CA1245846A - Fluid loss control in well cement slurries - Google Patents

Abstract

ABSTRACT

FLUID LOSS CONTROL IN WELL CEMENT SLURRIES

A polymer of monoallylamine, preferably a water-soluble polymer of monoallylamine, whether in free (i.e., unneutralized) form or in salt (i.e., partially or completely neutralized) form is used in conjunction with a sulfonated polymer such as a water-soluble lignosulfonate, condensed naphthalene sulfonate, or sulfonated vinyl aromatic polymer, to minimize fluid loss from the slurry during subterranean well cementing operations.
The polymer of monoallyl amine may be a homopolymer or a copolymer, and may be crosslinked or uncrosslinked. These components interact with each other in the presence of water to produce a gelatinous material that tends to plug porous zones and minimize premature water loss from the well cement slurry when present in the subterranean well formation. In addition, the gelatinous material so formed prevents de-stabilization of the slurry in the well formation.

Description

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case 5468-B

FLUID LOSS CC~TROL IN WELL CEMENT SL~RRIES

This invention relates to methods for controlling fluid lc~ss in well cementing operations and to formulations particu-larly adapted for this use, Over the years a number of low fluid-loss systems, formulations, and application techniques have been developed for permanent-type well completions and in more recent times, for oonventional wells. See in this connection, D. K. Smith, ementing, Society of Petroleum Engineers of AIME, pub., New 10 York and Dallas, 1976, and C. M. Stout and W. W. Wahl, Journal of Petroleum Technology, September 1960, pages 20-24.
A~ong the leading systems for controll mg fluid loss in well cementing operations are systems based on polyalkylene p~lyamines, polyalkylene polyimines, and mixtures thereof. See for example Gibson et al U. S. Pat. No. 3,491,049: Scott et al U. S. Pat. No. 3,511,314; Crinkelmeyer et al U. S. Pat. No.
4,131,578; McKenzie U. S. Pat. No. 4,413,681; Spitz et al U. S.
Pat. No. 4,482,381; and McKenzie et al, Oil & Gas Journal, March 1982, pages 146-148.
~0 As pointed out in the Spitz et al '381 patent, the liquid polyamines of this type require addition of sulfonated polymers to provide effective fluid loss control. While such combinations do function to control fluld loss, tbey cause de-stabilization of the cement slurry. In order to ameliorate this ~5 problem the manufacturers of the polyalkylene polyamines and , ~f~.

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polyalkylene polyimines resorted to chemical modification of these polymers by cross-linking. Unfortunately the additional processing required increased the cost of the materials quite significantly.
In accordance with this invention new, highly effective fluid-loss-control additive systems have been discovered for use in cementing subterranean well formations with an aqueous well c~ment slurry. m ese additive systems are, in combination, ~1) a sulfonated polymer and (2) a polymer of monoallylamine whether in free ~i.e., unneutralized) form or in salt (i.e., partially or cQmpletely neutralized) form. Experiments have shown that this invention makes it possible to control very effectively the amount of fluid loss that would otherwise occur in an aqueous cemant slurry when using neither such additive (1) or (2), or either such additive (1) or (2) in the absence of the other. In addition, tests have shown that de-stabilization of cement slurries was not experienced when using systems of this i~vantion. In other words, the slurried cement does not tend to sattle out to any significant extent prior to curing. Since ~0 sulfonated polymers are not only commercially available but are often used in downhole cement slurries, this invention makes it possible to overcome excessive fluid loss and achieve improved control of cementing treatments, all at relatively low cost.
As noted above, the polymer of monoallylamine used in ~5 the practice of this invention may be in the form of a free base ~i.e., the pendant -CH2NH2 groups are not neutralized with an acid) or it may be in the form of a partially or completely - . ~

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4~6 neutralized polymer (i.e., some or all of the pendant -CH2 ~ groups are neutralized with an acid and thus are in salt form). Suc~ salts are also known in the chemical arts as poly( noallylammonium) salts.
Accordingly, a preferred group of polymers of monoallylamine used pursuant to this invention may be depicted by the general formula:

-~ CH--CH2 ~- {~ CH - CH2 ~-m n Cl H2 ,CH2 10 NH2 NH2 Acid where m is a number from zero to 100,000 or more and n is a number from zero to 100,000 or more, the sum of m plus n being in the range of 10 to 100,000 or more. In the formulat Acid represents an organic or inorganic acid complexed with the amino group in the form of a salt. When n is zero or is very small 15 relative to m, the polymer may be deemed for all practical purpc~es a poly(monoallylamine). On the other hand when m is zero or is very small relative to n, the polymer may be deemed for all practical purposes a salt of poly(monoallylamine). There is of course no hard and fast dividing line between the two since ~0 the transition from one end of the scale to the other is a continuum.
Other preferred polymers of monoallylamine used pursuant to this invention are polymers as above depicted that have been chemically modified during their manufacture by copolymerization ~2'~

with small quantities of suitable polymerizable comonomers con-taining two or more double bonds in the molecule (e.g., triallyl-amine hydrochloride and the like) or by crosslinking or bridging with small quantities of a crosslinking agent having two or more groups reactable with the amino group (e.g., epichlorohydrin, ethylene dichloride, and the like). These chemically ~odified m~noallylamine polymers have essentially the same properties and c~aracteristics as the unmodified polymers depicted above except of course those related ~o molecular weight.
Unless the context indicates otherwise, all such poly-mers, w~lether in free or in salt form and whether in unmodified or modified (copolymerized, or crosslinked or bridged) form, will be collectively referred to hereinafter as a "polymer of monoallylamine".
In another of its embodiments this invention provides in a method of cementing a subterranean oil well fonnation with an aqueous s~ell cement slurry, the improvement in which the slurry c~ntains the combination of a sulfonated polymer and a polymer of monoallylamine, to provide controlled dehydration of the slurry 2n during the well cementing operation. By treating an aqueous well cement slurry with suitable quantities of a sulfonated polymer and, for example, poly(monoallylamine) or poly(monoallylammonium) salt of apprcpriate molecular weight, the slurry has enhanced resistance to dehydration during the cementing operatlon.
~5 A further embodiment of this invention involves the provision in an oil well cement Eormulation adapted for use in preparing well cement slurries of both a sulfonate polymer and a polymer of monoallylamine, to provide controlled del~ydration of the slurry during the well cementing operation.
Still another embcdiment of this invention involves providing in an oil well cement slurry adapted for use in a subterranean well cementing operation a fluid-loss-control substance formed by interaction in an aqueous medium of a sulfonated polymer and a polymer of monoallylamine, to provide a gelatinous substance capable of controlling dehydration of the slurry during the well cementing operation.
These and other embodiments of the invention will be still further apparent from the ensuing description and appended claims.
As will be shown hereinafter, even a polymer of mono-allylamine that is essentially insoluble in water can be successfully used in the practice of this invention. In short, use may be made of any polymer of monoallylamine (i.e., pcly(~onoallylamine) or poly(monoallylammonium) salt, whether a homopolymer or a copolymer or a crosslinked homopolymer or copolymer) that forms a gelatinous substance in the presence of ~0 water and a sulfonated polymer. In general however it is preferred in the practice of this invention to use a water-soluble polymer of monoallylamine.
Illustrative polymers of monoallylamine include:
- poly(monoallylamine) - poly(monoallylammonium chloride) (also referred to as polyallylamine hydrochloride) - poly(monoallylammonium bromide) ~..

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- poly(monoallylammonium bisulfate) - poly(monoallylammonium sulfate) - poly(monoallylam nium nitrate) - poly(monoallylammonium dihydrogen phosphate) - poly(monoallylammonium hydrogen phosphate) ~ poly(monoallylammonium phosphate) - poly(monoallylammonium formate) - poly(mo~oallylammonium acetate) - poly(monoallylammonium propionate) 1~ - poly(monoallylammonium p-toluenesulfonate) and like polymers. m e water solubility of some salts such as the sulfate and phosphate salts of polymers of monoallylamine tends to decrease with increasing sulfate or phosphate content.
In fact, completely neutralized poly(monoallylamine) sulfate 1~ ~Ecly(monoallylammonium sulfate)) and completely neutralized poly(monoallylamine) phosphate (poly(monoallylammonium phosphate)) tend to be essentially water insoluble. The pxeferxed polymeric salts are the hydrochlorides.
Polymers of monoallylamine falling within a wide range of molecular weights are suitable. For example, use may be made of polymers in salt form (e.g., unmodified poly(monoallylammonium hydrochloride) having a weight average molecular weight (as determined by the equilibrium sedimentation method -- see B. Vollmert, Polymer Chemistry, Springer-Verlag, New York, Copyright 1973, pp 361-369) -- ranging upwards from about 1,000, and preferably ranging upwards from about 7,000. Modified (e.g., suitably crosslinked) and unmodified polymers in salt form with -- 7 ~

weight average molecular weights below about 500,000 are preferred, those falling in the range of 10,000 to 200,000 being particularly preferred. ~he weight average molecular weight lsame test me~hod) of the free (i.e., unneutralized) S ullcrossliliied poly(~onoallylamines) ranges upwards from about ~00, preferably upwards from about 3,250, and most preferably upwards from akout 4,500. Modified (e.g., suitably crosslinked) and unmcdified polymers in free (i.e., non-salt) form with weight averaga molecular weights below about 325,000 are preferred.
10 Polymers of monoallylamine having weight average molecular weights falling outside of the foregoing molecular weight ranges may also be used, provided of course that their suitability and efficacy are established, for example by performing a few tests.
Methods for the synthesis of polymers of monoallylamine ~homopolymers and copolymers, both free bases and salts thereof, and crosslinked or bridged polymers thereof) have been reported in the literature. See for eYample U. S. Pat. No. 4,504,640 granted March 12, 1985, U. S. Pat. No. 4,528,347 granted July-9, 1985, European Patent Application 95,233 published November 30, ~ 1983, European Patent Application 131,306, published January 16, 1985, and S. Harada & S. Hasegawa, Macromolecular Chem., _aE_d Communications, 5, 27-31 (1984). One currently recommended procedure involves hydrochlorination of allylamine followed by radical polymerization of the resulting allylamine hydrochloride.
25 To convert the hydrochloride salt to the free polyallylamine (e.g., from which other salts can readily be produced) either of two different procedures is usually employed. One involves treatment of the polyallylamine hydrochloride solution with an alkali base such as sodium hydroxide to form an aqueous solution of the sodium chloride salt which is then subjected to dialysis and lyophilization. The other method utilizes a strong basic ion eYcllan~e resin for converting the polyallylamine hydrochloride solution into the polyallylamine solution which is then subjected to lyophilization to produce the free polymer Various molecular weight grades of polyallylamine and of polyallylamine hydro-chloride are presently available from Ni~to Boseki Co., Ltd.,Tokyo, Japan.
In preparing the crosslinked polymers of monoallylamine, use may be made of a variety of crosslinking agents. For example use may be made of alpha,beta-epoxy~g~ -haloalkanes, e.g., 3-chloro-1,2-epoxypropane, 3-bromo-1,2-epoxypropane, and 3-iodo~
1,2-epoxypropane; and their higher homolcgs such as 3-~lloro-1,2-eEx~Yybutane, 3-bromo-1,2-epoxybutane, 3-iodo-1,2-epoxybutane, 3-~lloro-1,2-epoxypentane, 3-chloro-1,2-epoxyhexane, 3-chloro-1,2-epoxyheptane, and the like. Likewise, dihaloalkanes may be ~ employed for this purpose, a ~ew typical examples being 1,2-di-haloethanes such as 1,2-dichloroethane (ethylene dichloride), 1,2-dibromoethane (ethylene dibromide), and 1-bromo-2-chloro-ethane; and their higher homologs such as 1,3-dichloropropane, 1,3-dibromopropane, 1,3-dichlorobutane, 1,4-dichlorobutane, 1,3-dibromobutane. 1,4-dibromobutane, l,S-dichloropentane, 1,7-dichloro-4,4-dimethylheptane, and the like. Other cross-linking agents, such as dicarboxyl acid chlorides, mono or 5~3~6 dialdehydes, and the like, known to t~.ose skilled in the art for crosslinkiny other polymeric materials, may also be used in effecting this crosslinking.
When producing crosslinked polymers of monoallylamine S t21e amo~mt of the crosslinking agent emplcyed should be controlled so as to avoid the formation of excessively cross-linked products. Ordinarily the proportions used will fall in the range of 50 to 8,000 parts by weight of crosslinking agent E~r million parts by weight of the monoallylamine homopolymer or copolymer being subjected to crosslinking. Departures from this range are feasible, and may be found useful. Preferably, from ~50 to 8,000 ppm of crosslinking agent is employed with poly(monoallylamine) having a weight average molecular weight in the range of 5,000 to 100,000, and from 50 to 250 ppm of cross-linking agent is employed with poly(monoallylamine) having awei~lt average molecular weight in the range of 100,000 to 350,000. In other words, it is desirable that the relative proportion of crosslinking agent to poly(m~noallylamine) be inv~rsely proportional to the weight average molecular weight of ~0 the poly(monoallylamine~ being crosslinked.
The poly(mDnoallylamine) subjected to the crosslinking process may be preformed or it may be generated or formed in situ. Preferably the poly(monoallylamine) is formed by neutralizing or partially neutralizing a poly(monoallylammonium) ~5 salt such as:
- poly(monoallylammonium chloride) - poly(monoallylammonium bromide) - poly(monoallylammcnium bisulfate) , ., - poly(monoallyla~monium sulfate) - poly(monoallylammonium nitrate) - poly(monoallylammonium dihydrogen phosphate) - poly(monoallylammonium hydrogen phosphate) and - poly(monoallylammonium phosphate).
It is particularly desirable to fonn the poly(monoallylamine) in situ by rendering an aqueous medium containing one or more of these acid salts neutral or alkaline in pH by the addition of a suitably strong base such as sodium hydroxide, potassium hydroYide, or the like. The preferred polymers for this use are the poly(monoallylammonium chlorides).
Among the polymerizable comonomers that may be used in forming monoallylamine copolymers are diallylamine hydrochloride, triallylamine llydrochloride, and the like. The copolymers should contain at least 95~ by weight and preferably at least 98% by weight of monoallylamine with the balance being one or more sucb c~lomars .
Sulfonated polymers of various typas are suitable for use in the practice o this invention. The most common ~0 sulonated polymers for this use are the lignosulfonates (i.e., sulfonat~d lignins), the condensed naphthalene sulfonates, and the sulfonatad vinylaromatic polymers.
The lignosulfonates are exemplified by the various salts of sulfonated lignin such as the alkali metal lignosulfonates, the alkaline earth metal lignosulfonates, and the ammonium ligno-sulfonates. These include calcium lignosulfonate, calcium sodi~
lignosulonate, sodium lignosulfonate, magnesium lignosulfonate, :
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calcium potassium lignosulfonate, barium lignosulfonate, potassium lignosu?fonate, lithium lignosulfonate, etc., as well as ligno-sulfonates that have been modified with organic acids, and the like. Some of these materials, especially the lignins (salts of 5 lignosulfcnic acid which are derived from wood) and the ligno-sulfonates modified with organic acids, are available as articles of ccmmerce. They are often used as cement retarders -- i.e., as additives to prevent the cement from setting too quickly -- or as additives to increase the pumpability of cement slurries in high-tem~erature wells. In the practice of this invention the lignosulfcnates exhibit a new property, that of reacting with the polymer of monoallylamine in the aqueous system to create a gelatinous material that tends to plug porous zones and minimi~e ~ater loss from the cement slurry.
The various condensed naphthalene sulfonates that may be employed are exemplified by the naphthalene sulfonic acid condensation products available commercially under the trade designation Lomar D. It is understood that these materials are col~densation products of formaldehyde and mononaphthalene sulfonic acid. Such condensation products are indicated in ~. S.
Pat. No. 3,511,314 to have molecular weights between 1,000 and 3,000 but use may be made of any condensed naphthalene sulfonate that reacts with the polymer of monoallylamine in the aqueous system to create a gelatinous material that tends to plug porous ~5 zones and minimize water loss from the cement slurry.
~ he sulfonated vinylaromatic polymers that may be used as the sulfonated polymeric co~ponent in the practice of this invention are exemplified by the sulfonated polystyrenes and ,: ~

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sulfonated vinyltoluenes, which are preferably used in their water-soluble salt forms. As pointed out in U. S. Pat. No.
4,413,681 these s~bstances can vary very widely in molecular weigllt, for eYample from 500,000 to 8,000,000, and suitable sulfollated polymers of this type are also available as articles of con~merce.
In practicing this invention any suitable ligno-sulfonate, condensed ~aphthalene sulfonate, or sulfonated vinylaromatic polymer may be used either singly or in various 10 combinations with each other. To determine the suitability of any given sulfonated polymer or mixture of sulfonated polymers, all that is re~uired is to perform a few simple tests first to establish that the given sulfonated polymer or mixture of sulfo-nated polymers reacts with the polymer of monoallylamine in an 15 aqueous system to create a gelatinous material and secondly to establish that the gelatinous material will tend to plug porous ~ones and minimize water loss from a cement slurry. Use of the standard test procedures referred to in the ensuing examples is deem~d particularly desirable for these purposes.
~0 For further details concerning sulfonated polymers of the types suitable for use in the practice of this invention, reference may be had, for example, to Gibson et al U. S. Pat. No.
3,491,049; Scott et al U. S. Pat. No. 3,511,314; Crinkelmeyer et al U. S. Pat. No. 4,131,578; McKenzie U. S. Pàt. No. 4,413,681;
25 Spitz et al U. S. Pat. No. 4,482,381, McKenzie et al, Oil & Gas Journal, March 1982, pages 146-148, and to the references cited therein, all disclosures relative to sulfonated polymers.

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l~hile not necessary, use may be m~de with water-soluble po ymers of monoallylamine of supplemental additives that serve as in situ cross-linking agents for such polymers when the polymer and the cross-linking agent are combined in an aqueous medium especially at a somewhat elevated temperature (e.~., 50 to 100~ C). Examples of such cross-linking agents are ethylene dichloride, epi~llorohydrin, ethylene dibromide, as well as other similar substances well known to those skilled in the art.
Amounts of such cross-linking agents ranging from 1 x 10 to 5 x 10 3 moles per mole of poly(monoallylamine) or water-soluble salt thereof are generally sufficient to produce cross-linking to an e~tent suitable for this purpose.
In practicing this invention the polymer of monoallyl-amine may be premixed with the lignosulfonate and the mixture added (with or wi~hout other additives) to the dry cement or to the aqu~ous cement slurry or to the water to be used in forming the slurry. ~lternatively, these additives may be introduced separately in either order or concurrently (with or without other additives) into the dry cement or into the aqueous cement slurry ~0 or into the water to be used in forming the slurry. For best results the aqueous cement slurries of this invention, irrespec-tive of the method in which they are formulated, should be used in the cementing operation within a relatively short time after preparaticn, e.g., within a few hours. Since the additives react 25 with each other in the presence of water to form a gelatinous phase, it is desirable to keep the formulations that contain both of them dry until the cement slurry is formed. For the same 5~46;

reason it is preferable to introduce at least one of these two types of additives into the slurry after it has been formed or while it is being formed, rather than introducing both before it is formed.
It is possible, thou~h not essential, to include in the c~mpositions of this invention conventional quantities of conven-tional additives used in well cement slurries. For example, materials such as calcium chloride, sodium chloride, plaster of Paris, sodium silicate (~a2SiO2), sea water, or the like, may 1~ be employed. A feature of this invention is that sea water may be used without adverse consequences, and this is advantageous in situations such as offshore drilling where sea t~ater is plentiful.
Other cementing additives may also be employed in the compositions of t~liS invention, provided of course that they do not materially pair the effectiveness of the fluid-loss-control additive system of this invention with whidl they are employed. Among the ather types of conventional additives that are deemed feasible for use in the compositions of this invention are light-weight additives (e.g., bentonite, diatomaceous earth, Gilsonite, coal, ~0 e~lded perlite, nitrogen, fly ash, sodium silicate, etc.), heavy-weight additives (e.g., hematite, ilmenite, barite, sand, salt, etc.) cement retarders (e.g., carboxymethyl hydroxyethyl cellulose, saturated salt, borax, etc.), filtration control additives, cement dispersants (friction reducers), mud decon-~5 taminants, silica flour, radioactive tracers, dyes, hydrazine,fiber, gypsum, and others. The suitability and amount of a such ancillary additives will in many cases be readily apparent to 5~6 those skilled in the art, and in any event can be readily determined by the simple expedient of running a few la~oratory tests.
The amounts of the polymer of monoallylamine and of the sulfonated polymer used in the compositions of this invention may be varied within reasonable limits. When furnished in the form of an additive combination, the amount of polymer of monoallyl-amine in the dry mixture will normally fall in the range of from 0.05 to 10 and preferably from 1 to 5 parts by weight per part by weight of the sulfonated polymer. The factor of chief importance is to use an amount of the sulfonated polymer that upon addition of water interacts with the amount of the polymer of monoallyl-amine being used in the formulation to form a gelatinous material tllat effectively minimizes fluid loss from the slurry during its use in a well cementing operation, yet does not cause the forma-tion of an excessively viscous, unpumpable mixture. Accordingly, it is generally recommended that in the cement-containing systems of this invention the amount of polymer of monoallylamine fall in th~ range of from 0.5 to 10, preferably from 1 to 5 parts by weight per each 100 parts by weight of cement and the amount of sulfonated polymer fall in the range of from 0.5 to 10, preferably from 1 to 5 parts by weight per each 100 parts by weight of cement, although depa~tures from these ranges may be feasible and may be utilized if determined to he suitabIe in any given instance, for example by means of a few simple tests.
In order to demonstrate the efficacy of the fluid-loss-control additiv~ systems of this invention, a group of tests were conducted using the standard test procedures essentially as described in API Specification ior Materials and Testin~ for Well Cements, Second Edition, June 15, 1984, Section 5, entitled "Preparation of Slurry" (pages 16-17), Section 9 entitled "Atmospheric Pressure Consistometer" (page 32), and Appendix F
entitled "Fluid-Loss Test (Tentative)" (pages 73-75). In these tests a Class H cement was used and a temperature of 150F was maintained during the 20 minute period in the consistometer. In essence, therefore, each test involved preparing the slurry including additive(s), transferring the slurry from the blender to the consistometer preheated to 150F, stirring the slurry for 20 minutes, transferring the slurry from the consistometer to the pr~heated fluid-loss cell at 150F, closing the cell, applying 1,000 psig to the top of the cylinder, and collecting and measuring the volume of the filtrate emanating from the bottom of the cell as a function of time.
The results of these tests are summarized in Table I.
e additives used in the tests and the abbreviations applied to them in the table are as follows:

Fluid-L:oss-Control Additives A = Poly(monoallylamine hydrochloride), 150,000 Mw from Nitto Boseki Co. Ltd.
B = Poly(monoallylamine hydrochloride), 10,000 Mw from Nitto Boseki Co. Ltd.
~5 C = Commercially-available fluid-loss-control additive;
reportedly one of the best on the market D = Another effective commercially-available fluid-loss-control additive Sulfonated Polymers Lig = Lignosulfonate salts (mainly Na and Ca salts) available from Reed Lignin as Marasperse CK-22 ~apll = A condensed naphthalene sulfonate available from Diamond Shamrock as Lomar D

Otller Additives CaC12 = Calcium chloride NaCl = Sodium chloride . .

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The aata in Table I indicate that effective fluid loss control can be achieved by the practice of this invention.
Example 2 illustrates the importance of avoiding use an excessive amount of the sulfonated polymer when formulating the composi-ti~ns of this invention. Examples 8 and 9 illustrate the need or utilizing both components of the fluid-loss-control systems of this invention. Example 10 indicates that in the particular system and proportions tested, poly(monoallylammonium chloride) with a weight average molecular weight above 10,000 would have been re suitable.
Another group of standard tests still further demon-strated the efficacy of this invention. Besides using the test procedures employed in Table I, in this group of tests the sta-bilities of the cement slurries were determined by use of the standard "Free Water" test as described in Section 6 of the ~PI
Specification for Materials and Testing for Well Cements, entitled "Determination of Free Water Content of Slurry". The results of this group of tests are summarized in Table II. The additives used in these tests and the abbreviations applied to them in 20 Table II are as follows:

Fluid-Loss-Control Additives B = Poly(monoallylamine hydrochloride), 10,000 Mw from Nitto Boseki Co. Ltd.
C = Commercially-available fluid-loss-control additive;
~5 reportedly one of the best on the market 8'~(~

E = Polyallylamine prepared fr~m poly(monoallylammonium chloride), 10,000 Mw (from Nitto Boseki Co. Ltd.) neutralized to pH 9 with sodium hydroxide F = Polyallylamine prepaxed from poly(monoallylammonium chloride), 150,000 Mw (from ~itto Eoseki Co. htd.) neutralized to pH 9 with sodiu~ hydroxide Sulfonated Polymer Lig = Lignosulfonate salts available from Reed Lignin as ~larasperse CK-22 Other Additive CaCl~ - Calciu~ chloride ~58'~6 (!J ~1 1~ O :2 1`1 0 0 ~ ,. , :.. 3 !~
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O O ~ ~ ~D r- r~ o a~ o ~"_ :.~ ~ l ~ ~ ~ ~ I 1-In Examples 14, 16-18 no evidence was seen of solids separation as indicated by streaking on inner graduated cylinder walls and there was no evidence of any settling of dense material in the bottom of the cylinder. In the control run of Example 19 significant water separation occurred. Also, Example 15 showed significant water separation indicating the need for calcium chloride with the poly(monoallylammonium chloride) used in this example.
A number of monoallylamine polymers were crosslinked and 1~ subjected to the foregoing test procedures. Examples 21 through 28 describe the manner by which these crosslinked polymers were formed.

Example 21 A 33 weight percent solution of polyallylamine hydro-lS chloride (Nitto Boseki Co., Ltd.) with a weight average molecularweight of 10,000 was prepared in a beaker using deminerali~ed water. Using sodium hydroxide pellets, the pH of the solution was adjusted to 8.5. m en, 3,500 ppm of epichlorohydrin based on the weight of the original poly(monoallylammonium chloride) was ~0 added to the solution and the beaker was immersed in a preheated oil bath. Crosslinking was carried out at 75C for 30 minutes.
m e resulting solution was then ccoled to 25C. m e resulting crosslinked product had an initial Brookfield Viscosity of 275 cps and subsequently became considerably more viscous.

-Exa~ple 22 The procedure of Example 21 was repeated in the same way with the exception that the proportion of the epichlorchydrin used was 5,000 ,~pm based on the weight of the initial poly(monoallyl-ammQnium chloride). The crosslinked product was a non-Newtonian fluid.

Example 23 Utilizing the same procedure as in Example 21, poly-allylamine hydrochloride (Nitto Boseki Co., Ltd.) having a weight 10 average molecular weight of 150,000 was crosslinked with epi-chlorohydrin in the amount of 150 ppm based on the weight of the initial polyallylamine hydrochloride. The crosslinked product was a non-Newtonian fluid.

Example 24 A 30 weight percent solution of polyallylamine hydro-chloride (Nitto Boseki Co., Ltd.) with a weight average molecular weight of 10,000 was prepared in a beaker using demineralized--ater. m e solution was 50% neutralized by adding sodium ~a hydroxide pellets (22 wt %) which increased the p~ to 9.1. After the NaOH dissolved, the solution was transferred to a round bottomed flask equipped with a reElux condenser, and 8,000 ppm of ethylene dichloride based on the weight of the original poly(mono-allylammonium chloride) was added to the solution. The mixture 25 was heated with stirring to 80 to 90-C and held at this tempera-ture for 30 to 60 minutes~ m e resulting solution waa then cocled to 25C. m e crosslinked product exhibited an initial Brookfield Viscosity of 160 cps.

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Example 25 m e procedure of Example 24 was repeated in the same way with the exception that the proportion of the ethylene dichloride used was 10,000 ppm based on the weight of ~he initial poly(mono-allylammoniuml chloride). The crosslinked product gave an initial Brookfield Viscosity of 414 cps.

Example 26 Utilizing the same procedure as in Example 24, polyallyl-amine hydrochloride (Nitto Boseki Co., Ltd.) having a weight average molecular weight of 150,000 was crosslinked with ethylene dichloride in the amount of 50 ppm based on the weight of the original polyallylamine hydrochloride.

Example 27 m e procedure of Example 26 was repeated in the same way with the exception that the proportion of the ethylene dichloride used was 100 ~pm based on the weight of tne original monoallyl-amine polymer. m e crosslinked product gave a Brookfield Viscosity of 1.5 million cps.

Example 28 ~0 The procedure of Example 27 was repeated in the same way except that in this case the proportion of the ethylene dichloride used was 300 ppm based on the weight of the original monooallyl-amine polymer. The crosslinked product exhibited a Brookfield Viscosity of over 8 million cps.

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The fluid-loss-control additives of Examples 21, 22 and 23, a commercially available polyethyleneimine fluid-loss-control additive (Additivc "G"), and a commercially available polyethylene p~lyamine fluid-loss-control additive (Additive "H") were tested as above. In addition, control tests were run wherein no fluid-loss-control additive was used. All tests samples contained lignosulfonate salt available fr~m Reed Lignin as Marasperse CK-22.
The results of these tests are summarized in Table III.

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' ' ' In another series of tests the crosslin}ced products of Examples 24 through 28 inclusive were subjected to the fluid loss test procedure referred to above. A commercially-available fluid-loss-control additive was also tested, as was a sample of 5 polyallylamine hydrochloride ("PA~-HCl") as received from Nitto Boseki Co., Ltd. Each composition tested contained 0.66 weight percent of lignosulfonate salt. Table IV summarizes the results of this group of tests.

Table IV -- Cement Fluid-Loss Tests 1 0 Fluid-Loss-Control Additive Dehydration Filtrate Fluid Loss, ~t~vC ~ ., ~,t~ Time, min. Vol., ~L ~rL/30 min.
Ex. 24 2.0 5 47 114 Ex. 25 2.0 3.5 28 82 lS Ex. 26 1.0 0.11 30 500 Ex~ 27 1.5 1.25 27 132 Ex. 28 2.0 2.3 26 93 PA~-HCl 2.0 35 30 28 Comm'l 2.0 60 20 17 ~0 As noted above, even essentially water-insoluble polymers of monoallylamine can be used in the practice of this invention.
To illustrate, the essentially water-insoluble phosphate and sulfate polymers were prepared from allylammonium phosphate and allylammonium sulfate using the procedures reported in U. S. Pat.
~5 ~o. 4,504,640. In addition, a sample of the phosphate polymer ~ , .

was converted to the ~ater-soluble hydrochloride polymer (intrinsic viscosity 0.419) by treatment with concentrated hydrochloric acid. The hydrochloride polymer ("PA~H") and both essentially water-insoluble products, poly(monoallylammonium S phosphate) ("PAAP") and poly( noallylammonium sulfate) ("PAPS"), as well as 10,000 ~Iw polyallylamine hydrochloride ("PAA-HCl", Nitto Boseki Co., Ltd.), were subjected to the same standard test procedures previously described, with but one exception. Since PA~P and PAAS are essentially water insoluble, each was ground in a Waring blender in the presence of dry Portland cement before mi~ing with water. The sulfonate polymer used was sodium ligno-sulfonate (`'Lig"). The test results, in which some of the systems ~dditionally contained sodium chloride, are shown in Table V.

Table V -- Cement Fluid-Loss Tests Fluid-Loss- Lig NaCl Control Additive Conc. Conc. Dehydration Filtrate Fluid Loss, ~dditive Conc, wt~ wt~ wt~ Time, min. Vol., mL mL/30 min.
None - - - 0.06 42955 to 1200 None - - 1.5 0.06 26 581 PAAr 3.5 - - 0.07 29.5 62 PAAP 3.5 - 1.5 0.25 28 307 PAAP 3.5 0.66 1.5 0.31 28.5 281 PAAP 2.5 - 1.5 0.12 28 450 PAAS 3.5 - - 0.07 31 658 PA~S 3.5 0.66 - 0.28 37 380 PAAH 2.0 0.66 - 12.3 33.5 52 PA~-HCl 2.0 0.66 - O.5 49 383 58~6 As will now be readily apparent to those skilled in the art, the fluid-loss-control additive systems of this ir.vention may be employed with a wide variety of conventional well cements, including tllose of API Classes A through F, whether of the ~rdinary, ~loderate, or High Sulfate Resistant ~ypes.
In the practice of this invention use may be made of mixtures of different polymers of monoallylamine of the type referred to hereinabove. Likewise, in the practice of this invention the sulfonated polymer may be (a) a mixture of two or more different lignosulfonates, (b) a mixture of two or more different condensed naphthalene sulfonates, (c) a mixture of two or more different sulfonated vinyl aromatic polymers, (d) a mix-ture of one or more lignosulfonates and one or more condensed nap~lthalene sulfonates, (e) a mixture of one or more lignosulfo-nates and one or more sulfonated vinyl aromatic polymiers, (f) ami~ture of one or more condensed naphthalene sulfonates and one or more sulfonated vinyl aromatic polymers, (g) a mixture of one ox more lignosulfonates, one or more condensed naphthalene sulfonates and one or more sulfonated vinyl aromatic polymers, or the like. It will also be appreciated that previously known fluid-loss-control additives may be used in conjunction with the fluid-loss-control additive combinations of this invention, provided of course that each previously known fluid-loss-control additive so used does not significantly impair the effectiveness ~5 of the system(s) of this invention with which it is used.
This invention is susceptible to considerable variation in its practice within the spirit and scope of the appended claims.

Claims (10)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A fluid-loss-control additive system adapted for use in cementing subterranean well formations with an aqueous well cement slurry, which additive system comprises in combination, an anhydrous mixture of (i) a sulfonated polymer and (ii) a polymer of monoallylamine.

2. A composition as claimed in Claim 1 in which the sulfonated polymer consists essentially of a water-soluble lignosulfonate.

3. A composition as claimed in Claim 1 in which the sulfonated polymer consists essentially of a condensed napthalene sulfonate.

4. A composition as claimed in Claim 1 in which the polymer of monoallylamine is represented by the general formula:
where m is a number from zero to 100,000 and n is a number from zero to 100,000, the sum of m plus n being in the range of 10 to 100, 000.

5. A composition as claimed in Claim 4 in which said polymer is crosslinked with a crosslinking agent having two or more groups reactable with the amino group.

6. A composition as claimed in Claim 1 in which the polymer of monoallylamine is a water-soluble polymer of monoallylamine.

7. A composition as claimed in Claim 6 in which calcium chloride or sodium chloride, or both are also included.

8. A dry cement formulation adapted for producing an aqueous well cement slurry for use in cementing subterranean well formations, which formulation comprises in combination, an anhydrous mixture of (i) uncured cement, (ii) a sulfonated polymer, and (iii) a polymer of monoallylamine; components (ii) and (iii) being capable of producing and being present in an amount sufficient to produce, upon the addition of water, a gelatinous material that tends to plug porous zones and minimize premature water loss from the well cement slurry when present in the subterranean well formation.

9. In a process of producing an aqueous well cement slurry for use in cementing subterranean well formations, the improvement which comprises incorporating into the slurry (i) a sulfonated polymer and (ii) a polymer of monoallylamine;
components (i) and (ii) being capable of producing, being present in an amount sufficient to produce, and producing upon contact with water, a gelatinous material that tends to plug porous zones and minimize premature water loss from the well cement slurry when present in the subterranean well formation.

10. A process as claimed in Claim 9 in which the slurry also includes calcium chloride or sodium chloride, or both.