSs must be available for all materials received.

All bulk materials from other companies delivered to Well Services facilities must be controlled by a Well Services employee authorized to operate that bulk facility. Loading and unloading areas must be clearly marked.

Transport units equipped with air compressors from third-party companies must use their air supply equipment to unload products.

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Make sure acid is transferred to a storage tank containing the same material or to a clean, empty tank. If acid is received in drums or tote tanks, then they should be stored in a safe area.

Before transferring acid into Schlumberger storage tanks, check the specific gravity of the acid using a hydrometer and determine the acid concentration.

Confirm that the volume of acid ordered matches the volume received.

Note:If the acid received does not match the strength and volume ordered, inform your supervisor immediately.

A material reception form should be completed stating supplier, receipt date, quantity, and description. Any differences should be noted.

Enter the acid description, concentration, volume received, and storage locations in the inventory system.

Follow safe procedures to flush all lines with water before the equipment is disconnected.

Note:When flushing acid out of lines, valves, and pumps with fresh water, make sure you use a flush rate high enough to ensure all the acid is flushed out.

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5.4 Inventory controlThe stock levels of acid and acid additives must be controlled and monitored. This is very important for the profitability of the Company. Effective inventory control reduces waste and costs, ensuring resources are optimized.

In some parts of the world, it is also a legal requirement to keep acid in a secure facility and maintain legal records of acid stocks.

34 | Acid Supply



Acid storage (Fig. 6-1) refers to equipment used primarily at the district or job site to hold acid until it is needed for a job.

The equipment used at Schlumberger districts for acid storage varies widely depending on location, local laws and regulations, and the level of acidizing services provided.

The preferred storage facility for an acid plant includes

acid storage tank

water storage tank

mix tank

acid fume scrubber

liquid additive system

Figure 6-1. Acid Storage Tanks at a Schlumberger Location

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revetment with a protective coating

loading dock.

The preferred facilities are not available at many locations. Typical levels of facility for acid storage and mixing are

high volume bulk storage capacity for more than one acid type with several acid storage tanks

fume scrubber

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6.0 Acid Storage

36 | Acid Storage

water tanks

transfer pumps

mixing equipment

additive storage facilities

small volume bulk storage with a few acid storage tanks, water tank, and transfer pump

warehouse storage for acid tote tanks and/or drums

mixing in transporters or in tanks at the job site.

There is a wide variety of tanks and other facilities.

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Figures 6-2 to 6-7 show the Hassi-Messaoud, Algeria, facility.

Figure 6-2. Fume Scrubber with Electric Water Pump Figure 6-5. Acid Mixing Tank with Electric Paddle

Figure 6-3. Acid and Water Storage Tanks Figure 6-6. Liquid Additive Storage Tanks and Pumps

Figure 6-4. Wilden Transfer Pumps and Acid Mix TankFigure 6-7. Acid Loading Area with Loading Arm/Hose

38 | Acid Storage

Figures 6-8 through 6-13 show the Midland, Texas, USA, Facility.

Figure 6-11. Liquid Additive Storage Tanks and Fume Scrubbers

Figure 6-9. Loading Area Access and Safety ShowerFigure 6-12. Liquid Additive Storage Totes, Fume Scrubbers and Loading Arm

Figure 6-10. Control Panel for Acid Plant Figure 6-13. Fume Scrubbers and Water Pumps

Figure 6-8. Acid Storage Tanks and Loading Area


Figures 6-14 to 6-19 show the Jebel AI, UAE, facility. Figure 6-14 shows the secondary containment and warning signs on rubber-lined tanks.

Figure 6-15. Rear of Acid Storage Tanks

Figure 6-16. Acid Valve and Suction on Acid Storage Tanks

Figure 6-14. Acid Storage Tanks 20,000 galUS Figure 6-17. Acid Storage Tanks

Figure 6-18. Restricted Access to Acid Plant

Figure 6-19. Suction and Fill-Up Lines on Acid Storage Tanks

40 | Acid Storage

Figures 6-20 through 6-25 show the Vernal, Utah, USA, facility.

Figure 6-25. Liquid Additive PumpsFigure 6-22. Chemical Bulk Storage

Figure 6-24. Outside RevetmentFigure 6-21. Acid Storage Tanks

Figure 6-20. Acid Building Figure 6-23. Fume Scrubber


Figures 6-26 through 6-29 show the Tengiz, Kazakhstan, facility.

Figure 6-26. General View of Acid Storage Tanks, Water Supply Tank and Fume Scrubber (with lagged point)

Figure 6-27. Acid Storage Tanks, Piping and Walkway (notice secondary containment wall)

Figure 6-28. Eye Wash Station (notice lagging for cold weather)

Figure 6-29. Acid Plant with Acid Railcar to Be Offloaded

42 | Acid Storage

Figures 6-30 through 6-34 show the facility at Montrose, Scotland.

Figure 6-30. Acid Bulk Plant Tank

Figure 6-31. 2 x 30,000-galUS Rubber Lined Acid Tanks and Fume Scrubber with Secondary Containment and Warning Signs

Figure 6-32. Safety Shower and Equipment at Loading Point Figure 6-34. Manifolding Between Acid Tanks

Figure 6-33. Acid Transfer Pumps


Figure 6-35 shows the plant at Aracaju, Mexico. Figure 6-36 is of a plant at an unknown location.

Figure 6-35. Acid Bulk Plant

Figure 6-36. Acid Storage Plant

44 | Acid Storage

Figures 6-37 through 6-39 show a few more plants.

Figure 6-37. Bakersfield, California, Acid Bulk Plant

Figure 6-38. Loading Acid, Villahemosa, Mexico (View 1)

Figure 6-39. Loading Acid, Villahemosa, Mexico (View 2)


Figure 6-40 shows the mV Galaxie in West Africa with 28,400 galUS raw acid storage capacity.

Figure 6-40. Galaxie Stimulation Vessel

Figure 6-41 shows the mV BIGORANGE 25 in the Persian Gulf. When acid tanks are installed on its back deck, the raw acid storage is 120,000 US gallons.

Figure 6-41. BIGORANGE 25 Stimulation Vessel

46 | Acid Storage

Figures 6-42 through 6-47 show various DeepSTIM vessels. As shown in Figure 6-44, the DeepSTIM has a 8,400-galUS raw acid storage capacity on the back deck. The DeepSTIM III has three 4,200-galUS acid storage tanks. In Figure 6-44, raw acid is stored in six 30,000 galUS tanks allowing 240,000 galUS of 28% HCI or 475,000 galUS of 15% HCI to be mixed in-line.

Figure 6-42. DeepSTIM Stimulation Vessel (View 1)

Figure 6-43. DeepSTIM Stimulation Vessel (View 1 and View 2)

Figure 6-44. DeepSTIM Acid Storage (View 4)


Figure 6-45. BIGORANGE XVIII (North Sea)

Figure 6-46. BIGORANGE XVIII Liquid Additive Storage and Pumps Figure 6-47. BIGORANGE XVIII (North Sea), Top View

48 | Acid Storage

6.1 Safety equipmentThe minimum safety requirements for acid plants are stated in Well Services Safety Standard 4: Facilities and Workshops. The type and quantity of safety equipment available must be determined by the requirements on the MSDS and the number of workers at the plant.

6.1.1 Acid bulk plant area

Note:All chemicals, except for bulk dry chemicals, must be stored on concrete pads that provide secondary containment (see Fig. 6-48).

Figure 6-48. Revetment Area Before Acid Tanks

The secondary containment must hold no less than 110% of the volume of the largest container in the storage area, with an additional 12-in free board.

Both the containment area and the loading slab must have a slope so that any spills are collected in a sump.

Note:All containers and tanks in the plant must be clearly marked with their contents.

The revetment area should be hydro-tested yearly and the results documented.

Each location must have a current Spill Prevention, Control, and Countermeasures (SPCC) plan. This plan must be updated as described in QHSE Standard 8: Environment, InTouch Content ID# 3605373.

6.1.2 Lining for acid storage areaAcid storage areas must have an acid-resistant lining. Numerous suitable coatings and lining are available. See examples of linings in Figures 6-49 and 6-50.

Note:The surface on which the linings or coatings are put must be clean and dry.

Figure 6-49. Protective Lining Laid in Acid Tank Area, View 1


Figure 6-50. Protective Lining Laid in Acid Tank Area, View 2

6.1.3 Loading slabA loading slab must be installed to prevent any spills from entering the ground. The loading slab must have a slope to collect any spills in a sump.

6.1.4 SignageAll bulk storage vessels must have signs (Fig. 6-50) that display the following items:

contents of the container

correct hazard warning labels for the country

hazard warning signs (e.g., Flammable or No Smoking)

“Confined Space Permit Required” decal or sign on each hatch of the storage vessel

location of fire extinguishers, first aid kits, spill kits, muster points, and exits must be well marked.

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Figure 6-51. Safety Signs on Acid Tank

Hazard warning

Product content

Hazard warning labels

Material label

6.1.5 Chemical storageChemical storage must meet the following requirements.

All chemicals must be protected by a roof or cover.

Any warehouses must be clean at all times.

Any spills must be cleaned up immediately and disposed of according to local regulations.

Chemicals must be stored separately by type.

Well Services product signs must be displayed near each product.

The sign must show the Well Services product code (example, A260) and the symbols for the PPE requirements.

Bulk tanks containing aromatic solvents must be separated from other bulk tanks by a wall or be in a separate storage area.

MSDSs must be available for all chemicals present in the plant.

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50 | Acid Storage

6.1.6 Safety shower and eye wash stations

Eye wash and safety shower stations must be installed according to Well Services Safety Standard 2: Emergency Shower and Eye Wash Stations, InTouch Content ID# 3313674. An eye wash station and a safety shower must be on the loading dock area and in the area where additives are mixed (Fig. 6-52).

Warning:Use only clean drinking water in both the safety showers and eye wash stations. Never use any other solution; your eyes could be damaged on contact.

Note:Install a water hose that will reach all parts of the high-risk area in addition to the safety shower and eye wash station.

Figure 6-52. Safety Shower and Eye Wash Station

Emergency shower

Eye wash station

When water is left in the eye wash stations, there is a risk of bacteria. To prevent this problem, add a water treatment chemical to the water tank.

Note:Make sure that the water treatment chemical is safe for use in eyes. The eye wash station must be washed and flushed with clean water every 30 days.

When an object or chemical enters your eyes, DO NOT rub the eyes. The best method to remove the object or chemical is to flush the eye with large quantities of clean water. Follow these procedures:

STEP 01 Go to the nearest eye wash station and push the handle of the valve.


STEP 02 Hold your eye lids open with your fingers and keep your eyes in the flow of clean water.

STEP 03 Wash your eyes for at least 15 minutes.

STEP 04 Request that a doctor check your eyes to make sure that the object or chemical is removed.

Warning:You must remove chemicals that come in contact with your eyes within 15 to 30 seconds.

Know the location of the eye wash stations and the safety showers.

Know how to use all the safety equipment in an area that handles hazardous chemicals.

6.1.7 Spill kitEach location must have an emergency spill kit (Figs. 6-53 and 6-54) for a chemical spill. The size of the kit and the amount of equipment in it are determined by the quantity of products stored.

A spill kit typically includes the following equipment.

shovels to remove contaminated dirt or chemical absorbent materials

bags of absorbent material to absorb chemical or oil spills

booms to contain spills within one area

chemical spill drums to contain the dirt or absorbent materials

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soda ash to control HCl spills; If HF acid is used at the location, use calcium carbonate to control the HF acid

new drums to contain leaking drums of chemicals.

Figure 6-53. Typical Mobile Spill Kit

Figure 6-54. Spill Kit Contents

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52 | Acid Storage

6.1.8 Oxidizer storage and transportOxidizers (e.g., B58, J218, J475, J479, and J569) can cause fires and explosions, and can release toxic vapors when mixed with incompatible materials. Oxidizers must be separated from other chemicals, either by being stored in a separate building or by being enclosed by cinder block or brick walls.

Refer to Well Services Safety Standard 17: Storage and Handling of Oxidizers (InTouch Content ID# 3334298) for the storage, handling, and transportation (Fig. 6-55) of oxidizers.

Figure 6-55. Oxidizer Shipping Box

6.1.9 Fire extinguisher

Note:Fire extinguishers must be easily available in case of a fire.

Fire extinguishers must be located in the loading dock area and the area where acids are mixed, and they must be protected from direct sunlight. A fire extinguisher must be on the solvent storage containment wall.

Fire extinguishers must be installed on hangers or in brackets. Install signs above the fire extinguishers that show their position.

Caution:Do not block access to the fire extinguisher.

6.2 Acid storage tanksAcid storage tanks are normally either steel tanks with an acid-resistant lining or polyethylene tanks. The capacity of tanks can vary from 5,000 to 20,000 galUS.

For stationary storage tanks in an acid plant, tanks made of high-density cross-linked polyethylene are recommended. Alternatively, tanks made of carbon steel with bonded crosslinked polyethylene inner liner can be used. However, the size of the tank is limited because the size of the curing ovens available to make these tanks is limited. Fiberglass is also used for acid storage tanks and for smaller acid transport tanks.

For mobile acid transports, tanks made of carbon steel with bonded crosslinked polyethylene inner liner are preferred, but again the size is limited.

6.2.1 Polyethylene tanks High-density cross-linked polyethylene (HDXLPE) tanks are the standard vertical storage tanks for acid used by Schlumberger (see Figs. 6-56 and 6-57). They are typically 12,000-galUS, 12-ft diameter, vertical tanks


with ladders to the top for access to the manway cover and level sensor. Each acid tank discharge is designed to be double valved.

Figure 6-56. 12,000 galUS HDXLPE Acid Storage Tank

Figure 6-57. Schematic of Acid Tank

Vent line to fume scrubber

Safety relief valve

Tank level controls

Fill line

12,000-galUS acid storage

tank

Level gauge

To mix / transfer

lineFC

6.2.2 Steel tanks with liningSteel storage tanks must be lined with a material that is resistant to acid. Rubber-lined (Fig. 6-58) or butyl-lined (Fig. 6-59) tanks have been used with normal capacities ranging 6,000 to 15,000 galUS.

Note:Manufacturer’s specifications must be checked to determine compatibility of fluids to be stored and transported with the coating/lining used under local conditions.

6.2.3 Tank linings and coatingsThe type of material and the type of lining used for acid storage and transportation tanks is dependent on the application, product availability, and cost.

Note:Mark all tanks to show coating/lining used and the fluid compatibility.

rubber: can only be used for straight acid, noninhibited acid, and zero additives. It should not be used to store solvents such as xylene or toluene. Any tanks with rubber linings must have a sign marked, “Rubber-Lined Tank—Do not cut or weld”.

Note:Never pull a vacuum on an HCl tank car. It could damage the rubber liner.

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Figure 6-58. 15,000 galUS Rubber-Lined Acid Tank

Rubber-Lined Tank (Specify with 0, 1 or 2 breakwater panels) Tank capacity 56,800 I (15,000 galUS) Tank weight, empty 13.5 t (29,700 lbm) Gross weight, full 81.6 t (179,900 lbm) Length 860 cm (28 ft 2 1/2 in) Height 393 cm (12 ft 10 1/2 in) Width 290 cm (9 ft 6 1/4 in)

Figure 6-59. 6,000 galUS Butyl-Lined Acid Tank

Butyl-Lined Tank Tank capacity 22,700 I (6,000 galUS) Weight, empty 6.8 t (15,00 lbm) Weight, full 34 t (75,000 lbm) Length 732 cm (24 ft) Height 290 cm (9 ft 6 in) Width 180 cm (5 ft 11 in)


tank-in-a-tank: used for many International Maritime Organization (IMO) offshore tanks. This lining is a rotationally molded crosslinked polyethylene tank that is formed inside the steel tank. Because the polyethylene shrinks when it cures, an annulus is formed between the liner and the steel. This annulus is then filled with spray-in foam insulation. The advantage of this lining is that it is resistant to most chemicals. However, it does not tolerate vacuum or high pressures well, limits the number of openings in the tank, prohibits baffles, is costly for large tankers, and is difficult to repair. Also, if xylene is stored in it for prolonged periods, xylene vapors can penetrate the lining and collect in the annulus.

bonded crosslinked polyethylene: much more expensive than the vinyl ester lining, but will last for a very long time with little maintenance. It can be applied to storage tanks as large as 10,000 galUS and can be used to store all fluids.

vinyl ester lining material: wide variety of these coatings available. The particular type should be checked for compatibility with fluids to be used. The tank preparation and application method must be professional to ensure quality. These linings tend to be quite brittle and can be damaged easily, but field repairs are possible. These materials are primarily used for transport tanks; they should not be used to store concentrated acids for extended time periods (more than 2 to 3 days).

Ceilcote Flakeline®

Derakane® 411

Tnemec #120

ChemLINE 784/32™ oxirane polymer.

stainless steel tanks: not suitable for storing acid. Hydrochloric acid will destroy the passivating layer of the stainless steel. Stainless steel tanks can be used to mix

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acid but any acid must be neutralized and the tanks and lines must be well cleaned after every job.

Note:Other materials are sometimes used, but check with the supplier for compatibility with acids and other fluids used before filling a tank made of some other material.

6.2.4 Pipe work and valves The recommended pipe work for use with hydrochloric acid is made from fiberglass-reinforced plastic (FRP). The valves are fiberglass composite valves.

For stationary acid tanks, all piping and valves must be independently supported. The pipe work should not be rigid; some flexibility is required to counter expansion/contraction effects.

Weather-exposed water lines must be heat traced and insulated where hard freezes are possible.

6.3 Fume scrubberHCl gas and mist emissions must be controlled because they have a corrosive effect on human tissue, potentially damaging respiratory organs, eyes, skin, and intestines. The fumes are also very corrosive to equipment and buildings.

56 | Acid Storage

Therefore, an acid fume scrubber (Figs. 6-60 and 6-61) should be used to prevent acid fumes from venting into the atmosphere while the acid tank is being filled, acid is being transferred, or normal venting from the storage tank is occurring.

Figure 6-60. Acid Fume Scrubber

Figure 6-61. Schematic of Acid Fume Scrubber

Spray head

Spray inlet

Overflow (1 in)

12-in OD pipe: Fill with

polypropylene saddles

Spray glass

Gravity drain (1 in)

Water fill inlet (2 in)

Gas inlet from HCI tanks (4 in)

Polyethylene base

To mix or holding tank

Water outlet (1 in)

Fume scrubber circulation C-pump on mounting plate

The acid fumes enter the bottom of the scrubber tower and are absorbed into water as the fumes travel upward and removed from the air.

A scrubber recirculation pump (e.g., a Marsh TE-7K-MD, Series 7 seal-less magnetic drive centrifugal pump as shown in Fig. 6-62) is used to ensure that the scrubber tower packing is wetted. During acid fill and transfer operations, the pump should be run continuously to ensure proper scrubbing of the fumes. During normal venting, the pump should be set to run 15 to 20 minutes every 2 hours when the temperature is above 32 degF. At temperatures below 32 degF, the pump should run frequently enough that water does not freeze in the pipe.

Figure 6-62. Marsh Pump Used for Fume Scrubber

6.3.1 AbsorberThe absorber scrubs vent gas from 36% HCl storage tanks during filling and when tank vapors thermally expand. It has the following features and functions.

The maximum recommended gas flow rate into the absorber is 150 cfm. The tower floods at a gas rate of 325 cfm.

The absorber tower is 12-in diameter with 9 ft of 1-in polypropylene pall ring packing.

The absorbing liquid is recirculated from the absorber integral storage sump to create an HCl solution that is periodically replaced. The absorbing liquid recirculation flow is 8 galUS/min.

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The absorber will scrub with an efficiency of 99% when the scrubbing liquid temperature is below 122 degF and the HCl concentration is below 22%.

The scrubbing liquid should be changed out when the HCl concentration reaches 22%. The absorber efficiency is a function of the opening temperature and the HCl concentration in the absorber sump. Efficiency decreases with an increase in temperature and with an increase in HCl concentration. A graph showing the removal efficiency versus HCl concentration in the sump is shown in Fig. 6-63.

Note:A log of absorbing liquid HCl concentration and change-out frequency should be kept to assure that the absorber scrubbing efficiency is maintained.

Figure 6-63. Fume Scrubber Absorption Efficiency

6.4 Water storage The water storage tank should be a 10,000-galUS tank and may be constructed of HDXLPE or steel. It can be located any place

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near the acid tanks except in the revetment. A float valve keeps the tank filled. A 6-in air break between the fill line and the maximum water level is required.

Note:The water for the eye washes and yard hydrants must not be taken from the water tank used to supply the acid plant.

A process water pump is used to provide water to the mix/transfer system and the acid fume scrubber.

6.5 Acid mix/transfer tankThe acid mix/transfer tank is a 6,800-galUS, cone-bottom, HDPE tank (see Fig. 6-64). The inlet piping enters the top and extends downward to half the height of the tank. A single 200-gpm centrifugal pump is used to transfer water and acid to the mix tank, mix the contents of the tank, pump water through the dry additive feed process, and pump the finished product to the transport truck. The various functions of the pump can be controlled and metered using a batch flowmeter.

58 | Acid Storage

Figure 6-64. Acid Mix Tank

SERVICE Manway w/blind Outlet Inlet dip tube Spare w/blind Vent Relief Rinse water Level switch Inlet dip pipe

MARK A B C D E F G H J

6.6 Liquid additive systemThe liquid additive storage and feed system consists of up to 10 polyethylene tote tanks of 330-galUS capacity each. The required number will vary depending on the district’s needs.

Hoover Materials Handling Group’s TuffTank II IBC tanks are recommended (see Fig. 6-65). These combine a rotationally molded high-density polyethylene bottle and heavy-duty wire mesh cage with a 2-in valve on the suction. They are available in 220- and 330-galUS capacities.

Figure 6-65. Liquid Additive Tank (Huff II Tank)

A 30-galUS/min air diaphragm pump such as the Wilden Pump (see Section 6.9.2.2) is used to transfer the additives. A batch-controller flow meter is used for measuring and controlling the liquid additive feed. The liquid additives can be pumped into the mix tank or fed directly to a transport. The tote tanks can also be filled by the liquid additive feed pump.

6.7 Dry additive systemIn some locations it will be necessary to mix dry powder additives with the acid. A schematic of a typical dry additive mixer is shown in Figure 6-66.


Figure 6-66. Dry Powder Mixer

Dry additive hopper

Manual feed control valve

Mixed product outlet

45 min

Liquid inlet

6.8 Pipe work, valves, and fittingsPipe work, valves, and fittings must be acid resistant; therefore, they are normally fabricated from PVC. A wide range of fittings and valves are available. Some of the older acid plants may have steel, rubber-lined lines and valves.

The standard FMC butterfly valves are used in acidizing operations.

Note:These valves need to be checked regularly for corrosion and swelling/deterioration of the rubber seats.

More expensive Kynar discs, Hypalon seats, and other parts are available for use in corrosive fluids.

6.9 Acid transferAcid transfer operations require special equipment.

6.9.1 Pressure transferIn some installations such as the stimulation boats and some acid storage plants, low air pressures are used to transfer acid from tank to tank, from tank to transporter, or from tank to acid blender. See Section 10.2 for a generic procedure.

Note:All tanks and equipment used in the transfer of acid using compressed air, such as tote tanks, acid tanks, and transfer lines must be designed, built, and tested as pressure vessels with working safety pressure relief valves (PRVs).

Caution:Safety risks are inherently associated with using air pressure to transfer acid. Well-documented operating and maintenance procedures must be in place and a HARC should be performed to address the added risks involved using acids under pressure.

6.9.2 Transfer pumpsSeveral acid-resistant pumps from different suppliers are used to transfer acid. These pumps must be well maintained to ensure good performance and help prevent leakage of hazardous materials. The most commonly used pumps are described in the following sections.

60 | Acid Storage

6.9.2.1 Delasco LZ-50 pumpThe skid-mounted, diesel-driven Delasco pump is a positive displacement pump used for transferring acids and other fluids. It is typically mounted in a protective/lifting skid with forklift slots. The equipment code is SUS-239 (see Figs. 6-67 and 6-68).

Figure 6-67. Delasco Pump (SUS239)

Figure 6-68. Delasco Pump Schematic

Pump hose: EPDM injection moulded

tube with spine

Rotor

Stator

Connecting sleeve

Rollers (stainless steel)

Counter

The Delasco pump is a peristaltic pump, in which a pressurized fluid flow is created by the rotation of stainless steel rollers pressing against the outside of a special flexible tube in a housing called a stator (see Fig. 6-67). The tube is compressed at a number of points in contact with the rollers and the fluid is moved

through the tube with each rotating motion. The tube opens to its natural state after the roller passes and fluid flow is induced to the pump. This process is called peristalsis. Flow rate is proportional to the rotation of the rollers.

The pump specifications follow:

differential pressure:

• 1.5 bar

flow rate:• 14 m3/h at 180 rpm

temperature (EPDM tube):

• 4 to 195 degF

dimensions:• 65.4 in L x 54.3 in W x 56.3 in H

weight empty):• 1144 lb

engine:• Diesel HATZ 1D41Z with TECHNODRIVE clutch

tube material:• Injection-molded, ethylene-propylene-diene-monomer (EPDM)

connecting sleeve:

• Five connections are available (serrated king nipple, threaded nipple in stainless steel or polypropolene, or three flnage connections in SS or PPP).

The advantages of peristaltic pumps are that the fluid does not contact any internal parts and seals and valves are not needed as in other pumps. Peristaltic pumps are also reversible and can be flushed to clean out the tubing or hose. Self priming is automatic on startup and does not require any special equipment. A flooded suction is only required for viscous products. Occasional dry running is possible without damage occurring. The pumped liquid acts in fact as a lubricant and coolant for the tube.


Maintenance Note:Always have a spare tube available and lubricate the tube regularly. Do not leave the tube full of acid or other chemicals. In cold weather the fluid will freeze and you will risk breaking the clutch when you try to restart it.

The flexible tube is the only wearing part. Maintenance is limited to regular lubrication. When necessary, the tube can be changed without dismantling the pump. Engine oil and diesel filters must be changed on a regular basis.

6.9.2.2 Wilden pump (SUS-271)The Wilden P800 pump is used widely to pump acids, acid additives, and other fluids used in Schlumberger (see Figs. 6-69 and 6-70).

Figure 6-69. Wilden Pump (SUS-271)

Figure 6-70. Wilden Pump Schematic

It is a positive displacement, reciprocating, air-operated, double-diaphragm pump. Two diaphragms are connected to a common shaft and act as a separation membrane between the compressed air and the liquid. Two inlet and two discharge check valves open and then close to direct liquid flow. The air distribution system alternately supplies air to the right side and then the left side of the pump.

Its major components are

wetted components: Water chambers and manifolds that come into contact with liquid are made from PVDF plastic. At temperatures below 12 degC, Teflon® PFA components should be considered.

nonwetted components: The air distribution system, air chambers, center block, and air valve are made from polypropylene.

elastomers: Diaphragms, check valves, valve seats, and O-rings are all elastomers. For the fluids used by Schlumberger, the preferred material for the diaphragms are:

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62 | Acid Storage

Teflon® PTFE, which is rated for a temperature range of 40 to 220 degF

Viton®, which is rated for a temperature range of –40 to 350 degF.

Note:Viton diaphragms are very expensive and should be only be used if temperatures could drop below freezing.

The pump specifications follow:

inlet/outlet diameter:

• 2 in (50.8 mm)

dimensions: • 31.7 in H x 23.8 in W x 13.9 in D

flow rate:• 0 to 624 lpm (164.9 gpm)

max pressure:

• 8.6 bar (125 psi)

max suction lift capability:

• 8.7 m wet (28.4 ft)

max diameter solids:

• 6.55 mm (1/4 in)

air inlet:• 13 mm (1/2 in) FNPT

The suction pipe size should be at least the equivalent or larger than the diameter size of the suction inlet, 2 in, on the Wilden pump. The suction hose must be noncollapsible, reinforced type because these pumps are capable of pulling high vacuums. All fittings and connections must be airtight, or a reduction or loss of pump suction capability will result.

Use air supply pressure up to a maximum of 125 psi.

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○Note:An air filter and lubricator with needle valve and air regulator should be used and regularly maintained.

Pump discharge rate can be controlled by limiting the volume and/or pressure of the air supply to the pump and/or by throttling the pump discharge by partially closing a valve in the discharge line of the pump.

When the pump discharge pressure equals or exceeds the air supply pressure, the pump will stop; no bypass or pressure relief valve is needed and pump damage will not occur. The pump can be restarted by reducing the fluid discharge pressure or by increasing the air inlet pressure.

Note:For maintenance, the pump should be well cleaned and emptied after each job and the air filter and lubricator should be checked regularly. Spare diaphragms should be kept in the location and ensure the correct diaphragms are used for the fluid(s) pumped.

6.9.2.3 Other pumpsMany other pumps are used to pump acid and other hazardous materials. Some of the most frequently used ones are described in the following:

Flowserve GRP centrifugal pump. This pump is used on the BIGORANGE XVIII (BOXVIII) stimulation vessel. It produces approximately 300 galUS/min. The GRP

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pumps have mechanical seals that are water flushed and require very little maintenance.

Ramparts centrifugal pump. The Ramparts centrifugal pump (model Pro-flo 4 in x 3 in) is an elastomer-lined (NordelTM) centrifugal with a 80 Durometer impeller used for transferring acids (see Fig. 6-71).

Figure 6-71. Ramparts Acid Pump

March Mfg. Comp: TE-10K-MD Centrifugal Pump (Series 10 - 210 gpm - AC Electric Motor). This pump is used as a transfer pump in acid bulk plants for 5 to 35% HCl and other chemical solutions. The casing and impeller are made of carbon-filled Kynar plastic (PVDF) and pump gaskets from Teflon. Flow rates range from 50 galUS/min minimum to 210 gpm maximum. The electric motor drive is a 10 HP, 230/460-V, three-phase, totally enclosed chemical duty motor (see Fig. 6-72).

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Figure 6-72. March Series-10 Centrifugal Pump

6.9.3 Standalone centrifugal pumpsA series of larger centrifugal pumps are used on location to transfer, circulate, and pressurize triplex pumps with inhibited acids. Several models are available that use either the standard Well Services RA5x6 or the RA10x12 centrifugal pump.

The SUS-264 skid-mounted, diesel-driven, 10x12 centrifugal pump is driven by a 350-bhp Caterpillar (CAT) C9 diesel-powered, electronic-controlled engine.

The SUS-235 is a CAT skid-mounted diesel-driven RA 56 centrifugal pump (Fig. 6-73).

Figure 6-73. SUS-235, RA5x6 Centrifugal Pump Skid

64 | Acid Storage

Maintenance of these centrifugal pumps is described in JET-4, Basic Oilfield Equipment.

Note:It is important to perform STEM-1 maintenance checks on the pump and engine before and after every job. Pay particular attention to lubricating the pump to ensure no acid or air leaks into the pump suction. Regular checks should be made on the impeller, impeller lock, and the volute for corrosion.

6.10 Liquid additive pumpsThe SUS-533 liquid additive unit is a Waukesha metering pump (Fig. 6-74). It is used for pumping corrosive liquid additives from remote or day tanks. The pump speed is adjustable to obtained the variable flow rate required (0 to 0.06 gal/rev).

Figure 6-74. Liquid Additive Skid (SUS-533)

Before every job, a bucket test should be performed to test the accuracy of the liquid additive pumps. If you don’t know how to do a bucket test, ask your supervisor.

6.11 Transfer hoses and connectionsIncorrectly used, poorly maintained, or damaged hoses and hose connections used to transfer acids are the main causes of acid leaks and related incidents.

The following describe important information and procedures to correctly use, maintain, and inspect hoses and hose connections.

Connections

Note:Review WS Technical Alert 2000-33, Low pressure Fittings/Connections (Camlok), InTouch Content ID# 3036459.

Camlok fittings are only approved for use in certain applications.

The WECO Figure 206 union shown in Figure 6-75 is the standard union for use in low-pressure acid transfer and liquid additive hoses. The 206 union provides a measure of safety that the Camlock union is unable to provide. When breaking a Figure 206 union, the union can separate and relieve pressure while the threads of the union are still engaged.

Figure 6-75. Two-in WECO Figure 206 Union

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King nipples using bolt-on clamps should be used to secure connections to hoses. They should not be made from aluminum or other materials that react with acid.

Note:The condition of the king nipples and connections should be checked regularly for excessive corrosion.

Two-inch hoses: Various hose types are used to transfer acid and acid additives (see Fig. 6-76 for an example). Some types used with Delasco and Wilden pumps are a PVC hose or layered hose with (UHMW/PE) inside and EPDM outside, and with wire reinforcement.

Note:Care should be taken to ensure these hoses are not crushed and that they are well flushed with water and then emptied after each use.

Figure 6-76. Hose for Wilden and Delasco Pumps

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Four-inch hoses: Suction and discharge hoses with 4-inch Figure 206 unions are recommended by Schlumberger for use when transferring acids on location using the standard centrifugal pumps.

Note:Regular checks must be performed on the condition of the hoses and connections for wear and corrosion. They must be well flushed with water and stored correctly after use.

Hose covers (see Fig. 6-77) on the discharge hoses are recommended for acid treatments. These will prevent acid or other hazardous fluids from being sprayed all over the location if a hose or connection failure occurs.

Figure 6-77. Four-in Orange Hose Covers on Discharge Lines

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7.0 Acid Transport Equipment

Acid is transported to the job site from the Well Services (WS) district in the concentrated form or premixed with water and additives added. This is done in mobile transporters dedicated to hauling acids or in skid-mounted transport tanks.

The standard equipment used in Schlumberger is described in the following sections. Filling and discharge procedures are detailed in Section 10. Operating Procedures.

7.1 Mobile acid transporterThe three standard acid transporters used in Schlumberger uses three acid transporters, the STF-151, STF-143, and STF-144 (shown in Figs. 7-1, 7-2, and 7-3). The specifications are listed in Table 7-1. The trailers store liquid additives or acids for transportation or use during treatments. The gravity-flow discharge outlets are located at the bottom rear of the tank. Discharge line butterfly valves are remote air-operated and the tanks are equipped with a spring return relief valve. A fill and recirculation manifold connects at the rear. A vacuum breaker equalizes air pressure during unloading operations. Manways are located at the top of the tanks for performing maintenance operations.

Note:The transporters have linings that are not designed to store concentrated acids for long periods of time.

Note:Many transporters are also used that are lined with rubber. Care should be taken not to use them for transporting inhibited acids (the acid inhibitor will degrade the rubber lining), and solvents such as xylene, U66, and diesel.

Note:Refer to the lining manufacturer’s recommendations for compatibilities of fluids.

Figure 7-1. STF-151 Acid Transporter

68 | Acid Transport Equipment


General Specifications STF-151 STF-143 STF-144

TankCapacity-Rear 4,000galUS(15,140L) 2,500galUS 1,667galUS(6,306L)

TankCapacity-Middle - - 1,667galUS(6,306L)

TankCapacity-Front 4,000galUS(15,140L) 2,500galUS 1,667galUS(6,306L)

TankMaterial 1/4-incarbonsteel

TankLiner VinylEster Rotationallymoldedpolyethylene

RegulatorySpecs. USDOT412

Trailer

Type Fifthwheel,tri-axle FifthWheel,tandemaxle Fifthwheel,dualaxle

Length 480in(12,190mm) 480in(12,190mm) 470in(11,938mm)

Width 96in(2,438mm) 96in(2,438mm) 96in(2,438mm)

Height 148in(3,759mm) 132in(3,553mm) 133in(3,378mm)

KingpinHeight 51in(1,295mm) 51in(1,295mm) 49in(1,244mm)

Weight(estimated) 17,700lbm(8,045kg) 20,000lbm(9,090kg)

Tires 11R22.5(12) 11R22.5(8) 275/70R22.5(8)

Manway Oneforeachcompartment

HoseRacks Curbside

DischargeLine 6-inlinewith3rearconnections

Fill&RecirculationLine Single3-inline,curbsiderear

VacuumBreaker Standard:equalizesairpressureduringunloadingoperations

PressureReliefValve Standard:springreturn

ButterflyValve StandardFMCWeco:remoteair-operated

WorkingPressure 12psi(0.8bar)

DesignPressure 24psi(1.6bar)

TestPressure 36psi(2.4bar)

Option-1 3compartmentsinlieuof2 - 2compartmentsinlieuof3

Option-2 Oversizedtyreswithspreadaxles

- -

Option-3 Arcticinsulationpackage(to-40degF/C) -

Table 7-1. Specifications of Mobile Acid Tankers



7.2 Acid transport tanksMany different types and sizes of tanks are used to transport acid in smaller volumes (500 to 2,000 galUS) to offshore and remote locations or when smaller acid volumes are required on location. Various names are used for these tanks:

Safraps

carboys

intermodal tanks

IMO/IMDG Tanks (conforming to the International Maritime Organization and International Maritime Dangerous Goods shipment requirements)

acid transport tanks or container tanks.

The smaller-volume tanks can be made from fiberglass or PVC mounted in a protective lifting cage. Steel tanks can be lined with rubber or a vinyl ester coating in a protective transport skid or the intermodal type of tank-in-a-tank design.

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7.2.1 SSS-111/SSS-121 acid transport tank The two standard Schlumberger tanks are the skid-mounted intermodal tanks, which come in two sizes: SSS-111 with a capacity of 1,000 galUS (see Fig. 7-4) and the SSS-121 with a capacity of 2,000 galUS (see Fig. 7-5). These are corrosion-resistant, tank-in-a-tank construction built to Standard A.B.S. certification to DOT Spec IM 101. They have a 3/16-in carbon steel outer skin and a 1/2-in crosslinked polyethylene inner liner. The annulus between the tank and the liner is filled with high-density polyethylene foam.

The fill and discharge outlets are located at the top of the tanks. An air unloading system pressurizes the tank for discharging material. Working pressure is 25 psi with rupture disc and relief valve pressure protection devices. A manway is located at the top of the tank for performing maintenance operations.

The heavy-duty skid has forklift slots and lifting eye connections on the top. The 1,000-galUS skids are designed to stack on top of each other.

Figure 7-4. 1,000 galUS Acid Transport Tank (SSS-111)


Figure 7-5. 2,000 galUS Acid Transport Tank (SSS-121)

7.2.2 Containerized transport tanksAcid tanks in a container frame (see Fig. 7-6) are used for transporting acid offshore in large volumes.

Figure 7-6. Containerized Acid Transport Tank

7.2.3 Safety devices on transport tanksSee Figure 7-7 for examples of the safety devices that should be present on acid transporter and tanks to help prevent the unplanned discharge of acid and damage to equipment and/or the environment.

protective frame: Tanks are skid-mounted with a crash frame to prevent damage to the tank.

dome guard and drain hose: The hatch and manway area is protected with a rubber-lined, raised lip that acts as a containment area for acid spills. A drain hose is normally connected to this area, allowing acid to fall to the ground. This area must be cleaned with fresh water when contaminated.

Blind caps: All discharge and fill lines must be equipped with blind caps, which must be attached to the line with a chain.

Caution:Use caution when opening the cap because hazardous vapors or mist may be expelled.

vent lines: Tanks must be equipped with a vent line for the air supply and to relieve any pressure that may build up inside the tank during storage and transport.

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Figure 7-7. Top Hatch of SSS-111 Acid Tank with Safety devices

2-in butterfly valve(teflon cover with 316 SS disc and Viton sear

3-in discharge line with cap

20-in manyway with Viton gasket

Air input

3-in Girard GE-IMF44 relief valve (64-psi) and gauge

with rupture disc (70-psi)

Air vent (1-in ball valve)

8-in hatch

Air regulator and gauge

GITS pop-off valves (12-psi) and gauge

3-in butterfly valve

pressure gauges: A pressure gauge must be included, to monitor air pressure supplied when unloading the tank and a pressure gauge to monitor vapor pressure inside the tank.

Note:Before opening the cap, verify that there is no positive pressure indicated on the relief valve gauge. Any positive pressure reading indicates that the rupture disc has failed and needs to be replaced. STOP and notify supervisor before continuing.

• relief valve: This valve will relieve pressure that builds up inside the tank into the vent line. The type of valve and its setting will depend on the tank type.

Note:The relief valve must be checked regularly as described in WS MB Section VII: # 625-E: Pressure Vessel and Relief Valve Inspection and Test Procedures.

rupture disc (also known as a burst disc): This disk is a non-reclosing pressure relief device, which provides a leak-tight

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seal. If a vessel’s internal pressure rises to a predetermined level, the rupture disc bursts, providing an instantaneous, unobstructed full relief of pressure. The disc must be replaced after such a relief.

Caution:The settings of the relief valve and burst disc type and rating must be according to tank manufacturer’s recommendations. DO NOT change them.


8.0 Acid Tank and Transport Equipment Maintenance

Many different kinds of tanks are used to store and transport acids. Proactive maintenance on the tanks and all related equipment is necessary to prevent failures and the possibly catastrophic consequences of failure, and to increase their useful lifespan.

This section covers the basic maintenance checks that should be performed. Many locations will have location-specific maintenance checks that must be performed. Check with your local Maintenance Department.

Note:Review the WS Safety Standards: No. 4, General Facility and Workshop, No. 12, Permit to Work System, and No. 15, Lockout/Tagout of Hazardous Energy Sources before performing any maintenance.

Before starting any work or inspection remember the following:

All required PPE must be worn.

Review previous STEM 1 inspection reports.

Tanks must be empty and isolated from any delivery systems, which could fill or pressurize, the tanks.

Tank manways or entrances must be maintained clear at all times.

Before entering the tank, ensure that air monitoring has been carried out.

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Before performing any hot work inside the tank, confirm that no gases or flammable fumes are present.

Relieve all pressure from equipment and lines before attempting repairs.

Do not tamper with safely valves.

Repair all leaks as soon as possible.

All replacement parts and accessories must be clean and suitable for use at the temperature and pressure of the intended service.

Note:Because hazardous materials are stored and transported in these tanks, and some tanks are defined as pressure vessels, some inspections and certifications will need to be performed by approved third-party inspectors in compliance with local regulations (e.g., DOT or IMDG/ADR).

8.1 Tank maintenanceTanks must be maintained according to the following procedures.

Note:Each location should establish frequency of checks depending on activity levels and usage of tanks.

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74 | Acid Tank and Transportation Equipment Maintenance

8.1.1 External vesselThe external vessel must regularly be checked/maintained as follows:

Regularly check the cleanliness of the vessel. Wash and clean as required.

Check for obvious signs of damage to the outer jacket, such as dents, pitting, or rust. Damage such as this could indicate that the internal lining of the tank has been damaged.

For polyethylene tanks, check for cracking, crazing, and brittle appearance. Check carefully the areas around fittings where different planes of the tanks join.

Check the condition of the paint on the vessel and pipe work. Clean, repair, and paint as required.

Check hazardous warning and capacity labels/signs.

Check for rust, pits, and leaks in welds (see example in Fig. 8-1).

Figure 8-1. Crack in Weld on Bottom Suction of a Transport Trailer

Check welds on the tank’s cradles or tank supports, which could crack because of fatigue, and check any tie-down bolts to ensure they are tight.

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Check the manway hatch and ensure it seals properly. Inspect the lid gasket for tears, rips, or worn spots.

Check to ensure the dome guard drain hose is not blocked or damaged. This hose is fitted to a hole in the side of the guard around the dome lid. The hose runs down the side of the tank to the bottom. Any spills around the dome lid are confined and fall down through this hose.

Ensure that the tank is not venting excessively or has a pressure buildup.

Ensure all pipe work is secure on the tank. Ensure drip trays, if present, are fitted and secure.

Ensure that level indicators, if present, are clean, working, and leak free. Repair any leaks.

8.1.2 Pipe work and acid hose fittingsThe pipe work and acid hose fittings must be very carefully checked as follows:

Ensure that acid is not trapped in any hoses or connections.

Check all valves for leaks. Check the valves for ease of operation and that all handles are fitted and indicate the correct flow path. Ensure handle stops are in place.

Ensure caps are fitted to connections.

Check hoses, flanges, and gaskets for leaks.

Check supports for external piping and plumbing.

Check condition and stability of independent supports for pipe work and valves to ensure some flexibility is possible.

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8.1.3 InstrumentationInstrumentation must be checked before each use.

Check operation and condition of pressure gauges, if the tank is fitted with them. Ensure that connections are not leaking and the glass face is not broken.

Check operation and condition of gauge manifold valves.

8.1.4 Tests and inspectionsThe following checks should be performed regularly.

Confirm that the pressure relief valve’s last certification/ test date is less than 12 months old. Also check the set pressure of the pressure relief valves to confirm that they are suitable for the application they are being used in.

Check date of installation and rating of rupture disc.

Check any certification of tank (if required). Is certification date still valid?

8.1.5 Tank linings and interiorThe linings and interior of the tanks should be maintained as described in the following guidelines.

Test acid tank internal linings in accordance with Dowell Maintenance Bulletin Number Section VII—Number 130C (MB#130C). The date of the test and the next test date must be stamped onto the tank test plate. The test results must be documented in a STEM report and filed in the equipment file.

Note:The integral linings test must be performed once every 30 months.

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Details for cleaning the inside of acid tanks before entry are given in MB#130C. Follow these guidelines and the procedures detailed in Well Services Safety Standard No. 25 - “Confined Space Entry” (InTouch Content ID# 3313705) and No. 12 - “Permit to Work” before any internal inspections of tanks are performed.

After each venting and cleaning, visually inspect the internal condition of the tank.

8.1.5.1 Lined tanksThe majority of lining failures occur because of

storage or transport of incompatible fluids. Check the manufacturer’s recommendations.

striking of the lining with metal gauge sticks and dropping hammers.

Perform the following inspections and maintenance on lined tanks.

Check all lap seams and lining for defects caused by physical damage.

Inspect the lining surface for blisters and looseness by sighting down the surface with an explosion-proof drop light. These defects will be seen as shadowed areas on the lighted surface. See Figure 8-2 for an example of a blister.

Figure 8-2. Blister in Rubber Lining Wrongly Used to Transport Solvents

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Look for cracks and check for possible contamination to lining by oil, extreme hardness or softness, and loss of resilience of the lining.

If failure of the lining is suspected and/or if major repair work has been carried out on the vessel, the Holiday Spark Test must be done. The procedures to do this are described in Maintenance Bulletin No. 120C. These tests must be performed by trained personnel.

If the results of the tests show a possible fault in the tank lining (which would be shown as positive ohmic reading during test, proving conductivity), then a more in-depth test of the tank is required.

Spot patching is inadequate to seal a modified section of the rubber lining.

The lining in some vinyl ester-lined tanks can be repaired using special repair kits from approved suppliers. In some cases, these repairs must be performed by trained personnel. Check with your maintenance supervisor when in doubt.

8.1.5.2 Unlined tanksCheck for rust, pits, and cracks in and near welds.

8.1.5.3 Polyethylene tanksIt is important that the inside and outside of the tank are clean. Use a bright light source to inspect the interior of the tank for cleanliness, from the manway cover.

8.1.6 Crash frame, skid, and lift pointsThe following describe minimum maintenance requirements for the crash frame, skid, and lift points.

Check skid or frame for damage.

Wash, repair, and paint as necessary.

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Ensure that drainage plugs are fitted and that plugs are closed before filling the tank.

Check access ladders and roof for damage. Ensure any handrails are stowed for transit.

Replace Haz-Chem stickers as necessary.

Ensure that 12-mm earth bosses are fitted and in good condition.

Inspect forklift lift points for damage.

Make sure that all slings and shackles, where fitted, are in place and that the test date shown on the frame stamping plate shows one full month remaining before the next statutory examination is due.

Ensure the safety and inspection certification is complete and current.

Ensure that fixed asset number stenciling is legible from all sides.

Ensure that tare, pay, and gross weight stenciling are clearly visible.

8.2 Trailer and tractorThe trailer and tractor hauling the tank need to be well maintained.

Check previous STEM 1 of tractor and trailer.

Perform STEM 1 check on the tractor (see Fig. 8-3): Check oil and water levels; fan belts; condition of air, fuel, and oil hoses; air and electrical systems; cleanliness; and fuel tank level. Correct any discrepancies.

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Figure 8-3. STEM 1 Check on Tractor

Trailer hook-up and condition (Fig. 8-4): Check hoses, glad-hand connections, fifth-wheel connection, and trailer lights.

Figure 8-4. Prejob Check of Trailer

Tires: Check air pressure and condition of tires of tractor and trailer. Are chock blocks available and used when the unit is parked.

Check that all lock nuts are in place and tight.

Ensure that all safety and regulatory paperwork is available.

Ensure that all safety equipment is available and in good condition.

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Ensure that correct transport decals, placards, and labels are properly used and clearly visible.

Note:Any modifications to equipment are to be done via Equipment Modification Request (EMR) and approved by management of area.

8.3 Additional testing and inspectionAdditional test requirements and procedures for tanks or transporters used to store and transport hazardous fluids are detailed in the following WS Maintenance Bulletins and Technical Alerts.

Section VII: # 130-C: Acid Storage Tank Facilities – Inspection and Maintenance Procedures

Section: VII, # 979 – Intermodal Portable Tank: Periodic Inspection and Testing Requirements

Section VII: # 978 – Marine Portable Tank: Periodic Inspection and Testing Requirements

Section VII: # 691C – DOT Cargo Tank Periodic Inspection and Testing Requirements

Section VII: # 767 – Mothball Procedure Rubber lined Acid Storage Tanks

Section VII: # 785 – DOT Spec. 57 (Metal) and 34 (Plastic) (Tote) Tank Inspection and Testing Procedure

Section VII: # 625-E: Pressure Vessel and Relief Valve Inspection and Test Procedures

Section VII: # 1007: Acid Tank Upgrades

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Maintenance Bulletin 1109 MUST DO, InTouch Content ID# 3036784

WS Technical Alert 2000-33: Low pressure Fittings/Connections (Camlok)

8.4 Acid plant housekeeping and maintenance

Routine inspection and maintenance of the equipment and facilities in the acid bulk plant should be performed and documented. The frequency and detail of these inspections should be established by management of the location. Maintenance procedures should be based on manufacturer’s recommendations.

Whenever a defect is identified, it should be repaired immediately and the repairs performed should be documented.

A checklist to aid in the housekeeping and maintenance of acid plant equipment is given in Figures 8-5 and 8-6.

8.5 Reporting and documentation

The following reporting and documentation, at a minimum, needs to be completed.

Complete STEM 1 report for all equipment checked and file reports in the equipment files.

Report any outstanding repairs orders to maintenance department.

Attach green tag to each item inspected if it is ready for the next job. Attach a red tag if the item requires further maintenance.

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Figure 8-5. Acid Plant Housekeeping and Maintenance Checklist


Figure 8-6. Acid Plant Housekeeping and Maintenance Checklist, Page 2


9.0 Acid Mixing Procedures and Calculations

Before any acid mixture can be prepared, it is necessary to calculate the correct volumes of water, concentrated acid, and additives.

The basic mixing procedure for all acid systems is as follows.

STEP 01 Put required volume of water in mix tank.

STEP 02 Add corrosion inhibitor and inhibitor aid.

STEP 03 Mix water and inhibitors thoroughly.

STEP 04 Add other acid additives and mix thoroughly.

STEP 05 Add concentrated acid and mix thoroughly.

Specific mixing procedures for different acid systems at the acid bulk plant or on location are detailed in Section 10.

Note:The Matrix Materials Manual is referenced throughout this section: see InTouch Content ID# 4013354.

9.1 HCl-specific calculationsConcentrated HCl is normally supplied at concentrations of 33 to 36%. This concentration is then diluted to the desired strength by adding

to the proper amount of water and additives (liquid or solid) to strengths of 5 to 28% HCl.

The formula to calculate the amount of concentrated acid that is needed to make a required volume of dilute acid is

Note:The specific gravity of different acid strengths can be found in tables in the Field Data Handbook and Matrix Materials Manual.

Example: To prepare 5,000 galUS of 15% HCl with 5 galUS/1,000 galUS A262 inhibitor and 1 galUS/1,000 galUS F104 surfactant, with concentrated acid of 34%, perform the following calculation:

SG 15% HCl = 1.0749

SG 34% HCl = 1.1709

Vol Conc. Acid =

5000 × 15 × 1.07491.1709 × 34

Volume Conc. Acid = 2,025 galUS 34% HCl

A262 Corrosion Inhibitor = 5 x 5 = 25 galUS needed

F103 Surfactant = 5 x 1 = 5 galUS needed

82 | Acid Mixing Procedures and Calculations

Note:Subtract the corrosion inhibitor volume and the volume of all other additives from the fresh water volume.

The volume of mix water should be reduced by the volume of corrosion inhibitor and other additives to be used, i.e., consider the total volume of water + additives as the mix-water volume.

Volume water = (5000 – 2025) – (25 + 5)

= 2,945 galUS = 70.12 bbl

9.2 Acetic acidAcetic acid concentrations can be prepared as shown in Table 9-1 using the indicated amounts of stabilizing agents L400 or L401.

Remember that you use L400 to make glacial acetic acid solution, or L401 to make a low freezing point acetic acid solution.

All concentrations of acetic acid from 2 to 12% require the same concentration of inhibitor for a specific temperature.

Table 9-1. Acetic Acid Preparation

Acetic Acid Concentration

SG @ 68 degF

To Make 1000-galUS Solution

L400 (galUS)

L401 (galUS)

2% 1.0012 19 26

3% 1.0025 25 39

4% 1.004 38 52

5% 1.0055 48 65

6% 1.0069 58 78

7% 1.0083 67 91

8% 1.0097 77 104

9% 1.0111 87 117

10% 1.0125 97 130

11% 1.0139 106 144

12% 1.0154 116 157

Note:Subtract the corrosion inhibitor volume and the volume of all other additives from the fresh water volume.

To mix,

Add approximately half the water to the mix tank.

Add the inhibitor(s).

Add the L400 or L401 and mix thoroughly.

Add and mix the remaining mix water.

9.3 Mud acid (HF + HCl)Mud acid is a mixture of inhibited HCl and HF. It can be prepared in one of three ways:

By blending a 20% solution of HF with HCl and water. Section 3, Appendix A,

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of the Matrix Materials Manual shows the components necessary to prepare 1,000 galUS of various mud acid solutions using H200 (20% HF), water, and various concentrations of HCl.

By diluting a storage mixture solution of 25% HCl + 20% HF solution with water and HCl. Section 3, Appendix B, of the Matrix Materials Manual provides the volumes and strengths of HCl and H152 (25% HCl + 20% HF) needed to prepare different strengths of 1,000 galUS of dilute mud acid.

By dissolving intensifier Y001 in HCl acid to obtain the desired concentration. Section 3, Appendix C, of the Matrix Materials Manual shows the components necessary to prepare 1,000 galUS of various mud acid solutions using Y001 (ammonium bifluoride). The expansion factor for Y001 when dissolved in water is 0.0933 galUS/lbm of Y001 added. Section 3, Appendix D, of the Matrix Materials Manual shows the equations used to calculate the components required to prepare mud acid.

Caution:Because of the dangerous properties of HF and Y001, special safety precautions must be taken when mixing and handling these acids (see Section 10.1).

9.4 Clay acidThe various clay acid systems can be prepared using one of three methods:

By mixing concentrated HCl with Y001 (ammonium bifluoride): See Section 3.3.5.1 of the Matrix Materials Manual.

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By mixing concentrated HCl with HF 20% (H200): See Section 3.3.5.2 of the Matrix Materials Manual.

By mixing HCl/HF Acid 25/20 H152 as a component with Y001. See Section 3.3.5.3 of the Matrix Materials Manual.

Example calculations for mixing clay acid are also presented in Section 3.3.6 of the Matrix Materials Manual.

9.5 Other acidsDetermination of mix components for other acid systems can be found in the Matrix Materials Manual (see InTouch Content ID# 4013354).

9.6 AcidMIX FormulatorAcid mixing calculations can also be performed using the Schlumberger website at e-Engineering Solutions:

http://e-engineering.sugar-land.oilfield.slb.com/

The acid mixing calculations determine the amounts of the various components necessary to generate the specified volume of the acid listed, including additives. The majority of Schlumberger acid systems can be calculated. A maximum of four fluid systems can be formulated at the same time.

The sequence to perform a calculation is as follows (see also Figs. 9-1 to 9-4):

Describe the acid system (HCl, HCl-HF, SXE, etc.) and enter bottomhole temperature (BHT), type of tubulars to be used, and whether H2S is present or not.

Give volume and strength of dilute acid required and the strength of the concentrated acid to be used.

Specify the type of acid additives in the system.

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Specify the additive concentrations.

The results will be calculated and presented on screen or as an Excel spreadsheet and a load-out sheet.

Using the example for HCl in Section 9.1, the results shown in Table 9-2 were generated by AcidMIX* Formulator.

Table 9-2. AcidMIX Formulator Calculation Output

System 1: 5,000 galUS – HCI – 15MixingInstructions

Productcode QTYper1,000 TotalQTY(galUS)

HCI 405 2,025Water 589 2,945A262 5 25F104 1 5

Totalvolume= 5,000galUSAciddensity 9.0lbm/galUS

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Figure 9-1. AcidMIX Formulator Input Screen 1

Figure 9-2. AcidMIX Formulator Input Screen 2




10.0 Operating Procedures

Generic operating procedures for transporting, transferring, and mixing acid are given in the following sections. These procedures will vary from one district to another, depending on the equipment used, the acid and additive types, and the location (acid bulk plant or wellsite).

Acid mixtures can be prepared at the bulk plant and transported to the wellsite, where they are either transferred to acid storage tanks or remain in the transport tanks. The acid mixture will then be pumped from the tanks when the job is performed.

Concentrated acid and the additives may be delivered separately to the job site, where they are prepared and mixed with water to provide the required acid mixture.

Note:Personnel should ask local management to explain the proper use of local loading facilities and mixing procedures.

10.1 Nine requirementsIn all these procedures, the following nine requirements must be understood before any operation is performed.

Correct PPE must be worn by all personnel. Safety equipment (shower, eye wash, and so on) must be available and have been function tested before the operation begins. Review the MSDSs to determine the PPE required.

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Fall protection may also be required if working on top of tanks.

Spill control equipment must be available, the location should have a Spill Response Plan, and personnel must have been trained in treating spills. A supply of neutralizing agent (e.g., soda ash for HCl) must be available in sufficient quantities to neutralize the maximum possible spillage. A water supply must be available near the storage or mixing site to dilute and flush any neutralized spillage.

All personnel should be up to date in the required Well Services and OFS safety training.

All personnel should have received operations training and be deemed competent in the tasks they are required to perform. Any trainees will be assigned a mentor.

A risk assessment must be performed and reviewed with all personnel involved for each operation. Contingencies must be discussed. Personnel should sign off attendance at this review.

Transferring chemicals should only take place through the use of closed system transfer pumps. Chemicals must not be added with open top buckets. All transfer pumps and equipment shall be flushed with water after use.

All personnel involved must be assigned responsibilities for which they are trained and understand.

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88 | Operating Procedures

STEM 1 maintenance checks must be performed on all equipment and the equipment must be green tagged to indicate no maintenance or repair is currently required.

Equipment used to store, transport, and mix acid must be clean and rust-free. Acid from a supplier generally contains <180 ppm iron. Higher concentrations of iron and other organic and inorganic compounds that can be picked up from dirty equipment will have a detrimental effect on the stimulation treatment.

10.2 Transferring acid from supply transporter to bulk plant

Transferring acid from an acid supply transporter to the acid bulk plant storage facility requires the following procedure.

STEP 01 Ensure the nine requirements listed in Section 10.1 are complete.

STEP 02 Park the acid supply transporter on a curbed and sloped loading slab, stop the engine, and place chock blocks under the wheels.

STEP 03 Set up warning signs such as “Danger—Acid Loading” or warning tape and secure the loading area.

STEP 04 If flammable fluids are to be transferred, then ensure that the fill pipe has an electrical ground connection and ground the tanker to the ground point.

STEP 05 Take a sample of the acid delivered and measure its SG with a hydrometer to confirm it is indeed the concentration that was ordered.

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STEP 06 Verify the storage tank to be connected to, and confirm the fluid level (with measuring stick or using tank level indicator). Subtract the amount already in the tank from the capacity of the tank, and confirm that the result is equal to or more than the amount you plan to unload into the tank.

STEP 07 Confirm that the acid storage tank vent line is open and lined up to the fume scrubber.

STEP 08 Confirm that the fume scrubber is working: check water level and ensure that the pump is on.

STEP 09 Rig up the hoses to connect the tanker/transporter to the fill-up line on the acid storage tank. Trace out the line completely from the delivery truck to the receiving tank. Check the condition of the hoses, lines, and connections.

STEP 10 Line up valves and transfer hoses, and using water, pressure test the discharge line/hose. Repair any leaks.

STEP 11 Prepare the transporter to transfer the acid, and confirm that the valve positions are correct.

STEP 12 Transfer the acid using the appropriate procedure:

12a. Using a transfer pump procedure

Start and prime the pump and confirm it functions.

Ensure the vent on tanker or hatch is open.

Start to transfer acid slowly, checking for leaks, and then increase the transfer

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rate. Confirm that the acid is discharging into the storage tank.

Occasionally check the fill gauge (sight glass or level indicator) to confirm that the tank is not about to overfill.

When discharging is almost complete, slow down the transfer rate.

12b. Using air pressure procedure

Provision must be made to accommodate the large volume of acid fume-laden air vented from the supply tank. It is critical to monitor the unloading process and to use the least amount of pressure possible to complete the transfer. Make sure the vent line size is equal to or larger than the tank fill and discharge lines.

Start air compressor on transporter and confirm that it is functioning. Check that the safety relief valves have current certification and are working. If the tank has a relief valve, verify that no positive pressure is indicated on the relief valve gauge. Any positive pressure reading indicates that the rupture disc has failed and needs to be replaced. Ensure that the tanker vent and hatches are closed.

Begin to slowly pressurize the tanker to the unloading pressure (refer to the designed working pressure of the tanker). Air pressure used to offload bulk acid can range from 5 to 20-psi depending on the system and distance of the tanker from storage tanks. An operator should be in attendance while pressure is building to observe any leaks or problems.

After the unloading air pressure is attained and flow from the transporter to the acid storage tank is verified, the

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transporter should be observed during the entire unloading procedure

Slowly vent the tanker 10 to 15 minutes before the tanker is empty. When the tanker empties, it will vent through the acid unloading line into the receiving system. The hose will jump and the sound of air rushing through will be evident when the trailer is empty and this venting begins.

Note:Do not use Schlumberger’s air supply to unload third-party vendor transporters that are equipped with air compressors.

STEP 13 Monitor discharge and fill-up piping/hoses for any leaks during the transfer. If a leak occurs, shut the transfer down and flush the line with fresh water. Repair the leak.

STEP 14 When the transport is empty, shut down the air supply and close the fill-up line on the storage tank and discharge line on the tanker.

STEP 15 Flush lines, valves, and pumps with water and close valves.


STEP 16 Switch off the fume scrubber pump and drain the scrubber.

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STEP 17 Disconnect the lines to the acid transporter and remove any ground wire(s).

STEP 18 Measure the fluid level in the acid storage tank and confirm that the volume of acid delivered is same as the volume that was ordered.

STEP 19 Complete the required paperwork and inventory management forms.

STEP 20 Check whether any spills occurred and clean them up as necessary. Perform any required housekeeping and a STEM-1 inspection of the equipment. Clean all the PPE and store it properly.

10.3 Loading transporter or tank with concentrated acid from bulk plant

Loading acid transporter or tanks with concentrated acid from the bulk plant storage facility requires the following procedure.

Note:The acid-proof rubber-tank liner and covering for fittings is fragile and easily damaged. Take care not to damage the liner when sampling or inspecting the tank.

STEP 01 Ensure the nine requirements listed in Section 10.1 are met.

STEP 02 Park the acid transporter or tanks in the acid loading area (see Fig. 10-1). Stop the truck engine and place chock blocks under the wheels.

STEP 03 Secure the loading area. Place warning signs such as “Danger—Acid Loading: signs on all open sides of the tanker or tank being filled.

STEP 04 Perform this safety checklist:

Open the vent line before opening hatches.

Visually inspect the inside of the transport tanks for cleanliness and to ensure that they are empty. Check that the tanks are undamaged and all seals in place.

Visually inspect fill and discharge lines, connections, dome lids, and hoses for damage.

If the tank has a relief valve, verify that no positive pressure is indicated on the relief valve gauge. Any positive pressure reading indicates that the rupture disc has failed and needs to be replaced.

STEP 05 Verify the acid plant storage tank to be connected to and confirm the fluid level with a measuring stick or using the tank level indicator.

STEP 06 Take a sample of acid and measure its SG with a hydrometer. This SG should be reported on the loadout ticket and be used to calculate the dilution ratios when mixing dilute acid.

STEP 07 Check that the capacity of the transport tanks is sufficient for the amount of acid to be loaded-out.

STEP 08 Rig up the hoses to fill the tanker/transporter from the acid storage tank.

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Figure 10-1. Loading Acid at a Schlumberger Acid Plant in Mexico

STEP 09 Line up the valves and using water, pressure test the discharge line/hose. Repair any leaks. Set the valves for acid transfer from acid storage tank to transport tank(s).

STEP 10 Start transferring acid slowly to the transport tank. Confirm that acid is discharging into the transport tank. Check for leaks and then increase the transfer rate.

STEP 11 Monitor the discharge and fill-up piping/hoses for any leaks during operation. If a leak develops, shut the transfer down and flush line with fresh water. Repair the leak before beginning the transfer again.

Note:Have a spill kit ready (i.e., soda ash) to neutralize any spillage.

Caution:Do not overfill tanks. The overflow will discharge through the vent line. This discharge will create a siphon and produce a very rapid vacuum in the tank, resulting in the tank being drained.


Note:Transfer from one acid storage tank at a time and open the suction valves from one tank only. If the discharge valves on two or more tanks are opened at the same time, then there may not be sufficient revetment capacity to contain a spill from a break in the mix/transfer suction or discharge piping.

STEP 12 Monitor level of acid transferred into the transport tank(s) and slow down transfer rate when required level is approached. Check acid level using tank level gauge(s) or dipstick.

STEP 13 When the transport tank is filled with the required volume of acid, close storage tank valve. Do not exceed stated capacity.

STEP 14 Measure the fluid level in the acid storage tank and confirm that the decrease in volume is the same as the increase in the volume in the acid transport tank(s). Flush lines, valves, and pumps with water and close the valves.

STEP 15 Rig down, taking care for any unflushed areas in the treating lines and equipment.

STEP 16 Complete the required paperwork and inventory management.

STEP 17 Perform any required housekeeping and STEM-1 checks of equipment. Clean and store all PPE. Check whether any spills occurred and clean up as necessary.

STEP 18 Check the acid tanks and/or transporter to ensure that all valves, protective caps, and dome lids are properly closed for transport.

Ensure that correct warning plates and dangerous goods and product labels been put in place on tanks and to front and rear of transport vehicle. Ensure that any old labels been removed.

Ensure that all tanks are properly secured to the trailer.

Ensure that a complete STEM-1 check been performed on the tractor and trailer.

10.4 Preparing acid mixtures for transport

Acid mixtures may be prepared in the acid mix tank at the bulk plant and then transferred to the transport tank, or they can be prepared directly in the transport tank (Fig. 10-2).


STEP 02 Park the acid transporter or tanks in the acid loading area (see Fig. 10-1). Stop the truck engine and place chock blocks under the wheels.

STEP 03 Secure the loading area. Place warning signs such as “Danger—Acid Loading: signs on all open sides of the tanker or tank being filled.

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Figure 10-2. Mixing Acid in Acid Tanks in Congo

Note:The acid-proof rubber-tank liner and covering for fittings is fragile and easily damaged. Take care not to damage the liner when sampling or inspecting the tank.

STEP 04 Perform this safety checklist:

Open the vent line before opening hatches.

Visually inspect the inside of the transport tanks for cleanliness and to ensure that they are empty. Check that the tanks are undamaged and all seals in place.

Visually inspect fill and discharge lines, connections, dome lids, and hoses for damage.

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If the tank has a relief valve, verify that no positive pressure is indicated on the relief valve gauge. Any positive pressure reading indicates that the rupture disc has failed and needs to be replaced.

STEP 05 Clean, rust-free tanks must be used to mix acid solutions. Confirm that the tank is compatible with the acid solution you plan to mix in it.

STEP 06 Take a sample of concentrated acid and measure its SG with a hydrometer. Confirm that the SG corresponds to the expected acid concentration.

STEP 07 Calculate the volume and concentration of each fluid to be loaded (water, acid, and additives) to give the total volume required. Confirm that the tank in which the mixing is to occur is large enough for the expected final volume.

STEP 08 Confirm fluid levels with a measuring stick or the tank level indicator of

the acid storage tank to be connected

water supply (tank or other).

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STEP 09 Confirm additive levels and function test liquid additive pump if additives are to be transferred using this pump. Perform a (bucket test) to confirm that the additive pump delivers accurate volumes of additives.

Caution:When water and some additives are added to strong acids, large amounts of heat are released that can cause boiling of the water and result in hot acid splashing out of the container. Acid or chemicals must be added to the water to allow the heat to be dissipated in the water.

STEP 10 Load the volume of fresh water necessary to prepare the desired quantity and concentration of acid into the acid mix tank.

Note:Remember that the volume of mix water must be reduced by the volume of corrosion inhibitor and other additives to be used. That is, add the total additive volume to fresh water volume to obtain the total mix-water volume.

STEP 11 Add the proper amounts of corrosion inhibitor and inhibitor aid to the mix water. Shut down the additive pump if one was used.

Note:Monitor all lines for leaks during the entire transfer and mixing process. If leaks occur, flush the lines with water and repair.

STEP 12 Circulate the mixture with the mixing pump thoroughly. Mixing can also be done using paddles, circulation pumps, or an air lance.

Using an air lance may cause excessive foaming in acid systems containing foaming agents and some surfactants and thus be considered too dangerous for some acid systems, so it is not recommended in these cases.

A paddle tank may not be appropriate if additives that may attack the seals of the paddles are used.

STEP 13 Add all other additives (e.g., F or W agents; see Section 3.5) using a chemical transfer pump, and mix thoroughly.

STEP 14 Meter in the predetermined volume of concentrated acid.

STEP 15 When the acid transfer is complete, flush lines with fresh water and close acid discharge and suction valves. Flush lines with a small amount of water. This water will go in to the tank being loaded unless provisions have been made to divert flow elsewhere.

STEP 16 Thoroughly mix the solution to uniformly distribute the acid and all additives.

STEP 17 Take a sample of the mixed acid and measure its SG with a hydrometer to check that the end concentration is the desired concentration.

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STEP 18 Line up and connect the valves and hoses to transfer acid mixture from acid mix tank to transporter/tank. Start slowly and verify acid transfer to tank.

STEP 19 Transfer the uniformly blended acid to the transporting tank truck.

STEP 20 Flush all lines and pumps with fresh water and rig down fill-up lines to acid transport tank(s). Take care for any unflushed areas in the treating lines and equipment.


STEP 21 Measure fluid levels in acid storage tank, water supply tank and liquid additive tanks and confirm volumes are same as those required for acid mixture prepared.

STEP 22 Complete the required paperwork and inventory management.

STEP 23 Perform any required housekeeping. Clean and store all PPE. Check for spills and clean up as necessary.

10.4.1 Special note: mixing mud acids containing HF

Warning:HF is highly corrosive to flesh. Use extreme care while loading or handling mud acid.

Each location should have specific written instructions about mixing and loading mud acid, taking into account the site-specific loading dock. Follow these principles in general:

STEP 01 Work at the dock level; stay off trucks.

STEP 02 All chemicals must be pumped through a closed system using a remote-controlled pump. Do not leave the pump unattended while it is on.

STEP 03 Ingredients must be added to a stationary mixing tank at the loading dock. Ingredients are to be added through fixed piping. An eductor should be installed in the fill line for adding solids.

STEP 04 Mixing must be done by jet circulation (no paddle shafts to leak). Do not use an air lance. No mixing should be done in the truck tanks. After mixing by circulation, transfer the mud acid to the truck tank through one hose.

STEP 05 Acid facilities should be constructed so that all lines can be flushed with water and emptied by gravity into the truck tanks. Drain all lines and hoses before unhooking them or knocking unions loose.

STEP 06 Keep all clothing and equipment dry. Be sure nothing is spilled but water.

STEP 07 Use only clean, fresh water for mix water. Do not use seawater to prepare mud acid.


10.5 Transporting acid to job siteOnce the required volume of concentrated acid or acid mixture is loaded into the acid transport tanker or tanks as described in Section 10.3, it must be transported to the wellsite location.

Hazardous materials can be transported safely if all the necessary precautions and good operating procedures are followed.

10.5.1 Equipment conditionA complete STEM-1 check must be performed on the tractor, trailer, and acid tanks. This check is described in Section 8.

10.5.2 Journey managementThe Schlumberger Journey Management and Driving Standard (SLB-QHSE-S001) should be applied to all journeys. The need for the journey, the transport route and potential hazards, weather conditions, convoy policies, driving hours, and communications must be reviewed.

If acid is being transported and bad weather (for example, icy roads, snow, or poor visibility) occurs, the vehicle must stop at the nearest suitable parking area. The vehicle may only continue its journey when the weather has improved. In some European countries, this is obligatory for all hazardous substances.

The driver must report all transport delays to the client as soon as possible, whether they are due to bad weather, breakdown, or other reasons.

The driver must ensure that the vehicle is under constant supervision or is parked in a safe place (secured against rolling), when it is not being driven.

10.5.3 Driver competencyThe driver must be familiar with the particular hazards associated with acids and, from this knowledge, understand the recommended relief and safety measures to be taken in an emergency.

10.5.3.1 Driver trainingHeavy Vehicle Drivers (Driver Training Level 2.3, Non Articulated, and 2.4, Articulated; and DT2.2, 2.3, and DT2.4), as defined in the QHSE Training and Certification Catalog, is mandatory for any employee who operates a heavy vehicle.

10.5.3.2 Environmental and human hazards

The driver must take every precaution to prevent acid escaping during loading, transport, and unloading. No unauthorized modifications should be made to design-approved tanks and their filling and emptying devices. All the hoses, including the hose couplings, carried for unloading the product must be made from an acid-resistant material.

10.5.3.3 Protective measures and rules of conduct

The driver must put on the prescribed PPE and equipment before driving up to the tank filling/discharge points. Filling the road tanker is usually carried out by acid bulk plant personnel. If the driver is involved in the loading work, he/she must observe the bulk plant’s safety procedures.

10.5.3.4 Driver conduct in the event of a hazard

The driver must take these precautions if a hazard occurs.


At the tank filling point, the driver must leave the hazard zone immediately if a hazard occurs. In doing so, he/she must follow the instructions given by the filling personnel.

When driving, or following an accident, the driver must

Follow the instructions given on the TREM card and MSDSs (the driver must be familiar with the contents of the TREM card and MSDSs before beginning the journey).

Follow the location-specific emergency response and spill plans. If a transport accident involving acid occurs, the driver must first inform local emergency authorities and then, contact his/her supervisor or line manager to provide the following information:

driver’s name

precise product designation

license plate of the vehicle and the tank number

the location

the position of your vehicle or the tank (e.g., parked normally on the road, slid off the road, upside down, jackknifed, and so on)

telephone number at which driver can be reached

status of the vehicle or tank (full or empty) before the accident

the position and quantity of any leaks

any other damage

any other vehicles or personnel involved

what local emergency authorities have been notified.

The driver must do everything possible to avert the danger while awaiting the

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arrival of the fire service and police, while taking care not to endanger himself or herself.

If there is a spill, the driver should take note of the wind direction and use that information to avoid breathing in the gas. He or she must not pass through or remain in the gas cloud.

10.5.3.5 First aidThe driver must have received first aid training relating to acid hazards and know what information to provide a doctor if an acid spill has caused harm.

10.5.4 Arrival at location

Note:Refer to Well Services Safety Standard 5: Pressure Pumping and Location Safety.

Upon arrival on location, the operator should do the following:

Inspect the equipment and ensure the tanks and hoses have not been damaged during transport. Inspect all valves and connections.

Check with job supervisor to determine where to spot the equipment to allow sufficient room for mixing and safely handling all products. Allow room for escape routes and placement of any ancillary safety equipment.

Note:The use of a land guide is required to position trailers.

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Ensure the unit is a safe distance from the wellhead and is upwind of the well head.

Ensure chock blocks are placed at wheels.

10.6 Transferring acid to or from a vessel or offshore rig

When transferring acid to or from a vessel or rig offshore, the generic operating procedures provided in Sections 10.2 to 10.4 must be followed. Some additional precautions and procedures will be required because of the hazardous nature of the operation. These should be documented and be available at the location, and may include the following.

STEP 01 Inform vessel or barge captain and local port authorities that acid transfer is to begin. There may be conflicts of work priorities.

STEP 02 Inform vessel/rig crew and dock personnel that acid transfer will take place. All unnecessary personnel to clear the area.

STEP 03 Check weather (wind and tides) to ensure no unacceptable conditions exist, and ensure the vessel is well secured.

STEP 04 Unauthorized access to certain parts of the boat/rig may be required, so make sure that these areas are secure.

STEP 05 Special valves and lines on the vessel or rig and Well Services process pipe work may need to be closed/open during loading of acid. Check and double check that the valves and lines are correctly positioned.

STEP 06 Allow sufficient slack in transfer hoses for swell and boat movement.

STEP 07 Acid storage tanks that are to be filled should be checked for loading and vessel stability. Check partially filled tanks

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(fluid movement inside tank). Ensure that the available capacity of the tank is sufficient for the amount of acid that is to be loaded into it.

STEP 08 Schlumberger personnel should coordinate the loading and have radio communication. One person on the quayside/boat and one person in the control room/rig floor must be present at all times.

STEP 09 All acid loads must be tallied as they are being pumped to/from the boat/rig to ensure that tanks are not overfilled if a level gauge or alarm fails.

STEP 10 Load/unload one acid tank at a time: make sure valves on other storage tanks are closed.

STEP 11 Do not completely fill the acid tank. Ensure that enough capacity remains to flush the lines.

STEP 12 Flush all lines from the sea chest back to the acid plant/transporter fill lines and clean acid lines from the supply point.

STEP 13 Use plastic tubs to catch any fluid in the hoses while breaking the connections.

10.7 Field mixing of acidsWhen it is not possible to deliver an acid mixture to the wellsite, then it is necessary to mix the concentrated acid with water and additives just before the job. This situation may occur when

The time of acid job is not fixed or acid is required on standby.

No mixing facilities are available at the Well Services location.

Transportation and logistical constraints (e.g., offshore and remote locations or tank/

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transport volume limitations) prevent mixing before transport.

The job design and acid formulation is not decided in time to mix before transporting.

The main method of mixing acid is by batch mixing in tanks. Acid, water, and additives are not always continuously mixed: most continuous-mix systems involve adding one or more additives to premixed acid formulations using metering pumps and flowmeters to control the proportioning. In the future, advances in real-time job monitoring and evaluation that will allow optimizing stimulation treatments with no waste products will require true continuous mixing of water and additives with raw acid on the fly.

10.7.1 Mixing HCl onsiteFollow these procedures to mix HCI onsite.


STEP 02 Ensure the following equipment is present:

acid transport or storage tank with concentrated acid

fresh water supply

mix tank(s) to hold required volume of diluted acid mixture (with circulation pump and/or paddles). Tanks must be clean and rust free.

circulation pump (if not included with mix tanks)

transfer pump and suction/discharge hoses for acid and additives

four-inch Figure 206 suction and discharge hoses with hose covers

safety equipment and PPE

hydrometer.

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STEP 03 Calculate the volume and concentration of each ingredient to be added (water, acid and additives) to result in the total volume required

Note:Add acid to water! Do not add water to acid!

STEP 04 Load the quantity of fresh water necessary to prepare the desired quantity and concentration of acid into the mixing tank.

The volume of mix water must be reduced by the volume of corrosion inhibitor and other additives to be used; i.e., consider the total additive volume as part of the mix-water volume.

Take into account tank dead volumes (if any) and line volumes. Dead volumes should be added to the volume of acid to be prepared to ensure the correct volumes can be pumped downhole.

STEP 05 Circulate the tank, hoses, and mixing system with the water and check for leaks before acid and additives are added.

STEP 06 Using a chemical transfer pump, add the proper amounts of corrosion inhibitor and inhibitor aid.

STEP 07 Circulate with the mixing pump to thoroughly mix. Mixing can be done using either paddles, circulation pumps, or an air lance (do not use air lance if foaming is likely).

STEP 08 Add all other additives (e.g., F and W agents) using a chemical transfer pump and mix thoroughly.

STEP 09 Meter in the predetermined volume of concentrated acid.

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STEP 10 When acid transfer is complete, flush lines with fresh water and close discharge and suction valves.

STEP 11 Thoroughly mix to provide uniform distribution of the acid and all additives.

STEP 12 Take a sample of acid and measure its SG with a hydrometer to check the concentration.

STEP 13 Just before pumping downhole, circulate acid tank contents a minimum of two tank volumes to ensure all additives are evenly dispersed in the acid.

Note:If there is a delay and mixed acid remains in surface storage/mix tanks for any length of time, discuss it with your supervisor. Acid inhibition times may need to be increased by adding of more inhibitors. Circulate tank two volumes at 8-hr intervals to ensure inhibitor and additive effectiveness.

STEP 14 Pump acid mixture as per design. Monitor tanks, hoses, and connections for leaks.

STEP 15 At end of the job, if any acid is left in the tanks, neutralize the mixture.

Add 25 kg soda ash (C109) to 10 bbl of fresh water, or

Add 3 kg caustic soda (M002) premixed in a bucket of water to 10 bbls of fresh water

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STEP 16 Dispose of the neutralized acid according to local procedures.

STEP 17 Flush all tanks and treating lines thoroughly with water, disposing of the water according to local procedures.

STEP 18 Rig down the equipment, taking care for any unflushed areas in the treating lines and equipment.

10.7.2 Mixing acetic acidMix acetic acid solutions according to the following procedure.




fresh water supply






hydrometer.

STEP 03 Calculate the volume and concentration of each ingredient to be added (water, acid and additives) to result in the total volume required.

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Caution:Add acid to water! Do not add water to acid!

STEP 04 Add about one-half of the mix water to a clean tank. The tank should be rust free.

Add the required amount of corrosion inhibitor and other additives to be used.

Mix thoroughly, either with paddles, a circulation pump, or an air lance (if foaming is likely, do not use air lance).

Add the required L400 or L401.

Add the remaining mix water.







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10.7.3 Mixing HF with Y1Follow these procedures to mix HF with Y1.


Note:Additional safety precautions are required when mixing and handling mud acid (see Section 4.3.5).



fresh water supply






hydrometer.

STEP 03 Calculate the volume and concentration of each ingredient to be added (water, acid and additives) for the total volume.

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STEP 04 Load about two thirds of the required fresh water into a clean mixing tank.

STEP 05 Add appropriate amounts of corrosion inhibitor, inhibitor aid, and other required acidizing additives, such as wetting agents, and iron control additives as needed. Add scale inhibitor additives if needed.

STEP 06 Mix thoroughly.

STEP 07 Add Y1 and mix until dissolved.

STEP 08 Slowly add required quantity of concentrated HCl acid while continuing to mix.

STEP 09 Mix thoroughly by paddling or circulating. The mixture must be sufficiently agitated to produce a uniform solution or dispersion of the corrosion inhibitor.

STEP 10 Add remaining water while continuing to mix.


STEP 12 Take a sample of acid and measure the SG with a hydrometer, to check the concentration.


STEP 14 Pump acid mixture according to design. Monitor tanks, hoses, and connections for leaks.





10.7.4 Mixing clay acidFollow these procedures to mix clay acid.




fresh water supply






hydrometer.

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Caution:Add acid to water! Do not add water to acid!

STEP 04 Add 3/4 of the required volume of water to a clean mixing tank.

STEP 05 Add the required amount of corrosion inhibitor(s). Mix thoroughly.

STEP 06 Add the required weight of Y001 and circulate or paddle until dissolved. Add the required volume of acid (HCl and H200 or H152) and circulate or paddle until dissolved.

STEP 07 Add Y006 and mix thoroughly to dissolve the Y006.

STEP 08 Add the remaining water to adjust the volume to the desired volume. Wash down any spills while water is still in the transfer line.

STEP 09 Circulate or paddle thoroughly to assure a homogeneous blend.

STEP 10 When acid transfer is complete, flush lines with fresh water and close discharge and suction valves.


STEP 12 Take a sample of acid and measure its SG with a hydrometer to check the concentration.







10.7.5 Mixing SXE acid systemsMix SXE acid systems according to the following procedure.




fresh water supply



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hydrometer.


STEP 04 Load about two thirds of the required fresh water into a clean mixing tank.

STEP 05 Add appropriate amounts of corrosion inhibitor, inhibitor aid, and other required acidizing additives, such as wetting agents or iron control additives as needed. Add scale inhibitor additives if needed.

STEP 06 Mix thoroughly.

STEP 07 Slowly add required quantity of concentrated acid while continuing to mix. If mixing mud acid with Y1, add Y1 before HCl. If mixing mud acid with concentrated HF, add HCl before the HF.

STEP 08 Mix thoroughly by paddling or circulating. The mixture must be sufficiently agitated to produce a uniform solution or dispersion of the corrosion inhibitor.

STEP 09 Add remaining water while continuing to mix.

STEP 10 Acid should be remixed just before adding to the oil phase to ensure that the corrosion inhibitor is dispersed uniformly.

STEP 11 Put the oil phase (diesel or kerosene) into separate clean mixing tank.

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STEP 12 Add the emulsifier (U080 for SXE or U103 for SXE HT) to the oil phase. Mix thoroughly by circulation.

STEP 13 Prepare the emulsion by slowly adding the acid to the circulating oil so that an oil-external phase emulsion forms.

Note:Avoid adding the acid too quickly. Mixing time is dependent on the shear rate, but slowly adding the acid is important.

STEP 14 Mix rate can be increased once the emulsion starts to form. You can tell it is starting to form as it changes color. A thousand gallons of emulsion can be prepared in 10 to 20 minutes.

STEP 16 Determine the emulsion quality by sampling the mixture and observing for 5 to 10 minutes. There should be no separation of the oil and acid. Alternately, collect a small amount of emulsion in a syringe. Carefully place a drop of emulsion in a beaker of water. If the emulsion is in the oil-external phase, the drop will settle down to the bottom of the beaker. If the emulsion is unstable, the drop will slowly disperse in the water, forming a skim of the oil on the water surface.

STEP 18 If separation occurs, the mixture is in the acid-external phase. If that is the case, allow the fluid to completely separate in the tank.

STEP 19 Resume agitation at the interface of the liquids or circulate from the bottom of the tank through a pump and back into the top of the tank. An oil-external phase emulsion should form as the acid phase is circulated back into the oil phase.


10.7.6 Mixing other acid systemsDetails of the procedures required to mix other acid systems can be found in the Matrix Materials Manual (InTouch Content ID# 4013354) or in documentation for the particular systems.




11.0 Acid Spills and Disposal

Acid spills must be prevented at all costs: clean-up and remedial work is very expensive, the environment is damaged, and Schlumberger’s reputation is harmed.

Even small volumes of spills cause damage and extra work. See Figure 11-1 of an acid spill (in South America) when it flows over the ground.

Figure 11-1. Acid Spill

Figure 11.2 shows that a little acid can go a long way.

Figure 11-2. Acid Spill from 55-galUS Drums

To avoid spills, all personnel must

perform proactive maintenance on all acid handling and storage equipment

establish and follow acid plant operating procedures, which must be updated with lessons-learned as necessary

use all necessary safety equipment, which must be operable

know the procedures and regulations in the country they operate

have a proactive QHSE attitude.

11.1 ReportingSpills must be reported to Schlumberger, and possibly must be reported also to client and local regulatory authorities, depending on their reporting requirements. The details and contact numbers should be included in the site-specific spill response plan and/or emergency response plan.

Per OFS Standard 2 (InTouch Content ID# 3260257) or the Web site http://www.hub.slb.com/display/index.do?id=id16324), all spills must be reported in QUEST. Incident severity is classified by the volume of spill as follows:

Light < 100 liters

Serious > 100 < 1,000 liters

Major > 1,000 < 10,000 liters

Catastrophic > 10,000 liters.

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108 | Acid Spills and Disposal

11.2 Spill prevention and control planSchlumberger Environmental Standard No. 8 (InTouch Content ID# 3605373) states “All sites shall establish and maintain a written Spill Prevention and Control Plan if hazardous substances are used or stored on the site, or if required by environmental laws and regulatory requirements. The SPC Plan shall address pollution prevention by identifying potential spill scenarios and developing procedures to prevent and control them.”

A spill prevention and control plan helps protect the environment in two ways:

It provides the procedures to prevent oil and chemical spills and waste releases.

Should a spill or release occur, it describes the protocols to minimize any harmful effects, including notification of appropriate government agencies as required by regulations.

All personnel involved with the handling of acids must be knowledgeable of the location’s spill response control plan and know what their responsibilities are in the event of an incident.

Some personnel will require special training in handling spills and also take part in spill response drills (see Fig. 11-3 showing a drill in Kazakhstan).

Figure 11-3. Acid Spill Exercise in Kazakhstan

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11.3 MSDSsThe MSDS for each product provides details of actions required if a spill occurs. Table 11-1 shows details from the MSDS of 15% HCl for the “Accidental Release Measures” required.

Table 11-1. Spill Response Measures on MSDS for 15% HCI

Mainphysicalhazards

Corrosivetometals.

Otherhazards Givesoffhydrogenbyreactionwithmetals.

Personalprecautions

Avoidcontactwitheyes.Donotgetonskinorclothing.Washthoroughlyafterhandling.Ensureadequateventilation.SeealsoSection8.

Methodsforcleaningup

Damup.Neutralizewithlimemilkorsodaandflushwithplentyofwater.Flushresidualwithplentyofwater.

Environmentalprecautions

Noinformationavailable.

11.4 Spill kitsEach acid storage and mixing facility must have a spill kit. This was described in Section 6.1.7 of this document. Personnel must be trained in the use of the spill kit.

Note:When materials from the spill kit are used, they must be replaced as soon as possible.

11.5 DisposalDisposal of acid waste from spills or from empty and used acid or acid material containers and drums must also be performed according to proper procedure.

Disposal requirements are detailed in the MSDS sheet. See Table 11-2, which shows an example of the “Disposal Considerations” from the MSDS sheet for 15% HCl.


Table 11-2. Disposal Considerations for 15% HCI from MSDS

Wastefromresidues

Disposeofbyinjectionorotheracceptablemethodinaccordancewithlocalregulations.

Contaminatedpackaging

Ifreusablecontainersareused,sendthembacktotheproductsupplier,aftertherequiredrinsing.Triplerinse,crushandshiptosanitarylandfillunlessprohibitedbylocalregulations.

EPARCRAhazardouswastecode

D002

Empty totes and drums should be returned to the location unless they have become the property of the client. Empty drums should be triple-cleaned and sent to an approved drum reconditioner if permitted by regulations. If reconditioning is not an option, empty drums should be sent to an approved sanitary landfill for disposal.

Note:Check with your location manager or QHSE manager for proper disposal procedures and regulations at your location.

110 | Acid Spills and Disposal



12.0 Appendix

Figure 12-1. Key Service Quality Requirements Matrix

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112 | Appendix


13.0 Check Your Understanding


1. What is the pH of 28% hydrochloric acid?A. 7B. ≥ 12C. 9 – 10D. ≤ 2E. 5 – 5

2. Which three types of safety hat three types of safety gloves should you wear when mixing mud acid (12% HCl + 3% HF)?A. cottonB. butylC. neopreneD. PVCE. leatherF. nitrile

3. What four items would you find in an acid bulk plant?A. surge tankB. Wilden pumpC. water storage tankD. spill kitE. weigh-batch blenderF. fume scrubber

4. What is the name of the Web-based program that can be used to determine acid system load-out requirements?A. i-DistrictB. AcidBLEND calculatorC. AcidMIX formulatorD. i-HandbookE. CemCADE

5. What is a TREM card?A. trailer repair and equipment

maintenance cardB. transport emergency cardC. trailer emergency clutchD. transport equipment maintenance

card

6. What safety standard should you know and follow when handling dangerous goods?A. OFS QHSE Standard S008B. WS Safety Standard 18C. OFS QHSE Standard S003D. WS Safety Standard 17E. all of the above

114 | Check Your Understanding

7. Which four additives might you find in an acid system?A. anti-sludge agentB. inhibitorC. fluid-loss additiveD. retarderE. surfactantF. extender

8. What volume of 34% HCl would you require to mix 10,000 gallons of 28% HCl?A. 10,000 galUSB. 5,527 galUS C. 8,022 galUSD. 4,050 galUSE. none of the above

9. Where would you find details of what actions are required if an acid spill occurs in the acid bulk plant?A. product labelB. load-out listC. MSDSD. invoiceE. TREM card

10. What is the order of mixing if you have to prepare 15,000 gallons of 15% HCl with 20 galUS/1,000 g A262 + 3 galUS/1,000 W54?___A. Add concentrated acid___B. Add inhibitor___C. Add water___D. Add demulsifier

11. Which WS safety standard should you know and follow if you must inspect the inside of a 12,000-galUS acid tank?A. 5B. 20C. 25D. 23

12. What is the capacity of the STF-143 acid transporter? A. 5,000 galUSB. 6,000 galUSC. 8,000 galUSD. 7,500 galUSE. none of the above

13. If a vehicle accident occurs and spill from an acid transporter taking 5,000 galUS of acid to a location, which of the following information must the driver provide?A. place or location of incidentB. time of incidentC. damage incurredD. police and fire brigade informedE. type of spillF. all of the above

14. If you have to neutralize a small acid spill in your location, what two products could you use?A. cementB. soda ashC. calcium chlorideD. caustic sodaE. sand


15. How often should the revetment of an acid storage plant be hydrotested?

A. every 6 monthsB. every 12 monthsC. every 24 monthsD. not required

16. An acid spill has occurred in your acid bulk plant. You estimate that 200 L of acid has been lost. How should you report the spill in QUEST?

A. No need to report incident B. RIR – light incidentC. RIR – serious incidentD. RIR – catastrophic incident

17. What three fluids can you store in a rubber-lined storage tank?

A. 20% HClB. waterC. xyleneD. inhibited acidE. dieselF. 7.5% HCl

18. What is the standard union for use in low pressure acid transfer and liquid additive hoses?

A. Camlock mild steelB. WECO Figure 1502C. Camlock brassD. WECO Figure 206E. all of the above

19. What is the mixing order when preparing 5,000 gallons of mixing HF acid with Y001 ammonium bifluoride?___A. Add corrosion inhibitor.___B. Add 2/3 water volume.___C. Add Y001.___D. Add water 1/3 water volume.___E. Add concentrated HCl acid.

20. You have to set up an acid storage plant that will be home to the following tanks:1 15,000-galUS acid storage tank2 6,000-galUS acid storage tank1 6,000-galUS water storage tank4 300-galUS chemical tote tank

A concrete slab measuring 12 x 12 meters has been built. How high should the surrounding wall be?A. 25-inB. 12-inC. 39-inD. 29-inE. no wall required

116 | Check Your Understanding


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