asphaltene dissolve

.y

REVIEW OF PARAFFIN CONTROL AND REMOVAL IN OIL

WELLS USING SOUTHWESTERN PETROLEUM

SHORT COURSE SEARCHABLE DATABASE

by

NOMAN SHAHREYAR, B.S.Ch.E.

A THESIS

IN

PETROLEUM ENGINEERING

Submitted to the Graduate Faculty of Texas Tech University in

Partial Fulfillment of the Requirements for

the Degree of

MASTER OF SCIENCE

IN

PETROLEUM ENGINEERING

xO Approved

December, 2000

E^^ ACKNOWLEDGEMENTS '^ ^ ^^ -

i\]f) cÔ 7 I am grateful to the Department of Petroleum Engineering at Texas Tech

^(?' ^ University for providing me with competitive departmental graduate scholarship and

giving me the opportunity to reach this stage in my education and development as an

aspiring engineer. I am also thankful to the Southwestern Petroleum Short Course

(SWPSC) Association and Watford Professors for financially supporting me as a research

assistant throughout my education at Texas Tech University.

To my thesis advisor, Dr. Lloyd Heinze, I would like to express my gratitude for

all his valuable guidance. His assistance on the problems I faced to complete the thesis

project was extremely helpful.

In addition, I am thankful to Dr. Scott Frailey and Dr. George Asquith for

agreeing to be on my thesis committee and patiently answering all my questions. Their

suggestions were very helpful as I worked through the revisions of my thesis.

I would also like to express my thanks to Dr. James Lea for providing me with the

technical literature on the paraffin treatment methods. I am also grateful to Dr. Paulus

Adisoemarta for his assistance and guidance in developing the SWPSC searchable

database. I am thankful to Dr. Herald Winkler for volunteering the out-of-stock SWPSC

conference proceedings from his personal collection, which were helpful to me as I

needed them to make a complete set of the SWPSC volume to develop the SWPSC

searchable database. I would also like to acknowledge Dr. Akanni Lawal's assistance in

my efforts to complete my duties as a graduate student advisor and in my attempts to

n

develop my technical writing skills. I am thankful to Ronda Brewer, Joan Blackmon.

Jennifer Weitman, Joseph Mclnemey, Margaret Ceja, and my friends at the Texas Tech

University for their co-operation.

Finally, I am grateful to my Dad, Masood Shahreyar, my Mom, Races Fatima,

and my brother, Rehan Shahreyar for encouraging me to attend Texas Tech University

for my graduate education.

ni

ty

TABLE OF CONTENTS

ACKNOWLEDGEMENTS ii

ABSTRACT vi

LIST OF TABLES vii

LIST OF FIGURES viii

CHAPTER

1. INTRODUCTION 1

1.1 Background Information 1

1.2 Scope of Work 3

1.3 Objectives 4

2. LITERATURE REVIEW 6

2.1 Chemistry of Petroleum Hydrocarbons 6

2.1.1 Paraffin or Alkane Series 8

2.1.2 Cycloparaffin or Napthene Series 10

2.1.3 Aromatic or Benzene Series 10

2.2 Basics of Paraffin Deposits 13

2.2.1 Causes of Paraffin Deposition 19

2.2.2 Methods of Paraffin Prevention and Removal 21

2.2.2.1 Mechanical Methods 22

2.2.2.2 Thermal Methods 23

2.2.2.3 Chemical Methods 23

2.3 Adobe Systems Incorporated 28

2.4 Society of Petroleum Engineers 30

IV

' ^

3. METHODOLGY 34

3.1 Installation of Computer Software 36

3.1.1 Installation of Acrobat Capture 2.0 37

3.1.2 Installation of Adobe Acrobat Reader 4.0 (Education Version) 38

3.2 Scanning and Conversion of SWPSC Conference Proceedings 39

3.3 Conditioning of SWPSC PDF Files 45

3.4 Indexing of enhanced SWPSC PDF Files 50

3.5 Customization of Adobe Acrobat 4.0 Program 53

4. EXAMPLE APPLICATION OF THE SWPSC DATABASE 60

4.1 Test of the SWPSC Searchable Database 60

4.2 Review and Summary of Paraffin Treatment Methods 63

4.2.1 Mechanical Treatment Methods 74

4.2.2 Thermal Treatment Methods 75

4.2.3 Chemical Treatment Methods 80

4.2.4 Other Treatment Methods 84

5. REVIEW OF SPE PAPERS ON PARAFFIN CONTROL AND

REMOVAL METHODS 95

5.1 Review and Summary of Paraffin Treatment Methods 95

5.2 Thermal Treatment Methods 107

5.3 Chemical Treatment Methods 108

5.4 Other Treatment Methods 111

6. CONCLUSIONS AND RECOMMENDATIONS 115 REFERENCES 117

</

ABSTRACT

The SWPSC Association, Inc. is a non-profit educational organization. The

objective of the SWPSC is to disseminate technical knowledge about existing oil field

problems, innovations/improvements in different areas of petroleum engineering, on-going

research projects, and field-proven techniques to efficiently and economically solve

various field problems. As of date, forty-six volumes of the SWPSC conference

proceedings have been published over the past 46 years, comprising of 1641 conference

proceedings. An initiative is undertaken to archive the SWPSC conference proceedings in

the electronic format. A detailed methodology is outlined to archive the SWPSC

conference proceedings from paper to the electronic format and to develop the SWPSC

searchable database with the use of previously available computer software. The SWPSC

database, developed in this work, is tested for its efficiency to retrieve the technical papers

on paraffin control and removal methods that have been presented over the past 46 years of

the SWPSC annual conferences. An overview of mechanical thermal, chemical, and other

published methods for paraffin treatment is provided after reviewing the 24 out of 36

retrieved SWSPC papers. In addition, the Society of Petroleum Engineers (SPE) image

library is used to retrieve technical papers on paraffin treatment methods from the SPE

collection of technical papers. After reviewing 19 out of 310 SPE technical papers, a

summary of thermal, and chemical methods for paraffin control is outlined. The paper

retrieval efficiency of both of these technical paper databases is compared and analyzed for

retrieving papers related to paraffin control and removal methods.

VI

^

LIST OF TABLES

4.1 A detailed summary of search results performed on the SWPSC searchable database with a keyword "Paraffin" 67

4.2 A list of authors of the SWPSC technical papers on Paraffin Treatment Methods during the SWPSC annual conference (1954-1999) 72

5.1 A detailed summary of search results performed on the SPE image library with a keyword "Paraffin" 101

5.2 A list of authors of the SPE technical papers on Paraffin Treatment Methods, Presented during the SPE conference (1951-1997) 106

vn

LIST OF HGURES

2.1 Stmctural formulas of some of the members of Paraffin or Alkane Series 9

2.2 Stmctural formulas of some of the members of Cycloparaffin or Napthene Series 11

2.3 Stmctural formulas of some of the members of Aromatic or Benzene Senes 12

2.4 A 1995 survey of the different states in the United States with paraffin related problems 14

2.5 A molecular stmcture for Asphaltene 16

2.6 Prediction of the amount of Asphaltene deposition from cmde oil

versus the volume of six different n-paraffin solvents 18

2.7 An illustration showing the electric downhole heater 24

2.8 An illustration showing hot oil injection 25

2.9 Screen shot of the SPE image library's paper search engine 32

3.1 An illustration of steps involved in developing the SWPSC searchable database...35

3.2 Adobe Capture 2.0 program's main window 41

3.3 Adobe Capture 2.0 program's preferences window 42

3.4 Adobe Capture 2.0nprogram's Input Folder Setup w indow 43

3.5 Adobe Capture 2.0 program's Output Folder Setup window 44

3.6 Adobe Capture 2.0 program's scan startup window 46

3.7 Adobe Acrobat 4.0 program's Open window 48

3.8 Adobe Acrobat program's General Info window showing document details of some enhanced SWPSC PDF document 49

3.9 Adobe Catalog 4.0 program's New Index Definition window 51

vni

^

3.10 Adobe Catalog program's Options window 52

3.11 Adobe Catalog 4.0 program's main window 54

3.12 Adobe Acrobat 4.0 program's search preferences window 55

3.13 Adobe Acrobat program's Add Index window 57

3.14 Adobe Acrobat program's built-in search engine window 58

4.1 Total Number of papers published each year during the SWPSC Conferences from 1954-1977 61

4.2 Total Number of papers published each year during the SWPSC Conferences from 1978-1999 62

4.3 Year-to-year (1954-1969) comparison of the total SWPSC technical papers versus SWPSC papers retrieved by keyword search "Paraffin." 64



4.6 Year-to-year (1954-1969) comparison of the total SWPSC technical papers, papers retrieved by keyword "Paraffin," and papers on Paraffin Treatment Methods 69



4.9 Hollow Sucker Rod String 76

4.10 Improvements in Oil Production during pre-squeeze. post-squeeze, and after hot oiling is resumed 82

IX

4.11 Schematic diagram of Linear Kinetic Cell 88

4.12 Number of remedial hot oil treatments required on the wells in Central Texas and Canada with biological treatment program 91

4.13 Number of remedial hot oil treatments required on the wells in Central Texas and Canada with biological treatment program 92

4.14 Improvement in well production with the installation of magnetic fluid conditioner 94

5.1 Total Number of papers published each year during the SPE Conferences from 1951-1975 96

5.2 Total Number of papers published each year during the SPE Conferences from 1976-1997 97

5.3 Year-to-year (1951-1966) comparison of the total SPE technical papers and SPE papers retrieved by keyword search "Paraffm" 98

5.4 Year-to-year (1967-1981) comparison of the total SPE technical papers and SPE papers retrieved by keyword search "Paraffin*" 99

5.5 Year-to-year (1982-1997) comparison of the total SPE technical papers and SPE papers retrieved by keyword search "Paraffin"' 100

5.6 Year-to-year (1951-1966) comparison of the total SPE technical papers, papers retrieved by keyword '"Paraffin," and papers on Paraffin treatment methods 103

5.7 Year-to-year (1967-1981) comparison of the total SPE technical papers, papers retrieved by keyword "Paraffin," and papers on Paraffin treatment methods 104

5.8 Year-to-year (1982-1997) comparison of the total SPE technical papers, papers retrieved by keyword "Paraffin,"" and papers on Paraffin treatment methods 105

5.9 Crude monthly rate producfion plot from well AG-50 against time 110

X

CHAPTER 1

INTRODUCTION

Today, almost every individual in the industry refers to publications/journals

pertaining to their concerned field. Publications/journals, without any doubt, help

individuals to gain knowledge from the past experiences and keep them updated w ith the

up-coming technology. Publications also help individual to develop and master their

professional skills. More can be learned about on-going research projects in the desired

area of interest by referring to the publications. These publications can be published as a

result of annual meetings, technical workshops, conferences, and seminars that are hosted

by different professional/educational organizations. Some of the examples of such

professional/educational organizations are: Society of Petroleum Engineers (SPE).

American Institute of Chemical Engineers (AICHE), American Society of Mechanical

Engineers (ASME), and Southwestern Petroleum Short Course (SWPSC). The

Southwestern Petroleum Short Course Association, Inc. (SWPSC) aims to disseminate

valuable knowledge and to update educators, researchers, and industry professionals by

hosting an annual conference in Lubbock, Texas.

1.1 Background Information

The SWPSC Association, Inc. is a non-profit educational organization. The

SWPSC headquarters is in the Department of Petroleum Engineering at Texas Tech

University, Lubbock, Texas. The Department of Petroleum Engineering at Texas Tech

University annually hosts the SV^SC conference in Lubbock, Texas.

The objective of the SWPSC is to disseminate technical knowledge about existing

oil field problems, innovations/improvements in different areas of petroleum engineering,

on-going research projects, and field-proven techniques to efficiently and economically

solve various field problems. Papers presented during the SWPSC conference are

categorized into the following areas:

• Drilling and well completions,

• Artificial lift,

• Stimulation and workovers,

• Reservoir operations and enhanced oil recovery,

• Production Handling,

• Environmental control,

• General Interest.

These categories contain subject areas such as corrosion and paraffin control,

sucker rod pumping, gas lifting, production optimization, enhanced oil recovery, well

stimulation, and drilling operations. The SWPSC technical papers, resulting from the

SWPSC conference, are presented by the scholars, researchers, and oil field personnel. The

next subsection illustrates the work required to organize the proceeding papers resulting

from the SWPSC conference.

9

1 nrrr' •'

1.2 Scope of Work

As of 2000, forty-six volumes of the SWPSC conference proceedings have been

published over the past 46 years. The forty-six volumes of the SWPSC comprise of 1641

conference proceedings. The SWPSC conference proceedings are one of the assets for the

Petroleum Industry. Oil and gas operators have presented a majority of the conference

papers from the Permian Basin region. In addition, the SWPSC conference has also been

successful in attracting presenters from all over the United States and different parts of the

world. Therefore, these conference proceedings are a good knowledge base for petroleum

engineering professionals, especially from the Permian Basin region, to gain knowledge

and develop technical sidlls.

The Department of Petroleum Engineering is the place from where these published

proceedings of the SWPSC are distributed to various libraries, oil companies, and

individuals all over the world. Unfortunately, the SWPSC headquarters does not have a

complete set of the 46 SWPSC volumes. It can be a time consuming and aggravating

process to find some desired conference paper from a set of SWPSC proceeding volumes

that are not present at one place.

In addition, one volume of the SWPSC, with an average of 325 pages, is added to

the SWPSC storage closet every year. As the time passes by, the number of published

proceedings will grow and storage of these catalogs might become a problematic issue. It

is required to find a way to save and archive this historical set of knowledge base on the

past experiences.

An initiative is undertaken to archive the SWPSC conference proceedings in an

electronic format that will preserve the conference papers presented o\'er the past 46 \cars.

The SWPSC proceeding volumes, in the electronic format, will be easily accessible and

elimmate the storage limitation issue. In addition, the SWPSC proceeding volumes will be

facilitated with the efficient paper searching capabilities. This will save considerable

paper-look-up time for finding any available particular information by eliminating the

manual search process in the SWPSC paper volumes. The next section outlines the

objectives of this work.

1.3 Objectives

The objectives of this thesis are as follows:

to develop an electronic database of the SWPSC technical papers using

commercially available software;

to test the effectiveness of the SWPSC electronic database by retrieving the

SWPSC conference papers on paraffin control and removal methods, published

over the past 46 years;

to summarize and categorize all the treatment methods for paraffin control and

removal from the SWPSC electronic database;

to retrieve and review the technical papers on paraffin control and removal methods

using Society of Petroleum Engineers (SPE) papers database;

to summarize and categorize the knowledge gained after reviewing the SPE

technical papers on paraffin treatment methods;

wmm^m^

• to analyze and compare the paper retrieval effectiveness and depth of the technical

information, provided by the retrieved papers from both of the electronic paper

databases (SWPSC and SPE) in the area of paraffin control and removal methods.

The objectives of this thesis are accomplished in the next five chapters. The

second chapter of this thesis provides a basic knowledge on the chemistry of petroleum

hydrocarbons, composition of paraffin deposits, causes of paraffin deposition, and other

treatment categories of paraffin prevention and removal. A brief overview of the computer

software required for developing SWPSC searchable database, and the Society of

Petroleum Engineers (SPE) is also outlined in the second chapter. The third chapter has a

detailed methodology to develop SWPSC searchable database. After the SWPSC is

developed, the SWPSC technical papers are retrieved on the paraffin control and removal

methods tests its search efficiency. After reviewing these retrieved papers, all the paraffin

treatment methods are summarized and categorized in the fourth chapter. In chapter five

all of the SPE technical papers are summarized and categorized on the paraffin control and

removal methods. The SPE database is used to retrieve the set of technical papers. At the

end conclusions are drawn and recommendations are made in the sixth chapter.

CHAPTER 2

LITERATURE REVIEW

Paraffin control and removal has always been considered a severe problem in the

oil fields since the beginnmg of the oil industry. Paraffin deposition can lead to loss in oil

production and transportation problems by accumulating in the tubing, producing formation

face, valves, and flow-lines. Various types of mechanical, thermal, and chemical based

methods have been available to the oil producers to economically combat the formation and

removal of paraffin deposits.

This chapter presents a basic knowledge on the chemistry of petroleum

hydrocarbons, composition of paraffin, causes of paraffin deposition, and general methods

that are available to control and remove paraffin deposition. A brief overview of the

computer software is also given here to introduce the reader to the software that will be

used to develop the SWPSC electronic database in this work. At the end of the chapter, an

overview on the Society of Petroleum Engineers (SPE) organization and the SPE image

library is presented.

2.1 Chemistry of Petroleum Hydrocarbons

Petroleum crude consists mainly of a mixture of carbon and hydrogen compounds

that are called "Hydrocarbon Compounds."' Cmde oil also contains small amount of

compounds containing sulphur, nitrogen, and oxygen. A number of hydrocarbon series

have been identified in cmde petroleum. General formulas for most of the commonly

found hydrocarbon series in the cmde oil are given below:

• Paraffin or Alkane Series (CnH2n+2),

• Cycloparaffin or Napthene Series (CnH2n),

• Aromatic or Benzene Series (CnH2n-6),

where n represents the number of each element in the hydrocarbon compound.

Petroleum hydrocarbons can be further categorized into saturated and unsaturated

hydrocarbons. A saturated hydrocarbon is a hydrocarbon compound in which all the carbon

atoms are attached to the hydrogen atoms rather than combining with themselves with one

1 '

or more double bonds. " The saturated hydrocarbons have only single bonds in the

compounds. An unsaturated hydrocarbon is a hydrocarbon compound in which all the

carbon atoms are attached to the hydrogen atoms. In addition, unsaturated hydrocarbons

have one or more double bonds in the hydrocarbon compound.

Petroleum hydrocarbons that belong to the saturated hydrocarbon group are stable

compounds. For this reason, they are the least chemically reactive among the petroleum

hydrocarbon series. This is because of the absence of double bonds in the compound. In

contrast, the hydrocarbons that are classified as the unsaturated hydrocarbons are unstable

compounds due to the presence of double bond in the hydrocarbon compound. Unsaturated

hydrocarbons are reactive to chemicals and heat. In addition, the reactivity of unsaturated

hydrocarbons increases with the increasing molecular weight of the compound.

FurtheiTnore, the stability of chemical stmcturing or bonding of the carbon and hydrogen

citoms in the dilferent series of petroleum hydrocarbon compounds is important factor

7

because it decides the placement of the first or simplest member in each series of the

petroleum hydrocarbon series.

2.1.1 Paraffin or Alkane Series

Hydrocarbon compounds that belong to the paraffin or alkane series can be derived

from a general molecular formula: CnH2n+2-' Alkanes are also called saturated

hydrocarbons with a name of each member ending with "-ane" such as: methane, ethane,

propane, and hexane. Figure 2.1 shows the stmctural formula of some of the members that

belong to paraffin series.' Methane, CH4, is the simplest hydrocarbon that belongs to the

paraffin series. Paraffin hydrocarbons are the least reactive in nature among the different

series of hydrocarbons. Starting from butane (Figure 2.1), it can be seen that there are two

possible aiTangements of carbon and hydrogen atoms in butane compound. Hydrocarbon

compounds that have the same molecular formula but various stmctural arrangements are

called isomers." ' ^ For example, the carbon atoms of butane can be arranged either in a

straight chain or in a branched chain and each carbon atom is linked as a single bond to

other carbon atoms in the hydrocarbon compound. In straight chain arrangement, each

carbon atom is attached to one or a maximum of two other carbon atoms, but in branched

chain arrangement at least one of the carbon atoms in the hydrocarbon compound is

attached to three other carbon atoms. As the number of carbon atoms in the hydrocarbon

compounds increases, the possible number of isomers also increases rapidly.

8

H

I H

H H H ft J [ I I

H'~G~C—v~C"~'H I I I j H H H H

H H H H H I ^ I I I

H"C'H: :" 'C - -C-C-H I I I I I H H H H H

H H I \

I T H H

V

H 1

H I

H H H J ; I

H - C - C - C - H i \ J H H H Propiru..

H-'C-C-C-H j I i H H H

)30blAiillv

H-C-H

H H-C-H

H

H-C—C

N

H

H

Figure 2.1. Structural formulas of some of the members of Paraffin or Alkane Series."

2.1.2 Cycloparaffin or Napthene Series

Cycloparaffins or napthenes can be represented by the same chemical formula as

olefins, i.e. CnH2n. Napthenes are saturated closed chain hydrocarbon compounds in

which each carbon atom is attached to two other carbon atoms. The existence of the

cyclopropane and cyclobutane hydrocarbons is not possible because of the instability of

chemical structuring or bonding in each of these members of cycloparaffin. The simplest

napthene compound contains five carbon atoms attached with a single bond to each other.

Figure 2.2 shows the stmctural formulas of some of the members of the cycloparaffin

hydrocarbon series.'

2.1.3 Aromatic or Benzene Series

The aromatic or benzene series hydrocarbons are closed chain hydrocarbon

compound and can be derived from the general molecular formula CnH2n-6-' The chemical

name of every aromatic hydrocarbon ends with "-ene" such as: benzene, toluene, xylene,

and naphthalene. Benzene is the simplest hydrocarbon compound from the aromatic

hydrocarbons series. A benzene ring contains six carbon atoms that are linked with a

double bond to one of their neighbor carbon atoms. Aromatic hydrocarbons can contain

single or multiple benzene rings in their stmctural formula. Figure 2.3 illustrates some of

the members that belong to the aromatic hydrocarbon series. "

10

CyclQ}y.^t'.iiii'c-

K,

S^ Ha Mailsylcyclopefttime

C C—H

DimethylcyclopenUict;

«2 -C

H2C "CH;

(

C-, dobcxaa -

K,

H^C / '

-GH3

HgC

•c

CKg

Mietliyicycloih^xwite

H,

HgC

H jC,

^C Hz

1, 2 I>iir.v'thyL«^vc-lobfK;i.T^

Figure 2.2. Stmctural formulas of some of the members of Cycloparaffin or Napthene Series."

11

, ^ '

HC,

CH

CH

H

HC

HC

'C-C><,

H x^"

1 H

C-CgHj

CH C H

HC

^ ,

/ ^

•r-

C-CHj

CH

(JTtSx'"-xy"i-<:ric'

H C ^ C H

'N.^

^ X -CH,

Meta-K'^luti;

CH3 r HC--\H

i CHj

HC

J .CH

H

HC*

"N

H

/ = \ . / ' ^ CH

CH

MsiJbihalcno

Figure 2.3. Stmctural formulas of some of the members of Aromatic or Benzene Series."

12

2.2 Basics of Paraffin Deposits

Paraffin is a w axy, solid substance that naturally occurs in cmde oil. Paraffin can

cause producfion and transportation problems by accumulafion in the well tubing, well-

bore perforations, pore spaces of producing formation, flow-lines, and the surface

equipment. Figure 2.4 shows a 1995 survey of \arious oil producing states in the United

States that had paraffin build-up problems" ' (cited by Fan and Llava"^^).

Paraffin deposits can range from pure white paraffin u ax to the deposits that totall>

consist of asphaltenes. Paraffin wax molecules are classified as a group of straight or

branched chain alkanes that can range from CigHsg to CsgHvg with very little branching,

depending on the hydrocarbon composition of the cmde oil. Paraffin wax tends to

precipitate out from the cmde oil in the oil production operations due to reduction in

temperature and pressure in the well-bore and the transportation lines. "Precipitation" is

the process in w hich the low -molecular-w eight paraffin w ax molecules become insoluble

in the cmde oil at a specific temperature and pressure and come out from the cmde oil in

the form of paraffin wax crystals.^ The low-molecular-weight molecules of paraffin wax

precipitate out of the cmde oil and act as nucleation agents for the high-molecular-weight

paraffin molecules. These nucleation agents either adhere to the tubing w all and flow-lines

or remain in the cmde oil in the form of dispersed paraffin w ax crystals. As the

temperature and pressure decreases, additional high-molecular-weight paraffin wax

molecules precipitate out of the cmde oil and start collecting and forming a layer on the

previously precipitated paraffin molecules, adhered to the tubing walls, flow -lines, and

present in the crude oil. Such phenomenon of paraffin collection on the precipitated

13

Figure 2.4. A 1995 survey of the different states in the United States with paraffin related problems. '

14

paraffin hydrocarbons is called "Deposition." Paraffin wax is chemically non-reacti\e by

nature and insoluble in the cmde oil at producing conditions.' The molecular weight of the

paraffin compounds can range from 250 to about 550. In addition, paraffin deposits may

possibly contain aromatic hydrocarbons, napthanes, resins, asphaltenes, oil, water, sand,

and silt.

Asphaltenes are dark-colored condensed aromatic hydrocarbons (Figure 2.5) that

can possibly contain nitrogen, oxygen, sulphur, and different metals in the molecule.'^

Asphaltenes are relatively high molecular weight compounds with the molecular weight

ranging from 1,000 to about 140,000. ' ^ Resins are high-molecular-weight hydrocarbons,

similar in composition to asphaltenes.''' ^ These organic compounds are insoluble in acids

and bases.

Asphaltene deposition is not as much dependent on the change in temperature and

pressure as compared to paraffin wax deposition. Asphaltene deposition is mainly caused

by the chemical changes in the crude oil. Asphaltene are present in the cmde oil in

dispersed/floating condition. Resins surround the asphaltene particles and help to keep

asphaltenes in the dispersed form in the cmde oil. Introduction of fluids such as CO2, HCl,

pentane, hexane, and gasoline can strip away the outer part (resins) of the asphaltene

particles, present in the cmde oil. Such phenomenon causes the asphaltenes to precipitate

out of the crude oil.^''^''^

A number of quick tests can differentiate paraffin wax from the asphaltenes.

Paraffin is soluble in warm gasoline whereas asphaltenes are insoluble in warm gasoline.

Paraffin wax melts in the temperature range of 104-248 °F whereas asphaltenes do not melt

15

Figure 2.5. A molecular structure for Asphaltene 18

16

but it decomposes at temperature above 300 ' .•^-'' Aromatic solvents such as benzene,

toluene, xylene, chloroform, carbon tetrachloride, and carbon disulfide have the ability to

dissolve asphaltenes and resins. ^ In addition, the asphaltenes and resins are insoluble in

propane, butane, and refined petroleum products such as kerosene and diesel oil.' ^ Figure

2.6 illustrates a relationship between the amount of asphaltene deposifion by addition of

paraffin solvents, ranging from C5H12 to C10H22, in the cmde oil. ^

According to Newberry,'^ "These deposits are very difficult to remove from a

system because normal thermal methods of hot oil or water are totally ineffective.

Removal is limited to tedious mechanical cutting operations or solvent soak techniques.

The use of readily available cheaper solvents such as diesels, kerosene or condensates are

also ineffective because their surface tension are too low for effective solution of the

asphaltenes" (p. 4).

Paraffin wax can be further categorized into macro-crystalline and microcrystalline

paraffin waxes.^' Macro-crystalline wax is a mixture of straight chain saturated

hydrocarbons with 20 to 50 carbon atoms. Macro-crystalline wax forms large needle-shape

crystals during the deposition process. On the other hand, microcrystalline wax mainly

consists of complex branched chain and cyclic compounds having 30 to 60 carbon atoms.

Microcrystalline wax produces smaller crystals upon deposition as compared to macro

crystalline wax.

Solubility of paraffin in cmde oil or pure petroleum solvents decreases with the

increase in molecular weight of the paraffin molecule. " Paraffin waxes are soluble in

solvents such as pentane and gasoline. These waxes are insoluble in aromatic soh ents such

17

A.

- C 7

X

n-Co'

T T a.o 3O.0

VOLUME OF SOLVENT ADDED (CC.)

10,0 50.0

Figure 2.6. Prediction of the amount of asphaltene deposition from cmde oil versus the volume of six different

n-paraffin solvents. ^

18

as benzene and toluene. Generally, the composition of paraffin deposits, after removing

suspended material such as sand and silt, contains:^^

• 40-60% paraffin wax,

• 30 % cmde oil,

• 10% resins, and asphaltenes.

2.2.1 Causes of Paraffin Deposition

Deposition of paraffin in the production and transportation equipment is mainly

caused by the loss of solubility of wax in the cmde oil. ' ^ Reduction in either temperature

or pressure or both contributes to the precipitation of paraffin from the cmde oil.

Reduction in temperature and pressure causes loss of light hydrocarbons from the cmde oil

solution that decreases the ability of the oil to hold the paraffin molecules in the cmde oil

and causes precipitation of paraffin from the produced oil. ' ^

According to Singhal et al., '^^ "When the equilibrium between the cmde oil and its

paraffin molecules is disturbed, paraffin precipitation takes place. The disturbance of

equilibrium occurs due to reduction in temperature and/or pressure of the flowing stream"

(p. 251).

Precipitation of paraffin can occur at any point from the bottom-hole of the well-

bore to the storage tanks. "Cloud" point and pour point are the two common measurements

of the paraffin characteristics.^ Cloud point is the temperature at which paraffin first

begins to precipitate out of the cmde oil solution. As the temperature decreases, these

19

precipitated paraffin particles attract to each other and form an interiocking paraffin-

particle-network. At one point, the crude oil become so thick that it does not pour. The

temperature at which the cmde oil does not pour is called the "Pour" point. Precipitation of

paraffin begins at the cloud point temperature and pressure of the dissolved paraffin content

in the cmde oil.

Reduction in temperature, either in the well-bore or the surface flow-line, is caused

by the expansion of gases, heat loss to the casing and cement in the well-bore, heat loss to

well-bore surrounding formation area, and heat loss to the surroundings of the

transportation lines (air, and soil). During the deposition process, paraffin precipitates out

of the cmde oil as single crystals. Such single crystals remain in the cmde oil solution in

dispersed form and tend to agglomerate around a nucleus, namely asphaltenes, to form

relafively larger paraffin particles. Paraffin accumulation is caused due to three deposition

mechanisms:''^•'"'•"-^''

• Molecular diffusion,

• Shear dispersion,

• Brownian motion.

Molecular diffusion occurs when the temperature of the flowing fluid in the tubing

and flow-lines falls below the cloud point temperature and paraffin molecules are

transported towards the walls of tubing and flow-lines due to the concentration gradient. In

shear dispersion, each paraffin molecule interacts with the nearby paraffin molecules, in

slower or faster moving streamlines, due to the rotary motion in the flow ing fluid. Such

multiple collision leads to the dispersion of the paraffin particles in the flowing fluid.

20

Molecular diffusion is driven by the concentration gradient whereas shear dispersion is

dri\'en by the velocity gradient. In Brownian motion, thermally agitated oil molecules

continually bombard small and sohd paraffin wax particles. Such phenomenon leads to a

small random Brownian movement of the bombarded paraffin particles. According to

Burger et al., ^ "'Molecular diffusion dominates at the higher temperatures and heat flux

conditions, whereas shear dispersion is dominant mechanism at the lower temperatures and

low heat fluxes" (p. 26).

2.2.2 Methods of Paraffin Prevention and Removal

Prevention of paraffin deposits can be achie\ed by keeping the paraffin wax

dissoh ed in the produced oil or by minimizing the adhesion or aggregation process of w ax

particles on the equipment surfaces. According to Matlach and Newberry, ""If the wax

content of the cmde oil is low to moderate (0-10%) these problems are periodic and

handled on an as needed' basis. With wax contents above 10% those cmde experience

se\ ere deposition and flow problems necessitating constant treatment to ensure continued

producfion" (p. 321). Various methods are available to handle paraffin deposifion. In

general, these methods can be categorized into three main categories: ' "~

• Mechanical,

• Thermal,

• Chemical.

21

2.2.2.1 Mechanical Methods

There are several mechanical methods to remove paraffin from the production

tubing and flow-lines. Rod scrapers, wire-line scrapers, flow-line scrapers, soluble and

insoluble plugs are the most commonly used mechanical tools for cleaning paraffin

deposits. ^•' • '•^2

A rod scraper is a cutting device that is attached to the sucker rod string in the rod

pump wells. Rods scrapers cut the accumulated paraffin from the inside wall of the

producfion tubing due to the reciprocafing acfion of the rods. The scraped paraffin wax

falls in the produced formation fluid in the tubing and carries up to the surface with the

produced fluid.

According to Allen and Roberts,^ a wire-line scraper is another type of paraffin

cutting tool that is widely used for paraffin deposit removal in the flowing or gas lift wells.

In wire-line scraper, a scraper is attached to the wire-line tool. The wire-line units can be

operated and controlled manually or automafically by some timing device.

Soluble and insoluble plugs are mainly used to remove paraffin deposits from the

flow-line. Soluble plugs are solid, short cylinders that are made of microcrystalline wax or

naphthalene. On the other hand, insoluble plugs are usually hard mbber or sharp-edged

plasfic spheres. One of the advantages of soluble plugs is their tendenc\ to dissolve in the

cmde oil after the paraffin treatment operation. Therefore, the need to reco\ er these

paraffin-cutfing plugs is eliminated. Injecfing soluble or insoluble plugs from one end of

the flow-line and then applying fluid pressure behind the plugs to push them along the

flow-lines accomplish removal of paraffin deposits.

11

2.2.2.2 Thermal Methods

Paraffin treatment using thermal methods involves adding external heat to the

system by minimizing heat loss to the surroundings.^' ^ ' ^''^ Installation of down-hole

electric heaters for heafing crude oil near the producing formafion (Figure 2.7) comes into

the thermal treatment category, but this method is limited due to high treatment expenses

and electrical power availability.^^ In the cmde transportafion lines, heat loss from the

produced formafion fluid can be minimized by proper insulafion of flow-lines or

maintaining high pressure in the flow-lines to prevent light hydrocarbons from coming out

of the produced formafion fluid.

As documented, the circulation of hot oil or hot water in the well-bore is one of the

most popular thermal methods for paraffin removal. ' ' ^ ' ' ^ Hot oil or hot water is

injected down the casing and up the tubing to melt or increase the solubility of the paraffin

deposits in the produced oil, accumulated on the tubing wall and the producing formation

face (Figure 2.8)." ^ Use of steam has also been reported in some areas to melt paraffin or

asphaltenes in the tubing, casing, or flow-lines. However, after application of thermal

methods it is necessary to maintain the temperature of the crude oil above the cloud point

temperature of the paraffin content in order to prevent the further deposition.

2.2.2.3 Chemical Methods

Chemicals are used to control paraffin deposifion by dissolving the accumulated

paraffin, inhibiting the paraffin wax crystal growth, and inhibifing the adherence of paraffin

23

Paraffin Deposition

Production Tubing

ownhole Heater

Figure 2.7. An illustration showing the electric down-hole heater 33

24

i:-^

Hot Oil

Paraffin_ Deposition

Production Tubing

Figure 2.8. An illustrafion showing hot oil injecfion 33

25

w ax crystals to the tubing wall and flow-lines. Chemical treatment of producing wells w uh

paraffin problems involves use of four categories of chemicals: ' '' ' ^'' ' ^

• Solvents,

• Dispersants,

• Detergents,

• Wax crystal modifiers.

Solvents used for dissolving exisfing paraffin deposits generally contain high

aromafic content. Solvents such as produced condensate, casing head gasoline, kerosene,

diesel oil, butane, pentane, xylene, toluene, benzene, carbon tetrachloride, and

carbondisulfide are used for remedial treatment of the paraffin deposits. Kerosene, diesel

oil, and low aromafic content condensates do not dissohe asphaltenes. However,

condensates with high aromafic contents, xylene, and toluene are excellent solvents for

asphaltenes. The solvent treatment technique involves penetrafion of the soKent into the

paraffin deposits to re-dissolve them into the crude oil.

Dispersants are chemical compounds that have the ability to keep paraffin particles

in the dispersed form as they crystallize in the produced cmde oil. Dispersants neutralize

the attractive forces between paraffin crystals itself and the attractive forces between the

paraffin crystals and tubing walls, transportation lines, and surface equipment. Such

phenomenon prevents the paraffin crystals from unifing and forming layers on the pipe

surfaces. ' '' '"^^ Paraffin treatment, using dispersants involves pumping the mixture of

dispersant and water/chemical solvent into the annulus of the well-bore. The dispersant

mixture is pumped out with the produced formafion fluid.

26

Detergents are surface-acfive compounds that have a tendency to water-wet the

paraffin crystals, formafion, producfion tubing, and the flow-lines in the presence of

\x /a t^r^ '15 , 19.31,39,40,41 c u ..• ,• . , • r

^'i'^^'• oucn wetting action neutralizes the cohesive forces among the

crystals and attracfive force between paraffin crystals, tubing, and flow-lines. Detergents

help in breaking up the paraffin deposits and preventing the dispersed paraffin particles to

accumulate along the tubing or flow-lines.

Crystal modifiers are usually polymeric materials such as polyethylene or any

branched chain polymers that inhibit or alter the wax crystal growth to prevent paraffin

crystal growth. ' ' These crystal modifiers combine with the paraffin molecules and

alter the paraffin crystal growth. According to Woo et al., ^ "Crystal modifier are usually

polymeric materials which prevent paraffin deposifion by dismpfing nucleation, co-

crystallizafion or modifying the crystal. They may also adsorb on the paraffin crystal

prevenfing agglomerafion or deposifion" (p. 2).

According to Holloway," "It is now recognized that the application of chemical

surfactants or detergents is extremely paraffin removal, and that the use of chemical

dispersants and crystal modifiers are effecfive in prevenfing its deposifion" (p. 3). In

addifion, Newberry and Barker recommended using paraffin dispersants and detergents

prior to well stimulafion such as acidizing or fracturing for paraffin deposit removal in the

well-bore.

27

2.3 Adobe Svstems Incorporated

With the advancement in computer and informafion technology, the demand for

available literature/informafion in the electronic document format is increasing everyday to

cut down the consumpfion of paper material." ^ As compared to paper documents, there are

several advantages of using documents in the electronic format:

• Fast and easy distribufion,

• Compact storage,

• Efficient search capability.

Adobe Systems, Inc. is one of the computer software companies involved in the

development of software tools to convert information from paper to the electronic format.

Adobe Systems, Inc. was founded in 1982 and is one of the software companies in the

United States. The company's headquarter is based in San Jose, Califomia."^

Reams of paper documents can be converted into searchable portable document

format (PDF) files with the use of Adobe's Acrobat Capture 2.0 software. According to

Tredennick,^^ "PDF supports keyword searches within the documents or across an entire

library. We can locate trial materials in seconds, browse the results, and pnnt what we

need. Previously, support staff spent days sifting through rooms full of papers to

accomplish this" (p. 1).

Using Adobe Capture 2.0, paper documents can be scanned as a bitmap page

images followed by conversion into PDF documents.' Such electronic PDF files have

exactly the same page layout, text format, and graphics as the original paper pages. In

28

addifion, these PDF files are fully searchable for any particular word or a stnng of words

inside the PDF document or a set of PDF documents.

Acrobat Capture works with four built-in optical character recognition (OCR)

s>stem. While processing text informafion from the paper image file, each of the OCR

systems agrees upon the validity of each word or letter by comparing with the words in the

dicfionary and then returns the informafion to the Capture program. Based on the

combined information from each of the OCR engines, Acrobat Capture finally generates

characters to store them into the created PDF file of that particular paper image document.

Acrobat Catalog 4.0 builds a full-text index file by copying the words from the

collecfion of PDF documents and then storing them into the index file. In addition, the

Catalog program saves the document details into the same index file by extracting them

from the document informafion secfion of each of the PDF document, provided that

document details were manually edited into the PDF document or a set of documents by

using Adobe Acrobat 4.0 (Educafion Version) program.

PDF documents provide an opportunity to the user to manually edit the document

details such as paper title, subject, author's name, and document related keywords into the

document informafion section of the PDF file. The document information secfion is

initially empty after documents are scanned and processed by the Capture 2.0 program.

Adobe Acrobat 4.0 (Education Version) can be purchased to edit the document details in

the document informafion secfion of the PDF files. Adobe Acrobat 4.0 is facilitated w ith

the built-in paper search capabilities to find the search the contents of the PDF

document(s).' ^

29

Adobe Acrobat Reader can be used by the users for \ iew ing the PDF document.

The disadvantage of using Acrobat Reader is that it cannot search the contents that are

present in the PDF document or a collecfion of PDF documents. Acrobat Reader + Search

is a modified version of the Acrobat Reader, developed by Adobe Systems, that can be

used to search for any particular informafion from a collecfion of PDF documents, based on

user provided keyword or a string of keywords. ^ Acrobat Reader's search engines access

an index file of the PDF document(s), created by the Adobe Catalog 4.0 software, to match

the text in the PDF files with the word or phrase provided by the user. Both, Acrobat

Reader and Acrobat Reader -i- Search, are freely distributed software and can be obtained

from the Adobe Systems website.

2.4 Society of Petroleum Engineers

The Society of Petroleum Engineers (SPE) Inc. is the largest individual petroleum

membership organizafion based in Richardson, Texas. ^ The primary objective of the SPE

organizafion is to gather and serve professional engineers, scientists, and managers in the

explorafion and producfion of oil and exchange the emerging technology to meet the

worid's energy needs all over the worid. Currenfiy, SPE membership list has more than

50,000 registered professionals from different oil and gas producing countries. Presently,

there are 145 SPE secfions in 54 countries. '

There are more than 30,000 technical papers in the SPE library's electronic

database that have been published during past years of SPE conferences.^^ These papers

are available both on the SPE image library CD-ROM and on the SPE website.

30

The SPE image library can be searched for any particular content in the collection

of SPE papers by using Wordkeeper retrieval software, developed by Columbus Digital

Connecfions." The SPE image library consists of two parts:

• a master disc,

• a set of image discs.

The SPE master disc contains, in the text format, the first page of each of the SPE

papers submitted since 1951. In addifion, the first-page text documents do not contain

figures, footnotes, Greek symbols, and equafions. Each of this first page text document is

linked with the corresponding complete paper including figures and equations, saved as a

paper's photographic image on the SPE image discs.

Wordkeeper retrieval software (Figure 2.9) can be mn from the master disc to

perform searches on the first page content of all the SPE papers. A search can be

performed on a collecfion of SPE papers by providing a parameter or a combinafion of

parameters such as SPE paper number, author, and keywords. Based on the provided

search parameter(s), a list of SPE paper fides is displayed on the screen. Each displayed

fitle is electronically linked with the corresponding paper's first page text document and the

paper's full photographic image for viewing the abstract or full contents of the original

document.

The SPE image library uses structured and unstructured searching strategies for

finding a list of SPE papers. In structured searches, the user given search parameter(s)

are matched with contents of the document information fields of all the SPE papers.

Such searchable document informafion fields include: SPE paper number, title, author(s).

31

r.*'**^*-*^'vV,' • * ••

!?CD Answer - [The SPE Image LibfaryiMAIN SEARCH]

3 File Edi( Options Browse Da(a Window Help

y^ gg i^ JO Igg fift g3

THE SPE IMAGE LIBRARV

Paper Number: Keywords in Title:

Author: Organization:

Journal Hane, Meeting Name or Location, Or UNSOLICITED:

Meeting/Journal Vear:

Word(s): Phrase:

Connection

J

[•Txl |5ji(J

NOTE: Use (*) for a Wildcard. Authors nanes are inuerted: Last, First, Middle.

J" Figure 2.9. Screen shot of the SPE image library's paper search engine.

32

publicafion date, author's organizafion (company, and university), conference name or

locafion, and journal's name (journal of petroleum technology). Unstructured searches

rely on matching the user provided word or a phrase with the contents of the first page ot

each of the SPE papers, present in the text document format.

33

CHAPTER 3

METHODOLOGY

The purpose for developing the SWPSC searchable database is to provide the

petroleum industry with a tool that would help them quickly retrieve any available

informafion, contained in the SWPSC proceedings in the electronic format. This chapter

describes the detailed methodology to develop the SWPSC searchable database. Forty-six

years of the SPWSC conference proceedings, in the paper format, are archived into the

electronic format.

With the use of previously available software, the electronic version of the SWPSC

proceedings will be fully searchable for the contents that are contained in the collecfion of

SWPSC documents. In addifion, the storage limitation issue to store the SWPSC paper

volumes will be eliminated. The following sequence (Figure 3.1) is used to develop the

SWPSC searchable database:

1. Install the computer software required to develop the searchable electronic database

for the past 46 years of SWPSC conference proceedings.

2. Scan and convert the paper copies of SWPSC conference proceedings to PDF files

using Adobe Capture 2.0 software.

3. Condition the previously converted raw PDF files. Adobe Acrobat 4.0 software is

used to edit and manually feed the document details of all the conference papers

into the document informafion section of the corresponding PDF documents. Data

34

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entry includes the following: conference paper fitle, subject, author's name, and

technical keywords related to the corresponding conference paper.

4. Index the condifioned PDF electronic files, using Adobe Catalog 4.0 software, by

creafing an index file. This index file is used by the Acrobat Reader's built-in

search engine to find the desired conference papers from the SWPSC electronic

database.

5. Customize the Acrobat Reader 4.0 software to perform an electronic search/query

on the collection of conditioned or enhanced SWPSC conference PDF files.

The next five secfions give a detailed descripfion of the procedure involved in

developing SWPSC searchable database.

3.1 Installafion of Computer Software

It is required to install the computer software for later use to develop the SWPSC

searchable database. List of the necessary computer software is given belov\':

• Acrobat Capture 2.0,

• Adobe Acrobat 4.0 (Educafion Version).

Given below is the step-by-step procedure to install the above-menfioned

software." ^ ^'^ Because the computer being used to develop searchable database has

Windows NT 4.0 installed on it as an operating system, all of the software installafion

procedure is given for Windows NT 4.0.

36

3.1.1 Installafion of Adobe Capture 2.0

To install the Adobe Capture 2.0 software, the following sequence is followed:

1. Restart and log on to the computer with administrative privileges. An account

with administrafive privileges is required to install software on the computer.

2. On the backside of the computer processor box, locate any available parallel port

and plug the hardware key, provided with the Acrobat Capture 2.0, into the parallel

port. The hardware key is required to be plugged in into the parallel port in order to

process the documents in Acrobat Capture 2.0. This hardware key is designed to

scan and process a maximum of 20,000 pages. If more than 20,000 pages are

required to be processed, an addifional hardware key is required to continue the

processing job.

3. Place the compact disc containing Acrobat Capture 2.0 software into the CD-ROM

drive. A new window appears on the monitor screen showing different file folders

available on the Capture 2.0 software compact disc.

4. Run the Acrobat Capture installafion program by clicking on setup icon, located

under the Capture2 file folder on the inserted compact disc.

5. The Acrobat Capture installafion wizard window appears on the screen. Follow the

step-by-step instrucfions on the screen.

6. Read the software license agreement and then click the Accept button to proceed to

the next screen.

7. A component selecfion window appears on the screen, showing the program files

available for installafion. Select all the programs and proceed to the next screen.

37

8. A new window appears with a list of a\ ailable drivers for the scanning de\ ice.

Select the driver that matches with your scanning device and then proceed to the

next screen by clicking the OK button.

9. In the next window, enter your name, your organizafion and the serial number for

the Capture software. After completing the user informafion form, click the Xext

button to start the software installafion.

10. A message window appears after the software installation is complete.

11. Fill out and submit the software registration form and then restart the computer.

12. Installafion of Acrobat Capture 2.0 software is done. Acrobat Capture program is

now ready to scan paper documents and convert them to the desired file format.

3.1.2 Installafion of Adobe Acrobat Reader 4.0 (Education Version)

Acrobat Reader 4.0 can be installed by following the steps below:

1. Restart Windows NT 4.0 and log on to the computer with administrator privileges.

2. Insert the Adobe Acrobat 4.0 (Educafion Version) compact disc in the CD-ROM.

An Adobe welcome window appears on the screen.

3. Click the next button located on the welcome window.

4. Click the "Install Adobe Acrobat 4.0" button. Follow the step-b} -step instrucfions

on the screen provided by the Acrobat installation wizard.

5. Read the software license agreement and then click the Accept button to proceed to

the next screen.

6. Check the custom button and then click the next button.

38

7. Select all the program files and then click on the next button to proceed to the user

information window.

8. Fill out your name, your organizafion (optional), and the serial number for your

Adobe Acrobat 4.0 software. Click on the next button to the start softw are

installafion.

9. After complefion of software installafion, a registrafion window appears on the

screen.

10. Fill out and submit the software registrafion form and then restart the computer.

11. Once the registration is complete, a message window appears on the screen asking

to restart the computer in order to complete the software installation.

3.2 Scanning and Conversion of SWPSC Conference Proceeding-

After the installafion of required computer software, the paper copies of all the

conference papers are to be scanned that have been published during the last 46 years.

Therefore, all the SWPSC conference proceeding catalogs are gathered and separated into

single pages starting from the 1954 conference year catalog.

Hewlett Packard's Scan Jet n scanner, equipped with an automafic document feeder

(ADF), is selected to scan the conference paper documents. Because approximately 14,580

conference proceeding pages were scanned and converted to image files, the ADF scanner

is the best selecfion to scan a stack of conference pages at a fime rather than scanning each

single page manually.

39

Prior to starting the paper-scanning job, it is required to customize the program

settings for the Acrobat Capture 2.0 program before performing a paper-scanning job. A

step-by-step procedure to setup the Capture 2.0 program is given below:

1. Run the Acrobat Capture 2.0 program.

2. Click the File tab on the menu bar, as shown in Figure 3.2.

3. Select the Preferences option on the pull-down bar. A Capture-Preferences window

appears on the screen.

4. Select the opfions, as shown in Figure 3.3, and then click the OK button.

5. Click the Input tab on the menu bar followed by Add Input Folder, located on the

Input tab's pull-down bar. An Input Folder Setup window appears on the screen.

6. Fill out the Description and Locafion text fields, as illustrated in the Figure 3.4, and

then click the OK button.

7. Click the Output tab on the menu bar followed by Setup Output Folder. An Output

Folder Setup window appears on the screen.

8. Select the setup opfions in the Output Folder window, as shown in Figure 3.5, and

then click the OK button.

Customizafion of the Acrobat Capture 2.0 program is complete. The scanning

procedure using Capture 2.0 program followed by format conversion of the scanned copies

is outlined. The following sequence of steps accomplishes the scanning of the SWPSC

conference papers followed by format conversion of the scanned papers:

1. Start the Acrobat Capture 2.0 program.

40

1^ Acrobat Capture 2.0 Input Process Output Help

j ^ Eefresh Folders F5 \ Preferences...

rocess 1 | Edit Custom Dictionary...

^ ' Alt>F4 1 Pull-down Bar

Tab

ess \Zy

n&B ^Mk

— Menu Bar

'O

I slJ-Scan \

I

i m

r ^toceis

. j ^ " ^

0 In

(•J/ Samples

Watch

paulus

< Path Not Available >

c.Acapture2\samplus ^ •"vrnfm. J.

To Review

PDF

HTML

Word Processo

Samples Out

< Path Not Available >

{ACQ} c:\capture2\review

I Most Accurate

Figure 3.2. Adobe Capture 2.0 program's main window.

41

Capture - Preferences

' Confirmations: R jConfirrn Deleting of Filesl

W Confirm Replacing of E>dsting Documents I F Confirm Appending to Existing Documents I Iv' Confirm Canceling of Processing

I PDF Compression Options: ^ Use Capture Defaults

r Use PDFvVriter Settings

P Downsample images (optimized)

jv* Show Splash Screen On Startup

Retain 30 Newest Daily Log Files {1 ..365}

Location for Temporary Files: c:\capture2\temp\capture

OK Defaults Cancel

Figure 3.3. Adobe Capture 2.0 program's preferences window.

42

Input Folder Setup

Description: SWPSC

r^Watch Folder for New Image Files i

W Collate Files by Common Prefix

r Collate All Selected Files if'A

OK Defaults Cancel

Figure 3.4. Adobe Capture 2.0 program's Input Folder Setup window.

43

Output Folder Setup

SWPSC

.JiiH~

Description;

Location

File Formats (Ctrl+Clickto toggle selection)

c \capture2 Bi

Acrobat Capture (ACD) Acrobat PDF [Normal] Acrobat PDF flmaqel Acrobat PDF rimaqe + Hidden Text ASCII Text Rich Text Format

yuspectSetting$

Processed Images

zJ

Figure 3.5. Adobe Capture 2.0 program's Output Folder Setup window.

44

2. Place a set of complete conference paper on the scanner's ADF with the paper title

facing in the opposite direction to the scanner's ADF surface.

3. Click the Process tab on the menu bar followed by the Scan to Input Folder tab. .A

scan window appears on the screen.

4. Fill out the Document Name text field. As shown in Figure 3.6, it is recommended

to use document names such as 1954001, 1984043, where the first four digits stand

for the year when the paper was published and the last three digits are used to

differentiate each paper as they are numbered in the conferences' paper catalogs.

5. Click the Start button on the Scan window to start the scanning of the conference

paper.

6. Once the scanning job is done for any particular set of a conference paper, click the

Process tab followed by the Process Input folder tab. This starts the format

conversion of the scanned paper from image to the portable document format (pdf).

7. Repeat the steps 2-6 to scan and convert the whole collection of SWPSC

conference papers into the PDF format.

3.3 Conditioning of SWPSC PDF Files

It was required to read all of the SWPSC conference proceedings and make a list of

keywords for each of those read papers to condition the SWPSC PDF documents. The

main objective for finding technical keywords from each of the conference papers,

presented during 46 years of the SWPSC conference, was to use them as an input

parameter in the document information section of each of the conference paper's PDF files.

45

Scan

Document N ami e:

195^001

Start Scanning at:

Front Side of Sheet Number:

First Image Filename:

]l 95-1001^001 atif

11 Start Defaults Cancel

Figure 3.6. Adobe Capture 2.0 program's scan startup window.

46

In addition, other parameters were also entered in the document information section of each

paper such as: paper title, subject, and author's name. For demonstration puipose, a step-

by-step procedure is outlined below on how to condition the SWPSC conference papers:

1. Start the Abode Acrobat Reader 4.0 program.

2. Click the File tab on the menu bar. A pull-down bar appears on the screen.

3. Click the Open tab, located on the pull-down bar.

4. An open window appears asking to locate the SWPSC PDF files on the computer.

5. Locate the file folder containing SWPSC files by pressing the arrow button as

shown in Figure 3.7.

6. Double click on any of the SWPSC conference paper's PDF file to display the

paper.

7. Click the File tab on the menu bar.

8. Move the mouse pointer to the Document Info tab, listed on the pull-down bar.

9. Click the General tab. A General Info window appears on the screen.

10. Fill out all of the empty fields in the general info box by entering the title, subject.

author's name, and technical keywords from the displayed conference paper. As an

example, completed Document Information of one of the SWPSC PDF documents

as shown in Figure 3.8.

i 1. Click the OK button to close the General Info window.

12. Click the File tab and then click the Save tab, located on the pull-down bar, to

save the conditioned or enhanced conference paper PDF document.

47

Open

Look in:

^1954001

§1954002

11954003

S i 954004

S i 954005

B1954006

•.11954

—j Removable Disk (D:)

mj (E:)

^ (F:)

_jJ Swpsc on 'Petroleum_engr1' (G

Zl Swspc ZjCdl

^^ 13 m

15

16

7

pe_apps on 'Pelroleum_engr1' •

18

Filename: . 1954001

Files of Ivpe; Acrobat (^pd[)

1954019

1954020

1954021

±1 Open

• • i • • Ml

Cancel

Figure 3.7. Adobe Acrobat 4.0 program's Open window.

48

Geneial Info

Title:

E:\ThesisM954020.pdf

Jubject:

Care and Maintenance of Long Stroke

Artificial Lift

Author:

Keywords:

finding:

Clyde H Lietzow

I hydraulic pump production rod air bale

] Left Edge j j

Creator: Acrobat Capture Server 2.0

Producer: AcrobatPDFWrlter3.01 forWindows

Created: Wednesday. June 30.1999 4:46:08 PM

Modified: 8/10/1999 3:41:52 PM

Optimized: Yes File Size (Bytes): 362540

PDF Version: 1.2

OK Cancel

Figure 3.8. Adobe Acrobat program's General Info window showing document details of some enhanced SWPSC

PDF document.

49

13. Repeat the steps 2-12 to scan and comert the whole collection of SWPSC"

conference papers.

3.4 Indexing of enhanced SWPSC PDF Files

Adobe Acrobat Catalog software builds a single full-text index tile of all the PDF

document files. A searchable database of all the text present in a PDF document or a

collection of documents is called a ''full-texf index. Adobe Acrobat Reader uses a full-

text index file to locate any desired PDF document from the collection of indexed PDF

documents. The steps below create the full-text index file for the collection of 46 \ ears

of SWPSC enhanced PDF documents:

1. Run the Adobe Acrobat Catalog 4.0 program.

2. Click the Index tab on the menu bar.

3. Click the New tab on the pull-down bar. As shown in Figure 3.9, a New Index

Definition window appears on the screen.

4. Fill out the Index Title field with an appropriate title for the index file.

5. Click the Options button. An Options window appears on the screen. Select the

appropriate option boxes, as shown in Figure 3.10, and click the OK button.

6. Click the Add button located to the right of the Include Directories text field area on

the New Index Definition window. A new Browse for Folder window appears

requesting location of the file folder that contains conditioned or enhanced PDF

files of all the SWPSC conference papers.

50

New Index DeMnilion

Index File:

UNTITLED

Index Title: j

Index Description:

Include Directories

-Exclude Directories-

*«"»»4*'

i>e

Cancel

" 3 Qp'i

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ions...

Build

Add...

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Figure 3.9. Adobe Catalog 4.0 program's New Index Definition window.

51

Options

Words to not include in index

Add Remove

Word:

f Do not include numbers

rV/ord Options .<4-.

F iCase Sensitive R^Sounds Like p Word Stemming

r Optimize for CD-ROM

r Add I D s to Acrobat 1.0 PDF files v:-,ff •

OK Cancel

Figure 3.10. Adobe Catalog program's Options window.

52

7. Locate the file folder that contains SWPSC conditioned PDF files and then click the

OK button.

8. Click the Build button to start creating an index file. A new w mdovv appears on the

screen asking to specify the file directory or location to save the index file. Sa\ e

the index file in the same folder where the SWPSC enhanced PDF files are saved

and then press the OK button to start the indexing process. Figure 3.11 shows the

indexing of enhanced PDF files in progress.

3.5 Customization of Adobe Acrobat 4.0 program

In this section, a step-by-step procedure is presented on how to customize the

search parameter fields in the Acrobat search engine. In addition, a procedure is also

outlined on how to link the SWPSC index file with the Acrobat search engine for finding

information from a collection of SWPSC conference papers.

1. Start the Acrobat Reader 4.0 program.

2. Click the File tab on the menu bar.

3. Move the mouse pointer to the Preferences tab on the pull-down bar and click the

Search tab. An Acrobat Search Preferences window appears on the screen.

4. Select the options, as shown in Figure 3.12, and click the OK button.

5. Click the Edit tab on the menu bar and move the mouse pointer to the Search tab.

A new pull-down bar appears.

6. Click the Select Indexes tab. An Index Selection window appears.

53

Acrobat Catalog

File Index Help IH

Status: Indexing Group 1

Index: SWPSC

0 files in index.

File: q:\swspc\cd3\1999\1999031 .pdf

Page: 4 out of 8

File Count: 31 out Of 512 Files in Group 1

6%

£top

Messages:

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^

ij

Figure 3.11. Adobe Catalog 4.0 program's main window.

54

Acrobat Search Preferences

Query— ~7

\i^ iSfiow Fieidsi s . . . . . r 7 7 .f

W Show Options

f~ Show Date

r~ Hide on Search

Resu l ^^ -•Sim's,"

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Figure 3.12. Adobe Acrobat 4.0 program's search preferences window.

55

7. Click the Add button and locate the index file, as shown in Figure 3.13. Select the

index file and click the Open button.

8. Click the Ok button on Index Selection window.

The customization of the Acrobat Reader is done. A search can be performed from

any available information in the developed SWPSC searchable database. The given

sequence below is followed to find desired technical information from the SWPSC

searchable database:

1. Run the Acrobat Reader 4.0 program.

2. Click the Edit tab on the menu bar.

3. Move the mouse pointer to the Search tab and click the Query tab. An Adobe

Acrobat Search Engine appears on the screen, as shown in Figure 3.14.

4. Complete the desired text field(s) in the search engine window and click on the

Search button. Based on the entered information, a list of found SWPSC technical

paper(s) is displayed on the screen.

After the SWPSC database is developed, the whole database is copied to compact

disc (CD). Only 3 CDs are required to accommodate this whole collection of SWPSC PDF

documents.

Searches can be performed on the SWPSC papers' database by paper title, subject,

author's name, keyword(s), or any combination of all these search parameters. This

searchable database supports both structured and unstructured searching methods. Unlike

the unstructured search routine in SPE image library where only the contents on the first

56

.''" *' Currently unavailable indexes'afe grawdput .>*^>

Figure 3.13. Adobe Acrobat program's Add Index window.

57

Adobe Acrobat Search

Find Results Containing Text

Vv'ith Document I n f o ^

Title

Subiect

Author j

Keywords

îflimwirii-'riffrTr ••'' •

H^lttHttaMMMH

Options

jearch

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. j^ppr m^^m'f'o^. ,, '^"""•mmmms^^^mmm

W Vjjord Stemming Pilhesaurus

P Sounds Like I ... . , „ _

^ g in the SWPf C indej^

r" Match Case

V Proximity >-;„:.;

SSWM

Figure 3.14. Adobe Acrobat program's built-in search engine window.

58

page of the conference paper can be searched, the SWPSC database permits to search for

any particular information from the full content of the SWPSC PDF file or set of PDF files.

59

CHAPTER 4

EXAMPLE APPLICATION OF THE SWPSC DATABASE

The SWPSC searchable database, developed in this work, is a fast and efficient

knowledge base tool for the petroleum industry especially from the Permian Basin.

Available literature can be quickly found on the possible solutions to a particular existing

problem. By using the SWPSC searchable database, it is now possible to perform searches

for any particular information that is available in a collection of the SWPSC PDF

documents.

The SWPSC searchable database supports both the structured and unstructured

search strategies. Unlike the unstructured search procedure in the SPE image library where

only the word or a phrase, present on the first page of the collection of SPE technical

papers, can be matched with the user provided search parameter (word or phrase), the

SWPSC searchable database allows searches from the full contents of the SWPSC PDF

documents. The SWPSC searchable database is used in the next section to test its

efficiency for retrieving SWPSC technical papers that have been published on paraffin

control and removal methods over the past 46 years of the SWPSC annual conference.

4.1 Test of the SWPSC Searchable Database

By using the Adobe Reader (Adobe Reader with built-in search engine) software, a

search is performed to retrieve the SWPSC conference papers. There are 1641 SWPSC

conference papers that have been published over the past 46 years (Figures 4.1 and 4.2).

60

(0 o > 0) o c 0) k.

0) « • -c o o o </)

0)

# of SWPSC Papers

Figure 4.1. Total Number of Papers published each year during the SWPSC Conferences from 1954-1977.

61

(0 0) >-o o c

c o o o 0) Q.

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1999 1998 1997 1996 1995 1994 1993 1992 1991 1990 1989 1988 1987 1986 1985 1984 1983 1982 1981 1980 1979 1978

-

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Figure 4.2. Total Number of papers published each year during the SWPSC Conferences from 1978-1999.

62

The word "paraffin" is used one-by-one in the title and key\\ ord text-field sections

of the Adobe Reader's built-in search engine. The search results, by using keyvsord text-

field, are illustrated in Figures 4.3,4.4 and 4.5. Thirty-six out of 1641 SWPSC conference

papers are retrieved that contain literature related to paraffin. Table 4.1 provides detailed

search results of the retrieved papers.

4.2 Review and Summarv of Paraffin Treatment Methods

The SWPSC searchable database is fast and precise tool for retrieving the SWPSC

conference papers on paraffin treatment methods. The maximum number of papers,

retrieved after the paper search from the SWPSC searchable database, are found b>

performing a search using a word "Paraffin" in the keyword text-field secdon of the Adobe

Reader search engine (Table 4.1). These 36 SWPSC papers are reviewed to find all the

treatment methods for paraffin control and removal. After reviewing all these 36 papers, it

is found out that 24 out of 36 contain literature on paraffin treatment methods (Figures 4.6,

4.7, and 4.8). In Table 4.2, a list of authors is tabulated who have presented technical

papers on paraffin control and removal methods over the past 46 years of the SWPSC

annual conference. All the published treatment methods for paraffin control and removal

are categorized and summarized in the next four subsections.

63

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CD 00 CO

en

SWPSC Conference Year (1954-1969)

05 CD C7)

L. • Total # of Papers • Papers retrieved by keyword "Paraffin"

Figure 4.3. Year-to-year (1954-1969) comparison of the total SWPSC technical papers versus SWPSC papers retrieved by

keyword search "Paraffin."

64

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• Total # of Papers • Papers retrieved by keyword "Paraffin"

Figure 4.4. Year-to-year (1970-1985) comparison of the total SWPSC technical papers versus SWPSC papers retneved by


65

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• Total # of Papers • Papers retrieved by keyword "Paraffin"

Figure 4.5. Year-to-year (1986-1999) comparison of the total SWPSC technical papers versus SWPSC papers retrieved by


66

Table 4.1. A detailed summary of search results performed on the SWPSC searchable database with a keyword "Paraffin."

Year

1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978

Total # of Papers

21 31 46 44 44 48 43 39 45 34 29 32 28 26 26 26 24 29 25 31 27 44 47 36 33

Papers retrieved with a word "Paraffin"

Search by Title text-field

2 2 2 1 3 -

1 -

-

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1 -

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1 -

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Search by Keyword text-field

3 3

Papers containing Paraffin Treatment

Methods

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67

Table 4.1. (Continued)

Year

1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999

Total # of Papers

^ 28 32 40 26 38 43 43 37 28 40 39 46 37 40 41 31 41 37 41 35 41

Papers retneved with a word "Paraffin"


-

-

-

1 -

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-

-

-

1 2 -

1 2 1 -

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-

-

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-

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SWPSC Conference Year (1954 -1969)

• Total # of Papers

• Papers retrieved by keyword "Paraffin"

ED Papers containing Paraffin Control and Removal Methods

Figure 4.6. Year-to-year (1954-1969) comparison of the total SWPSC technical papers, papers retrieved by keyword "Paraffin," and papers

on Paraffin Treatment Methods.

69

Q. (0 Q.

"TO u

o o h-O </) Q.

47 44

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ED Papers containing Paraffin Control and Removal Methods



70

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to 00 00

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cn o T-00 o) a> O) O) o>

SWPSC Conference Year (1986 -1999)



Dl Papers containing Paraffin Control and Removal Methods



71

v* ^0r

Table 4.2. A list of authors of the SWPSC technical papers on Paraffin Treatment Methods during the SWPSC annual conference (1954-1999).

Author

Addison G. E. Brown M. J. Bishop M. D.

Brock R.

Barker K. M. Cushner M. C. Cotney C. R. Comey J. D.

Chee W. Cunningham J. A.

Crawford J. D. DobbsJ. B. Garbis J. S. Haynes J. Herman J.

Ivanhoe K.

Jordan R. M. KingS.R.

# of papers on Paraffin Treatment Methods

2

2

Category and Method for Paraffin Treatment

Thermal (Hot Oiling) Thermal (Exothermic Reaction)

Other (Biological Treatment) Chemical (Squeeze Treatment with

Dispersant) Thermal (Hot Oiling)

Chemical (Crystal Growth Modifier) Chemical (Solvent)

Other (Magnefic Fluid Conditioning) Other (Biological Treatment)

Thermal (Hot Oiling) Chemical (Solvent)

Thermal (Exothermic Reaction) Chemical (Crystal Wax Modifier)

Other (Linear Kinetic Cell) Thermal (Hot Oiling)

Thermal (Hot Oiling), Other (Plastic Coating)

Other (Plasuc Coating) Chemical (Solvent)

72

L


Author

KingS.R. KostoffN. V. Lukehart C. O

McKinneyT. B. Mancillas G.

MsCaskill B. M. Mansure A. J.

Mendell J. L.

Olsen H. R. O'GradyC.

Snedeker K. D. Shroyer L. L. Trainer J. C. Woo G. T. Wilson J. J.

Woodward D. R. While J. M. Ward J. L.

Young M. A.

# of papers on Paraffin Treatment Methods

2


Chemical (Solvent) Chemical (Dispersant)

Other (Butane Injection) Chemical (Solvent)

General Chemical (Solvent, Dispersant)

Thermal (Hot Oiling) Chemical (Sohent. Dispersant,

Crystal Wax Modifier) Chemical (Crystal Wax Modifier)

Other (Biological Treatment) Mechanical (Scraper, Soluble Plug)

Other (Linear Kinetic Cell) General

Chemical (Crystal Wax Modifier) Other (Biological Treatment) Other (Biological Treatment)

Other (Plastic Coating) Mechanical (General)

Mechanical (Rod Scraper)

73

4.2.1 Mechanical Treatment Methods

Before the 1950's, more importance was given to removal of paraffin deposition

rather than prevention of paraffin formation. One of the mechanical methods for paralTin

removal from the production tubing was based on using the wire-line scraping tool.'^ The

wire-line scraping device is equipped with the knife-edge cutters which could thoroughly

scrape the paraffin deposits from the inside surface of the tubing string while pulling the

wire-line tool up through the tubing.

In the 1950's, a device called a "rabbit" was available in the market for commercial

use. A rabbit is a mechanical scraping device, which is dropped down through the tubing

string while well is in shut-in condition. ^ It is allowed to fall down freely to the stop ring,

placed below the bottom level of paraffin deposits in the tubing string. The diameter of the

rabbit gets bigger as soon as it hits the stop ring. After the well production is resumed, the

well fluid pressure pushes the rabbit up back towards the wellhead. Paraffin deposits are

scraped from the tubing wall by cutting edges of the rabbit and carried up to the surface

with the produced fluid. Once the rabbit reaches to the top, it is retrieved out from the

wellhead.

Another effective mechanical method, available for paraffin removal from tubing

strings and flow-lines, was the use of soluble plugs. ' One of the advantages of soluble

plugs was their tendency to dissolve in the crude oil after the paraffin treatment operation.

Therefore, the need to recover these paraffin-cutting plugs was eliminated. Soluble plugs

had strength enough to clean the paraffin accumulation from the inside walls of the tubing

string and flow-lines by applying a fluid pressure behind the plug. A variety of different

74

diameter soluble plugs were available for several tubing and flow-line sizes. Because the

use of soluble plugs was not an expensive operation, Ward^^ recommended using soluble

plugs frequently to prevent a large paraffin accumulation. For cultivated areas, where all

the flow-lines with low flow rate were installed below the ground surface, Snedeker^^

emphasized more on running soluble plugs on a strict schedule to clean flow-lines from

paraffin deposits.

The oil industry was introduced with a new technology for paraffin removal from

rod pumped wells by using rod type paraffin scrappers. According to Young, ^ the rod

scrappers gained populanty between 1946 and 1950. The Huber rotating flat blade, triple

horn spiral, sunshine continuous spiral, and crall type spiral were the most popular types of

the sucker rod paraffin scrappers.

With the advent of hollow sucker rod string (Figure 4.9), heat loss to the well-bore

CC - i c

surrounding formation was considerably reduced. ' Hot oil was injected down to the

tubing through the hollow rod string. The hollow rod had a check valve at its bottom end.

After the injected hot oil reaches the check valve, it enters to the tubing string and further

flows down to the bottom of the well-bore to melt and dissolve paraffin deposits from the

tubing wall. Ward^^ recommended using hollow rod string in high paraffin producing

fields because of high installafion costs as compared to convendonal rod installations.

4.2.2 Thermal Treatment Methods

The hot oiling or watering method gained wide acceptance for paraffin deposit

removal because of its simplicity in application, low cost to accomplish treatment jobs, and

75

Figure 4.9. Hollow Sucker Rod String n

76

- ' M . 1 ^ i^l^^

immediate paraffin treatment results. According to Snedeker, ^ the hot oiling and steaming

were two of the most common thermal methods for paraffin deposit removal in the rod

pumped wells. Steam or crude oil with a temperature approximate!) 300 F vscre miccted

into the annular space between the tubing stnng and casing. This technique allovsed the

injected steam or hot oil transferring heat to the paraffin deposits, accumulated on the inner

surface of the tubing string, through the tubing walls and thus softening and dissoh ing the

paraffin into the produced formation fluid. Paraffin melts and dissolves in the tubing fluid

and carries up to the surface with produced formation fluid.

However, there were many disadvantages in using this method which had been

ignored during the past years of paraffin removal operadons.^^'^' One of the disadvantages

in hot oiling operations was the composition of the source oil used for paraffin treatment

operations. It was a general practice to draw source oil for hot oiling from the bottom of

the storage tanks, located near the paraffin treatment wells. These storage tanks usually

contained crude oil with high quanfifies of paraffin contents, as the produced oil coming to

these storage tanks was usually from the same wells that were to be treated for paraffin

deposits removal.

At the surface pressure and temperature conditions, paraffin and asphaltic

components of the crude oil have a greater tendency to precipitate and settle on the bottom

of the storage tanks. Crude oil with paraffin content oil is heated and pumped down to the

well-bore for paraffin removal. It starts losing heat to the walls of the tubing, casing, and

fluid produced by the formation. By the time injected hot oil reaches the bottom of the

annular space between casing and tubing string, it can loose enough heat to precipitate

77

paraffin deposits, present in the injected hot oil itselfi In addifion, light hydrocarbons

vaponze from the injected hot oil and cause the loss of oil from the hot oil. Such light

hydrocarbons, escaped from the injected hot oil, travel up to the wellhead as a gas and

cause an increase in the percentage of paraffin in the remaining hot oil. Such increase of

paraffin's percentage in the injected oil raises the cloud point and thus, causing paraffin

precipitation in the injected hot oil at relatively higher temperature.

Injection of high paraffin content hot oil and the loss of light hydrocarbons causes

severe damage to the producing formafion by plugging the face of the formation with

paraffin, precipitated from the injected hot oil and formadon fluid near the bottom of the

well-bore. This happens when the hydrostafic pressure, applied by the fluid column in the

annulus near the bottom-hole area of the well-bore, becomes greater than the formation

pressure and fluid column exerts pressure on the injected hot oil near the producing

formation. This pressure forces the hot oil with precipitated paraffin content to invade into

the producing formafion face.

HeiTnan et al. ' '' recommended the following possible solufions to the

disadvantages of using high paraffin content oil:

• Use of oil from the top of the storage tanks as the source oil for hot oiling

operations.

• Periodical clean up of the producing formafion face.

• Use of chemical dispersants in the source oil to prevent paraffin precipitafion from

the injected hot oil itself.

• Use of other available fluid (low salinity water) as a source injection fluid.

78

Oil field operators were also successful in removing paraffin deposits from the face

of the producing formafion by using different expensive techniques such as explosive shots

of nitroglycerine, down-hole electrical heaters, and heat-generating chemical reactions that

heat up and dissolve paraffin deposits from the producing formafion face. The importance

of direct heat of the sunshine was also considered as one of the available methods for

controlling paraffin deposition in the flow-lines, laying on the surface. ^

Recently, a novel method was introduced to the oil industry for paraffin wax and

1 ^

asphaltene removal by generafing an exothermic reacfion. The reacfion process was

reported to be non-aqueous and produced a paraffin dispersant as a reaction by-product that

prevented re-deposition of dispersed paraffin in the treated fluid at normal temperature.

One of the advantages of non-aqueous based exothermic reacfion was to prevent the

formafion of water/oil emulsion while treafing crude oil for paraffin removal. The process

of the exothermic reacfion involved generafion of heat by mixing an organic acid

compound with an organic base compound or inorganic base on the surface and pumping

the mixture through the tubing to generate temperature enough (>212 °F) to melt and

disperse paraffin wax and asphaltene deposits. A number of solvents were available to

carry the reactants to the paraffin affected area in the production zone. After the treatment

well was shut-in for 20-40 minutes, pumping the injected fluid back to the surface retrieved

melted or dispersed paraffin wax and asphaltenes. Brown and Dobbs' stated three major

advantages of using exothermic method for paraffin removal: • Sufficient heat release to melt paraffin deposits.

• Excellent behavior of reactant-carrier solvent at elevated temperatures.

79

Complete removal of paraffin affected lines due to produced paraffin dispersant

from in-situ exothermic reacfion.

4.2.3 Chemical Treatment Methods

Before the second half of the 20" century, most of the paraffin removal jobs wcie

accomplished by mechanical means only. ^ Use of mechanical methods to prevent or

remove paraffin accumulation became economically prohibitive with the advent of offshore

production technology. It became necessary to use chemical methods for paraffin build-up

inhibifion or removal.* "

Chemical solvents were used as a paraffin softening agents to break up or soften

accumulated paraffin into small and soft paraffin particles from the inside surface of the

producfion and transportafion lines so that produced formafion fluid could flush the

dispersed paraffin particles along the line. For softer paraffin deposits (composed of lighter

paraffin hydrocarbons), a mixture of white gasoline or kerosene with chemical solvents was

frequently used to treat such deposits. The type and amount of the paraffin deposits were

the two major deciding factors for the volume of solvent to be used for paraffin treatment

purpose. McKinney^ ' ^ recommended obtaining a paraffin sample from the troublesome

wells with paraffin accumulation problem and testing the sample in different chemical

solvents to And the best solvent available to treat the well. For cleaning flow-lines with

severe paraffin deposifion, a small amount of solvent was suggested to flush through the

line to gradually remove paraffin without clogging the flow-lines followed by pumping

larger volume of solvent along the flow-lines.

80

I

- ^

Chemical treatment of wells with paraffin problems required frequent injecfion of

chemical solvents in the annular space between tubing string and casing to mix with the

crude oil in the bottom of the hole. Confinuous injection of paraffin inhibitors into the well

casing and surface lead lines was often reported to minimize build-up and accumulation of

paraffin crystals in the produced formation fluid. Use of an efficient chemical solvent of

chlorinated type, namely carbon tetrachloride, caused severe corrosion problems in many

production facilities and consequently was banned by the government for use in the oil

fields. At the same time, carbon bisulfide was widely accepted as an efficient chemical

solvent for paraffin inhibition. Extreme care was recommended in handling carbon

bisulfide because of its potential to quickly react upon exposure to flame

Reduction in hot oiling operations was achieved with the development of

systematic squeeze treatment technique. According to Brock, ^ the squeeze treatment

method was tested on two of the producing wells in Test Lease No.3 in Spraberry

Formation, West Texas, in June 1983. Before squeeze treatment operation, hot oiling

method was practiced on both of the test wells to prevent paraffin accumulation on the

producing formation face and the tubing. The squeeze treatment was performed by mixing

25 barrels of crude oil with one drum of chemical (dispersant), pumping the mixture into

the annulus, and flushing the annulus with 150 barrels of produced water at a controlled

pumping rate not exceeding 2.5 barrels per minute. After the squeeze treatment, it was

reported that none of the test wells were hot oiled for over one year. Figure 4.10 shows the

improvement in well production in one of the treated wells, from Test Lease No. 3, during

pre-squeeze, post squeeze, and after hot oiling was resumed.^°

81

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\ . A A / ^ ^ 3 ^ - , ^ ~

A A . ji.,' r

MONTHS BEFORE AND AFTER SQUEEZ." ANO AFTER HOT OILING RESJMEO

— > * i —

Figure 4.10. Improvements in Oil production during pre-squeeze, post-squeeze, and after hot oiling is resumed.^

(12-0 pre-squeeze, 0 - 1 2 post-squeeze, 0 - 9 hot oiling)

82

i

According to Lukehart,''^ a study on the paraffin deposition mechanism revealed

that the key factor behind paraffin separation from the crude oil, under well and flow-lines

operating conditions, was the solubility of paraffin in the produced oil. In April of 1956, an

experimental butane injection unit was installed on one of the oil producing wells in Carter

County, Oklahoma, in an attempt to reduce the paraffin treatment costs. The reason \\ h\

butane was selected for the injection purpose was because of its availability and cost

effectiveness. After two years of successful operation, paraffin control using this butane

injection technique saved approximately $2,200 over previous control methods on that

particular well. In general, the frequency and amount of butane injection was dependent

upon surface temperature conditions. Oil operators were able to reduce the paraffin control

cost as much as 90 percent over hot watering that was previously practiced on this well for

paraffin control.

In an attempt to minimize the treatment costs on producing wells with potential

paraffin problems, a novel method was tested on one of the producing wells in the Ackerly

Dean Unit in the Dawson County, Texas. The technique involved the addition of crystal

growth modifier in both solid and liquid forms to the well fracturing fluid. After the

successful fracture treatment of the well, no paraffin deposition problem was reported

during the next six months. Because the addifion of paraffin inhibitor was a one-time job,

it allowed for the operators to evaluate economics and choose from the available paraffin

deposition control and/or removal methods for the well treatment in future time.

Use of blended and refined condensate feedstock consisting of high multiple

aromatic hydrocarbons, became popular for dissolving and/or controlling paraffin and

83

asphaltene related problems.^^ Petroleum distillates were blended and refined to get

natural solvents with high solvency, demulsifying and wettability properties. These natural

solvents proved to be cost effective and offered enhancement to the other available paraffin

treatment methods. One of the techniques to enhance the paraffin treatment by hot oiling

or hot watering was to add the natural solvents (10% by volume) to the hot oil or water

treatment. According to King and Cotney, ^ "Although condensate should not be injected

into the formation it may be economical and practical to use them as flush volumes.

Injecting 5% to 20% of the refined natural solvents in front of the condensate treatments

can greatly enhance the performance. The condensate will wash all the solvents to bottom

and provide a diluting fluid to the paraffin saturated production" (p. 262).

4.2.4 Other Treatment Methods

A number of production techniques were practiced in the oil fields to prevent

paraffin precipitation. According to Ward, ^ more emphasis was put on paraffin control

than deposit removal. It was suggested that changes should be made in the operating

conditions which cause paraffin accumulation such as temperature change in the production

tubing and flow lines, loss of light hydrocarbon compounds from the crude oil mixture, and

pre\cntion of precipitated paraffin cr\stals to agglomerate in the well producing fluid. A

number of oil field operators were successful in removing the semi-fluid paraffin deposits

from high capacity oil wells by periodically pumping the wells at higher flow rates.

Ward^^ further mentioned that the above stated method could lead to formation damage due

84

to gas or water coning. Several production methods were suggested to control paraffin

build-up problems as follows:^^

• Maintaining a vacuum in the annulus of the well-bore to reduce heat loss from the

produced formation fluid in the tubing. The presence of vacuum minimizes the

heat loss by eliminating the medium required to transfer heat between the tubing

and the surrounding formation.

• Minimizing heat loss from the produced formation fluid in the transportation lines

with a use of small diameter flow-lines. Small diameter pipe reduces the travel

time of flowing fluid that leads to lower heat loss to the surrounding through pipe

walls.

• Using a backpressure regulator on the production tubing to prevent vaporization of

light hydrocarbons from the produced oil.

Injection of heated gas was also reported in some gas lifted wells to prevent paraffin

deposition. This method was limited to field application due to the low heat capacity of the

injected gas. ^

Removal of paraffin deposits had always been a never-ending problem lor the oil

operators. Oil industry was always in search of more economical method for paraffin

removal. Plastic coated pipes served a two-fold purpose in wells with potential paraffin

and corrosion problems by preventing paraffin build-up and protecfing the tubing string or

flow-line against the corrosive elements. White stated that the success of plasfic coafing

to prevent paraffin build-up was 80-85% dependent upon the coating application procedure

and from 15-20% on the plastic coating material. According to Jordan,^^ surface roughness

85

•X

^

was the main factor contributing to the characteristics and amount of the paraffin

deposition.

Even though the use of plastic coated tubing strings and flow-line was proved to be

a successful means of preventing paraffin deposition, in some cases plastic coated

equipment was not able to prevent paraffin build-up on the inner surfaces of the production

and transportation lines. Jordan^^ explained this phenomenon by analyzing the physical

and chemical characteristics of three widely used oil field plastics that are given below:

• Phenol formaldehyde - It has excellent resistance to temperature, chemicals, and

molecule infusion such as H2O, H2S, and CH4. It has a vcr\ glossy, smooth surface.

In the case of contact with abrasive material such as sand, it deforms ver\ badly and

thus affects the surface smoothness.

• Epoxy Phenolic - This type of coating has less resistance to chemicals,

temperature, and molecule infusion as compared to phenol formaldehyde. It has

more erosion resistance to abrasive materials than phenol formaldehyde.

• Pol> urethane -This type of plastic coating is the least resistant to temperature,

chemicals, and small molecule infusion among all these mentioned plastic

coating types. In the case of an abrasive environment, polyurethane has a

tendency to deform slightiy and maintain its smoothness.

By looking at the physical characteristics of all these plastic coating types, it was

recommended to use phenol formaldehyde or epoxy phenolic in abrasion free producing

wells. In case of abrasive environment, use of polyurethane was recommended to control

paraffin build-up problems.

86

"sv

In 1978, a linear kinetic cell (LKC) was introduced to control scale formation in the

water system.' ' In the eariy 1980s, the LKC system was tested on various types of oils in

an attempt to find the applications of LKC system in oil industr\. Tests of LKC s\ stem

showed positive results in preventing paraffin accumulafion by polanzation and

stabilization of molecules within the fluid.

Paraffin molecules are present in the crude oil in dipole stage. Due to the intimate

contact with oil for several years, these paraffin molecules have posifive and negafive

charge ends. The LKC system involves polarization of charged paraffin molecules to

prevent deposifion and thus molecular suspension within the flowing fluid. The LKC

system had great advantages over the past methods of paraffin removal. Use of the LKC

system for paraffin removal resulted in the eliminafion of chemical solvents, paraffin

disposal problems, routine hot oiling operations to remove paraffin deposits, and increased

producfion. As shown in Figure 4.11, untreated crude oil with paraffin molecules enters

from one end of the LKC system and passes through the highly charged electric field.^'

Such high-energy electrical forces polarize the charged molecules in the oil and orient the

positive and negative ends of the polarized molecules in such a way that the molecules

come out from the LKC system in the form of a molecular chain. Once the molecular

chain of the paraffin molecules is formed, the force of attracfion between the tubing wall

and paraffin molecules is weakened due to the unavailability of free positive and negative

ends. Such phenomenon results in the suspension and stabilization of the paraffin

molecules in the crude oil and prevents molecules to adhere on the tubing walls and flow

lines.

87

• " - ^ v

r < ^ - #

^

(l

Figure 4.11. Schematic diagram of Linear Kinetic Cell. 71

88

During late 1980s, a large number of wells with severe paraffin accumulation

problems were treated by using biological products.^' " During experimental treatment

operations, three biological products were tested in the field. Two of those three biological

products were in a liquid form and contained anaerobic bacteria in the range of 10 -10^

bactena cells/ml. In addition, the third biological product was in the powdered form and

contained a mixture of aerobic bacteria with a cell concentration of 10 ^ cells/gm. A liquid

biocatalyst and an inorganic nutrient were also included in the powdered biological product

system to supplement the growth of aerobic bacteria and to enhance the metabolic

(decomposition) reactions of high molecular weight paraffin into smaller molecules within

the crude oil. These biological products, supplied b\ three different manulaciurci>, Had

non-toxic and non-hazardous properties.

Depending on the severity of paraffin accumulation, the frequcnc) of treatment

varied from one to two treatments per month. While using liquid biological product, one to

six gallons of the liquid was used to pump down in between the tubing string and casing.

The treatment was followed by brine water flush to allow the liquid biological product

mixture to reach the paraffin-affected area in the well bore. When treating with the

powdered product, a mixture of brine water and powdered product used to pump in the

annular space between the tubing string and casing followed by a brine water flush. Before

injecfion of the flush water, it was required to add specific amount of biocatalyst and

inorganic nutrient in the flush water, which would supplement the bacterial growth in the

injected biological product mixture and enhance metabolic reactions in paraffin deposits.

89

Because bacteria need water to live and metabolize available hydrocarbons through

contact with oil/water interface. Bishop and Woodward^" recommended selecting the wells

for biological treatment that had water cut in excess of 1%. Reduction in bactenal activit)

was reported in low water cut wells. However, a combination of biological, mechanical, or

thermal methods was also suggested for treating wells with a water cut less than 1%. In

addition, a number of difficulties were encountered while treating flowing wells due to high

flow rates, gas expansion, and lower water cut. One of the reasons for paraffin treatment

failure using biological treatment methods was the high fluid level of produced formation

fluid in the annulus. High fluid level in the annulus hindered the placement of biological

products to the paraffin affected area in the well-bore. For high fluid level wells,

circulation of biological mixture was recommended for proper placement of the treatment

mixture to the production zone for paraffin deposit removal. The presence of hydrogen

sulfide (H2S) in the well can inhibit bacterial activity. According to Bishop and

Woodward,^^ the biological treatment was failed in two wells with a H2S concentration in

excess of 6% in the solution gas. After 60 days of treatment operations, the concentration

of H2S reduced the bacterial count to 10 bacteria cell/ml that resulted in the failure of

paraffin treatment operation. The biological treatment method was pracficed on 563 wells

in Central Texas and Alberta. The need for hot oiling as a combination method to control

problems was completely eliminated in most of those wells. Figures 4.12 and 4.13 show

the number of remedial hot oil treatments, required after the wells were put on the

72

biological treatment program for paraffin deposit removal.

90

" ^

POWDER BACTERIA PRODUCT

HOT OIL (5.7%)

NO HOT OIL (94.3%)

LIQUID BACTERIA PRODUCT

HOT OIL (52.3

NO HOT OIL (47,7%)

Figure 4.12. Number of remedial hot oil treatments required on the wells in Central Texas and Canada with biological

72

treatment program.

91

^

POWDER BACTERIA PRODUCT

HOT OIL (12.4%)

NO HOT Olu {87.6%J

LIQUID BACTERIA PRODUCTS

NO' HOT OIL (58.6%)

Figure 4.13. Number of remedial hot oil treatments required on the wells in Central Texas and Canada with biological

treatment program. 72

92

m-m>^mmif N

Some oil producers used magnetic fluid conditioners (MFC) to treat paralTin

accumulation problems in the oil well. " No external power was required to operate this

magnetic tool. The MFC system made a great contribution in reducing paraffin treatment

costs and increasing oil production. In the MFC system, produced crude oil and water is

passed through strong permanent magnetic field within the tool. Strong magnetic fields

inhibit the accumulation of scale and paraffin by changing the growth pattern of paraffin

and scale crystals.

Installafion of the MFC system required the rods and pump to be pulled up to the

surface so that magnefic tool could be attached to the bottom of the pump. It was necessary

to determine the environment in the well for effective MFC design. MFC installations

were cost effective and environmentally safe as compared to chemical, thermal, or

mechanical methods. Figure 4.14 illustrates the increase in well production after MFC was

installed to control the severe paraffin accumulation problems in a particular well in

Manistee County, Michigan. " Prior to MFC installation, hot oiling, and chemical

treatment methods were used to control paraffin build-up problems.

93

^ ' Tw—im

0 wmm(mmmmm^/<^:^mmmr<^^^^ 0 5 10 16 20 25 30 05 40 45 50 55

OAVS A«er Maq-W€« M C iggg

Figure 4.14. Improvement in well producfion with the installation of magnetic fluid conditioner. 74

[Before Mag-well MFC (graph on the front side) - 0-55, After Mag-well MFC (graph on the backside) - 0-55]

94

CHAPTER 5

REVIEW OF SPE PAPERS ON PARAFFIN CONTROL

AND REMOVAL METHODS

The SPE image library contains 29,918 technical papers that have been presented in

the SPE conference from 1951-1997. Figures 5.1 and 5.2 show the year-to-year

distribution of these published SPE papers. By using the Wordkeeper retrieval software, a

built-in software facilitated with the SPE image library, a search was performed to retrieve

the SPE papers, containing literature on paraffin. The word "Paraffin" is used one-b\-onc

in the tide and keyword text-field secfions of the Wordkeeper retrieval software. The

search results are illustrated in Figures 5.3, 5.4, and 5.5. In addition, Table 5.1 provides

detailed search results of the retrieved papers.

5.1 Review and Summarv of Paraffin Treatment Methods

Paper search on the SPE image library, performed with a word "Paraffin" in the

keyword text-field, resulted with 310 papers out of 29,918 SPE technical papers (Table

5.1). These 314 SPE papers are reviewed to find all the treatment methods for paraffin

control and removal. After reviewing these papers it was found that only 19 out of 314

papers contained literature on paraffin treatment methods (Figures 5.6, 5.7, and 5.8). In

Table 5.2, a list of authors is tabulated who have presented technical papers on paraffin

control and removal methods. All the reviewed treatment methods for paraffin control and

removal are categorized and summarized in the next subsecfions.

95

• N v

X.

(0

o > 0) o c o c 0 o lU Q. 0)

975 974 973 972 971 970 969 968 967 966 965 964 963 962 961 960 959 958 957 956 955 954 953 952 951

'MMmmjmim 426 • ' > " " - >> "JiHWiM^ I 4 g 5

3 393 454

3 407 3 348

3 317 3 291

^••y"j'.'iJ^"'M,?"

2S3 263 = 3 245 = 1 2 5 1 =1242 3 231 = 3 252 226

3 189

177 86

=]76 3 73

=3 39 3 35 3 34

P7. # of SPE papers

Figure 5.1. Total Number of papers pubhshed each year during the SPE Conferences from 1951-1975.

96

1 ^

(0

o > o o c 0)

c 0 o LU Q. (/)

1997 1996 1995 1994 1993 1992 1991 1990 1989 1988 1987 1986 1985 1984 1983 1982 1981 1980 1979 1978 1977 1976

" ;""j wn'vi 11612 mm-w'iî^- r:>îiîi^MM«wMifw'iP4#' ^^ 1 9 3 3

^^^^^^^^^^Z^^^^^^^^^' ^ ^ ^ ^ ^ ^ ^ ^ ^ S l ] ^ 223 1598 ! j ^ i ^ ^ ^ ^ • ' ' > 'v>m>mAM>->- \ 1801

3 1736 w)'»«v-wjv*?!>w-y!j'M! ••>,'m,>>>>>mwm>mî^wmmM'w>'>r'''rr''^;' <",>»." \ 1 5 7 9

' . ' ' ' - T Z a 1940 " " " ^ wm7,-:wim. vmj»h>".mwm 1 2 9 0

wrm^^^mim'mmmj^my^^^^mmmm.

3 1220 'gTyj^g-wj'jjag'^.gffl^-îyg''g^ 1 2 5 1

«'g>'»> ';';»i»»ggi 99Q

3 998 ^m^m^m^^îmi'^^^îif^

^ S ^ ^ 8 5 9 733

ZZZSS11813 -'**•• - I 907

221584

3 472

= 1 5 2 6

3 471

Z1497

3 471

# of SPE papers

Figure 5.2. Total Number of papers published each year during the SPE Conferences from 1976-1997.

97

^ • «> M i l . ! . . i t l » -»n» ' - n ^

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252

(0

L.

a Q.

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210 226

177

86

73 76 ^

34 35 39

189

242 ^^^ 245 231 r-1

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i I

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r O L O CD

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u 5 c n cn OT cn

• " 3 -

.X3 cn

SPE Conference Year (1951-1966)

• Total # of Papers MPapers retrieved by keyword "Paraffin":

Figure 5.3. Year-to-year (1951-1966) comparison of the total SPE technical papers and SPE papers retrieved by keyword search "Paraffin."

98

MlJiW • " ""'^ ^-

584

0) a n

CL "re o 'E u

I -UJ Q. CO »^

o


D Total # of Papers MPapers retrieved by keyword "Paraffin"


99


DTotal # of Papers "Papers retrieved tDy keyword "Paraffin'


100

Jil

T "

^ w

Table 5.1. A detailed summary of search results performed on the SPE image library with a keyword "Paraffin."

Year

1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973

Total # of Papers

7 34 35 39 73 76 86 177 210 189 226 252 231 242 251 251 263 291 317 348 407 454 393

Papers retrieved with a word "Paraffin"


-

-

-

-

1 -

-

1 -

1 -

2 -

1 1 2 1 -

1 1 1 2 -

Search by keyword text-field

-

-

1 -

1 -

3 1 3 2 3 5 5 5 4 8 4 3 4 2 2 6 -


Methods

-

-

-

-

-

-

-

-

-

1 =

-

-

-

-

-

-

-

1 -

-

-

-

101


Year

1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997

Total # of Papers

465 426 471 494 471 526 472 584 807 813 733 859 998 990 1251 1220 1290 1940 1579 1736 1801 1598 1933 1612

Papers retrieved with a word ""Paraffin"


1 2 1 -

-

1 -

1 -

2 4 2 3 -

1 3 2 4 2 3 6 4 2 7

Search by keyword text-field

4 4 3 1


Vleihods

-

1 1 -

2 2 3 7 6 6 15 8 12 7 14 16 10 14 14 14 16 21 23 25

-

1 i

-

-

1

-

2

1 !

!

2

-

2

4

1

.

1 2

102

= ^

12 a

Q.

"(5 o 'E o I-m Q. w « ^ 0

-— CNJ r o L O L O L O cn cn cn

SPE Conference Year (1951 -1966)

nTotal# of Papers Bi Papers retrieved by keyword "Paraffin"

n Papers coritaJning ParaffJnJ3qntrol and Removaj Methods

Figure 5.6. Year-to-year (1951-1966) comparison of the total SPE technical papers, papers retrieved by keyword "Paraffin,'" and

papers on Paraffin treatment methods.

103

j f ^

a »rr-«'-^'n i - r F* "Ifc ^'' "

w

584

12 0) a n Q. 75 o 'E o h-LU CL (/} 1^ 0

454

407

348 317 n

291 263 r-i

393

497 465 471 „ 471

426

'/

526

y

472

^

>

SPE Conference Year (1967 -1981) D Total # of Papers

B Papers retrieved by keyword "Paraffin"

jP Papers containing Paraffin Control and Removal Methods j

Figure 5.7. Year-to-year (1967-1981) comparison of the total SPE technical papers, papers retrieved by keyword "Paraffin," and


104

j i r ^ ^ ^

:H>>»

^

a re

Q.

"re o 'E u I -LU OL W

.a E z

SPE Conference Year (1982 -1997)

nTotal# of Papers • papers retrieved by keyword "Paraffin" D Papers containing Paraffin Control and Removal Methods|

Figure 5.8. Year-to-year (1982-1997) comparison of the total SPE technical papers, papers retrieved by keyword "Paraffin." and


105

:;2s

Table 5.2. A list of authors of the SPE technical papers on Paraffin Treatment Methods, presented during the SPE conference (1951-1997).

Author

Ashton J. P. Beyer A. H Brown F. G. Barker K. M. Cheyne A. J. Collesi J. B. Credeur D.J. DobrotaS.C. Donovan S. C. George R. E. Haynes H. H. Khahl C. N. Kirspel L. J.

Lenderman G. L. Lazar 1.1.

Lukehart C O . McSpadden H. W.

Mitchell T. I Mansure A. J. Nguyen H. T. Osbom D. E.

Purdy I. L. Pelger J. W. Romeu R. K. Rabinovitz ?? Rocha N. 0 . Sutton G. D. Santos P. C.

Stefanesu M. M. SantamariaS. S.

Scott T. A. SilvaE. B. Streeb L. P. Tyler M. L.

Velasco T. T.

Number of Papers Presented on Paraffin Treatment Methods

2

2

2

2

3


1

Thermal Other (Down-hole Emulsification)

Other (Biological Treatment) Thermal (Hot Oiling)

Other (Vacuum Insulated Tubing) Thermal (Heat & N2 System) Thermal (Heat & N2 System) Other (Biological Treatment) Thermal (Heat & N2 System) Other (Biological Treatment)

Chemical (Squeeze Treatment) Thermal (Heat & N2 System) Thermal (Heat & N2 System)

Chemical (Squeeze Treatment) i Other (Biological Treatment)

Other (Butane Injection) Thermal (Heat & N: System) Thermal (Heat & N: System)

Thermal (Hot Oiling) Thermal (Heat & N2 System)

Other (Down-hole Emulsificafion) Other (Vacuum Insulated Tubing)

Other (Biological Treatment) Thermal (Heat & N2 System) Thermal (Heat & N2 System) Thermal (Heat & N2 System)

Other (Aqueous Solufion System) Chemical (Solvent)

Other (Biological Treatment) Other (Biological Treatment) Thermal (Heat & N2 System) 1 Thermal (Heat & N2 System) Other (Biological Treatment) Thermal (Heal t!v N: S\stcm)

1 1 Thermal (Heal (S>: .\2 SNÎCIH)

106

^

5.2 Thermal Treatment Methods

Development of a thermal treatment process by generafing in-situ heat and nitrogen

offered an alternative method to hot oil and hot water treatments'^" ~ The heat and

nitrogen generafing method required mixing of an aqueous solution of sodium nitrate

(NaNOs) with an aqueous solution of ammonium chloride (NH4CI). Mixing of these i\s o

aqueous solufions was performed on the surface. Chemical reaction between these tv\ o

solutions produces nitrogen gas, heat, and non-damaging by-products (water, and sodium

chloride).

Even though the chemical reacdon between the two aqueous solutions started at the

surface, the rate of reacfion was controlled by adding a calculated amount of methanol/

acetic acid solution and manipulating pump rates to attain maximum generated heat at the

predetermined depth in the well. Heat loss was also minimized by controlling the rate of

chemical reaction that was one of the main disadvantages in the hot oil or hot water

treatments. The heat and nitrogen generafing system was designed to reach the maximum

temperature of 462 °F.

McSpadden et al.^' stated that the paraffin treatment by heat and niiiogcn

generating system was long lasdng than treatment by hot oil or chemical solvents in the

treated wells. Even though it was possible to inject the aqueous mixture either in the tubing

or the casing, the injection of the mixture was preferred through the tubing to predict the

heat loss and maximum generated heat more accurately. In addifion, it was recommended

to pump the mixture in the annulus to avoid sucker rod pulling. Treatment procedure using

heat and nitrogen generating system is as follow s:

107

^x

^

• Injection of xylene as a preflush in the amount of 50 gallons per foot of the

depth interval.

• Injection of NaNOs and NH4CI as an aqueous mixture in the tubing.

• Shut-in of the well for 24 hours transfer the heat by conduction to the

paraffin affected areas near the producing formation face.

According to Kirspel et al., " the treatment using heat and nitrogen generating

system was applied on well B during September 1985. Four treatments were pertormed on

this well (Figure 5.9) in a time span of 10 months. Collesi et al. ^ stated that after

successful treatment of paraffin affected wells using heat and nitrogen generating system,

the application of this method was extended to treat the flow-lines. The treatment mixture

contained 50% aqueous solution of NaNOs and NH4CI, 43% xylene, 59r was dispersant,

and 2% emulsifier. The well that was connected to the flow-line was shut-in and the

treatment solution was pumped through the flow-line to remove paraffin, located in the

Main Pass field area. The funcfion of the emulsifier was to create an emulsion of the

aqueous solution (NaNO:, and NH4CI) and the chemical solvent (xylene) that would

increase the paraffin dissolving capabilifies of the chemical solvent due to generated heat in

the system.

5.3 Chemical Treatment Methods

According to Santos, ^ the solvent treatment was applied on one of the paraffin-

affected wells (AG-50) in Renconcavo Bainano Basin, Northeastern Brazil. A monthly

production of the crude oil from this well (AG-50) before treatment, after the first

108

^

^

treatment, and after the second treatment is illustrated in Figure 5.9. This well was treated

twice using chemical solvent method with a four-month time interval. On the first job, the

well was shut-in for four days after naptha was injected as a chemical sol\ ent into the

annulus. After the first treatment job, a slug of diesel oil was injected into the annulus and

then well was shut-in for ten days to soak the well-bore nearby formation with injected

diesel oil. Santos^^ stated that the soaking fime of solvents in chemical treatment jobs was

an important factor to dissolve and remove paraffin deposits.

In 1985, a new squeeze treatment method was tested on two oil-producing wells in

West Texas. According to Hayne and Lenderman, "The aim was to put a slow-

dissolving solid paraffin inhibitor into the formation. The paraffin inhibitor was squeezed

into the formafion in liquid form and then caused to precipitate by an activator" (p. 552).

Prior to the squeeze treatment, these two wells were being treated by hot oiling 3-4 times

every year. A step-by-step procedure was followed to perform squeeze treatment in one of

the wells in West Texas and is as follow:

• Injection and circulation of hot oil with one drum of paraffin dispersant

down the annulus and up the tubing to pre-flush the well-bore before the

squeeze treatment.

• Injection of 10 barrels of crude oil down the annulus, mixed with six drums

of activator.

• Injection of 10 barrels of water into the annulus to separate the activator

from the inhibitor.

109

I I l l l lMHimHHIH^^^

1000'

JlOO

ft

6 •53 10

T—T—I I I—r—1—f r I I—j—I—I—I—r-T-T'i—r—i—i—r—i—r~r--i—i—i—i—i—i—i T ' T

-3^ -24 -12 0 12 -48 T

-24 -12 Time, months

24

Figure 5.9. Crude monthly rate production plot from well AG-50 against time

(Pre-treatment = -48 to 0 months, after first treatment = 0 to 4 months, after second treatment = 4 to 24 months)

38

110

^

• Injecfion of a mixture containing six drums of paraffin inhibitor w ith 60

barrels of crude oil down the annulus.

• Over-flush of 270 barrels of water into the annulus to push the previoush

injected fluids into the formation.

• Shut-in the well for 24 hours.

According to King and Cotney,'"^ "Unique condensate feedstocks can be blended

and refined to produce formation and reservoir fluid compafible natural sohenis" (p. 120).

The natural solvents were also used in combinafion with the hot oil at a rafio of 10% by

volume to the hot oil treatments. Such combinafion allowed the hot oil to dissolve low

molecular weight paraffin and solvents to dissolve the high-molecular-weight paraffin

particles. When using condensates for paraffin treatment, Cotney'^ recommended injecting

natural solvents in the rafio of 5-10% to the total volume in front of the condensate

treatment.

5.4 Other Treatment Methods

Biological treatment using microorganisms (bacteria) was also one of the methods

to control paraffin accumulation problems. ^" ^ These microorganisms were neutrally

charged naturally occurring marine organisms that required water to survive and

metabolize available hydrocarbons through contact with oil/water interface. In addition,

these microorganisms required the biocatalyst and inorganic nutrient to supplement the

bacterial growth and enhance the metabolic reacfions in paraffin deposits. In 1991, the

biological treatment was applied on 91 wells with paraffin accumulation problems in

111

Oklahoma. One of the wells was located in Canadian County. Oklahoma. This well w as

previously being treated with paraffin solvent and paraffin dispersant to control the paraffin

deposition. In addifion, the well was also being hot oiled four times per year. Pelger ^

recommended using the biological treatment method on this well. The well was batch

treated with the biological products and then shut-in for 24 hours. The average oil

producfion was increased by 36.5 barrels of oil per month. The average increase in

production of oil from those 91 wells was 2664 barrels of oil per month. The biological

treatment method reduced the paraffin treatment costs by 18.1% by eliminating chemical

treatments, reducing hot oiling treatments cycles, and reducing mechanical cutting

frequency of paraffin from the wells in that area.

Another attempt was made on the five wells with paraffin deposifion problems in

the Ausfin Chalk Formafion in East Texas. Previously, these wells were being treated by

hot oiling as often as twice a week. Each of these wells was batch treated by mixing one

pound of paraffin treafing bacteria and 12 gallons of biocatalyst with one banel of water,

injecfing the mixture in the annulus, and flushing the well with 3 barrels of w ater. The

wells were then shut-in for 24 hours to allow the biological product to react w ith the

paraffin deposits in the well-bore. The frequency of biological treatment on these 5 wells

ranged from 1 to 2 treatments per month. Santamaria and George^^ concluded that the

biological treatment was limited to wells that produced water and that had bottom-hole

temperature below 210 '^.

In 1990, the vacuum insulated tubing was installed in one of the wells in the

Norman wells oilfield, located in Northwest Canada. This oilfield had 167 producing

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wells of which 52 wells were rod-pumping wells and rests of them were gas lift wells.

Vacuum insulated tubing was comprised of two tubings with different diameters, welded at

both ends of the tubing joints. The annular section of these welded tubings was evacuated

to vacuum. The purpose of creating a vacuum in the tubing annulus was to minimize the

heat loss to the area, surrounded by the tubing (casing, cement, and formafion).

Prior to the vacuum insulated tubing installation, the paraffin was being removed by

using the wire-line dewaxing/scraping tools. The frequency of paraffin treatment was once

after every 3 days. After the installadon of vacuum insulated tubing, the treatment

frequency using wire-line scraping tools was reduced to once per month.

Down-hole emulsificadon of the produced formation fluid was also one of the

methods to reduce paraffin deposifion by forming an oil-in-water emulsion from the

produced fluid in the well-bore and water wetfing the steel surfaces with a water film to

inhibit the adherence of paraffin wax on the tubing wall. " Application of this method was

dependent on the water cut and gas-oil ratio (GOR) of the producing well. This method

required the water cut to be above 35% in the producing well to provide sufficient water for

forming an oil-water emulsion and protective water film. In addition, the producing GOR

below 1000 standard cubic ft. of gas per 1 barrel of oil was required to suppress the gas

turbulence in the tubing. Gases with high flow rates would pre\ cnt the formation of an oil-

water emulsion and water film. Below given sequence of steps w as followed to treat each

of those 6 wells using down-hole emulsificadon method:

• Injecfion of 300 barrels of hot oil down the annulus and up the tubing to

clean the exisdng wax deposits from the well bore.

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• Injecdon of a 100 barrel mixture of 0.2 f (by volume) detergent w iih hot

water (225 '^) into the annulus to coat the steel surfaces in the well-bore.

• Injecfion of 2% (by volume) aqueous solufion down the annulus

confinuously for 7 weeks.

During the seven weeks of treatment period, no hot oiling w as required in 4 out of 6

treated wells. On an average, the monthly hot oiling need to treat these 6 wells was

reduced by 44%.

In 1974, an aqueous based chemical mixture was used for paraffin treatment in

one of the wells, located in Trenton Formafion. ^ Prior to the water based chemical

treatment, this well was being hot oiled on monthly basis for paraffin deposit removal.

After the chemical treatment, the oil producfion was increased by almost 25%. In

addition, the well was maintained its increased producfion for six months and no hot

oiling was required during that fime on this well. The aqueous based chemical treatment

required the injection of 20 barrels of warm water with 20 gallons of chemical A into the

well-bore. The chemical mixture was injected down the annulus and pumped back to the

surface through the tubing. The chemical treatment was applied once every two weeks

on this well.

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CHAPTER 6

CONCLUSIONS AND RECOMMENDATIONS

The SWPSC searchable database provides eas> and fast searching/retneving

facilities to retrieve technical papers by searching paper fitle, subject, author, and

keywords, presented over the past 46 years of SWPSC annual conference. A full-text

search can be performed on the knowledgebase, available in the SWPSC database, by usmg

Adobe Reader software. In addition, some of the advantages of SWPSC PDF documents

include fast and easy electronic distribudon and compact storage.

The paper retrieval capability of the SWPSC searchable database is more precise

than the SPE image library for retrieving technical papers on the paraffin control and

removal methods. A search on the SWPSC database, with a keyword "Paraffin", retries ed

36 technical papers that have been published over the past 46 years. After reviewing these

36 papers, twenty-four papers were found to have treatment methods for paraffin control

and removal. In contrast, a search with a same word (Paraffin) on the SPE image library

resulted with 310 technical papers. After a review of those 310 SPE technical papers, it

was found out that 19 papers had literature on the paraffin treatment methods. Chapters 4

and 5 of this thesis provide a summary of all the methods on paraffin control and remo\ al

that have been published in the SWPSC and SPE publicaUons over the past five decades. It

can be concluded that the SWPSC literature is more field-oriented whereas the SPE

literature is more theoretical and research-oriented in the area of paraffin control and

removal methods.

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The knowledgebase, contained in the SWPSC and SPE databases, on paraffin

control and removal methods is not evenly distributed by the paper authors. There are 34

authors in the SWPSC publicafions and 35 authors in the SPE technical papers,

respecdvely, who have presented different methods for paraffin treatment over the past fi\'e

decades. Names of only three authors (Mansure A. J., Barker K. M., and Lukehart C. O)

were found to be in common in both the SPE and SWPSC databases.

A majority of papers that have been published in the SWPSC publications are

related to chemical methods for paraffin treatment. On the other hand, the authors in the

SPE papers are more inclined to talk about thermal (Heat and Nitrogen generating system)

and biological ways of curing paraffin accumulafion problems.

It is recommended to further test the paper retrieval efficiency of the SWPSC

searchable database on other topics related to oil field operafions such as well fractunng,

artificial lift methods, and enhanced oil recovery. Out of the 19 reviewed SPE technical

papers that provided knowledge on the paraffin treatment methods, there were 5 technical

papers on the Heat and Nitrogen generafing system (Thermal) and 5 technical papers on

Biological treatment method. As a matter of fact, paraffin treatment by Heat and Nitrogen

generadng system has never been introduced in the SWPSC annual conference in the past.

It is further recommended to invite the authors of Heat and Nitrogen generating s> stem and

Biological treatment method to the SWPSC conference in future.

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REFERENCES

1. Nelson, W. L. Petroleum Refinerv Engineering. Third Edition, McGraw Hill Book Company, Inc., New York, 1949.

2. Kurtz, B., and Schmeriing, B. Chemistry of Petroleum Hvdrocarbons. \'olume I. Reinhold Publishing Corporadon, New York, 1954.

3. Bell, H.S. American Petroleum Refining. Third Edidon, D. Van Nostrand Company, Inc., New York, 1945.

4. Gary, J. H. Petroleum Refining. Marcel Dekker, Inc., New York, 1975.

5. Fuson, R. C, and Snyder, H. R. Organic Chemistrv. Second Edifion, John Wiley & Sons, Inc., 1954.

6. Singhal, H. K., Sahai, G. C, Pundeer, G. S., and Chandra, K.: "Designing and Selecfing Wax Crystal Modifier for optimum Field Performance Based on Crude Oil Composidon," SPE 22784, Paper presented at the 1991 SPE Annual Technical Conference and Exhibidon, Texas, October 6-9, 1991.

7. Newberry, M. E., and Barker, K. M.: "Formafion Damage Prevention Through the Control of Paraffin and Asphaltene Deposifion," SPE 13796, Paper presented at the 1985 SPE Producfion Operadons Symposium, Oklahoma, March 10-12, 1985.

8. Houchin, L. R., and Hudson, L. M.: "The Predicfion, Evaluation, and Treatment of Formadon Damage Caused by Organic Deposition," SPE 14818, Paper presented at the 1986 SPE Symposium on Formafion Damage Control, Louisiana, February 26-27, 1986.

9. Allen, T. O., and Roberts, A. P.: Production Operations. Volume 2, Oil & Gas Consultants Intemafional, Inc., Tulsa, 1982.

10. Bucaram, S. M.: "An Improved Paraffin Inhibitor," SPE 1544, Paper presented at the 1966 SPE Annual Fall Meefing, Texas, October 2-5, 1966.

11. Moore, E. W., Crowe, C. W., and Hendrickson, A. R.: "Formafion, Effect and Prevenfion of Asphaltene Sludges During Stimulafion Treatments," SPE 1163, Paper presented at the 1965 SPE Rocky Mountain Regional Meeting, Montana, June 10-11, 1965.

12. Brown, M. J., and Dobbs, J. B.; "A Novel Exothermic Process for the Removal of Paraffin Deposits in Hydrocarbon Production," SWPSC, Lubbock, TX. 1999.

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13. Addison, G. E.: "Idenfificafion and Treafing of Down-hole Organic Deposits." SPE 18894, Paper presented at the 1989 SPE Production Operations Symposium, Oklahoma, March 13-14, 1989.

14. King, S. R., and Cotney, C. R.: "Development and Applicadon of Unique Natural Solvents for Treafing Paraffin and Asphaltene Related Problems," SPE 35265, Paper presented at the 1996 SPE Mid-Condnent gas Symposium, Texas, April 28-30, 1996.

15. Newberry, M. E.: "Crude Oil Producdon and Flow-line Pressure Problems," SPE 11561, Paper presented at the 1983 Production Operafion Symposium, Oklahoma, February 27-Marh 1, 1983.

16. Tutde, R. N.: "High-Pour-Point and Asphaldc Crude Oils and Condensates," SPE 10004, Paper presented at the 1982 SPE International Petroleum Exhibition and Technical Symposium, China, 1982.

17. Sutton, G. D.: "Aqueous Systems for Paraffin Removal." SPE 5704, Paper presented at the 1976 SPE Symposium on Formafion Damage Control, Texas. January 29-30, 1976.

18. Pacheco-Sanchez, J. H., and Mansoori, G. A.: "In Situ Remediadon of Heavy Organic Deposits Using Aromadc Solvents," SPE 38966, Paper presented at the 1997 SPE Lafin American and Caribbean Petroleum Engineering Conference and Exhibition, Brazil, August 30-September 3, 1997.

19. Broaddus, G.: 'Well- and Formafion Damage Removal with Nonacid Fluids," SPE 17111.1988.

20. Tejeda, P., Lira-Galeana, C, and Rodriguez, F.: "Analysis of a Thermodynamic Micellization Model for Asphlatene Precipitation," SPE 38968, Paper presented at the 1997 SPE Latin American and Caribbean Petroleum Engineering Conference and Exhibidon, Brazil, August 30-September 3, 1997.

21. Elsharkawy, A. M., Al-Sahhaf, T. A., Fahim, M. A., and Al-Zabbai, W.: "Determinadon and Prediction of Wax Deposition from Kuwaiti Crude Oils," SPE 54006, Paper presented at the 1999 SPE Lafin American and Caribbean Petroleum Engineering Conference, Venezuela, April 21-23, 1999.

22. Rai, R., Sarkar, B.. and Dalai, V.: "Mulfiphase Transportafion of High Waxy Crudes," SPE 27061, 1995.

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23. Escobedo, J., and Mansoori, G. A.: "Viscometric Principles of Onsets of Colloidal Asphaltene Flocculafion in Paraffinic Oils and Asphaltene Micellization in Aromafics," SPE 28729, Paper presented at the 1994 SPE International Petroleum Conference and Exhibidon, Mexico, October 10-13, 1994.

24. Singhal, H. K., Sahai, G. C, Pundeer, G. S., and Chandra, K.: "Designing and Selecfing Wax Crystal Modifier for optimum Field Performance Based on Crude Oil Composidon," SPE 22784, Paper presented at the 1991 SPE Annual Technical Conference and Exhibidon, Texas, October 6-9, 1991.

25. Addison, G. E.; "Paraffin Control More Cost-Effecfive," SPE 13391, Paper presented at the 1984 SPE Eastern Regional Meeting, West Virginia, October 31-November 2, 1984.

26. Sutton, G. D.; "Paraffin Precipitadon During Fracture Sfimulafion," SPE 4411, September 1974.

27. Newberry, M. E., Addison, G. E., and Barker, K. M.: "Paraffin Control in the Northern Michigan Niagaran Reef Trend," SPE 12320, Paper presented at the 1983 SPE Eastern Regional Meedng, Pennsylvania, November 9-11, 1983.

28. Burger, E. D., Perkins, T. K., and Striegler, J. H.: "Studies of Wax Deposition in the Trans Alaska Pipeline," SPE 8788,1981.

29. Hamouda, A. A., Davidsen, S.: "An Approach for Simuladon of Paraffin Deposidon in Pipelines as aFuncdon of Flow Characteristics With a Reference to Teeside Oil Pipeline," SPE 28966, Paper presented at the 1995 SPE International Symposium on Oilfield Chemistry, Texas, February 14-17, 1995.

30. Madach, W. J., and Newberry, M. E.: "Paraffin Deposifion and Rheological Evaluafion of High Wax Content Altamont Crude Oils," SPE 11851, Paper presented at the 1983 SPE Rocky Mountain Regional Meeting, Utah, May 23-25, 1983.

31. McClaflin, G. G., and Whitfill, D. L.: ''Control of Paraffin Deposidon in Production Operations," SPE 12204, Paper presented at the 1983 SPE Annual Technical Conference and Exhibidon, California, October 5-8, 1984.

32. Woo, G. T., Garbis, S. J., and Gray, T. C: "Long-Term Control of Paraffin Deposifion," SPE 13126, Paper presented at the 1984 SPE Annual Technical Conference and Exhibidon, Texas, September 16-19, 1984.

33. Keafing, J. F., and Wattenbarger, R. A.: "The Simulation of Paraffin Deposidon and Removal in Well-bores," SPE 27871, Paper presented at the 1994 SPE W csircn Regional Meefing, California, March 23-25, 1994.

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34. Barker, K. M.: "Formation Damage Related to Hot Oiling," SPE 16320. Paper presented at the 1987 SPE Producfion Operations Symposium, Oklahoma, March 8-10, 1987.

35. Mansure, A. J., and Barker, K. M.: "Insights Into Good Hot Oiling Pracdces," SPE 25484, Paper presented at the 1993 SPE Producfion Operations Symposium, Oklahoma, March 21-23, 1993.

36. Sutton, G. D.: "Aqueous Systems for Paraffin Removal," SPE 5704. Paper presented at the Symposium on the Formadon Damage Control. Texas, January 29-30, 1976.

37. King, G. E., and Holman, G. B.: "Hydrocarbon Solvents: An Alternative to Acid for Removing Some Formadon Damage," SPE 14136. Paper presented at the 1986 SPE Intemafional Meedng on Petroleum Engineering, China. March 17-20, 1986.

38. Santos, P. C: "Removal of Nearbore Formadon Damage From paraffin Is Better Achieved Using Solvents," SPE 38965, Paper presented at the 1997 SPE Lafin American and Caribbean Petroleum Engineering Conference and Exhibition, August 30-September 3, 1997.

39. Bomba, J. G.: "Offshore Pipeline Transport of Waxy Crude Oils," SPE 14622, 1986.

40. Holloway, F. H.: "The Chemical Treatment of Offshore Oil and Gas Producdon," SPE 6678, Paper presented at the 1977 SPE Offshore Europe Conference, Scotland, September 14-15, 1977.

41. Fan Y., and Llave, F. M.: "Chemical Removal of Formadon Damage From Paraffin Deposifion Part I - Solubility and Dissolufion Rate," SPE 31128, Paper presented at the 1996 SPE Intemadonal Symposium on Formafion Damage Control, Louisiana, February 14-15, 1996.

42. Llave, F. M., and Fan, Y.: "Summary Report: Formadon Damage Workshop," NIPER/BDM Report No. 0173, September 30, 1995.

43. O'Rear, J.: "Going from Pulp to Pixels." Online. Available WWW: http://www.adobe.com/epaper/features/pulppixel/main.html

44. Wamonk, J.: "Good Ideas come from everywhere in the Company." Online. Available WWW: http://www.adobe.com/aboutadobe/main.html

45. Horzewski, A.: "Spodights." Online. Available WWW: http://www.adobe.com/epaper/spothghts/hollandhart/main.html

120

!•> lite

http://www.adobe.com/epaper/features/pulppixel/main.html

http://www.adobe.com/aboutadobe/main.html

http://www.adobe.com/epaper/spothghts/hollandhart/main.html

46. "Outputfing Files From Acrobat Capture 2.0x in Word Processing Formats." Online. Available WWW: http://www.adobe.com/support/techdocs/1626a.htm

47. Adobe Acrobat Capture® 2.0. This software installadon manual is included w ith a Adobe Acrobat Capture 2.0 software package.

48. "Introducfion to Acrobat Reader." Online. Available WWW: http://www.adobe.com/support/techdocs/ac76.htm

49. Adobe Acrobat 4.0.This software installadon manual is provided with the Adobe Acrobat® 4.0 (Educafion Version) software package.

50. "The Society." Online. Available WWW: http://www.speca.org/societv.html

51. "Mission." Online. Available WWW: http://www.speca.org/mission.html

52. "Membership." Onhne. Available WWW: http://www.spe.org/content/l,l 116,2,00.html

53. "The SPE Image Library." Instrucfion manual, provided with the purchase of SPE Image library CD-ROM kit.

54. Kostoff, N. v.: "Use of Chemical Dispersants to Control Paraffin Problems and Method for Determining the Treatment Requirements," SWPSC, Lubbock, TX, 1964.

55. Ward, J. L.: "Non-Chemical Control Of Paraffin In Wells," SWPSC, Lubbock, TX, 1955.

56. Snedeker. K. D.: "Paraffin Control And Removal In Hydraulically Pumped Wells," SWPSC, Lubbock, TX, 1954.

57. Young, M. A.: "Sucker Rod Type Paraffin Scrappers," SWPSC, Lubbock, TX, 1957.

58. McKinney, T. B.: "The Use of Solvents to Control Paraffin in Rod-Pump Wells and Flow-lines," SWPSC, Lubbock, TX, 1954.

59. Barker, K. M., Addison, G. E., and Cunningham, J. A.: "Disadvantages of Hot Oiling for Down-hole Paraffin Removal in Rod Pumping Systems," SWPSC, Lubbock, TX, 1984.

60. Brock, R.: "An Experimental Paraffin Control Treatment Technique," SWPSC, Lubbock, TX, 1989.

121

http://www.adobe.com/support/techdocs/1626a.htm

http://www.adobe.com/support/techdocs/ac76.htm

http://www.speca.org/societv.html

http://www.speca.org/mission.html

http://www.spe.org/content/l,l

^

61. Mansure, A. J., and Barker, K. M.: "Pracdcal Hot Oiling and Hot Watering for Paraffin Control," SWPSC, Lubbock, TX, 1994.

62. Herman, J., and Ivanhoe, K.: "Survey of Best Pracdces for Paraffin and Asphaltene Control - A Preliminary Report," SWPSC, Lubbock, TX, 1999.

63. McCaskill, B. M.: "Use of Chemical For Paraffin Control." SWPSC. Lubbock, TX, 1956.

64. Mendell, L. J.: "Paraffin Wax Deposits and Chemical Inhibitors."" SWPSC. Lubbock, TX, 1970.

65. Crawford, D. J.: "Scale and Paraffin - Causes and Methods of Control," SWPSC, Lubbock, TX, 1966.

66. Lukehart, C. O.: "A Case History of Paraffin Control Using Butane," SWPSC, Lubbock, TX, 1960.

67. Garbis, J. S., Olsen, H. R., Cushner, M. C, and Woo, G. T.: 'A Novel Technique for Avoiding Paraffin Problems - A Field Study in the Ackerly Dean Unit, Dawson County, Texas," SWPSC, Lubbock, TX, 1984.

68. King, S. R., and Cotney, C. R.: "Unique Natural Solvents For Treadng Paraffin and Asphaltene Related Problems," SWPSC, Lubbock, TX, 1996.

69. White, J. M.: "Paraffin Control By Plasfic Coadng," SWPSC, Lubbock, TX. 1956.

70. Jordan, R. M.: "Paraffin Deposifion and Prevention in Oil Wells," SWPSC, Lubbock, TX, 1967.

71. Shroyer, L. L., and Haynes J.: "Paraffin Control For Oil Wells And Transport Lines Using Linear Kinedc Cell Technology," SWPSC, Lubbock, TX, 1992.

72. Bishop, D. M., and Woodward, R. D.: "Biological Paraffin Treatment Programs." SWPSC, Lubbock, TX, 1990.

73. Wilson, J. J., Chee, W., O'Grady, C, and Bishop, D. M.; "A Field Study Of Down-hole Microbial Paraffin Control", SWPSC, Lubbock, TX, 1993.

74. Comey, D. J.: "'Advancements In The Use of Magnefics For Controlling Deposits and BS&W in Oil Wells." SWPSC. Lubbock, TX, 1993.

75. McKinney, T. B.: "Solvents For Paraffin Control," SWPSC. Lubbock, TX, 1955.

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76. Purdy, I. L., and Cheyne A. J.: "Evaluadon of Vacuum-Insulated Tubing for Paraffin Control at Norman Wells," SPE 22102, Paper presented at the 1991 SPE Intemafional Arcfic Technology Conference, Alaska, May 29-31, 1991.

77. Romeu, R. K., Khalil, C. N., and Rabinovitz, A.: "Paraffin Precipitation in the Formadon in Dom Joao Field, Brazil," SPE 21108, Paper presented at the 1990 SPE Ladn American Petroleum Engineering Conference, Brazil, October 14-19, 1990.

78. McSpadden, H. W., Tyler, M. L., and Velasco, T. T.: "In-Situ Heat and Paraffin Inhibitor Combinadon Prove Cost Effecdve in NPR #3, Casper, Wyoming." SPE 15098, Paper presented at the 1986 SPE California Regional Conference, Califomia, April 2-4, 1986.

79. Khalil, C. N., Rocha, N. O., and Silva, E. B.: "Detecdon of Formafion Damage Associated to Paraffin in Reservoirs of the Reconcavo Baiano, Brazil," SPE 37238, Paper presented at the 1997 SPE Intemafional Symposium on Oilfield Chemistry, Texas, February 18-21, 1997.

80. Ashton, J. P., Kirspel, L. J., Nguyen, H. T., and Creuder, D. J.: "In Situ Heat System Sdmulates Paraffinic Crude Producers in Gulf of Mexico," SPE 15660, Paper presented at the 1986 SPE Annual Technical Conference and Exhibition, Louisiana, October 5-8, 1986.

81. Mitchell, T. I., Donovan, S. C, Collesi, J. B., and McSpadden, H. W.: "Field Applicadon of a Chemical Heat and Nitrogen Generafing System," SPE 12776, Paper presented at the 1984 SPE Califomia Regional Meedng, Califomia, April 11-13, 1984.

82. Collesi, J. B., Scott, T. A., and McSpadden, H. W.: "Surface Equipment Cleanup Udlizing In-Situ Heat," SPE 16215, Paper presented at the 1987 SPE Production Operadons Symposium, Oklahoma, March 8-10, 1987.

83. Haynes, H. H., and Lenderman, G. L.: "Cost-Effecfive Paraffin Inhibitor Squeezes Can Improve Producfion Economics," SPE 15178, Paper presented at the 1986 SPE Rocky Mountain Regional Meedng, Montana, May 19-21, 1986.

84. Beyer, A. H.: "Down-hole Emulsificafion for Improving Paraffinic Crude Production," SPE 2676, Paper presented at the 1969 SPE Annual Fall Meeting, Colorado, September 28-October 1, 1969.

85. Lazar, 1.1., Stefanescu, M. M., and Dobrota, S. C: "MEOR, the Suitable bacterial Inoculum According to the Kind of Technology Used: Results from Romania's Last 20 Years' Experience," SPE 24207, Paper presented at the 1992 SPE Symposium on Enhanced Oil Recovery, Oklahoma, April 22-24, 1992.

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86. Brown, F. G.: "Microbes: The Pracdcal and Environmental Safe Solution to Production Problems, Enhanced Production, and Enhanced Oil Reco\ er\."" SPE 23955. Paper presented at the 1992 SPE Permian Basin Oil and Gas Recovcr\ Conference. Texas. March 18-20, 1992.

87. Streeb, L. P.. and Brown, F. G.: "MEOR-Altamont Bluebell Field Project,'" SPE 24334. Paper presented at the 1992 SPE Rocky Mountain Regional Meeting. Wyoming, May 18-21. 1992.

88. Pelger. J. W.: "Well-bore Stimulation Using Microorganisms To Control and Remediate Existing Paraffin Accumulations," SPE 23813. Paper presented at the 1992 SPE Intemational Symposium on Formation Damage, Louisiana, Februar>' 26-27, 1992.

89. Santamaria. M. M.. and George, R. E.: "Controlling paraffin-Deposition-Related Problems by the Use of Bacteria Treatments," SPE 22851. Paper presented at the 1991 SPE Amiual Technical Conference and Exhibition. Texas. October 6-9, 1991.

90. Bilderback. C. A., and McDougall, L. A.: "Complete Paraffin Control in Petroleum Production,"" SPE 2175. Paper presented at the 1968 SPE Annual Fall Meeting, Texas. September 29-October 2, 1968.

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