05 Cementing Materials

8/12/2019 05 Cementing Materials

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Standard cement slurries require water to fill the void between particles. CemCRETE slurriesfill the interparticle void with more solids, giving superior cement properties.

Cementing Services and Products Materials 39

Materials

IntroductionIn todays remote areas and extreme environments, exploration puts increasing demands on thetechnology required for developing new reserves. No new technology is better tailored to thesedemands than Advanced Cement Technology from Schlumberger. Incorporating 10 years of R&D,Advanced Cement Technology provides a range of cement alternatives, tailored to the well, toachieve zonal isolation for the life of the well.

CemCRETE Advanced Cement Technology decouples set-cement properties from slurry den-sity. With CemCRETE systems, properties such as permeability and strength are superior tothose of conventional cements. Slurries can be lighter (or heavier) than ever, without compro-mising properties of the set cement.

CemSTONE systems, the newest generation of Schlumberger Advanced Cement Technology,offer set-cement properties that can be adjusted to meet the requirements of the well. They arepurpose-built to withstand mechanical stresses and changes in temperature and pressure thatdamage conventional cements. CemSTONE systems offer control over properties never possiblewith conventional oilwell cement, allowing you to meet your requirements for such set proper-ties as flexibility, expansion and impact resistance.


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Properties of CemCRETE cements are superior to those of cement made usingconventional technology.

40 Cementing Services and Products

CemCRETE concrete-based oilwell cementing technologyCemCRETE slurries are systems that allow deeper casing points, better high-pressure, high-temperature (HPHT) wells or reduced time WOC in deepwater. Special formulations enablerepair in wells where microcements are ineffective. CemCRETE slurries are available in differ-ent formulations for various applications.

LiteCRETE* slurry systems provide the high strength and low permeability, even at densities

as low as 900 kg/m

3

[7.5 lbm/gal], necessary to cement across weak formations.DeepCRETE slurries let you cement shallow, weak zones in wells drilled in deepwater, mini-mize the risk of shallow water flow and return to drilling in a short time.

DensCRETE* technology gives you very high-density cements (to 2,880 kg/m3 [24 lbm/gal]),for well control with low viscosity.

SqueezeCRETE* remedial cementing slurries are specifically designed to solve problems bypenetrating narrow gaps more efficiently, without bridging or dehydrating during placement.

CemCRETE Advanced Cement Technology is a high-performance alternative to conventionaloilwell cement slurries that changes the fundamental rules for cementing. Casing strings can beset deeper without worrying about lost returns. Cements in HPHT wells can be placed at lowercirculating pressures and higher rates. Channels and failures in primary cement too small forrepair using microcement slurries can be repaired. CemCRETE slurries produce new answers fortodays tough problems, providing zonal isolation for the life of the well.

Unfortunately, in conventional cementing slurries, the amount of water needed for mixing andpumping is much more than is optimum for set cement. CemCRETE technology disconnectsthese two phases of cement performance to give both optimum slurry properties and excellentset-cement performance.

CemCRETE technology increases the solids content of the slurry by using engineered particle-size distribution. Smaller particles fill the void space between larger ones, resulting in a slurryrequiring less water, yet retaining good fluid properties. Putting more solids into your cement pro-vides greater compressive strength, reduces cement permeability and increases resistance to cor-rosive fluids. Choosing solids with different properties allows slurry designs to meet therequirements of the application.

CemCRETE designs mean cements for production casing can be lower density while main-taining optimum properties for isolation. You can set lighter, longer cement columns. Casingpoints can be deeper. The set cement performs better than standard cement for the life of the

well. In remedial operations, increasing solids content improves the penetrating ability of theslurry and decreases placement pressures.

0.10

0.05

Permeability(mD)

0.15

0.20

0.25

0.00

12.0 lbm/galConventional

cement

12.0 lbm/galLiteCRETE

cement

15.8 lbm/galConventional

cement

17.5 lbm/galDensCRETE

cement


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LiteCRETE low-density slurry systemWhen cementing across weak formations, it can be difficult to place sufficient cement behind thecasing without using extended, low-density cement slurries or multiple-stage cementing opera-tions. A simple, low-density slurry that performs like conventional-density cements can eliminatethese restrictions and allow you to set casing deeper or perhaps eliminate a casing string.

The new LiteCRETE high-performance system enables you to redesign your casing program.

LiteCRETE technology, a member of CemCRETE Advanced Cement Technology family, providesproduction-quality cement properties at extended-slurry densities. LiteCRETE slurries can bemixed from 900 to 1,560 kg/m3 [7.5 to 13 lbm/gal] for effective placement across weak zones.Once set, these cements provide compressive strength and permeability that are superior toproperties of other lightweight systems and even comparable to those of 1,900-kg/m 3

[15.8-lbm/gal] cement.

Strength and permeability of LiteCRETE slurries are superior to propertiesproduced by foamed cement.

Materials 41

3500

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2500

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0

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Compressivestrength

(psi)

Density (lbm/gal)

Foamed cement

LiteCRETE cement

Permeability(log mD)

Density (lbm/gal)

3

2

1

0

1

2

3

4

8 9 10 11 12 13


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Low-density LiteCRETE slurry frequently eliminates stage cementing in long intervals. Withperformance similar to higher-density slurries, you can get exceptional perforation quality with-out reducing cement integrity. LiteCRETE systems are even strong enough for hydraulic fractur-ing treatments or setting kickoff plugs.

In some cases, special properties may be built into CemCRETE slurry systems to meet specificperformance criteria. For instance, casing strings through permafrost zones must be cementedwith slurries having protection from freezing. For this application, Schlumberger developed

Arctic LiteCRETE cement.

Applications Across weak formations where high-performance cement is required

Slurries with densities as low as 900 kg/m3 [7.5 lbm/gal]

Alternative to stage cementing or topping out

Alternative to foamed cement

Across completion intervals

Kickoff plugs

Benefits Production-quality zonal isolation across easily fractured formations

Longer cement columns without losses caused by hydrostatic pressure

Elimination of two-stage cementing

Less damage to completion intervals resulting from slurry or filtrate invasion

Whipstock plugs at lower densities with less tendency for contamination or falling downhole

Features Cement with low density but that has completion-quality properties

Slurry preparation without special equipment or additional personnel

Set-cement properties vastly superior to those of other lightweight systems at equivalentdensities



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DeepCRETE deepwater cementing solutionDeepCRETE slurries let you cement weak zones in deepwater wells, minimize risk of shallow-water flow and return to drilling in a short time.

Drilling in deepwater environments means higher costs. Weak formations can fail under thehydrostatic load of the cement column, causing incomplete zonal coverage, additional delay andmore expense. Slow-setting cement can allow flow of shallow water or gas, risking the integrity

of the well and potentially the surface location. Low BHT can delay compressive strength devel-opment, increasing WOC time. When cementing operations are completed, every minute spentWOC costs money.

DeepCRETE technology is a combination of efficient technologies for cementing in the diffi-cult deepwater scenario where the temperature is low and shallow flows may exist. It is a part ofthe Schlumberger deepwater drilling solution. The DeepCRETE solution isolates the formationwith a lightweight cement slurry (1,2001,650 kg/m3, 1014 lbm/gal) that develops strengthfaster than conventional cement systems without requiring special equipment or personnel.DeepCEM additives, which facilitate rapid strength development in the low temperatures, arecombined with CemCRETE technology to form a highly effective system that provides the shorttransition time, early strength development and good fluid-loss control necessary to cement thesurface and conductor casing in deepwater wells with risk of shallow flow. The lighter weightallows placement across weak formations.

DeepCRETE systems, with a lower heat of hydration, are the right choice in areas where gashydrates are a concern. DeepCRETE cement is less permeable than conventional cements andtherefore protects the casing from corrosive brines.

DeepCRETE systems mixed at 1,500 kg/m3 [12.5 lbm/gal] develop sufficient compressivestrength to return to drilling in less than 24 hr even at 4C [40F]. When combined withSchlumberger gas migration technology, DeepCRETE systems provide the right solution forshallow water or gas-flow problems.

Applications Placement of full columns of cement for complete coverage across weak, shallow formations

in deepwater

Potential shallow water or gas flows

Benefits Cement circulation to surface across weak shallow formations

WOC time minimized in low-temperature environments

Control and isolation of shallow water or gas formations

Low-density, low-temperature cementing without complicated equipment setup or additionalpersonnel on the rig

Features Rapid compressive strength development even at 4C [40F]

Low density with compressive strengths comparable to those of higher-density cement

Low density with low permeability

Slurry preparation without special equipment or additional personnel

Compatible with Schlumberger gas migration technology

Materials 43


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DensCRETE Advanced Cement TechnologyWhen working on HPHT wells, the fewer unplanned concerns there are, the smoother the opera-tion runs. An ideal cement system offers a simple robust design, lower viscosity and the versatil-ity of slurry density that can be easily increased on location.

Using unique engineered-particle-size technology, DensCRETE systems give you very high-density cements, up to 2,880 kg/m3 [24 lbm/gal], with low viscosity. Because of higher com-pressive strength and lower permeability, DensCRETE slurries outperform conventionalhigh-density slurries to provide high-pressure zonal isolation for the life of your well.

The primary applications for DensCRETE technology include high-pressure primary cement-ing, well control plugging, whipstock or kickoff plugging, and grouting operations.

CemCRETE technology results in slurry formulations that have excellent flow properties. Frictionpressures are much reduced, so slurries can be placed at greater flow rates to reduce place-ment time and enable better mud removal.

At low temperatures, 1500-kg/m3 [12.5-lbm/gal] Deep CRETE slurry develops strength faster than conventionalClass G cement with density of 1895 kg/m3 [15.8 lbm/gal]. WOC time is reduced, saving rig time and reducing costs.


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Frictionpressure

(lbf/1000 ft)

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Pump rate (bbl/min)

Conventional cement

DensCRETE cement

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Time (hr)

20 25 30

Pressure

(psi)

DeepCRETE at 12.5 lbm/gal

Class G at 15.8 lbm/gal

At 65F


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High-pressure drilling can require sudden changes in mud weight. With DensCRETE tech-nology, you can quickly increase the slurry density by 120 kg/m3 [1 lbm/gal] on location. Withreduced risks, shorter placement times and lower costs, DensCRETE systems offer the high-density cementing alternative with higher performance.

Applications

High-pressure primary cementing High-density slurries to 2,880 kg/m3 [24 lbm/gal]

Well control plugs

Sidetrack and whipstock plugs

Grouting

Benefits Easier slurry placement in narrow fracture-pressure/pore-pressure windows

Reduced costs and risks associated with long WOC

High-density cements that can be continuously mixed

Features High-density cement slurry with lower viscosities

Greater density differentials with high-density drilling fluids

Shorter placement times, allowing use of slurries with shorter pumping time, andconsequently shorter WOC time

Stability at high temperatures without special additives

Easy design of high-density systems

Reduced additive requirements

Ability to increase the density at the wellsite using special additives

SqueezeCRETE remedial cementing solutionsOil and gas wells, old or new, can develop isolation problems that normal cements or even micro-cement cannot repair. Microannuli, leaking liners and old perforations are just some of the prob-lems that may remain even after multiple cement squeeze attempts. SqueezeCRETE technologyis specifically designed to solve these problems by enabling more efficient slurry penetrationinto narrow gaps without bridging or dehydrating during placement. It even penetrates fartherand more efficiently than microcement.

In laboratory testing, SqueezeCRETE slurry has been injected into gaps as small as 120micrometers [0.005-in.]. SqueezeCRETE slurry develops more than 13.8-MPa [2,000-psi]compressive strength and extremely low permeability. This system can seal liner tops,

microannuli or other areas where primary isolation has failed. SqueezeCRETE systems areresistant to acid and corrosive brine, allowing the cement to seal old perforations even whenfuture acid stimulations are planned. SqueezeCRETE systems can be prepared usingconventional cementing equipment.

Materials 45


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Applications Microannulus repair Repair of leaking liner tops

Repair of leaking perforations

Squeeze of small channels

Plugging and sealing of old gravel packs

Benefits Improved penetration into difficult-to-repair and difficult primary isolation problems

Superior channel-filling properties for complete isolation repair

Low placement pressures for improved fluid placement

Restoration of zonal isolation or well integrity

Features Superior injectivity compared to other remedial systems, including microcements

Superior slurry properties, including low viscosity, low fluid loss

Superior set-cement properties, including high compressive strength and low permeability

In this 120-micrometer [0.005-in.] slot test, well-dispersed microcement bridged immediately afterentering the slot. SqueezeCRETE slurry penetrated and filled the entire length of the slot, providinga complete, effective seal.


Syringe containingthe slurry to be injected

Transparentplate

Porous plate

Spacer medium,delimitinga channel

Filter paper

Injection point Injection point

Well-dispersed microcement slurry SqueezeCRETE slurry


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CemSTONE Advanced Cement TechnologyCemSTONE systems provide reliable, long-term zonal isolation despite changing downhole con-ditions. These systems control set-cement properties, such as flexibility, expansion and impactresistance, so the cement can withstand stresses that destroy conventional oilwell cements. Thefollowing systems are included in the CemSTONE family.

FlexSTONE systems provide mechanical properties that can be adjusted to match the wellbore

stresses and provide permanent zonal isolation to seal wellbore fluids behind casing.DuraSTONE* Advanced Cement Technology systems are tougher and have better impact resis-tance than conventional cements, so they are more durable and provide better isolation underrugged drilling and completion conditions.

Even when conventional cement is properly placed and initially provides zonal isolation,changes in downhole conditions can induce stresses that cause the cement sheath to lose itsintegrity. Large increases in wellbore pressure, temperature or tectonic stresses can crack thesheath and can even reduce it to rubble.

Radial movement of casing caused by temperature changes, pressure changes or cement bulkexpansion can cause the cement to lose its bond to the casing, and bulk shrinkage can cause thecement to lose its bond to the formation. In either case, a microannulus is created. Changes inmud weight during drilling and completion can contribute to these pressure changes.Temperature or pressure changes can also generate tensile stresses that can cause cracking of

the cement sheath and loss of zonal isolation.Proprietary additives, combined in proven engineered-particle blends, enable CemSTONE sys-

tems to meet specific mechanical property requirements: elasticity, expandability, compressiveand tensile strength, durability, and impact resistance. As a result, these systems can withstanddownhole stresses for the life of the well, providing long-term wellbore integrity that conventionalcement cannot.

This long-term integrity reduces remedial cementing costs, ensures isolation for stimulationtreatments, and reduces the possibility of annular pressure during a gas wells producing life. Itcan also extend the productive life of steam injection wells and wells in tectonically active areas.Durable, impact-resistant systems substantially improve success when setting problematic kick-off plugs, leading to rig time savings and ultimately lower drilling cost. These systems alsoimprove the stability of the cement sheath across other areas subjected to high drilling impacts,such as multilateral junctions.

Combined with stress analysis model software, these CemSTONE slurries provide powerfulengineered solutions. Engineers can model changes that will occur in the cement sheath over thelife of the well and optimize the mechanical properties of the set cement to compensate for thesechanges. The result is zonal isolation for the life of the well.

Materials 47


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Modern well construction techniques can destroy conventional cements.CemSTONE systems have superior mechanical properties.


Microannuli are createdby changing the fluid weight.CemSTONE systems canexpand to reseal the well.

Complicated completiontechniques such as multilateralsshatter conventional cement.CemSTONE systems providebetter durability.

Temperature shock that occurswhen hot produced fluids pass

through lower-temperaturesurface casings causesstress cracks in conventionalcement. CemSTONE systemsare very resistant to thermaland mechanical stresses.

Any changes in wellborestresses can cause lossof isolation. Stress analysismodel software can helpoptimize design parameters

to improve well life.


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FlexSTONE Advanced Cement TechnologyFor years cements were designed based on the optimal properties necessary for slurry placement.The set-cement propertieshigh compressive strength and low permeabilitywere assumed tobe sufficient for all well conditions. Today, the importance of an isolation material that will lastunder complicated well stresses is better understood.

The set cement must withstand stresses caused by changes in temperature and pressure in the

wellbore throughout the wells life. This reliability is especially relevant considering the expenseand difficulty of repairing wells.Changes in pressure caused by production, injection or high-pressure treatments can impose

stresses on the cement through the casing. Isolation is always needed across the productive inter-vals, but it is also needed in other intervals that may protect valuable surface waters or preventmovement of corrosive or hazardous liquid or gas behind the casing. Changes in temperaturesresulting from production of high-temperature fluids or injection of hot fluids, such as steam, canexpand the casing and create great stresses in the cement sheath. These changes can cause ten-sile stresses that crack the cement.

FlexSTONE Advanced Cement Technology systems offer mechanical properties that can beengineered to meet the changing stresses in the wellbore: lower permeability than conventionalcements, good compressive strength, better flexibility and better chemical resistance. With theseproperties customized to the well, the system will resist stresses and maintain isolation.

FlexSTONE systems also expand to seal any microannulus. Because FlexSTONE cements areengineered to be more flexible than the formation they seal, this expansion of the cement sheathoccurs both outward (i.e., toward the formation) and inward (i.e., toward the casing), thus assur-ing complete hydraulic isolation.

With FlexSTONE systems, you will have a seal in your well that provides long-term protectionfrom microannuli formation, stress cracks, corrosive fluid invasion, annular gas pressure andfluid migration. As part of the new Advanced Cement Technology solution, FlexSTONE systemsoffer zonal isolation for the life of the well.

Applications HPHT gas wells

Casings subjected to changing stress loading

Casings isolating gas, either productive or nuisance

Steam injection wells

Areas with high tectonic stresses

Benefits Zonal isolation during and after stimulation treatments

Extended productive life of steam injection wells

Long-term isolation and casing protection in dynamic stress environments

Long-term isolation and casing protection in corrosive environments

Protection from annular gas and fluid migration

Prevention of sustained casing pressure

Prevention and healing of microannuli resulting from decreases in pressure or temperaturewhile drilling and completing

Materials 49


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Features Mixed and pumped with conventional equipment

Flexibility adjusted to the requirements for the life of the well

Linear expansion two to three times greater than possible with conventional cement systems

Lower permeability than conventional cementindependent of slurry density

Resistance to corrosive fluids

Properties of conventional cements are not adequate for difficult well isolation.FlexSTONE systems have higher ratios of strength to Youngs modulus (T/E) andhigher bond strength while maintaining low permeability.


T/E ratio Permeability(D)

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Bond strength(MPa after 4 weeks set time)

Well isolationproperties

Conventional cementFlexSTONE system


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DuraSTONE Advanced Cement TechnologyPreviously, oilwell cements were designed to be pumped, to develop strength and then to remainrelatively undisturbed behind casing, thereby providing isolation and pipe support throughoutthe production cycle of the well. Mechanical shocks during further drilling or other well opera-tions that can destroy the integrity of the cement sheath were not considered, although theycould impair zonal isolation.

Modern reservoirs require more complicated technology. Complex drilling programs call forbicentered bits, multilaterals or milled windows, and difficult sidetracks. Completions use largerperforations or higher perforation densities in ever thinner producing intervals. Isolation in thesesituations is critical; it requires a tougher material with better tolerance to vibration and impact.

DuraSTONE Advanced Cement Technology systems are more durable or tougher than con-ventional systems. DuraSTONE systems have all the desirable properties of production-qualitycement, but they survive flexural stress, vibration and impact. With DuraSTONE designs, you canmaintain zonal isolation across sections of the well that will be subjected to extreme mechanicalimpact stresses.

Drilling tests have shown DuraSTONE systems to be two to three times tougher than conven-tional cements; this allows faster kickoff in less distance, even in hard formations.

As part of the new Advanced Cement Technology solution, DuraSTONE systems offer zonalisolation for the life of the well.

Applications Multilateral completions

Reentry wells

Sidetrack plugs, especially in hard formations

Across shoes where impacts are high during subsequent drilling

Benefits Zonal isolation integrity across multilateral junctions

Improved security against failure of the cement sheath in high-impact areas

Better isolation in high-density, precision perforating

Improved success in setting sidetrack plugs

Features Engineered mechanical properties

Mixed and pumped with conventional equipment

Increased durability

High resistance to impact

Lower permeability than conventional set cementindependent of slurry density

Broad density range (1,2003,360 kg/m3 [1028 lbm/gal])

Greater drilling resistance for faster sidetracks

Materials 51


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DuraSTONE Advanced Cement Technology systems are more durable and have betterimpact resistance than conventional cements, so they provide better isolation under

rugged drilling and completion conditions. The conventional cement (top right) failedafter 6 impacts while the DuraSTONE cement (bottom right) held up to more than82 impacts.


DuraSTONE systems are tougher than conventional cement. They have betterdrilling resistance and impact resistance, and significantly more energy isrequired to cause flexural failure.

Drillingresistance

Energy forflexural failure

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Impactresistance

DuraSTONEsystem

performance

Conventional cementperformance

3X

15X

3.5X


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Cementing slurry systemsPortland cements that conform to American Petroleum Institute (API) Specification 10A (ISO10426-1:2000) are supplied where available or by request. These cements are supplied asOrdinary (O) grade (Classes A and C), Moderate Sulfate Resistant (MSR) grade (Classes B, C, Gand H), or High Sulfate Resistant (HSR) grade (Classes B, C, G and H). Sulfate resistance is nec-essary to protect against attack of the hydrated (set) cement by soluble sulfates. Where several

grades exist, local requirements determine the grade that is available.

Lightweight cements

Lightweight cements are used to control losses to weak or high-permeability formations. In mostcases, cement extended by the addition of water and additives to prevent water separation areadequate to control the losses. These cements generally have low strength and high permeabil-ity. However, when low density with either high strength or low permeability is required, specialformulations are necessary to meet those requirements.

Applications for lightweight cements include very weak, fractured, and highly permeable orvuggy formations. Such cements can be used in primary, squeeze or plug cementing.

Materials 53

Low-density LiteCRETE cement or foamed cement can float on water. After a short period,the high-porosity foamed cement sinks as a result of water absorption. LiteCRETE cementcontinues to float as a result of its low porosity and permeability, which is beneficial forpreventing gas flow and damage to the cement or casing by corrosive fluids.


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LiteCRETE cement

LiteCRETE cement is a special formulation using patented technology to produce very lowpermeability and high strength. LiteCRETE cement is discussed in detail in the section onCemCRETE cements.

D049 lightweight cement

D049, TXI lightweight oilwell cement is a special cement with lightweight components inter-ground to provide an economical low-density, high-yield slurry. Because of the composition, thelow specific gravity and the particle size of the grind, slurries can be mixed over a wide densityrange without extenders. This feature gives high versatility and flexibility to D049 lightweightcement. By varying the mix water-to-cement ratio, slurries can be mixed over a density range of1,440 to 1,700 kg/m3 [12.0 to 14.2 lbm/gal] without excessive free fluid or high rheology.

Because of the chemical composition and particle size, D049 lightweight cement providesexcellent strength. Strengths at low densities are superior to those of conventionally extendedcements. In most cases, the strength of D049 lightweight cement is adequate for completion,making a tail slurry unnecessary. Elimination of a separate tail slurry can simplify the cementingoperation and improve the quality of the isolation.

D049 lightweight cement requires no blending and no special additives. Properties of D049lightweight cement can be adjusted to meet almost any performance criteria needed to cementa well.

Foamed cement

Cement is foamed by adding a gas (generally nitrogen) and surfactants. Foamed cement has beenvery effective in controlling losses when very weak formations are cemented or where formationsare highly permeable. The thixotropic nature, in addition to the low density of the cement, makesit highly effective in these scenarios. In addition to their low density, foamed cement slurries pro-vide excellent strength and relatively low permeability compared with low-density cements pre-pared by conventional means. Foamed cement has greater durability than conventional cements.

This cement can be made at virtually any density, depending on the density of the base slurryand the amount of gas. Virtually any cement used in the oil field can be used as the base slurry.

A further advantage of foamed cement is that the density at which it is mixed can be selectedimmediately prior to the job, unlike the case of preblended cements. Additionally, by merelyadjusting the gas ratio, the density can be changed during the job to provide slurries with differ-ent properties in different parts of the well.



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Improved bonding cements

FlexSTONE cementadvanced flexible cement technology

FlexSTONE cement systems provide mechanical properties that can be adjusted to match thewellbore stresses. When designed with the assistance of stress analysis model software, flexibil-ity and expansion properties provide permanent zonal isolation to seal wellbore fluids behindcasing. See page 48 for details on FlexSTONE cement.

WELBOND cementimproved bonding cement system

WELBOND* improved bonding cement systems were developed to improve zonal isolationthrough better bonding. They improve the cement-to-pipe and cement-to-formation bonds by con-trolling fluid loss and by adhesion properties provided by latex additives. Furthermore, their lowpermeability when set prevents fluid movement behind the casing.

For optimal bonding properties, the latex concentration is adjusted to control fluid loss below70 mL/30 min. When bonding is not an issue but fluid-loss control is a necessity, the latex isadjusted to control fluid loss to less than 100 mL/30 min. This formulation provides a cost-effective alternative to polymeric fluid-loss agents, particularly at high temperatures.

WELBOND slurries can be used over the entire range of temperatures, densities and depthsthat normally occur in oil and gas wells.

SALTBOND cementcement system for cementing across salt zones

The cementing of wells penetrating massive salt formations poses a number of problems.Frequently, cementing across salt formations makes it necessary to use slurries containing highconcentrations of salt. Historically, salt-saturated cement slurries have had technical limitations.Many additives cannot tolerate saline environments or are degraded in the presence of salt.Other additives, which can tolerate the salt, often result in undesirable performance.

Effects of the salt and additives used with it have led to poor early strength development, espe-cially when conventional fluid-loss additives were used. The unusually high plasticity of saltcauses it to deform, or flow, when it is subjected to stress. Thus, under normal overburden pres-sures salt zones will typically encroach upon a well drilled through them. The nonuniform natureof this flow results in point-loading on casing strings, often causing their failure and collapse. To

reduce this risk it is essential that the cement slurry develops good early compressive strength,thereby preventing the movement of the salt formation into the wellbore.

One of the key performance problems in high-salinity cements is obtaining sufficient controlof fluid loss. Many polymers do not perform well in high-salinity systems. Thus, standard fluid-lossadditives could not provide the level of fluid-loss control needed and drastically increased slurryrheology. Additionally, formulations for cementing through salt greatly delayed strength develop-ment, leading to operational delays and exposure to hazards while waiting for the cement to set.

SALTBOND* slurries are specially designed for use across salt zones. They use a special addi-tive that provides fluid-loss control and dispersion in salt-rich slurries. API fluid-loss values as lowas 40 mL/30 min are obtained as are good rheological characteristics, short controllable thick-ening times, and good early strength. The normal temperature range over which these slurriescan be applied is 49 to 121C [120 to 250F] BHCT.

SALTBOND slurries contain 18 to 37% (based on the weight of water) salt and exhibit the

following properties: fluid loss as low as 40 mL/30 min

very low rheological characteristics

short controllable thickening times

good early strength development.

Materials 55


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With a low rate of fluid loss and low rheology values at high salinities, the SALTBOND servicealso provides controllable thickening times and high early compressive strengths. The result isvaluable protection against casing collapse.

SALTBOND slurry offers these advantages:

good fluid-loss control (less than 100 mL/30 min)

low placement (friction) pressures to help prevent loss of circulation

high early compressive strength to help prevent casing collapse

predictable slurry properties attained with only one additive (and one retarder, if required)

good bonding against salt formations

no potential dissolution of the salt formation while cementing.

RFC regulated fill-up cement

RFC* regulated fill-up cement slurries are highly thixotropic, forming a rigid gel structure shortlyafter slurry movement has stopped. They also expand. RFC slurries provide a number of distinctadvantages over conventional cement slurries because of their thixotropic and expansive prop-erties. Thixotropy minimizes losses and provides better bonding and zonal isolation through

expansion. RFC cement is a mixture of Portland cement and plaster.With minimized losses, RFC slurries provide more predictable fill-up in the well. RFC slurries

are advantageous in any application in which it is desirable for the slurry to quickly becomeimmobile after placement. In addition to primary cementing where losses are minimized, thesesystems can also be used to provide a gelled barrier to prevent further penetration duringsqueeze cementing, thus improving success of squeeze cementing.

An important property of RFC cement is the expansion of the set cement. The plaster reactswith the tricalcium aluminate in Portland cement to provide expansion during the early strengthdevelopment. This expansion acts to compensate for slight dimensional changes in the piperesulting from thermal or pressure changes following cement placement. Thus, the expansionhelps prevent microannulus development, resulting in improved zonal isolation.

SELFSTRESS expanding cement systemSELFSTRESS* expanding cement provides improved bonding. The maximum application tem-perature is 85C [185F] BHST. SELFSTRESS cements can be used where thixotropic propertiesare undesirable. SELFSTRESS cement is composed of Portland cement, plaster and salt or dis-persant, depending on the application. Other additives, such as retarders, fluid-loss agents, dis-persants, and extenders may be used as required.

Fast strength development

DeepCEM Cement

When cementing at shallow depths below the mudline in deepwater wells, rapid strength devel-opment is critical to prevent water flow and to provide adequate strength to continue operations,

avoiding costly waiting time.DeepCEM cement additives provide the dispersion needed to minimize adverse gelationeffects, minimize friction pressure and to enhance compressive strength development. DeepCEMdispersant D185, unlike most dispersants, does not retard at the very low temperatures encoun-tered at shallow depths below the mudline. This property, coupled with the rapid set-enhance-ment offered by D186, the DeepCEM set enhancer, provides the rapid strength developmentneeded in this tough cementing environment. DeepCEM set enhancer provides much more rapidstrength development than standard accelerators.



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Slurries formulated with DeepCEM additives are simpler and easier to design than other slurryformulations for deepwater cementing. When used with DeepCRETE Advanced CementTechnology slurries, these benefits are provided in a system that has low density, avoids lossesand sets rapidly.

This same technology is used in land operations where fast strength development at lowtemperatures is required.

ARCTICSET cementcement system for use through permafrost

ARCTICSET* cements are designed for low-temperature applications across permafrost zones.They will not freeze but will set and develop adequate strength in wells having temperatures aslow as 9C [15F]. ARCTICSET cements have low free-water separation, low permeability, excel-lent durability to temperature cycling, and controllable pumping times and gel strength properties.To ensure that the mix water does not freeze before the cement hydrates, a freeze depressant isused. Heat of hydration is low to prevent thawing of the permafrost.

ARCTICSET formulations are available for a variety of wellbore conditions including normaldensity, lightweight and with lost circulation materials (LCM).

Right-angle set cement

At low temperatures, conventional accelerators like calcium chloride often do not provide eitherearly setting or rapid strength development. This is especially true below 20C [68F].

Right-angle set cement systems are designed for use at low temperature, between 0C [32F]and 30C [86F], where short WOC time and/or short transition time are required. Applicationat temperatures to 50C [122F] is possible. Regardless of the temperature, a compressivestrength of 500 psi can be obtained 1 to 2 hr after the setting begins, while the slurry transitiontime from 30 to 100 Bc consistency is only a few minutes. The thickening time can be adjustedeasily between half an hour and several hours, without impairing this right-angle setting prop-erty.

Right-angle set cement is known by several names, depending on the application, includingsurface-set cement and quick-setting cement.

Materials 57


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Cements for harsh environments

In some situations, cement with special resistance properties is required. This is true in wellswith soluble sulfates that can attack the cement (generally controlled by the chemistry of thePortland cement during manufacture) or when other chemical compounds may contact thecement. Sulfate resistance is imparted to the cement in moderate- and-high-sulfate resistantcements during manufacture. Resistance to attack by other chemicals is controlled by selectionof the components added to the cement or by using special cements, such as synthetic cement.

Acid-resistant cement

In some situations, cement is exposed to acid. Portland cement is acid soluble, although in mostcases acid treatment does not cause failure to the cement sheath. When large volumes of acid arepumped at high rates and expose old perforations that have been sealed with cement, the plugsin the perforations sometimes fail. Acid-resistant cement can prevent such failures.

Acid-resistant cement is made from conventional API cement with a special formulation oflatex that reduces the permeability of the cement and imparts acid resistance. When used forplugging perforations, this formulation has been effective in wells where acid treatments havecaused failure of the plugged perforations in other cement formulations.

When complete resistance to attack by acid or other chemicals is required, synthetic cementcan be used.

Carbon dioxide-resistant cement

Carbon dioxide-resistant cement was developed for completions in wet carbon dioxide environ-ments. Applications include source, injection and production wells in carbon dioxide enhancedoil recovery projects or oil and gas wells with high levels of carbon dioxide. Under these condi-tions, wet carbon dioxide chemically attacks cement. The end result is a loss of strength andstructural integrity in the casing sheath.

This cement is 45% more resistant to carbon dioxide leaching than either conventional cementor typical fly ash-cement blends of equivalent density. Although the carbon dioxide corrosion rateis dependent on the amount of water present and is difficult to predict, the use of carbon diox-ide-resistant cement translates into improved performance with respect to completion life atapproximately the same cost per sack as conventional cement. These systems are applicable inthe temperature range of 16 to 93C [60 to 200F].

Because of their low permeability, the cements of Advanced Cement Technology, CemCRETEand CemSTONE cements are well-suited for such use, either on their own or supplemented withthe special treatments used to prepare the acid-resistant cement or carbon dioxide-resistantcement.

Synthetic cement

Synthetic cement is designed for completing waste-disposal wells. It is characterized by high cor-rosion resistance and high compressive and shear-bond strength. Synthetic cement is resistantto attack by strong acids and bases, such as 37% hydrochloric, 60% sulfuric and 50% sodiumhydroxide, at elevated temperatures. However, it is not resistant to organic solvents such as ace-tone or chlorinated solvents. The system density can be adjusted from 1,140 to 1,560 kg/m3 [9.5to 13.0 lbm/gal]. The upper temperature limit of synthetic cement is between 93 and 104C [200and 220F], depending on the required pumping time.

Remedial cementing is another application for synthetic cement. Computer modeling showsthat it can enter microleaks and microannuli at low differential pressures.



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UniSLURRY cement systemsThe UniSLURRY cement system concept is a new methodology for designing cement slurries inwhich the additives use chemistry designed to perform specific functions. Because they are built-for-purpose, they are highly effective and have minimal effects on properties other than those forwhich they are intended. Only a few universal additives are required to work in the entire rangeof well conditions, from conductor casing to production liner. Additionally, UniSLURRY additives

work together synergistically.These features improve the entire cementing process, from prejob laboratory testing to executionin the field. The innovative, superior chemistry common to all UniSLURRY additives provides tech-nical and economical advantages, such as reduced additive consumption and shorter WOC times.Prejob laboratory testing is shorter and more efficient because a few reliable and predictableUniSLURRY additives have taken the place of many less-efficient additives. Stocking of materials atthe warehouse and on location is more efficient because fewer additives are needed to complete allcement jobs. Mixing on location is improved because smaller quantities of additives are required.

UniSLURRY systems can be used for all cementing operations, including casings, liners, plugs andsqueeze jobs. The UniSLURRY concept can be used over a wide temperature and density range,addressing most oilfield cementing requirements.

The UniSLURRY family consists of four members: UNIFLAC* S solid and UNIFLAC L liquid uni-fied fluid-loss additives and UNISET* LT and UNISET HT liquid unified retarders. These versatile,

unified additives cover all cementing conditions and bring to everyday cementing operations aquality previously found only in highly technical areas such as deepwater or HPHT wells. Theirversatility simplifies the logistics of cementing operations by reducing the number and quantity ofadditives that have to be transported and stored at the wellsite. The environmentally friendlyUniSLURRY products are used for both land and offshore operations. They are the first choice whenlogistics are an issue; e.g., on offshore or remote locations.

Conventional cementing additives have addressed a particular range of temperature and set ofconditions, such as maximum water salinity or cement type, making them highly specialized. Thisspecialization has made the design of cement slurries both time-consuming and complicated.

The UniSLURRY products perform over a broader range of temperatures and salt concentrationsand work in any application; cementing casing or liner, squeeze or plug. Their performance is con-sistent and practically independent of the cement type or brand. UNIFLAC additives and UNISETadditives work synergistically, allowing reduction of additive concentration while maintaining slurry

quality.The benefits of the UniSLURRY additives extend to every aspect of the cementing operation:

Laboratory testingUniSLURRY additives make the laboratory-testing process more efficient.Consistent and predictable, the UniSLURRY additives work with simpler and more reliabledesigns (both UNIFLAC additives and UNISET additives exhibit nearly linear dependence on tem-perature and other parameters).

LogisticsWhen cementing with traditional additives, the temperature limitations often make itnecessary to use different sets of additives on different strings of pipe. This makes it necessary tostock numerous additives, both at the warehouse and at the wellsite. Because UniSLURRY addi-tives can be used on all casings from conductor to liner, surplus additives from one job can be usedon the next cementing job. Unnecessary handling between jobs is avoided, precious space on therig is conserved, and waste is reduced, thus reducing the overall cost and enhancing operational

safety and efficiency. Job executionUniSLURRY technology simplifies cement job execution at the wellsite. Fewer

additives are required to obtain the needed slurry properties. This benefit simplifies the mixingoperation, especially in remote locations using liquid additives.

All UniSLURRY additives share some common benefits and features.

Materials 59


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Benefits Simplified slurry design

Cost-effective

Minimized rig time

Fewer additives for simplified wellsite logistics

Low sensitivity to cement variations for reduced slurry-design time

Features Universal fluid-loss and retarder additives for any condition

Low sensitivity to cement brands

Low sensitivity to temperature and concentration variations

Lower concentrations needed

Highly predictable concentration and thickening time

Minimized WOC time

Environmentally friendly chemistry

UNIFLAC unified fluid-loss additive for cementInadequate fluid-loss control can lead to serious problems during cementing operations. Loss offluid from the cement slurry can result in friction pressure increases, shorten thickening timeand increase the risk of microannulus and loss of zonal isolation.

UNIFLAC additive is a universal and cost-effective solution for fluid-loss control in all cementingapplications. The additive is a custom-made, third-generation polymer that is available in liquid(D168) or solid (D167) form. The solid additive can be dry-blended with the cement or predissolvedin the mix water. Its robust properties make slurry design very simple and produce predictableresults in the field, from the conductor casing to the liners. Test results demonstrate the very low sen-sitivity of UNIFLAC additive to variations in temperature or concentration. It also has a low sensi-

tivity to cement brands.The same additive is used at all temperatures, from 10 to 260C [50 to 500F]. Synergy betweenUNIFLAC additive and Schlumberger UNISET retarders provides additional operational benefits.When used with UNIFLAC additive, the concentration of UNISET retarder required to achieve adesired thickening time is reduced and early compressive strength development reduces WOC time.

UNIFLAC L additive concentration to achieve API fluid loss of 50 mL/30 minis easily predictable at different temperatures and slurry densities.


0.6

0.5UNIFLAC L

(gal/sk)

0.7

0.8

0.9

0.4

0.2

0.1

0.3

0.0

50 150 250 350 450

Temperature (F)

13.0 lbm/gal16.2 lbm/gal18.5 lbm/gal


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Use of UNISET retarder with UNIFLAC additive results in synergy thatallows much reduced concentrations.

Applications All cementing applications

Wells with temperatures from 10 to 260C [50 to 500F]

Benefits

Economical Savings from less WOC time

Simplified slurry design

Simplified logisticsfew additives required

Features Low sensitivity to cement brands

Low sensitivity to temperature

All densities

Fresh to salt-saturated mix water

Compatible with all additives, including calcium chloride accelerator and silicate extenders Synergy with Schlumberger UNISET retarders

Low concentration requirements

Excellent slurry rheology

UNISET set control additivesSchlumberger UNISET set control additives provide a unique set of properties that are not avail-able with conventional retarders. Cement retarded using UNISET additives exhibits a rapid set-ting behavior, even with longer thickening times for increased safety factors. Their synergisticbehavior with UNIFLAC additives allows lower concentrations (as much as two-thirds reduction),

thus improving economics.

Materials 61


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When UNISET HT additive is used, extended thickening times do not result inthe excessive WOC times found with conventional retarders.

Excessive retardation by conventional retarders impairs strength development, extending WOCtime and making the cement vulnerable to invasion by well fluids or mechanical damage fromchanging stresses in the well. In extreme cases, some cementing treatments must be done inseveral stages to avoid excessively long setting times. This complicates and increases the overall costof the operation.

UNISET HT additive retards to provide sufficient time to place the cement, yet promotes early and

rapid strength development to minimize WOC time. UNISET HT additive is also much less sensitiveto temperature variations than other cement retarders. It is the preferred retarder for the mostchallenging situations when temperature is not well defined or if there is a large difference betweentemperature at the top of the liner and the bottom of the cement.

Applications All cementing operations

Benefits Simplified slurry design

Much reduced risk of problems from inherent temperature errors

Cost benefits from simplified logistics, reduced additive usage and shorter WOC time Lower concentrations required due to synergy with UNIFLAC additives

Features Full range of temperature

All densities

Fresh water and seawater

Highly reliable and predictable concentration and thickening time response

Only two additives needed for entire temperature range

Synergistic with UNIFLAC fluid-loss additives

Rapid setting and compressive-strength development


4

3

Ratio of time to reach50 psi at 320F (hr)to thickening time

at 350F (hr)

5

6

7

2

1

2 4 6 8 10 12

Thickening time at 350F (hr)

D121/D28

D121/D28

16-lbm/gal slurry


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UNISET additives are available for low- to moderate-temperature and high-temperature applica-tions. UNISET LT additive covers applications to about 120C [250F], and UNISET HT additivecan be used from about 80 to 260C [180 to 500F].

UNISET retarders are compatible with most other Schlumberger cementing additives.

Cementing additivesThe following paragraphs and tables describe the performance of cementing additives by func-tional group. Some materials are discussed in more detail in sections on specific functionalsystems. The Cementing Additive Quick Guide and Cementing Additive List provide descriptions

of additives listed by functional group and by code, respectively. The list gives general applicationconditions for each additive. These application conditions reflect those tested during productdevelopment. In many cases, the products can be used outside the quoted conditions with testingappropriate to specific applications.

Accelerators

Accelerators are materials that cause cement to hydrate and develop strength earlier and faster.They are commonly used to provide improved strength at low temperatures and to counteract theretarding effects of other additives. Accelerators also shorten the thickening time.

Antifoam and defoam agents

Antifoam agents prevent or reduce the foaming tendencies of cement when it is mixed. This isnecessary because the properties of cement slurries and the set cement depend on thewater/cement ratio. Most field mixers determine the ratio by measuring the density of the slurry,so entrained air causes the slurry to be mixed at improper ratios. Some materials can be used asantifoam agents, but not as defoamers. Other materials act as either defoamers or foam preventers.

Antigelation agents

In some cases gelation is caused by the chemical makeup of the cement. Many times this gela-tion can be controlled by dispersants, but special materials may be required.

The relationship between concentration and temperature is linear, makingconcentration selection simple when using UNISET HT retarder. The graphshows the concentration required for a thickening time of 4 to 5 hr.

Materials 63

0.4

0.2

Concentration(gal/sk)

0.6

0.8

1.0

0.0180 200 220 240 260 280 300 320

Pump rate (bbl/min)


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Surfactants

Surfactants are used in chemical washes and spacers with OBM and to create stable foam whenadding a gas to make foamed cement.

Special additives

There are a number of additives that do not fit neatly into functional groupings. Fibers are used

for controlling lost circulation (see section on CemNET advanced fiber cement). Special types offibers also improve the impact resistance and tensile strength of cement (see section onDuraSTONE cement).

The flexibility of cement can be improved by the use of special additives. This increase in flex-ibility provides increased resistance to failure by mechanical stresses imposed on the cementduring well operation. (See section on FlexSTONE cement.)

Granular salt (sodium chloride) and potassium chloride are used primarily to change the ionicnature of the water in the slurry, which helps to minimize adverse formation interactions. Incases where the formation is salt, high concentrations of salt, up to saturation, are commonlyused to prevent leaching salt from the borehole wall.

Silica is used to combat strength retrogression. Strength retrogression is a change in thehydration products that are formed when cement is exposed to high temperatures (>110C

[230F]). Silica is available in coarse or fine grades for cementing.

Suspending and antisettling agents

Occasionally, segregation can occur in a cement slurry. This segregation may be in the form ofwater separation (known as free fluid) or in solid particle sedimentation. In either case, amaterial to suspend the solids is used to maintain slurry integrity.

Thixotropic additives

Thixotropic additives produce an intentional gelation of the cement to aid in placement of thecement. Thixotropic cement is discussed as RFC cement on page 56.

UniSLURRY additivesUniSLURRY additives have unique and synergistic properties. These additives have been pur-pose built to perform their function and have properties that distinguish them from other fluid-loss or set-control (retarder) additives. UniSLURRY additives, UNIFLAC fluid-loss additive,UNISET LT retarder and UNISET HT retarder are discussed on pages 5963.

Weighting agents

Weighting agents are used to increase the density of the cement when needed for well control.

Spacers

Spacers are generally thickened, weighted fluids used to aid in mud removal and to separate the

mud from the cement to prevent any compatibility problems.

Chemical washes

Chemical washes are generally thin fluids with surfactants to aid in mud removal and to separatethe mud from the cement to prevent any compatibility problems.

The following tables list additives by functional category (Cementing Additive Quick Guide)and by additive code (Cementing Additive List).

Materials 65


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Cementing Additive Quick-Guide

Code Form, Liquid (L) Material and/or Application Temperature Rangeor Solid (S) Application (BHCT except where noted)

Accelerators

D044 S Sodium chloride No limit

D077 L Calcium chloride Below 55C [130F]

D186 L Set enhancer 755C [45130F]

S001 S Calcium chloride Below 55C [130F]

S002 S Calcium chloride Below 55C [130F]

Antifoam Agents

D046 S Foam preventer No limit

D047 L Foam preventer No limit

D144 L Defoamer No limit

D175 L Defoamer No limit

M045 L Defoamer No limit

Chemical Washes

D122A L Chemical wash concentrate No Limit

D191 L Surfactant for washes and spacers Maximum 250C [482F]D192 L Chemical wash concentrate No Limit

DeepCEM Additives

D185 L Low temperatures; nonretarding Maximum 57C [135F]

D186 L Set enhancer 755C [45130F]

Dispersants

D065 S Freshwater systems Maximum 121C [250F]

D065A S SALTBOND additive for high-salinity systems Maximum 121C [250F]

D080 L Liquid equivalent to D065 Maximum 121C [250F]

D080A L SALTBOND additive for high-salinity systems Maximum 121C [250F]

D121 S Dispersant, retarder, fluid-loss additive 121274C [250525F]

D145A L Low temperature Maximum 85C [185F]D185 L Low temperature; nonretarding Maximum 57C [135F]

D604AM L SALTBOND additive for high-salinity systems Maximum 121C [250F]

D604M L Easy-to-disperse cement Maximum 121C [250F]

Expanding Additives

D053 S Additive for RFC and SELFSTRESS systems Maximum 85C [185F]

D174 S Low to moderate temperatures Maximum 110C [230F] BHST

D176 S High temperatures 80204C [176400F] BHST

Extenders

D020 S Bentonite Maximum 232C [450F] BHST

D035 S Class F fly ash Maximum 232C [450F] BHST

D048 S Class F fly ash Maximum 232C [450F] BHST

D056 S Diatomaceous earth No limit

D072 S Expanded perlite Maximum 232C [450F] BHST

D075 L Sodium silicate Limited by ability to retard

D079 S Sodium metasilicate Limited by ability to retard

D124 S LITEFIL* ceramic microspheres Maximum 232C [450F] BHST

D125 S Expanded perlite Maximum 232C [450F] BHST

D128 S Attapulgite Maximum 232C [450F] BHST

D132 S Class C fly ash Maximum 232C [450F] BHST


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Cementing Additive Quick-Guide (continued)

Code Form, Liquid (L) Material and/or Application Temperature Rangeor Solid (S) Application (BHCT except where noted)

Spacers

D182 S Additive for MUDPUSH II spacer Maximum 149C [300F]

D190 S MUDPUSH WHT additive Maximum 232C (450F)

Special Additives

D030 S Coarse silica; strength retrogression control No limit

D044 S Salt No limit

D053 S Additive for RFC and SELFSTRESS cements Maximum 85C [185F]

D066 S Silica flour; strength retrogression control No limit

D111 L Additive for RFC cement Maximum 85C [185F]

D140 S Activator for PERMABLOK plug Maximum 80C [176F]107C [225F]

D606 S Gelation suppressant No limit

J120 S Polymer for polymer plug 93C [200F]

M117 S Potassium chloride No limit

SurfactantsD139 L Stabilizer for foamed cement Maximum 232C [450F]

D607 L Wash or spacer for OBM removal Maximum 232C [450F]

F040 L Aid in OBM removal Maximum 232C [450F]


F078 L Foaming agent for foamed cement Maximum 232C [450F]


F104 L Foaming agent for foamed cement Maximum 232C [450F]

U066 L Solvent for OBM removal Maximum 232C [450F]

U100 L Solvent for OBM removal Maximum 232C [450F]

Suspending Agents

D153 S Antisettling agent Maximum 149C [300F]

D162 L Antisettling agent Maximum 149C [300F]

Thixotropic Agents

D053 S Additive for RFC and SELFSTRESS cements Maximum 85C [185F]

D111 L Additive for RFC cement Maximum 85C [185F]

Weighting Agents

D018 S Ilmenite No limit

D031 S Barite No limit

D076 S Hematite No limit

D151 S Calcium carbonate No limit

D157 S Micromax Maximum 232C [450F]

D165 S Additive for DensCRETE slurries No limit

D166 S Additive for DensCRETE slurries No limit


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Materials 69

Cementing Additive List

Code Name Application Description SG Primary Purpose

D008 Retarder/ Moderate White powder Used primarily with high-salinity slurries.fluid-loss temperatures Strong viscosifier; provides some fluid-lossadditive control. Concentration: 0.051.0% BWOC.

Temperature: 54104C [130220F] as retarder;

to 232C [450F] as fluid-loss additive.

D013 Retarder Low to moderate Brown powder 1.23 Temperature: to 60C [140F] when usedtemperatures alone and 85C [185F] with a dispersant.

Concentration: 0.10.5% BWOC. Can beused in fresh water and seawater.

D018 Ilmenite High-density slurries Black granules 3.504.50 High-density slurries and spacers to2300 kg/m3 [19 Ibm/gal].

D020 Bentonite Cement extender Light tan to 2.65 API untreated bentonite. To 25% BWOC whengray powder dry blended. About one-fourth as much is

required when prehydrated. Minimum density:1380 kg/m3 [11.5 Ibm/gal]. Attapulgite (D128)is used in salt water.

D024 Gilsonite Lost circulation Black granules 1.07 LCM. Concentration: 10.6106 kg/t [110 lbm/sk].control Temperature to 149C [300F].

D028 Retarder High temperatures Dark brownish 1.25 Temperature: 104149C [220-300F];Can be used to 204C [400F] with a retarder aid.

Concentration: 0.051.0% BWOC. Can be usedin fresh water and in high-salinity systems.

D029 Cellophane Lost circulation Clear thin flakes 1.45 LCM. Concentration: 1.35.3 kg/tflake control [0.1250.5 Ibm/sk].

D030 Silica Strength White to tan granules 2.65 100-mesh silica sand. Prevents strengthretrogression retrogression at temperatures abovecontrol 110C [230F]. Concentration: 3550%

BWOC. D030 is preferred to D066 (silica flour)in dense, low-water-ratio slurries.

D031 Barite Weighting agent Grey or tan powder 4.33 High-density slurries and spacers(to 2300 kg/m3 [19 Ibm/gal]).

D035 LITEPOZ 3 Cement extender Tan to gray powder 2.48 Class F fly ash. Normally substituted for aextender portion of the cement on an absolute volume

basis (e.g., in USA, 35:65) or blended on abulk volume basis (e.g., in Canada, 1:1).

D042 KOLITE lost Lost circulation Black angular 1.30 LCM. Granular material of controlledcirculation control granules particle size distribution.additive Concentration: 10.6106 kg/t [110 lbm/sk].

D044 Granulated Accelerator; White granules 2.16 Sodium chloride. Used where formations aresalt inhibit clay swelling; sensitive to fresh water. Accelerates cement

facilitate bonding in set when used at concentrations to 15%

salt formations BWOW (by weight of water). At 18% BWOW,its effect is essentially neutral and thickening

times are similar to those obtained with freshwater. Above 18% BWOW, D044 retards settingof cement. Used above 18% to minimizeleaching of salt formations.

D046 Antifoam Control foaming of Tan solid 1.50 General purpose solid foam preventer.cement slurries Typical concentration: 2 kg/t [0.2 Ibm/sk].


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Cementing Additive List (continued)


D047 Antifoam Control foaming of Colorless liquid 1.00 General purpose liquid foam preventer.cement slurries Typical concentration: 4.5 L/t [0.05 gal/sk]

for cement slurries and 6 L/m3 [0.25 gal/bbl]for spacers.

D048 LITEPOZ 6 Cement extender Gray to tan powder 2.01 Class F fly ash. Normally substituted for aextender portion of the cement on an absolute volume

basis (e.g., in USA; 35:65) or blended on a bulkvolume basis (e.g., in Canada, 1:1).

D053 Cement agent Thixotropy and White powder 2.70 Additive for RFC cement and SELFSTRESSexpansion cement. Thixotropic slurries (RFC cement)

are used for lost circulation control and theirexpansive properties. SELFSTRESS cementis used for its expansion. Effective up to85C [185F].

D056 Extender Cement extender Light gray granules 2.10 Diatomaceous earth.

D059 FLAC* fluid- Salt cement slurries White powder 1.36 Fluid-loss control additive for salt slurries.

loss additive Can be used in fresh slurries with dispersant.Temperature range: 3893C [100200F].Typical concentration: 0.5 to 1% BWOC.Retards at low temperatures.

D065 TIC* Freshwater or low Light brown powder 1.43 Powerful cement dispersant. Concentration:dispersant salinity slurries 0.11.5% BWOC. Can be used with seawater.

Temperature to 121C [250F].

D065A SALTBOND Fluid-loss control for Light brown powder 1.43 Dispersant and fluid-loss additive for high-additive high salinity slurries salinity slurries when difficult-to-disperse

in salt cement is used. Temperature to121C [250F].

D066 Silica flour Strength White to tan granules 2.65 Fine silica flour (finer than 200 mesh). Preventsretrogression strength retrogression at temperatures above

control 110C [230F]. Concentration: 3550% BWOC.Preferred over D030 in lightweight slurries andat very high temperatures.

D072 Perlite Cement extender White, fluffy powder 2.40 Expanded volcanic glass. Used in shallow wells;collapses at high pressure (significant at20.7 MPa [3000 psi]).

D075 Sodium silicate Cement extender Colorless liquid 1.38 Silicate-based liquid extender. Preferred forseawater applications. When used with freshwater, requires calcium chloride addition

to the mix water. Typical concentration:1854 L/t [0.20.6 gal/sk]. Minimum density:1,380 kg/m3 [11.5 Ibm/gal]. Accelerates set.

D076 Hematite Weighting agent Reddish brown powder 4.95 High-density slurries and spacers to

2,300 kg/m3 [19 Ibm/gal].

D077 Liquid calcium Cement slurry Clear to straw 1.38 Liquid form of calcium chloride. Used in freshchloride accelerator colored liquid water or seawater. Maximum concentration

of 35.5 L/t (0.4 gal/sk).

D079 Sodium Cement extender White solid 2.40 Sodium metasilicate extender. Most applicablemetasilicate for low bulk-storage requirements, such

as remote locations and offshore.Typical concentration: 0.253% BWOC.Minimum density: 1,380 kg/m3 [11.5 Ibm/gal].Accelerates set.


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D132 Cement Carbon dioxide- Tan to gray powder 2.67 Class C fly ash; component of carbonagent resistant cement dioxide-resistant cement.

D139 Foamed Foamed cement Clear to hazy 1.07 Used to maintain downhole stability of

cement yellow liquid foamed cement.stabilizer Usual concentration: 9 L/t [0.1 gal/sk].

D140 Hardener Hardener for Yellow liquid 1.24 Hardener for PERMABLOK rigid gel system.PERMABLOK lost Temperature: to 80C [176F]. May be extendedcirculation plug through laboratory testing to 107C [225F].

Concentration: 520% by volume of solution,depending on temperature, required gel timeand rigidity.

D144 Antifoam High-salinity slurries White liquid 1.00 General purpose liquid foam preventeradditive and spacers and defoamer. Added to the mix water. Typical

(efficient in any fluid) concentration: 15 L/t [0.010.05 gal/sk] forcement slurries and 2.4 L/m3 [0.1 gal/bbl]for spacers.

D145A Liquid Low temperatures Viscous liquid 1.24 Dispersant, much less retarding than D080.dispersant Temperature: to 85C [185F] in freshwatersystems. Usual concentration: 4 to27 L/t [0.05 to 0.3 gal/sk].

D150 Retarder High temperatures Dark brown liquid 1.11 Liquid equivalent to D028. Temperature:104149C [220300F]; to 204C [400F]with a retarder aid. Concentration:236 L/t [0.020.4 gal/sk].

D151 Calcium Weighting agent White powder 2.70 Graded calcium carbonate. Weighting materialcarbonate for spacers for spacers, especially where acid solubility

is required.

D152 Premium Extender Light tan to 2.65 Premium grade of bentonite having betterbentonite gray powder fluid-loss control properties when used at

high concentrations (>12%).

D153 Antisettling Suspending additive White to gray powder 2.53 Maintains slurry stability at downholeadditive temperature conditions. For all densities.

Temperature: to 149C [300F].Concentration: 0.11.5% BWOC.

D154 Extender Low temperatures Gray powder 2.20 Microsilica. Improves performance of most setcement formulations; better strength and lowerpermeability. Useful for lightweight systems to1,320 kg/m3 [11 Ibm/gal], especially at low

temperatures (to 85C [185F]).Concentration: 520% BWOC.

D155 Extender Low temperatures Gray liquid 1.40 Suspension of microsilica in water. Improvesperformance of set cement; usually gives better

strength and lower permeability. Useful for light-weight systems to 1320 kg/m3 [11 Ibm/gal].Concentration: 90360 L/t [14 gal/sk].

D157 Weighting High-density slurries Red brown powder 4.80 Compatible with freshwater and high-agent salinity slurries to 232C [450F]. Applicable

1,9202,640 kg/m3 [1622 lbm/gal]. Very smallparticle size (5 micrometers) enables additiondirectly to mix water, allowing last-minutedensity increases.


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D161 UNISET HT High temperatures Clear liquid 1.08 Compatible with freshwater slurries andretarder salinities to 25% salt BWOW and any density.

Works synergistically with UNIFLAC fluid-lossadditives. Concentration: 9225 L/t [0.12.5 gal/sk].

Effective temperature: 85232C [185450F].

D162 Liquid Sedimentation control Off-white liquid 0.84 Compatible with freshwater and high-antisettling salinity slurries. For all densities.additive Temperature: to 149C [300F].

Concentration: 0.452.3 L/t [0.0050.025 gal/sk].

D165 CemHD DensCRETE slurries Reddish powder 4.95 Special grade of hematite for DensCRETE slurries.

D166 CemD DensCRETE slurries White powder 2.65 Special grade of silica for DensCRETE slurries.

D167 UNIFLAC S Fluid-loss control White powder 1.32 Compatible with freshwater and high-salinityadditive slurries. Temperature: to 204C [400F].

All densities. Typical concentration:0.1 to 0.8% BWOC.

D168 UNIFLAC L Fluid-loss control Colorless to yellow 1.08 Liquid version of D167. Compatible withadditive liquid freshwater and high-salinity slurries.Temperature: to 204C [400F]. All densities.Typical concentration: 981 L/t [0.10.9 gal/sk].

D174 Expanding Low to moderate Tan powder 3.22 Temperature: 27110C [80230F].cement temperatures Typical concentration: 35% BWOC.additive

D175 Antifoam High-salinity slurries White liquid 0.99 General purpose liquid foam preventer andadditive and spacers (efficient defoamer. Added to the mix water. Typical

in any fluid) concentration: 15 L/t [0.010.05 gal/sk] forcement slurries and 2.5 L/ m3 [0.1 gal/bbl]for spacers.

D176 Expanding High temperatures Tan powder 3.54 Temperature: 80204C [176400F].

cement Typical concentration: 15% BWOC.additive

D177 UNISET LT Low to moderate Light green liquid 1.10 Can be used with fresh water or seawater.additive temperatures Concentration: to 26 L/t [0.3 gal/sk].

Low sensitivity of thickening time tochanges in temperature or concentration.Maximum temperature: 121C [250F] ifused in combination with UNIFLAC additive(D167 or D168).

D182 MUDPUSH II Low to moderate Red brown powder 1.32 Concentrate for preparing MUDPUSH II spacer;spacer temperatures used with freshwater, seawater, or high-salinityadditive spacers. MUDPUSH II spacer density can be

designed to 2,400 kg/m3 [20 lb/gal].Temperature: to 149C [300F].

D185 Dispersant Low temperatures Colorless liquid 1.04 DeepCEM additive for cold environment ofdeepwater. Nonretarding. Temperature: to57C [135F]. Rheology is not affected by salt(D044) or calcium chloride (S001).


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D186 Set enhancer Low temperatures Green liquid 1.35 DeepCEM additive for cold environment ofdeepwater. Enhances the set profile ofcement; accelerates cement hydrationresulting in early compressive strength

development. It is especially effective withGASBLOK LT additive (D500) and D185dispersant. D186 can be used withDeepCRETE systems. Preferred temperature:755C [45130F]. Compatible with freshwater or seawater.Concentration: to17.8 L/t [0.2 gal/sk].

D190 MUDPUSH High temperatures Colorless powder 1.23 Viscosifies to suspend weighting agentsWHT additive and control fluid loss in MUDPUSH WHT

high-temperature spacer, which has atemperature limit of 232C (450F).Density: to 2,400 kg/m3 [20 lb/gal].

D191 Surfactant For spacers and Clear opalescent liquid 0.98 Environmentally friendly surfactant used inwashes for removal washes and MUDPUSH spacers for removal

of OBM of OBM, low-toxicity OBM or synthetic OBM.Temperature: to 250C [482F].Typical concentration: 48 L/m3 [2 gal/bbl].

D192 Chemical Mud thinning, Dark brown liquid 1.18 Environmentally friendly surfactant usedwash dispersing and in washes. No limit on temperature.concentrate removal

D300 Fluid-loss Low to moderate Green liquid 1.00 Nonretarding. Compatible with calcium chloride.additive temperatures Compatible with salinity to 10% BWOW.

Temperature: 27120C [80250F].Concentration: 32117 L/t [0.351.3 gal/sk].Only dispersants D145A and D185 can beused with D300 fluid-loss additive.

D500 GASBLOK LT Gas migration Yellow liquid 1.01 Nonretarding liquid additive.

additive control at low Temperature: to 71C [160F].temperatures Density: 1,2601,970 kg/m3 [10.516.4 lbm/gal].

Compatible with fresh water and seawater.Typical concentration: 45180 L/t [0.52.0 gal/sk].

D600G GASBLOK MT Gas migration White liquid 1.02 Latex additive. Temperature: 66121C [150250F].additive control additive Concentration: 130260 L/t [1.53.5 gal/sk] in

GASBLOK slurries; 90180 L/t [12 gal/sk] asWELBOND cement. Lower concentration isrequired when used for fluid-loss control only.

D602 Diatomaceous Cement extender White to gray powder 2.10 Naturally occurring material used as extender.earth

D604AM SALTBOND Fluid-loss control for Dark brown liquid 1.21 Salt system dispersant and fluid-loss additive.additive high salinity slurries Temperature: to 121C [250F].

Concentration: 2781 L/t [0.3-0.9 gal/sk].

D604M Dispersant Easy-to-disperse Dark brown liquid 1.21 Formulated to minimize overdispersion.cements Temperature: 121C [250F].

Concentration: 0.99 L/t [0.010.1 gal/sk].

D606 Gel- Antigelling additive White crystals 2.68 Eliminates primary gelling tendency of cementsuppressing with improperly balanced sulfate. Typicaladditive concentration: 0.51.0% BWOC.


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D607 Surfactant For spacers and Yellow liquid 0.99 Typical concentration: 210% by volume.washes for removalof OBM

D700 GASBLOK HT Gas-migration-control White liquid 1.02 Latex additive. Typical temperature:additive additive for high 121191C (250375F). Concentration:

temperatures 177310 L/t [23.5 gal/sk]. The addition ofD701 (high-temperature latex stabilizer)may be required.

D701 GASBLOK Stabilizer for Clear yellow 1.05 Used to stabilize D700 GASBLOK slurry;stabilizer GASBLOK slurries viscous liquid necessary. Typical concentration: 5% by

volume of D700.

D800 Retarder Low to moderate Dark brown powder 1.26 Lignosulfonate retarder with reduced tendencytemperatures for gelation. Temperature: 52121C [125250F]

BHCT; can be extended to 154C [310F] whenused with a retarder aid. Compatible with freshwater or salt water (to saturation).Concentration: 0.252% BWOC.

D801 Retarder Low to moderate Dark brown liquid 1.18 Liquid version of D800. Temperature:temperatures 52121C [125250F] BHCT; can be extended

to 154C [310F] when used with a retarderaid. Compatible with fresh water or saltwater (to saturation). Concentration:4.5-36 L/t [0.05-0.4 gal/sk].

F040 EZEFLO* For spacers and Clear liquid 1.04 Typical concentration: 210% by volume.surfactant washes for removal

of OBM

F057 Surfactant For spacers and Yellow liquid 1.07 Typical concentration: 210% by volume.washes for removalof OBM

F078 EZEFLO For spacers and Clear amber liquid 0.89 Typical concentration: 210% by volume.surfactant washes for removal Also used for foaming cement slurries

of OBM with nitrogen or air.Typical concentration: 1918 L/t [0.10.2 gal/sk].

F103 EZEFLO For spacers and Clear colorless liquid 0.94 Typical concentration: 210% by volume.surfactant washes for removal

of OBM

F104 Foaming Foamed cement Clear amber liquid 1.01 For foaming cement slurries with nitrogen or air.additive Also used in washes and in MUDPUSH spacers

for removal of OBM.Typical concentration: 210% by volume.Typical concentration: 918 L/t [0.10.2 gal/sk].

J120 Polymer Polymer Plug White powder 1.00 Polymer for use in Polymer Plug lost circulation

lost circulation system control system.

J237A Fluid-loss Fluid-loss control in Creamy liquid 1.06 Typical concentration: 6 L/ m3 [0.25 gal/bbl].additive chemical washes

M045 Antifoam Washes and spacers White liquid 1.00 General purpose liquid foam preventer andadditive defoamer. Added to the mix water. Typical

concentration: 5 L/t [0.05 gal/sk] for cementslurries and 2.5 L/m3 [0.1 gal/bbl] for spacers.


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M117 Potassium Clay stabilizer White to gray 1.98 Used in washes and spacers as a claychloride crystals stabilizer. Typical concentration: 3% BWOW.

Sometimes used in cement slurry to controlswelling shales.

S001 Calcium Accelerator White solid 1.75 Calcium chloride 77%. Typical concentration:chloride 1 to 2% BWOC. Increases temperature of slurry

when dissolved.

S002 Calcium Accelerator White solid 1.75 Calcium chloride 95%. Typical concentration:chloride 1 to 2% BWOC. Increases temperature of slurry

when dissolved.

U066 Mutual For spacers and Colorless to 0.90 Used in washes and in MUDPUSH spacers forsolvent washes for removal white liquid removal of OBM and particularly environment-

of environmentally tally safe OBM. Typical concentration: 210%safe OBM by volume.

U100 Mutual For spacers and Colorless to 0.90 Used in washes and in MUDPUSH spacers forsolvent washes for removal white liquid removal of OBM and particularly environment-

of environmentally tally safe OBM. Typical concentration: 210%safe OBM by volume.

Note: Temperatures, concentrations and other conditions of application are typical. Testing may allow extension of ranges.

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05 Cementing Materials