CA1159642A - Oil well cementing process and composition - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
The disclosure describes a high efficiency non-gell-ing cement retarder composition having a high degree of pre-dictability for controlling the rheology and setting time of hydraulic cement. The composition comprises a combination of at least one water soluble hydroxy carboxylic acid and a low molecular weight sulfomethylated lignin wherein the lignin has a narrow molecular weight range and an average molecular weight in the range of about 2,000-10,000. The lignin is substantially sulfoalkylated at the position ortho to the free phenolic group of the benzene ring of the lignin mole-cule and the sulfonate radical is in the form of acid, salt or combinations thereof and is attached to the ortho position by an alkylidene radical having one to three carbon atoms.
A process of sealing at an elevated temperature a zone pene-trated by a wellbore using the above cement retarder is also disclosed.

Description

1 15~6~

This invcnti~n relates to cement compositions and more partlcularly to the use of hydraulic cement compositions for sealing or cementing subterranean zones or subterranean zones penetrated by a well such as cementing the annular S space in an oil well between the surrounding formation and casinq. In particular the invention relates to an improved hydraulic cement composition for cementing zones at elevated temperatures in which the setting time of the cement compo-sition is controlled or extended by the addition of a highly efficient non-gelling retarding agent which produces a hydraulic cement composition having a degree of predict-abilit~ for the setting time.
Typically, the subterranean zones are cemented or sealed by pumping an aqueous hydraulic cement slurry into the zone. In cementing the annular space of an oil well, the cement slurry is pumped down the inside of the casing and back up the outside of the casing through the annular space. Any cement slurry remaining in the casing is displaced and segregated using plugs and an aqueous die-placement fluid. Frequently the high temperatures encounteredin subterranean zones will cause premature setting of the hydraulic cement. This requires additives which extend or retard the setting time of the cement slurry so that there is adequate pumping time in which tv place and displace the aqueous cement slurry in the desired zones. Previously known retarding agents are frequ2ntly unpredictable, typically produce erratic results with different brands of cement and frequently cause premature gelation of the cement slurry.

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96~2 Gelation reEer~ t~ an abnormal increase of viscosity of the aqueous cement slurry to a value without a significant increase in the compressive strength of the cement composi-tion. This increase in aqueous cement slurry viscosity makes the slurry difficult or impossible to pump at a viscosity of 70 poise or above t~hich is defined as the set point herein.
The cement composition has not attained an adequate compres-sive strength.
Prior art cement compositions and additives are described in the following list of 14 patents:
U.S. 2,549,507 to Morgan et al U.S. 2,579,453 to Post et al U.S. 2,674,321 to Cutforth U.S. 2,676,170 to Patterson et al U.S. 2,680,113 to Adler et al -~
U.S. 2,775,5B0 to Scarth U.S. 2,872,278 to Putnam et al U.S. 3,034,982 to Monroe U.S. 3,053,673 to Walker U.S. 3,135,727 to Monroe U.S. 3,344,063 to Stratton U.5. 3,748,159 to George U.S. 3,766,229 to Turner U.~. 3,821,985 to George.
Fundmentals of oil well cementing are described in the book PETROLEUM ENGINEERING DRILLING AND WELL COMPLETIONS, by Carl Gatlin, Prentice l~all, 1960. Background of and information on hydraulic cement compositions and additives can be found .
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''` ~ l~g642 in the following books:
LIGNIN STRUCTURE A~D REACTIONS, ADVANCES IN CHEMISTRY
SERIES, 1959, American Chemical Society, 1966;
MECHANICAL BEHAVIOR OF HIOEI POLYMERS, by Turner Alfrey, Interscience Publishers, 1948, and HACKH'S CHEMICAL DICTIO~ARY, ~th Ed., McGraw-Hill, 1969.
I'he hydraulic cement compositions of this inven-tion solve or eliminate many of the problems pointed out above.
The hydraulic cernent compositions of this invention do not have the gelation problem, the retarder composition is more efficient than prior art retarder compositions, the retarder has less variation with different brands of cement' cement compositions have much better predictability or reproduci-bility of setting times with a given brand of cement, and hydraulic cement cornpositions have better rheology character-istics. Thus the improved cement compositions of this in-vention have practically eliminated the problems of unpredict-ability and irreproducibility of results which are particularly severe in high pressure deep wells where the temperatures may exceed 300F and 15,000 PSI.
The concentration of retarder composition of this invention required to produce the desired pumping time for or delay in setting of a cement slurry at a given circulat-ing temperature is not as critical as with conventional lignosulfonate retarders. The thickening time at a given retarder concentration is less tempera-96~2 ture dependent than with conventional retarders. This reduces the possibility of over retarded slurries at cooler temperatures encountered at the top of long liners or tie back strings. The retarder compositions of this invention provide the desired pumping times and allow earlier strength development. When cementing long strings -this can reduce the ~OC (waiting on cement to set) time by 8-12 hours. Thus, the retarder compositions of this invention are more predictable in performance than con-ventional lignosulfonate retarders especially with various brands of cement. Tlle compositions of this invention act not only as retarders but also as a dispersing agent which can reduce fluid loss from gel type or high clay cement slurries. I~hen the retarder composition of this invention ~-is blended in a cement slurry, viscosity of the slurry decreases slightly and remains constant or does not in-crease significantly until the cement begins to et. This improvement in rheology or viscosity characteristics with improved predictability makes use of the compositions much easier than with conventional retarders. In addition, the retarder compositions of this invention are generally non-toxic, non-flammable, non-hazardous; compatible with cements, other additives and with most other well fluids and mix readily in aqueous systems with minimum agitation.
The high efficiency, non-gelling cement retarder composition of this invention has a high degree of pre-dictability for controlling rheology and setting time of hydraulic cement comprising a low molecular weight sulfo-~ ~9~2 alkylated li~nin which is substantially sulfoalkylated in the lignin molecule at positions on the benzene ring which are ortho to the phenolic hydroxyl group. In the sulfoalkyl group the sulfonic acid group ( SO3H) is con-nected to the ortho position on the benzene ring by a methylene or substituted methylene group. This methylene or substituted methylene group is referred to herein as an alkylidene radical having one to five carbon atoms.
This alkylidene radical with sulfonic acid radical can be represented by the formula (-R-SO3H3 wherein R is the methylene group or alkyl portion having one to five carbon atoms and preferably one to three carbon atoms.
The unexpected properties of this retarder are thought to he due to the dif~erences in average molecular weight or average molecular size and molecular structure. The evidence showing these differences is illustrated in the examples which show the unexpected properties. The sulfoalkylated lignin of this invention is a low molecular weight material having an average molecular weight or molecular 20- size in the range of about 2,000-10,000 and preferably about 3,000-5,000. It is also thought to have a narrow molecular weight distribution. Prior art lignosulfonate compounds have a molecular weight or molecular size of about 10,000 and higher and the sulfonate substituent or radical attached directly on the carbon atom of the lignin molecule which is in the alpha position of the phenyl propyl side chain. This phenyl propyl or aliphatic chain is attached at a position on the benzene ring which ; ~

~ 1~96~2 is para to the phenolic hydroxyl group discussed herein~
For lignosulfonate the phenolic hydroxyl group can be re-placed by an alkoxy group as indicated by Rl-Ph-OR2 wherein l~l is the phenyl propyl side chain, Ph is phenyl or the benzene rin~ and R2 is hydrogen or alkyl. The sulfo-alkylated retarder composition of this invention has sub-stantially all of the sulfoalkyl gxoup (i.e., -R-SO3H) in the position ortho to the phenolic hydroxyl group of the benzene ring of the lignin molecule.
The sulfoalkylated lignin retarder of this invention does not have a significant degree of sulfonation at the alpha carbon atom as do the prior art lignosulfonates.
Thus, the sulfoalkylated lignin retarder of this invention is an entirely different chemical composition as shown by the unexpected and significantly different properties shown herein. The sulfoalkylated lignin retarder of this invention can be considered to be a sulfoalkylated lignin of high purity, low molecular weight with a narrow molecular weight distribution. This is thought to be due to the significantly different procedure used for its preparation.
The sulfoalkylated lignin retarder for compositions of this invention can be prepared by catalytic oxidatlon of the sulfite liquor from a wood pulping process. This oxidation removes polysacchaxides and wood sugars and substantially desulfonates the lignin molecule which is recovered as a residue. This purified lignin is separated from the liquor. The high purity, low molecular weight lignin molecule is then substantially sulfoalkylated , 6 ~ 2 ~y the addition of sulfonating agent such as sodium sulfite in the presence of an aldehyde or ketone having one to five car~on atoms at about 150-190C and 180-220 atmospheres.
In this process, the aldehyde or ketone furnishes the S alkylidene group which attaches at a vacant ortho position on the benzene ring in the lignin molecule and connects the sulfonate group through a methylene radical to the benzene ring at a position ortho to the free phenolic hydro~yl group. Some benzene rings may have more than one sulfoalkyl group attached and some benzene rings may have no sulfoalkyl substituents. The sulfur content of the sulfoalkylated lignin is between about 3-10% and preferably 3-8%.
This sulfonate group can be in the form of the acid, a salt or combinations thereof. The salt can be in the ~-form of ammonium or metal salt involving an alkali metal; an alkaline earth metal; or metals such as iron, copper, zinc, vanadium, titanium, aluminum, manganese, ;~
chromium, cobalt or nickel; or combinations thereo.
The salts ~hich are readil~ soluble in aqueous sys~ems, such as those of the alkali metals, sodium and potassium, are preferred although the salts of alkaline earth metals and other metals can be ussd under certain circumstances.
The alkyl portion of the sulfonate substituent is derived from the aldehyde or ketone used in the sulfo-alkylation step. Formaldehyde is a preferred alkyl source because it simply connects the sulfonate group to the ortho position by a one-carbon atom methylene group.

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~cetone would produce an alkylidene group having a methyl group on each side of the methylene group; methyl ethyl ketone would result in a methyl and an ethyl alkyl group attached to the Methylene group; and propionaldehyde would result in an ethyl group attached to the methylene bridge. Theoretically, any aldehyde or ketone could be used for forming the alkylidene radical but the stereo chemistry and solubility must be considered in selecting the size and configuration of the aldehyde or ketone use for this component. A preferred sulfoalkylated lignin of this invention has a molecular weight in the range of about 3,000-4,000, a one carbon atom alkylidene radical and a sulfur content of about 3 8% by weight.
~nother preferred hydraulic cement composition of this invention can be considered to be a modified low mol~cular t~eight sulfoalkylated ligninr This modified retarder composition is a combination of the high purity substantially sulfoalkylated lignin described above and at least one water - soluble hydroxy carboxylic acid. These hydroxy carboxylic acids have a synergistic effect of increasing the effectiveness and operable temperature range of the basic retarder composi~
tion. The ~refer~ed carboxylic acids are substantially alphatic carboxylic acids and preferably polyhydroxy carboxylic acids having at least one terminal carboxy group which can be in the form of the acid, a salt or mixtures thereof as described above for the sulfonate groups.
Particularly preferred polyhydroxy carboxylic acida have a molecular weight in the range of about 125-250 and ~ ~9~2 ha~e a hydroxyl group attached to the carbon atom adjacent to the carboxy group as shown by the formula ~ /OH~ O ~
~f-C, J
H OEI
These carboxylic acids include gluconic acid, tartaric acid and equivalents thereof. These equivalents include the various stereoisomers of the above acids particularly the asymmetric or optically active isomers. Thus, the preferred group of hydroxy carboxylic acids are substan-tially linear aliphatic acids having about 4-10 carbon atoms, and pr~ferably 4-8 carbon atoms. The molecular size and number of hydroxy and carboxylic groups will affect the water solubility. The hydroxy carboxylic acid is preferably present with the sulfoalkylated lignin in a weight ratio of acid to lignin preferably in the range of about 1:0.1-5.0 and preferably in the range of about 1:0.2-3~0.
The hydraulic cement compositions of this invention are typically used in the form of an aqueous slurry of hydraulic cement with a concentration of retarder mixed in the aqueous slurry to control or delay the cement setting time so that it exceeds the pumping time with an adequate safety margin. Sufficient water is added to the slurry to make the omposition pumpable. As used herein the hydraulic cement is typically a Portland cement which is set by the water of the slurry in the absence of air which is excluded by placement of the cement in the zone to be sealed. The low molecular weight sulfoalXylated ~ ~96~2 lignin retarder of this invention is preferably present in the aqueous hydraulic cement slurry in a concentration up to about 2~, and preferably up to 1%, by weight based on the dry cement. Higher retarder concentrations and other cement can be used when necessary in unusual circumstances.
A defoaming agent is typically added as are fluid loss additives, friction reducing additives, salts such as sodium chloride and potassium chloride, weighting additives and other conventional additives as aescribed in the references cited above. Pozzolana cement, high alumina cement or high gel (high clay content) cement can be used for special applications. The low molecular weight sulfoalkylated retarder composition of this invention has high reproducibility and predictability when used with most high quality cements which are typically used in the petroleum industry~ However, certain brands which are not manu~actured to standard specifications, such as thGse which are not sufficiently calcined or having varying degrees of free lime remaining in the cement, will produce substantial variations from the standard high quality brands. It is not clear whether the free lime causes the problems or is merely an indication when the problems exis~. These variations can be readily determined by preliminary tests which make even these substandard cements readily predictable and may merely require slightly higher retarder concentrations to off~et the chemical composition variations of the cement or excess lime content.

1 ~96~2 In a preferred process for using the non-gelling hydraulic cement composition of this invention having a degree of predictability of setting time and containing the high efficiency retarder, the retarder composition is mixed with the hydraulic cement as an aqueous slurry with the retarder concentration up to about 2% on a dry cement weight basis. The hydraulic cement mixture is pumped without gelation into the zone to be sealed or cemented and the hydraulic cement mixture is maintained in the zone until an adequate compressive strength is attained. In this process the retarder concentration preferably up to about

2~ on a dry cement weight basis is calculated to control the setting time of the hydraulic cement slurry to exceed the pumping time within an adequate safety margin. Due to the higher efficiency of the retarder and greater pre-dictability of the hydraulic cementing compositions of this invention, the portion of the safety margin pre-viously required for these variations can be substantially reduced. The safety margin now need primarily allow time only for unexpected equipment dificulties. This reduction in the safety margin time or time which the typical oil drilling rig is waiting for the cement to set can result in a substantial economic advantage due to the higher efficiency and predictability of the hydraulic cement compositio~s of this invention. The modified low molecular weight sulfo-alkylated lignin of this invention or the combina~ion of the sulfoalkylated lignin with the hydroxy carboxylic acids improve the efficiency and predictability of the compositions ~-~ 1~9~42 of this :invention even more and therefore are preferably used.
The basic sulfoalkylated lignin retarder composition of this invention can be used up to a temperature (i.e., BHCT) sli~htly in excess of about 210F and the modified retarder composition containing the hydroxy carboxylic acids can be used up to a temperature of about 400F~
The molecular weight o the sulfoalkylated portion of the composition of this invention i5 determined by diffusion techniques. These differences between the sulfoalkylated lignin compositions of this invention and the prior art lignosulfonates are shown by the examples.
The following examples serve to illustrate various embodiments of the invention and enable one skilled in the art to practice the invention. Parts, percentages, pro-portions and concentrations are by weight unless indicatedotherwise.
Samples of calcium (CaLS) and sodium lignosulfvnates (NaLS) and a preferred sulfomethylated lignin (SML) compo-sition of this in~ention were analyzed chemically by spectroscopy using X-ray, infrared, and ultraviolet radia-tion techniques. The samples were prepared and analyzed - " 1 lS9~-2 by standard procedures such as those described in ABSORP-TIO~ SPECTROSCOPY, by Robert P. Bauman, John Wiley & Sons, Inc., 1962. X-ray diffraction merely showed that both the lignosulfonate and sulfoalkylated lignin were noncrystalline.
Chemical analysis indicated the following con-stituents by weight:
% C % H~ % Ca % S
CaLS 39.1 4.3 7.6 3.9 ~aLS 42.2 4.6 0.3 7.4 SML 45.0 3.8 0.2 6.2 The sulfur content of NaLS and SML was thought to include some inorganic sulfur (e.g. CaSO4) entrained from cation exchange or sulfonation liquor.
For ultraviolet ( W ) technique which scanned 190- -360 millimicrons tm~u) for both NaIS and SM~J showed a major peak at about 202-205 millimicrons with shoulder or decreasing peaks at about 230 and 310-320 millimicrons. The samples were in water at a 0.02 gram per liter concentration and were run in a one cm path length cell.
me infrared (IR) tran~mittance scan from 2.5-30 microns or 300-400 cm 1 showed peaks at the following wave lengths (~) in cm 1 NaLs:3440; 2940 2840*; 1590 1495 1450; 1415; 1250*;
1200, 1140*; 1035; 930*; 640 and 590.
SML: 3440: 2940; 2840; 1675, 1590; 1495, 1450; 1415;

' 9~2 1355, 1250*, 1200, 1140*, 1070; 1035, 930*; 850:
775, 735; 590 and 525.
The starred values (*) are shoulder peaXs or peaks which are not very distinct. Samples for the IR scan were mulled in NUJOL mineral oil and run between salt plates.
EX~MPLES
For the following examples each sample was pre-pared by measuring an 800-gram portion of the designated dry cement into a cylindrical container of approximately 800 milliliters volume. Dry or powdered additives are desig-nated as a percentage o~ the weight of the dry powdered cement unless indicated otherwise. Dry powdered additives are measured and blended with cement. A portion of tap water equal to the weight percentage of the dry cement is slurried with the dry cement and additives with vigorous mixing. The slurry is stirred for an additional 30 seconds at a high rate. Liquid additives are blended into the water.
Samples were tested according to standard procedures set forth in API Method RP-lOB.
For thickening *ime tests a sample portlon is stirred in a container of about 500 milliliters at a tempera-ture and pressure schedule determined by API method ~P-lOB.
The container is heated from ambient temperature under pressure. It contains a direct reading consistometer which is calibrated with a potentiometer calibrating device to read directly in units of consistency (API-RP-lOs). The set time ~ 1~96~2 or setting point is the time or point at 70 units of con-sistency or viscosity.
API ~ethod RP lOB provides the following casing schedule for bottom hole circulating temperature (BHCT) and bottom 5 hole static temperature (BHST) at the indicated depths:
Depth (ft.) BHCT (F) BHST (F) 8,000 (2440 m)* 125 (51.67C)* 200 (93.33C)*
10,000 (3050 m) 144 (62.22C) 230 (110.00C) 12,000 (3660 m) 172 (77.78C) 260 (126.67C) 1014,000 (4270 m~ 206 (96.67C)- 290 (143.33C) 15,000 (4575 m) 226 (107.78C) 305 (151.66C) 16,000 (4880 m~ 248 (120.00C) 320 (160.00C) 18,000 (5490 m) 300 (148.89C) 350 (176.67C) 20,000 (6100 m) 340 (171011C) 380 ~193.33C) 1522,000 (6710 m) 380 (193.33C) 410 (210.00C) *Metric Equivalents ~ luid loss is the number of milliliters or cubic centimeters of liquid forced through No. 50 Whatman filter paper or through 325 mesh screen according to API publication ~P-lOB (Section 8).

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96~2 Predictable ~ehavior TABLE I
Lone Star Class H Cement 38% H2O

Thickening Times Ilours:Minutes SllL* API Casinq Simulation Tests Retarder 8,000' -10,000' 12,000' 14,000' 0.20 2:35 2:04 1:33 --0.25 4:20 2:37 -- --0.30 5:50 3:11 2:31 1:58 0 35 __ 5:20 0.40 -- -- 4:12 3:01 0.50 -- -- 7:18 3:47 0.60 -- -- __ 4 09 0,70 -- -- -- 5:12 Lone Star Class H Cement 46% H2O
0.16 2:43 ~
0.20 -- 2:25 2:15 1:55 0.24 3:51 ~
0.30 6:40 3:28 3:G1 2:32 0.34 -- __ 3 58 -- :
0-35 -- 6:13 -- __ 0.38 -- -- 4:17 --0.40 -- 11:22 -- 3:32 0.44 -- -- 5:37 --0.60 -- -- -- ~:10 Sulfomethylated lignin retarder.

96~2 Increasing the retarder concentration results in corresponding increase in thickening time until a satu-ration point is reached. Beyond this point, slight increases in the retarder concentration result in greatly increased thickening times.
TABLE II

Set Times Obtained with Commercially Available Calcium Lignosulfona~e and the Sodium Salt of Sulfomethylated Lignina Percent Set Times -Percent Sodium Hours:Minutes Retarder Chloride API Casing (by wt. (by wt. Simulation Tests Retarder Cementwater) 14,000' - 206 _ Sulfomethylated Lignin 0.3 -0- 1:58 0.4 -0- 3:01 0,5 -0- 3:47 0.6 -0- 4:09 0 7 ~ 5:12 Calcium Lignosulfonate 0.3 -0- 3:25 0.4 -0- 4:05 0.5 -0- 1 34b 0.6 -0- 1:35 Sulfomethylated Lignin 0.3 18.0 1:44 0.4 18.0 2:27 0.5 18.0 2:45 0.6 18.0 3:42 0.7 18.0 ~:33 0.8 18.0 5:12 Calcium ~ignosulfonate 0.2 18.0 1:32bb 0.3 18.0 1:40b 0.4 18.0 1:48 0.5 18.0 2:05b 0.6 18.0 2:40b aAll slurries consisted of 800 grams Lone Star Class H Cement with 304 grams (38%) water, and indicated amount~ of additive and sodium chloride.
bSlurry gelation was observed, i.e., viscosity reached 70 units of consistency but slurry had ~ ~596d~2 not developed significant compressive strength at that time. Others reached a viscosity of 70 units and set with compressive strength at approx-imately the same time.

S ~t higher temperatures slurries containing the con-ventional retarder tend to form unpumpable heavy gels prior to development of significant compressive strength, however, use of the sulfomethylated compound yielded slurries which were well dispersed until final hard set ~-of the cement was obtained. This is illustrated in Table II which lists the set time and percent added retarder for both fresh and salt water slurries containing either the commercially available calcium salt of lignosulfonate or the sodium salt of the new sulfomethylated compound. As noted in the table, many of the slurries containing the calcium salt tended to form heavy gels (i.e., slurry is unpumpable and thus, considered set when the viscosity reaches 70 units of consistency even though it may have gelled with no compressive strength at that time); this results in an erratic dependence of set time on retarder concentration. For example, in the fresh water slurrles, increases in retarder concen~ration in excess of approxi-mately 0.4~ (Table II) result in decreased rather than the expec~ed increased set times; this effe~t is not found for the new compound which shows a reasonable set time increase as the retarder concentration i8 increa~ed in both fresh and salt water slurries.

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6~2 Predictable Behavior One Cement to Another TABLE III
Effect of Cement Brand on Set Timea Percent Set Time -Additive Hours:Minutes (by wt. API Casing Type of Cement Additive of cement 14,000'-206F
_ Lone Star Class H Sulfomethylated (Maryneal)b Lignin 0.5 3:37 Lone Star Class H Calcium h (Maryneal)b Lignosulfate 0.5 1:34 Lone Star Class H Sulfomethylated (New Orleans)~ Lignin 0.5 2:45 Lone Star Class H Calcium (New Orleans)C Lignosulfate 0.5 0:40h Trinity Class Hd Sulfomethylated Lignin 0.5 2:46 Trinity Class Hd Calcium h Lignosulfate 0.5 3:02 Southwestern Sulfomethylated Class He Lignin 0.5 3:19 ' Southwestern Calcium Class IIe Lignosulfate 0.5 4:05 Oklahoma Class Hf Sulfomethylated Lignin 0.5 3~00 Oklahoma Class E~f Calcium Lignosulfate 0.5 3:45h Dyckerhoff Class Bg Sulfomethylated Lignin 0.5 2:44 Dyckerhoff Class B~ Calcium Lignosulfate 0.5 2:45 ~ 1596~2 aSlurries consisted of 800 grams indicated cement, 304 grams (38%) water tby wt. of cement), and additive with the exception of the slurries containing Dyckerhoff Class B which contained 368 grams (46~) water.
bCement manufactured by Lone Star Industries, Inc., Maryneal, Texas.
CCement manufactured by Lone Star Industries, Inc., New Orleans, Louisiana.
dCement manufactured by Trinity, Portland Cement Division, Dallas, Ft. Worth, Houston, Texas.
eCement manufactured by Southwestern Portland Cement Company, El Paso, Texas.
fcement manufactured by OKC Corporation, Pryor, Oklahoma.
gCement manufactured by Dyckerhoff Zementwerke AG, ~iesbaden-Biebrich, Germany.
hThese slurries yelled prior to hard set.
.

At constant concentration of the new retarder, reasonably consistent set times are obtained for slurries containing cements produced by different manufacturers (Table III). This contrasts with the similar results for calcium lignosulfonate which vary drastically from one cement to another.

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96~2 aSlurries consisted of cement, 38% water and additive.
bSlurry reached a viscosity of 70 units and set with compressive strength at approximately the same ~ime.
CSlurry reached a viscosity of 70 units but had no com~ressive streng~h until approximately two hours later.
dSML is sulfomethylated lignin and NaLS is sodium ligncsulfonate.
- eConsistency measured direc~ly in units of con-sistency according ~o ~PI publication RP-lOB.
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96~2 Lower Temperatures TABLE V
Set Times Obtained with Calcium Lignosulfonate and the Sodium Salt of Sulfomethylated Lignin Percent Retarder Set Times - Hours:Minutes (by wt. API Casing Simulation Tests Retarder Cement) 10,000' 12,000' Sulfomethylated Lignina 0.3 -- 2:30 0.4 -- 3:57 0-5 -- 8:00 Calcium Lignosulfonate 0.3 -- 3:10 0.4 -- 2:21 0.6 ~ -- 1:40 Sulfomethylated Ligninb 0.08 2:58 --0.12 3:29 --0.16 4:00 --0.20 4:50 --0.24 6:33 --Calcium Lignosulfonate 0.40 1:44CC __ 0.80 3:20 -- ~-aSlurries consisted of Dyckerhoff Class G, 44% water and indicated additive.
bSlurry consisted of LonghornTM Class H Cement with 44% water, 35% coarse silica flour (60-140 mesh~, ~
0.75% CFR-2TM friction reducer and 18% sodium '-chloride salt. CFR-2 is beta-naphthalene sulfonic ~-acid condensed with formaldehyde and mixed with 10% polyvinyl pyrrolidone. CRF-2 is described in U.S. Patent No. 3,359,225.
Slurries showed severe gelation effects.

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6~2 Compressive Strength T BLE VI
Class il Cement with 38% Water Retarder Concentration Giving 4.0 Hr. Pumping Time on 12,000 ft. Schedule Slurries Pumped 2 hrs. on 12,000 ft. Schedule and placed in Autoclaves at Indicated T0mperature Compressive Strength Temperature Compressive Strength Using Conventional F Using SML
Lignosulfonate Retarder Cement Retarder tPSI) _ (PSI) 8 hrs 12 hrs24 hrs ~ hrs 12 hrs 24 hrs ~IS* 290 2260 170 650 1690 2790 * - Not Set Compressive strength tests were run on slurries con-taining calcium lignosulfonate or sulfomethylated lignin.
The cement employed in these tests was Lone Star Clas~ H.
In these tests, slurries containing retarder to giv~ four hour pumping times on a 12,000' ca~ing schedule were used~
The slurries were pumped ~wo hours at a 12,000' ca~ing schedule and placed in autoclaves at four different temperatures to simulate the actual conditions encountered from the top to the bottom of a cement column in a well.
The compressive strengths were then determined after 8, 12 and 24 hours according to ~PI publication RP-lOB ~Section 6). After 8 hour~, the slurries containing lignosulfonate had not set at the lower temperatures. However, the slurries containing sulfomethylated l ignin were all set with ~igni-ficant strengths. The sulfomethylated lignin ~lurrie~consistently showed more rapid strength development through-out these tests.

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P-, ~ ~96~2 ~11 slurries contained Lone Star Class H Cement, 28% water, and indicated amounts of retarder, llalliburton fluid loss additive, and sodium chloride.
After mixing, the slurries were stirred on the Halliburton Consistometer for 20 minutes at 100F
and fluid loss determination conducted at 109 PSI
press~re on a 325 mesh ~creen at the same temperature.
b56% I~EC (hydroxyethyl cellulose) with 44% CFR-2.
C60% HEC, 20% defoamer with 20% CFR-2.

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.
-2a-i ~ 1~9642 . Sulfomethylated lignin functions in gel cement slurries as a dispersant and fluid loss additive. Pre-viously, two separate retarders were required; one for non-gel slurries which was calcium lignosulfonate and S another for gel slurries which wa~ calcium sodium ligno-sulfonate.

~ , 6~2 Extension with Tartaric Acid TABLE IX
Set Times Obtained with a Mixture of the Sodium Salt of Sulfomethylated Lignin and Tartaric Acid in a 2:1 Weight Ratio*
Set Times % Retarder _Hours:Minutes (By Wt API Casin Simulation Tests Cementj 16,000' -18,000' 20,000' 22,000' 0.4 1:55 -- __ __ 0.5 4:20 -~
0.6 5:57 1:40 -~
0.8 -- 2:31 -- --0.9 -- 3:~3 1 0 ~~ 4:3~
~ 5-13 -- 2:00 1.2 -- __ 3 43 __ 1.3 -- -- -- 2:2 1.6 -- -- 5:10 --1.8 ~ 6:32 3:1?
.0 ~ 3:25 .6 ~ -- 4:10 *All slurries consisted of Lone Star Class H Cement, 35% SSA-l, 54% water, and indicated amounts of retarder.
SSA-l is fine silica flour which is added to cement slurries at high tsmperature to prevent strength retro-gression. Over 97% of the silica particles pass through a 200-mesh (U.S. Std. Sieve Series~ screen.

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, :

~ 1~9~2 TABLE X

~xtension of Set Times of Slurries Containing Sulfomethylated Lignin by the Addition of Borax Percent Percent Sulfomethylated Borax Set Time - Hours:Minutes Liynin ~By Wt. (By Wt. API Casing Schedule Cement) Cement) _,000' 16,000' 0.7 0.6 3:00 --0.8 0.6 4:22 --0.9 0.6 5:12 --0.4 0.7 -- 1:54 0.6 0.7 -- 3-54 0.8 0.7 -- 5:20 0.95 0.7 __ 7:10 Set times obtained with sulfomethylated lignin can be extended by the addition of boric acid or water soluble salt of boric acid (e.g., salts of ammonia, alkali or alkaline earth metals). This extension makes possible the use of the sulf~methylated lignin retarder at higher temperatures. Examples of extenders of this type are:
(1) Boric acid, (2) Na2B4O7 10 H2O (Borax), (3) Ma2BsOg 5 H2~

(4) R~5O8 4 ~2~

(5) LilB5O8 5 H2O~
(6~ NaBO2 4 H2O, similiar compounds and mixtures thereof.

This application is a division of application Serial No.

256,589, filed July 8, 1976.

Claims (8)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A high efficiency non-gelling cement retarder composition having a high degree of predictability for controll-ing rheology and setting time of hydraulic cement comprising a combination of at least one water soluble hydroxy carboxylic acid and a low molecular weight sulfo alkylated lignin wherein said lignin has a narrow molecular weight range and an average molecular weight in the range of about 2,000-10,000 wherein said lignin is substantially sulfoalkylated at the position ortho to the free phenolic group of the benzene ring of the lignin molecule wherein the sulfonate radical is in the form of acid, salt or combinations thereof and is attached to the ortho position by an alkylidene radical having one to three carbon atoms.

2. A high efficiency non-gelling cement retarder composition having a high degree of predictability of claim 1 for controlling rheology and setting time of hydraulic cement comprising a combination of at least one water soluble hydroxy carboxylic acid and a low molecular weight sulfoalkylated lignin, wherein said carboxylic acid is substantially aliphatic acid having about four to ten carbon atoms and at least one terminal carboxyl group in the form of the acid, salt or combinations thereof; and wherein said sulfoalkylated lignin has a molecular weight in the range of about 2,000-10,000 and which is substan-tially sulfoalkylated in the ortho position with the sulfonate radical in the form of acid, salt or a mixture thereof and is attached to the ortho position by an alkylidene radical having one to three carbon atoms and contains about 3-8% sulfur by weight.

3. A high efficiency non-gelling cement retarder composition having a high degree of predictability of claim 1 for controlling rheology and setting time of hydraulic cement comprising a mixture consisting essentially of at least one water soluble polyhydroxy carboxylic acid and a low molecular weight sulfoalkylated lignin; wherein the weight ratio of acid to lignin is in the range of about 1:0.1-5; wherein said carboxylic acid is a substantially linear polyhydroxy aliphatic acid having at least one terminal carboxyl group in the form of acid, salt or mixtures thereof; and wherein said sulfoalkylated lignin has a molecular weight in the range of about 2,000-10,000 and which is substantially sulfoalkylated in the ortho position with the sulfonate radical in the form of acid, salt or a mixture thereof and is attached to the ortho position by an alkylidene radical having one to three carbon atoms and contains about 3-8% sulfur by weight.

4. A non-gelling hydraulic cement composition having a high degree of predictability containing a retarder for controlling rheology and setting time of hydraulic cement comprising a mixture of hydraulic cement, at least one water soluble hydroxy carboxylic acid and a low molecular weight sulfoalkylated lignin; wherein the weight ratio of said acid to lignin is in the range of about 1:0.1-5; wherein said carboxylic acid is a substantially linear aliphatic acid having at least one terminal carboxyl group in the form of acid salt or mixtures thereof; and wherein said sulfoalkylated lignin has a molecular weight in the range of about 2,000-10,000 and which is substantially sulfoalkylated on the benzene ring of the lignin molecule in the position ortho to a hydroxy group and the sulfo-nate group is attached to the ortho position by an alkylidene radical having one to three carbon atoms.

5. A non-gelling hydraulic cement composition having a high degree of predictability containing a retarder for controlling rheology and setting time of hydraulic cement comprising an aqueous slurry of hydraulic cement mixed with up to about 2% by weight on a dry cement basis of a retarder consisting essentially of at least one water soluble hydroxy carboxylic acid and a low molecular weight sulfoalkylated lignin; wherein the weight ratio of acid to lignin is in the range of about 1:0.1-5; wherein said carboxylic acid is a substantially linear aliphatic acid having at least one terminal carboxyl group in the form of acid, salt or mixtures thereof; and wherein said sulfoalkylated lignin has a molecular weight in the range of about 2,000-10,000 and which is substantially sulfoalkylated on the benzene ring of the lignin molecule in the position ortho to a hydroxy group and the sulfonate group is attached to the ortho position by an alkylidene radical having one to three carbon atoms.

6. A process for sealing at an elevated temperature a zone penetrated by a wellbore using a high efficiency non-gelling hydraulic cement retarder composition having a high degree of predictability for controlling rheology and setting time comprising mixing an aqueous slurry of hydraulic cement with up to about 2% on a dry cement weight basis of a retarder consisting essentially of a low molecular weight sulfoalkylated lignin; wherein the concentration of retarder is calculated to control the setting time of said hydraulic cement to exceed the pumping time; wherein the sulfoalkylated lignin has a molecular weight in the range of about 2,000-10,000 and which is subs-tantially sulfoalkylated on the benzene ring of the lignin molecule in the position ortho to the free phenolic hydroxy group and the sulfonate group is attached to the ortho position by an alkylidene radical having one to three carbon atoms;
pumping said hydraulic cement mixture into said zone and maintaining said hydraulic cement mixture in said zone until a high compressive strength is attained.

7. A process for sealing at an elevated temperature a zone penetrated by a wellbore using a high efficiency non-gelling hydraulic cement composition having a high degree of predictability for controlling rheology and setting time comprising mixing an aqueous slurry of hydraulic cement with up to about 2% on a dry cement weight basis of a retarder consisting essentially of at least one water soluble hydroxy carboxylic acid and a low molecular weight sulfoalkylated lignin;
wherein the concentration of retarder is calculated to control the setting time of said hydraulic cement to exceed the pumping time; wherein the weight ratio of acid to lignin is in the range of about 1:0.1-5.0; wherein said carboxylic acid is a subs-tantially linear aliphatic acid having at least one terminal carboxyl group in the form of acid, salt of mixtures thereof;
wherein said sulfoalkylated lignin has a molecular weight in the range of about 2,000-109000 and which is substantially sulfo-alkylated on the benzene ring in the lignin molecule in the position ortho to the free phenolic hydroxy group and the sulfonate group is attached to the ortho position by an alkylidene radical having one to three carbon atoms; pumping said hydraulic cement mixture into said zone without gelation and maintaining said hydraulic cement mixture in said zone until a high compress-ive strength is attained.

8. In a process for cementing a zone at an elevated temperature by pumping an aqueous hydraulic cement slurry into said zone, the improvement of controlling the setting time of said cement and preventing gelation of said cement by mixing with said hydraulic cement a high efficiency non-gelling retarder consisting essentially of a mixture of at least one water soluble hydroxy carboxylic acid and a low molecular weight sulfoalkylated lignin, wherein the concentration of retarder is calculated to control the setting time of said hydraulic cement to exceed the pumping time, wherein the weight ratio of said acid to lignin is in the range of about 1:0.1-5.0; wherein the carboxylic acid is a substantially linear aliphatic acid having at least one terminal carboxyl group in the form of acid salt or mixtures thereof, wherein said sulfoalkylated lignin has a molecular weight in the range of about 2,000-10,000 and which is substantially sulfoalkylated on the benzene ring in the lignin molecule in the position ortho to the free phenolic hydroxy group and the sulfonate group is attached to the ortho position by an alkylidene radical having one to three carbon atoms.