CA1160033A - Oil base fluids containing cationic organophilic clays - Google Patents

Abstract

ABSTRACT

An oil base fluid containing an organophilic clay gellant is disclosed. The gellant is the reaction product of an organic cationic compound, an organic anionic compound and a smectite-type clay.

Description

OIL BASE FLUIDS CONTAINING ORGANOPHILIC CLAYS

This invention relates to organophilic organic-clay complexes which are dispersible in organic liquids to form a gel therein. More particularly such gels are useful in oil base muds and oil base packer fluids.
It is well known that organic compounds containing a cation will react with clays which contain a negative layer-lattice and exchangeable cations to form organo-philic organic-clay products. The reaction of an organic cation containing at least one alkyl group of at Least 10 carbon atoms with clay generally results in organoclays swellable in certain organic liquids.
Prior publications include U S. Pat. No. 2,531,427, and U.S Pat No 2,966,506 and the book "Clay Mineralogy", 2nd Edition, 1968 by Ralph E. Grim (McGraw Hill Book Co , Inc.), particularly Chapter 10, Clay-Mineral-Organic Reactions; pp. 356-368 - Ionic Reactions, Smectite; and pp. 392-401 - Organophilic Clay-Mineral Complexes Maximum gelling (thickening) efficiency from these organoclays is achieved by adding a low molecular weight polar organic dispersing material to the composition.
Such materials are disclosed in U S. Patents: O'Halloran

2,677,661; McCarthy et al. 2,704,276; Stratton 2,833,720;
Stratton 2,879,229; and Stansield et al 3,294,683 The use of such dispersion aids was found unnecessary when us-ing particular organophilic clays derived from substituted -2- ~6~3 quaternary ammonium compounds as disclosed in Finlayson et al 4,105,578 and Finlayson 4,208,218.
Prior organophilic clays have exhibited limited broad range gelling utility due to fluctuating dispersion and viscosity properties. While the materials disclosed in U.S. Patent 4,105,578 have not shown such deficiencies, such materials are difficult and costly to produce.
Summary of the Invention An oil-base fluid of this invention which com-prises an oil phase and from about 1 to about 50 lbs. per barrel of the fluid of an organophilic gellant comprising the reaction product of an organic cationic compound, an organic anionic compound and a smectite-type clay having a cation exchange capacity of at least 75 milliequivalents per 100 grams of said clay.
Detailed Description of the Invention The oil base fluid of the present invention consists of an oil phase and from about 1 to about 50 lbs. per barrel of fluid of an organophilic clay gellant. Preferably, the fluid is non-aqueous. A suitable oil phase of this invention may be crude petroleum and fractions thereof, including but not limited to diesel oil, kerosene, fuel oil, light lubri-cating oil fractions, and heavy naptha having a boilingrange between about 300F to about 600F. The preferred oil phase material is diesel oil.
The a~ount of the organophilic clay employed should be effective to obtain the necessary degree of gellation (thickening) of the oil-base fluid for the intended application, that is, drilling fluid or packer fluid. The minimum concentration of organophilic clay needed to gel a particular fluid is dependent upon factors such as the type of organophilic clay used, the characteristics of the oil phase, the maximum temperature to which the fluid is to be raised, and the type of emulsifier, if any. The maximum concentration of organophilic clay is limited to that which will form a pumpable fluid.
The concentration of organophilic clay within the range of about 1 to about 50 lbs. per barrel (42 gallon ~6~033 barrel of fluid) will generally provide a sufficiently gelled fluid for broad applications. Preferably about 1 to about 10 lbs. per barrel are employed in the preparation of oil-base drilling fluids whereas amounts from about 6 to 50 lbs. per barrel have been found adequate for the preparation of oil-base pac~er fluids. It has been found that when the organophilic clay is mixed into the oil-base fluid, essen-tially complete gelling is achieved at low shear mixing.The resulting oil-base fluid is a stable oil-base fluid at surface temperatures below -20F and downhole temperatures up to 500F. The formation of the stable fluid occurs in a matter of minutes following addition and low shear mixing of the organophilic clay in the oil base fluid.
A packer fluid is prepared in accordance with this invention by adding to an oil medium the organophilic clay. The composition of the packer fluid is regulated as discussed above to provide a pumpable composition. Optional emulsifiers, weighting agents, and fluid loss control materials may be added at any time. Once prepared, the packer fluid is transferred, such as by pumping, into a well bore, at least one portion of which is to be insulated.
The oil-base fluid can be prepared and used either before drilling commences or while drilling is in progress.
The method of adding the ingredient to prepare the fluid is not critical. Mixing is accomplished with conventional devices capable of developing a low shear mixing force.
Greater mixing force may be employed even though not necessary. Once prepared, the emulsion drilling fluid is transferred, such as by pumping, into a well bore and circulated to the bit and through the borehole in contact with the walls thereof.
The organophilic clays of this invention can be prepared by admixing the clay, organic cation, organic anion and water together, preferably at a temperature within the range from 20C. to 100C., more preferably 35C. to 77C.
for a period of time sufficient for the organic cation and organic anion complex to intercalate with the clay particles.
The mixing step is followed by filtering, washing, drying _4_ ~ 3 and grinding. The addition of the organic cation and organic anion may be done either separately or as a complex.
In using the organophilic clays in emulsions, the drying and grinding steps may be eliminated. When admixing the clay, organic cation, organic anion and water together in such concentrations that a slurry is not formed, filtration and washing steps can be eliminatecl.
The organophilic clays of the invention may also be prepared by admixing the organic anion with an aqueous clay slurry preferably at a temperature between 20C.
and 100C. for a sufficient time to prepare a homogenous mixture followed by the addition of the organic cation in sufficient amounts to satisfy the cation exchange capacity of the clay and the cationic capacity of the organic anion.
The mixture is reacted with agitation at a temperature between 20~C. and 100C. for a sufficient time to allow the formation of an organic cation-organic anion complex which is intercalated with the clay and the cation exchange sites of the clay are substituted with the organic cation.
Reaction temperatures below 20C or above 100~C, are not preferred due ~o the need for additional processing eguipment.
The organic cationic compounds useful in this invention may be selected from a wide range of materials that are capable of forming an organophilic clay by exchange of cations with the smectite-type clay. The organic cationic compound should have a positive charge localized on a single atom or on a small group of atoms within the compound.
Preferably the organic cation is selected from the group consisting of quaternary ammonium salts, phosphonium salts, sulfonium salts and mixtures thereof wherein the organic cation contains at least one linear or branched alkyl group having 8 to 60 carbon atoms. More preferably, the organic cation contains one member selected from a first group consisting of a ~,y - unsaturated alkyl group having less than 7 aliphatic carbon atoms, a hydroxyalkyl group having 2 to 6 carbon atoms, and an aralkyl group and mixtures thereof and a second member selected from a second group consisting -5- ~L6~3 alkyl group. More preferably, two additional members of the compound are individually selected from a third group consisting of a ~, Y-unsaturated alkyl group having less than 7 aliphatic carbon atoms, a hydroxyalkyl group having 2 to 6 carbon atoms, an aralkyl group, an alkyl group having from 1 to 22 carbon atoms and mixtures thereof.
The organic cation may be selected from a group consisting of the formulae:

and wherein X is nitrogen or phosphorus, Y is sulfur, R1 is an alkyl group having 8 to 60 carbon atoms; and R2, R3 and R4 are individually selected from the group consisting of hydrogen; hydroxyalkyl groups having 2 to 6 carbon atoms;
alkyl groups containing 1 to 22 carbon atoms; aryl groups;
aralkyl groups containing 1 to 22 carbon atoms on the alkyl chain; and mixtures thereof. Preferably, X is nitrogen.

The long chain alkyl radical may be branched or unbranched, saturated or unsaturated, substituted or unsub-stituted and should have from 8 to 60 carbon atoms in thestraight chain portion of the radical. Preferably, R1 is an alkyl group having 12 to 6n carbon atoms. More preferably, R1 is an alkyl group having 12 to 22 carbon atoms.
The long chain alkyl radicals may be derived from naturally occurring oils including various vegetable oils, ~G~3~333 such as corn oil, coconut oil, soybean oil, cottonseed oil, and castor oil and various animal oils and fats such as tallow oil. The alkyl radicals may be derived synthetically from sources such as alpha olefins.
Representative examples of useful branched, saturated alkyl radicals include 12-methylstearyl; and 12-ethylstearyl. Representative examples of useful branched, unsaturated radicals include 12-methyloleyl and 12-ethyloleyl. Representative examples of unbranched saturated radicals include lauryl, stearyl; tridecyl;
myristal (tetradecyl); pentadecyl; hexadecyl; hydrogenated tallow and docosonyl. Representative examples of un-branched, unsaturated and unsubstituted long chain alkyl radicals include oleyl, linoleyl; linolenyl, soya and tallow.

R2, R3, R4 R?, R3, and R4 are individually selected from the group consisting of hydrogen; a hydroxyalkyl group having 2 to 6 carbon atoms; an alkyl group containing 1 to 22 carbon atoms; an aryl group an aralkyl group containing 1 to 22 carbon atoms in the alkyl chain of the aralkyl group, and mixtures the~eof.
Preferably, R2 is selected from a group consist-ing of a ~,y -unsaturated alkyl group having less than 7 aliphatic carbon atoms , a hydroxyalkyl group having 2 to 6 carbon atoms, and a aralkyl group containing 1 to 22 carbon atoms in the alkyl chain of the aralkyl group and mixtures thereof. Preferably R3 and R4 are individually selected from a group consisting of a ~,y -unsaturated alkyl group, a hydroxyalkyl group having 2 to 6 carbon atoms, an alkyl group having 1 to 22 carbon atoms, an aralkyl group which - 35 includes benzyl and substituted benzyl moieties including fused ring moieties having linear or branched chains of 1 to 22 carbon atoms in the alkyl portion of the aralkyl group and mixtures thereof.
Th,e hydroxyalkyl group may be selected from a hydroxyl substituted aliphatic radical having from 2 to 6 aliphatic carbons wherein the hydroxyl is not substituted at the carbon adjacent to the positive charged atom. The alkyl group may be substituted with an aromatic ring. Representa-tive examples include 2-hydroxyethyl; 3 hydroxypropyl;
4-hydroxypentyl; 6-hydroxyhexyl; 2-hydroxypropyl; 2-hydroxybutyl; 2-hydroxypentyl; 2-hydroxyhexyl; 2-hydroxy-cyclohexyl; 3-hydroxycyclohexyl; 4-hydroxycyclohexyl;
2-hydroxycyclopentyl; 3-hydroxycyclopentyl; 2-methyl-2-hydroxypropyl; 3-methyl-2-hydroxybutyl; and 5-hydroxy-2-pentenyl.
The alkyl group containing 1 to 22 carbon atoms may be linear or branched, cyclic or acyclic, substituted or unsubstituted. Representative examples of useful alkyl groups include methyl; ethyl; propyl; 2-propyl; iso-butyl;
cyclopentyl; and cyclohexyl.
The alkyl radicals may be derived from sources similar to the long chain alkyl radical, R1, above.
~he preferred ~,y -unsaturated alkyl group may be cyclic or acyclic, unsubstituted or substituted.
unsaturated alkyl radicals preferably contain less than 7 aliphatic carbon atoms. Aliphatic radicals substituted on the ~,Y - unsaturated group preferably containg less than 4 carbon atoms. The~ , r -unsaturated alkyl radical may be substituted with an aromatic ring that is conjugated with the unsaturation of the ~,y moietyO The~ ,y -radical may also be substituted both with aliphatic radicals and aromatic rings.
Representative examples of cyclic~ unsaturated alkyl groups include 2-cyclohexenyl and 2-cyclopentenyl.
Representative examples of acyclic ~,~ - unsaturated alkyl groups containing 6 or less carbon atoms include propargyl;
2-propenyl; 2-butenyl; 2-pentenyl; 2-hexenyl; 3-methyl-2-bu-35 tenyl; 3-methyl-2-pentenyl; 2,3-dimethyl-2-butenyl; 1,1-di-methyl-2-propenyl; 1,2-dimethyl-2-propenyl; 2,4-pentadienyl;
and 2,4-hexadienyl. Representative examples of acyclic-aromatic substituted compounds include 3-phenyl-2-propenyl;
2-phenyl-2-propenyl; and 3-(4-methoxy phenyl)-2-propenyl.
Representative examples of aromatic and aliphatic sub-- -8~ 6~ 0 33 stituted materials include 3-phenyl-2-cyclohexenyl;

3-phenyl-2-cyclopentenyl; alkyl group may be substituted with an aromatic ring.
Examples of aryl groups would include phenyl such as in N-alkyl and N,N-dialkyl anilines, wherein the alkyl groups contain between 1 to 22 carbon atoms; ortho-, meta- and para-nitrophenyl, ortho-, meta- and para-alkyl phenyl, wherein the alkyl group contains between 1 and 22 carbon atoms, ~-, 3-, and 4- halophenyl wherein the halo group is defined as chloro, bromo, or iodo, and 2-, 3-, and 4-carboxyphenyl and esters thereof, where the alcohol of the ester is derived from an alkyl alcohol, wherein the alkyl group contains between 1 and 22 carbon atoms, aryl such as a phenol, or aralkyl such as benzyl alcohols; fused ring aryl moieties such as naphthalene, anthracene, and phenanthrene.
Representative examples of an aralkyl group, include benzyl and those materials derived from compounds such as benzyl halides, benzhydryl halides, trityl halides, 1-halo-1-phenylalkanes wherein the alkyl chain has from 1 to 22 carbon atoms such as 1-halo-1-phenylethane; 1-halo-1-phenylpropane; and 1-halo-1-phenyloctadecane substituted benzyl moieties such as would be derived from ortho-, meta-and para-chlorobenzyl halides, para-methoxybenzyl halides;
ortho-, meta- and para-nitrilobenzyl halides, and ortho-, meta- and para-alkylbenzyl halides wherein the alkyl chain contains from 1 to 22 carbon atoms; and fused ring benzyl-type moieties such as would be derived from 2-halomethyl-naphthalene, 9-halomethylanthracene and 9-halomethyl-phenanthrene, wherein the halo group would be defined as chloro~, bromo-, iodo-, or any other such group which serves as a leaving group in the nucleophilic attack of the benzyl type moiety such that the nucleophile replaces the leaving group on the benzyl type moiety.
A compound is formed of the above described organic cation and an anionic radical which is selected from the group consisting of chloride, bromide, iodide, nitrite, hydroxide, acetate, methyl sulfate and mixture thereof.
Preferably the anion is selected from the group consisting -9~ 33 of chloride and bromide, and mixtures thereof, and is more preferably chloride, although other anions such as iodide, acetate, hydroxide, nitrite, etc., may be present in ~he organic cationic compound to neutralize the cation.
Organic cationic salts may be prepared by methods as disclosed in U.S. 2,355,356, 2,775,617 and 3,136,819.
The organic anions useful in this invention should be capable of reacting with an organic cation and form intercalations with a smectite-type clay as an organic cation-organic anion complex. The molecular weight (gram molecular weight) of the organic anion is preferably 3,000 or less, and most preferably 1,000 or less and contains at least one acidic moiety per molecule as disclosed herein.
The organic anion is preferably derived ~rom an organic acid having a pKA less than about 11Ø As indicated, the source acid must contain at least one ionizable hydrogen having the preferred pKA in order to allow the formation of the organic cation-organic anion complex and subse~uent intercalation reaction to occur.
Also useable is any compound which will provide the desired organic anion or hydrolysis. Representative compounds include:
1) acid anhydrides includin~ acetic anhydride, maleic anhydride, succinic anhydride and phthalic anhydride;
2) acid halides including acetyl chloride octanoyl chloride, lauroyl chloride, lauroyl bromide and benzoyl bromide:
3) 1,1,1-trihalides including 1,1,1-trichloroethane and 1,1,1-tribromooctane; and

4) orthoesters inlcuding ethyl orthoformate and ethyl orthostearate.
The organic anions may be in the acid or salt form. Salts may be selected from alkali metal salts, alkaline earth salts, ammonia, and organic amines.
Representative salts include: hydrogen, lithium, sodium, potassium, rnagnesium, calcium, barium, ammonium and organic amines such as ethanolamine, diethanolamine, triethanolamine, methyl diethanolamine, butyl diethanolamine, diethyl amine, . , dimethyl amine, triethyl amine, dibutyl amine, and mixtures thereof. The preferred alkali metal salt is sodium.
Suitable acidic functional organic compounds include:
1) Carboxylic acids including:
(a) benzenecarboxylic acids such as benzoic acid, ortho-, meta- and para-phthalic acid, 1,2,3-benzene tricarboxylic acid; 1,2,4-benzenetricarboxylic acid;
1,3,5-benzenetricarboxylic acia; 1,2,~,5-bezene tetra-carboxylic acid; 1,2,3,4,5,6-benzènehexacarboxylic acid (mellitic acid);
(b) alkyl carboxylic acids having the formula H-(CH2)n - COOH, wherein n is a number from O to 20, such compounds include acetic acid; propionic acid; butanoic acid; pentanoic acid; hexanoic acid;
heptanoic acid; octanoic acid; nonanoic acid; decanoic acid; undecanoic acid; lauric acid; tridecanoic acid;
tetradecanoic acid; pentadecanoic acid; hexadecanoic acid;
heptadecanoic acid octadecanoic acid (stearic acid);
nonadecanoic acid; and eicosonic acid.
(c) alkyl dicarboxylic acids having the formula HOOC-(CH~)n-COOH, wherein n ranges from 0 to 8, such as oxalic acid; malonic acid; succinic acid; glutaric acid; adipic acid; pimelic acid; suberic acid; azelaic acid;
and sebacic acid;
(d) hydroxyalkyl carboxylic acids such as citric acid; tartaric acids; malic acid; mandelic acid;
and 12-hydroxystearic acid;
(e) unsaturated alkyl carboxylic acids such as maleic acid; fumaric acid; and cinnamic acid;
(f) fused ring aromatic carboxylic acids such as napthalenic acid; and anthracene carboxylic acid;
(g) cycloaliphatic acids such as cyclohexane carboxylic acid; cyclopentane carboxylic acid; furan corboxylic acids.
2) Organic sulfur acids including:
(a) sulfonic acids including~
(1) benzenesulfonic acids such as ~.3L66~c~33 benzenesulfonic acid; phenolsulfonic acid; dodecylbenzene-sulfonic acid; benzenedisulfonic acid, benzenetrisulfonic acids; para-toluenesulfonic acid; and (2) alkyl sulfonic acids such as methane sulfonic acid; ethane sulfonic acid; butane sulfonic acid; butane disulfonic acid; sulfosuccinate alkyl esters such as dioctyl succinyl sulfonic acid; and alkyl polyethoxy-succinyl sulfonic acid; and (b) alkyl sulfates such as the lauryl half ester of sulfuric acid ancl the octadecyl half ester of sulfuric acid.
3) Organophosphorus acids including;
(a) phosphonic acids having the formula:
O
Il R-P(OH)2 wherein R is an aryl group or alkyl having 1 to 22 carbon atoms;
(b) phosphinic acids having the formula:
O
ll wherein R is an aryl group or alkyl group having 1 to 22 carbon atoms, such as dicyclohexyl phosphinic acid:
dibutyl phosphinic acid; and dilauryl phosphinic acid;
(c) thiophosphinic acids having the formula:
S

"

wherein R is an aryl group or alkyl group having 1 to 22 carbon atoms such as di-iso-butyl dithiophosphinic acid;
dibutyl dithiophosphinic acid; dioctadecyl dithiophosphiric acid;
(d) phosphites, that is diesters of phosphorous acid having the formula: HO-P(OR)2; wherein R
is an alkyl group having 1 to 22 carbon atoms such as dioctadecylphosphite;
(e) phosphates, that is diesters of phosphoric "

-12- ~G~V33 acid having the formula:
o ..
Ho-p - (oR)2 wherein R is an alkyl group having 1 to 22 carbon atoms, such as dioctadecyl phosphate.
4) Phenols such as phenol; hydroquinone;
t-butylcatechol; p-methoxyphenol; and naphthols.

5) Thioacids having the formulae:
S
ll R-C-OH, O
..
R-C-SH
and S

"
R-C-SH
wherein R is an aryl group or alkyl group having 1 to 22 carbon atoms, such as thiosalicylic acid; thioben~oic acid;
thioacetic acid; thiolauric acidi and thiostearic acid.

6) Amino acids such as the naturally occurring~
amino acids and derivatives thereof such as 6 aminohexanoic acid; 12-aminododecanoic acid, N-phenylgylcine; and 3-aminocrotonic acid.

7) Polymeric acids prepared from acidic monomers wherein the acidic function remains in the polymer chain such as low molecular weight acrylic acid polymers and copolymers; styrene maleic anhydride copolymers.

8) Miscellaneous acids and acid salts such as ferrocyanide; ferricyanide; sodium tetraphenylborate;
phosphotungstic acid; phosphosilicic acid, or any other such anion which will form a tight ion pair with an organic cation, i.e., any such anion which forms a water insoluble precipitate with an organic cation.
For convenience of handling it is preferred that the total orclanic content of the organophilic clay reaction ,., ~16~33 -13~

products of this invention should be less than about 50% by weight of the organoclay. While higher amounts are usable the reaction product is difficult to filter, dry and grind.
A sufficient amount of organic cation is employed to satisfy the cation exchange capacity of the clay and the cationic activity of the organic anion. Additional amounts of cation above the sum of the exchange capacity of the clay and anion are optional. For example, smectite-type clays require at least 90 milliequivalents of organic cation to satisfy at least a portion of the total organic cation re~uirement. Use of amounts from 80 to 200 M.E., and preferably 100 to 160 M.E. are acceptable. At lower milli-equivalents rations, an incomplete reaction will occurresulting in an ineffective gellant.
The amount of organic anion added to the clay should be sufficient to impart to the organophilic clay the enhanced dispersion characteristic desired. This amount is defined as the milliequivalent ratio which is the number of milliequivalents (M.E.) of the organic anion in the organoclay per 100 grams of clay, 100% active clay basis. The anion milliequivalent ratio should preferably range from 5~to 100 and preferably 10 to 50.
The organic anion is preferably added to the reactants in the desired milliequivalent ratio as a solid or solution in water under agitation to effect a macroscopically homogenous mixture.
Smectite-type clays occur naturally or are pre-pared synthetically. Suitable clays include montmorillonite, bentonite, beidellite, hectorite, saponite, and stevensite.
In particular smectite-type clays should have a cation exchange capacity of at least 75 milliequivalents per 100 grams of clay. Particularly desirable types of clay are the naturally-occurring Wyoming varieties of bentonite and hectorite, a swelling magnesium-lithium silicate clay.
Suitable synthetic clays may be synthesized by conventional means including pneumatolitic and hydrothermal methods.
The clays, especially the bentonite type clays, are preferably converted to the sodium form if they are not ~ ~6~ 33 already in this form. This can conveniently be done by preparing an aqueous clay slurry and passing the slurry through a bed of cation exchange resin in the sodium form.
Alternatively, the clay can be mixed with water and a soluble sodium compound such as sodium carbonate and sodium hydroxide followed by shearing the mixture with a pugmill or extruder.
The cation exchange capacity of the smectite-type clays can be determined by the ammonium acetate method.
The clay is preferably dispersed in water at a concentration from about 1 to 80% and preferably about 2%
to 20%, and more preferably about 2~ to 7~. The slurry is agitated prior to reaction.
The organic cationic compounds of the invention were prepared by standard prior art methods starting with an amine having the desired number of long chain alkyl groups bonded to the nitrogen atom. This long chain alkyl amine was then reacted by reductive alXylation with an aldehyde and/or by nucleophilic displacement of an alkyl halide to form the desired quaternary ammonium compound.
The fluid of this invention may contain the aqueous phase includes aqueous solutions of inorganic salts such as sodium chloride and calcium chloride. While addition of these salts is optional, such salts increase the osmotic pressure of the water phase of the formations containing hydratable clays.
The a concentration of water in the fluid is deter-mined by factors such as fluid weight requirements, flow properties desired, bottom-hole temperatures and the operational requirements of drilling, coring, or comple-tion. In general, it is preferable to employ a volume percent of water ranging from about 2 to about 50%. This range renders the oil-base fluid fire-resistant upon exposure to temperatures that would ignite the oil. In addition, the fluid has excellent tolerance to wa~er contami-nation; and fluid flow properties can be controlled at values comparable to those of water-based fluids.

-15- ~L6~33 Conventional emulsifiers should be employed for the water-in-oil phase and may be employed for the non-aqueous fluid. The amount of emulsifier employed is primarily dependent upon the amount of water present and the extent of emulsification desired. Generally from 2 to 30 lbs. per barrel and preferably from 5 to 20 lbs. per barrel have been found satisfactory to achieve the necessary gel strengths and filtration control.
The compositions may optionally contain convention-al weighting agents such as barite for controlling fluid density between 7.5 and 22 lb/gal as well as fluid loss control agents.
The smectite-type clays used in the Examples were hectorite and Wyoming bentonite. The clay was slurried in water and centrifuged to remove essentially all of the non-clay impurities which may amount to 10% to about 50% of the starting clay composition. The Wyoming bentonite clay slurry was passed through a bed of cation exchange resin to convert it to the sodium form.
Examples 1 to 4 demonstrate the preparation of various organic cationic compounds which compounds may be used as reactants with an organoclay to form the organo-philic clay reaction products of this invention.
The organic cationic compounds exemplified arerepresentative of the cations of the invention and are not intended to be inclusive of only operative compounds.
The following examples are given to illustrate the invention, but are not deemed to be limiting thereof. All percentages given are based upon weight unless otherwise indicated. Plastic viscosity, yield point, and ten second gels were measured by the procedure described in API RP13B, American Petroleum Institutes Standard Procedure ~or Testing Fluids, 6th Ed., April 1~76.
Example 1 Allyl methyl di(hydrogenated-tallow) ammonium chloride (AM2HT).
824.7 g methyl di(hydrogenated-tallow) amine, 350 ml isopropyl alcohol, 250 g NaHCO3, 191.3 gmO allyl , . .

-16- ~6~33 chloride, and 10 gm. allyl bromide (as a catalyst) were mixed in a 4-liter reaction vessel equipped with a condenser.
The mixture was heated and allowed to reflux. A sample was removed, filtered, and titrated with HCl and NaOH. The reaction was considered complete as there was 0.0% amine HCl and 1.8% amine. The final analysis of the A~2HT showed an effective gram molecular weight of 831.17.
Example 2 A 3% clay slurry (sodium form of Wyoming bentonite) was heated to 60C with stirring.~ 4.8637g (M.E. Ratio -22.5) of an organic anionic compound, sodium benzoate (M.W.
144.11) was dissolved in water. The organic anion solution was added to the clay slurry and reacted for 10 ~inutes at 60C. 136.89 g (M.E. ratio - 122.5) ethanol methyl di (hydro~enated-tallow) ammonium chloride [EM2HT] (M.W.
745) (Armak Co., Division of Akzona Corp.) is dissolved in a 50% 2-propanol aqueous solution. The cation sGlution was added and stirred for 45 minutes at 60C. The organoclay (EM2HT/benzoate/bentonite~ was collected on a vacuum filter.
The filter cake was washed with hot water and dried at 60C.
The dried organoclay was ground using a hammer mill to reduce the particle size and then sieved through a U.S.
Standard 200 mesh screen.
Example 3 A 3% clay slurry (sodium form of Wyoming bentonite) was heated to 60C. with stirring. 7.83g (M.E. Ratio 22.5) of an organic anionic compound, p-Phenolsulfonic acid sodium salt (M.W. 232.19) was dissolved in water. The organic anion solution was added to the clay slurry and reacted for 10 minutes at 60C. 134.42g (M.E. ratio -122.5) benzyl methyl di(hydrogenated-tallow) ammonium chloride BM2HT was dissolved in a 50% 2-propanol aqueous solution. The cation solution was added and stirred for 45 minutes at 60C. The organoclay (BM2HT/p-phenolsulfonate/
bentonite) was collected on a vacuum filter. The filter cake was washed with hot water and dried at 60C. The dried orqano-clay is ground usinq a hammer mill to reduce the particle size and then sieved through a V.S. Standard 200 mesh screen.

-17 ~16~33 Example 4 A 3% clay slurry (sodium form of Wyoming bentonite) was heated to 60C. with stirring. 5.40g (M.E. Ratio -22.5) of an organic anionic compound, sodium salt of salicylic acid (M.~. 160.11) was dissolved in water. The organic anion solution was added to the clay slurry and reacted for 10 minutes at 60C. 134.72g (M.E. ratio -122.5) of AM2HT prepared in Example 1 is dissolved in a50% 2-propanol aqueous solution. The cation solution was added and stirred for 45 minutes at 60C. The organoclay (AM2HT/salicylate/bentonite) was collected on a ~7acuum filter.
The filter cake was washed with hot water and dried at 60C.
The dried organoclay was ground using a hammer mill to reduce the particle size and then sieved through a U.S. Standard 200 mesh screen.
Examples 5-9 0.63 bbl of diesel oil, 8 pounds emulsifier (Invermul, NL Industries, Inc.), 8 pounds filtration control, amine lignite (Duratone HT, NL Industries, Inc.), 4 pounds lime, and 0.11 bbl. of water was stirred for 20 minutes.
22 pounds of calcium chloride~ 325 pounds of barite (Baroid/NL Industriesl Inc.) and 5 pounds of of the three bentonite clay thickeners prepared in Examples 2-4 in addition to commercial products dimethyl di(hydrogenated-tallow) ammonium chloride (2M2HT)/bentonite and benzyl methyl di(hydrogenated-tallow) ammonium chloride (BM2HT)/
bentonite.
The mixed fluid was tested at 95~F. for standard rheology data and the results are shown in Table 2~ None of the Examples settled following stirring:

~6~C~33 ( Table 2 Yield 10 sec. 10 min.
Point Gel Gel Example #/ 2 ~/ 2 / 2 No. Gellant Compound ; 100ft 100ft 100ft S E~12HT/benzoate/ 16 8 12 bentonite 6 BM2HT/p-phenolsulfonate/ 24 14 16 bentonite 7 AM2HT/salicylate/ 18 10 14 bentonite 8 2M2HT/bentonite 30 16 19

9 BM2HT/bentonite 24 14 18 The unstirred batches of Examples 5-9 were rolled at 150F for 16 hours and no settling was noted in any ~xample.
The fluid was stirred for 25 minutes and tested at 88F for standard rheology data as in Example 5. The results are shown in Table 3 below. None of the Example settled following Stirring Table 3 Yield 10 sec. 10 min.
Point Gel Gel Example ~/ #/ ~/ 2 No. 100ft2 100ft2 ldOft 14 7 1û

350 mlbatches of fluid consisting of 0.60 of diesel oil, 8 pounds emulsifier (Invermul(~), NL
Industries, Inc.), 8 pounds amine lignite filtration control (Duratone(~, NL Industries, Inc.), 5 pounds lime, 0.20 bbl of ll.O ppg calcium chloride, and 320 pounds of 35 barite (Baroid~, NL Industries, Inc.) were admixed, stirred for 15 minutes in a Hamilton Beach mixer and cooled to 28F in an ice bath. A 6 lb/bbl concentration of gellants EM2HT/benzoate/bentonite, BM2HT/p-phenol-sulfonate/bentonite and AM2HT/salicylate/bentonate 40 produced in Example 2-4 in , g over a 5 minute period at low shear with a Lightnin mixer.
The cold examples in a viscometer cup, were placed on a Fann 35 viscometer and stirred at 600 rpm while the temperature rose to 70F. The batches;were then placed in a preheated cup jackets set at 125F and allowed to heat to 110F. The plastic viscosity, yield point and 10-sec gel were measured at every 5F increment between 30 to 70F and at every 10F
increment between 70 to 110F. The results of the measure-ments are presented in Figure 1.
Examples I0-14 at 115F were stirred for 15 minutes in a Hamilton Beach mixer and cooled to 80F and tested as with Example 5. The results are presented in Table 4 below.
Table 4 Yield 10 sec. 10 min.
Point Gel Gel Example ~/ 2 ~/ 2 #/ 2 No. Gellant Compound 100ft100ft 100ft E~2HT~benzoate/ 40 17 20 bentonite 11 BM2HT/p-phenolsulfonate/ 51 27 29 bentonite 12 A~;2HT/salicyllate/ 54 23 30 ~5 bentonite 13 2i~2~T/bentonite 50 21 26 14 BM2HT/bentonite 50 23 28 Example 20-14 Batches of fluids consisting of 0.41 bbl of diesel oil and 12 pounds of gellant clays prepared in Examples 2, 3, 4 and 5 in addition to 2i~2HT/bentonite amd BM2HT/Bentonite which were prepared without anionic reactants were admixed and stirred for five minutes in a Hamilton Beach mixer at low speed. 0.41 bbl of diesel oil, 18 pounds asphalt (Baroid~ sphalt, NL Industries, Inc.) and 0.275 pounds of barite, (Baroid~ NL Industries, Inc.) were admixed with the prepared batches above and stirred for 15 minutes in a Hamilton Beach mixer.
350 ml samples of Examples 15 through l9 were tested for rheological properties as in Example 5 at 93F.

~L~6~333 ~20-The results are presented in Table 5 below.
Table 5 Yield 10 sec. 10 min.
Point Gel Gel Example #/ #/ #/
No. Gellant Compound 100ft2 100ft2 100ft2 __ EM~HT/benzoate/ 15 7 27 bentonite 16 BM2HT/p-phenolsulfonate/ 17 7 31 bentonite 17 AM2HT/salicylate/ 15 4 11 bentonite 18 2M2HT/bentonite 54 34 74 19 BM2HT/bentonite 25 11 40 350 ml samples of Example 15 through 19 were hot rolled at 150F for 16 hours. After cooling the batches to 80F, settling of solids were checked prior to measurement of rheological properties as in Example 5 at 93F. The 2n results are shown in Table 6 below.
Table 6 Yield 10 sec. 10 minO
Point Gel Gel Example #/ 2 #/ 2 2 ~o. Gellant_Compound 100ft100ft 100ft EM2HT/sodium benzoate/37 10 40 bentonite 16 BM2HT/p-phenolsulfonate/ 37 13 55 bentonite 17 AM2HT/salicylate/ 52 17 78 bentonite 18 2M2HT/bentonite 91 55 100 19 BM2HT/bentonite 69 39 108 Mud cake and filtrates were stirred back into the respective samples and the batches were aged for 16 hours at 350F.
Each batch was cooled to 80F and checked for solids settling. The batches were stirred for 5 minutes and tested as with Example 5. The results are shown in Table 7 below.

.~

2 ~ 13 33 ( Table 7 Yield 10 sec. 10 min.
Point Gel Gel Example #/ #/ 2 No. Gellant Compound ~ lOOft2 100ft lOOft2 EM2HT/benzoate/ 68 10 34 bentonite 16 BM2HT/p-phenolsulfonate/70 14 51 bentonite 17 AM2HT/salicylate/ 62 15 30 bentonite 18 2M2HT/bentonite 120 45 82 13 BM2HT/bentonite 99 41 78 Examples 20 to 24 350 ml. batches of fluids consis~ing of 0.69 bbl of diesel oil, 6 pounds emulsifier (EZ mul, ~L Industries, Inc.), 0.17 bbl of water, 225 pounds of barite (Baroid~3NL
Industries, Inc.), 24 pounds of calcium chloride and 6 pounds of gellant clays EM2HT/benzoate/bentonite, Bl~l2HT/
p-phenolsulfonate/bentonite and AM2HT/salicylate/bentonite prepared in Examples 2-4 respectively in addi~ion to 2M2HT/
bentonite and BIY2HT/ bentonite described in Example 5 were admixed and stirred for 20 minutes in a Hamilton Beach mixer.
350 ml. batches of Examples 20 through 24 were tested at 88F for rheolo~ical properties as in Example 5.
The results are presented in Table 8 below.
Table 8 ~ield 10 sec. 10 min.
Point Gel Gel Example #/ 2 ~/ 2 ~/ 2 No. Gellant Compound 100ft100ft100ft -EM2HT/benzoate/ 9 4 6 bentonite 21 ~Y2HT/p-phenolsulfonate/ 8 4 6 bentonite 22 AM2HT/salicylate/ 9 4 5 bentonite 23 2M2HT/bentonite 9 5 6 24 BM2HT/bentonite 8 4 5 . , ~

-22- ~ 033 350 ml sample of Example 20 through 24 were hot rolled at 150F for 16 hours. After cooling the batches to 80F, settling of solids was checked prior to measurement of rheological properties as in Example 5 at 84F. The results are shown in Table 9 below.
Table 9 Yield 10 sec.10 min.
Point Gel Gel Example #/ 2 #/ 2 #/ 2 No. 100ft 100ft 100ft 24 ~ 4 5 Mud cake and filtrate were stirred back into the respective samples and the batches were aged for 16 hours at 3soF.
Each batch was cooled to 80F and checked for solids settling. The batches were stirred for 5 minutes and tested as with Example 5~ HT-HP filtrates were conducted on each batch at 350 F. The results are shown in Table 10 below.
Table 10 Yield 10 sec. 10 min.
Point ~el Gel Example #/ 2 #/ 2 #/ 2 No. 100ft 100ft 100ft Example 25-29 350 ml. batches of a fluid consisting of 0.63 bbl of diesel oil, 8 pounds emulsifier (Invermul, NL Industries, Inc.), 0.11 bbl of water, 325 pounds of barite (Baroid, NL
Industries, Inc.), 8 pounds filtration aid (Duratone - NL
Industries, Xnc.), 22 pounds of calcium chloride, ~ pounds -- -23- ~6~33 lime and 9 pounds of gellant clays, EM2HT/benzoate/bentonite, BM2HT/p-phenolsulfonate/ bentonite, and AM2HT/salicylate/
bentonite prepared in Examples 2-4 respectively, commercial`
clays 2M2HT/bentonite, BM2HT/ bentonite described in Example 5 above and an additional commercial clay.
350 ml samples of Examples 25 through 29 were tested at 92F for rheological properties as in Example 5.
The results are presented in Table 11.
Table 11 Yield 10 sec. 10 min.
Point Gel Gel Example #/ 2 #/ 2 #/ 2 No. _ellant Composition 100ft100ft 100ft 1525 EM2HT/sodium benzonate 40 14 18 bentonite 26 BM2HT/p-phenol sulfonic acid 55 28 33 bentonite 27 AM2HT/salicylic acid 43 18 20 bentonite 28 2M2HT/bentonite 60 22 33 29 BM2HT/bentonite 51 24 28 The batches were aged for 16 hours at 300F, cooled to 80F, checked for solids settling. The batches were stirred for 10 minutes and tested as with Example 5 at 90F. The results are shown in Table 12 below.
Table 12 Yield 10 sec. 10 min.
Point Gel Gel Example#/ 2 #/ 2 #/ 2 30No. 100ft 100ft 100ft ~.3L~136~33 It will be obvious to one skilled in the art that the invention may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention and all such modifications are intended to be included within the scope of the following claims.

Claims (23)

1. An oil-base fluid comprising an oil phase and from about 1 to 50 pounds per barrel of said fluid of an organophilic clay gellant comprising the reaction product of an organic cationic compound, an organic anion and a smectite type clay having a cation exchange capacity of at least 75 milliequivalents per 100 grams of said clay such that an organic cation - organic anion complex is intercalated with the smectite-type clay and the cation exchange sites of the smectite-type clay are substituted with the organic cation.

2. An oil-base packer fluid which comprises an oil phase and from about 6 to 50 lbs. per barrel of said fluid of an organophilic clay gellant comprising the reaction product of an organic cationic compound, an organic anion and a smectite-type clay having a cation exchange capacity of at least 75 milliequivalents per 100 grams of said clay such that an organic cation - organic anion complex is intercalated with the smectite-type clay and the cation exchange sites of the smectite-type clay are substituted with the organic cation.

3. In a method of insulating casing in a wellbore which comprises pumping an oil-base packer fluid in an annular space within said wellbore and thereafter gelling said packer fluid, the improvement comprises a packer fluid having an oil phase, and from about 6 to 50 pounds per barrel of said fluid of an organophilic clay gellant compris-ing the reaction product of an organic cationic compound, an organic anion and a smectite-type clay having a cation exchange capacity of at least 75 milliequivalents per 100 grams of said clay such that an organic cation - organic anion complex is intercalated with the smectite-type clay and the cation exchange sites of the smectite-type clay are substituted with the organic cation.

4. The gellant of Claim 1 or 2, wherein the organic cation is selected from the group consisting of:

and wherein X is nitrogen or phosphorus, Y is sulfur; R1 is an alkyl group containing 8 to 60 carbon atoms; and R2, R3 and R4 are selected independently from the group consist-ing of hydrogen, a hydroxyalkyl group having 2 to 6 carbon atoms, alkyl groups containing 1 to 22 carbon atoms, aryl groups, aralkyl groups containing 1 to 22 carbon atoms on the alkyl chain, and mixtures thereof; and smectite-type clay having a cation exchange capacity of at least 75 milliequivalents per 100 grams of said clay, such that an organic cation - organic anion complex is intercalated with the smectite-type clay and the cation exchange sites of the smectite-type clay are substituted with the organic cation.

5. The gellant of Claim 1, wherein R1 is a long chain alkyl group having 12 to 60 carbon atoms.

6. The gellant of Claim 5 wherein R1 has from 12 to 22 carbon atoms.

7. The gellant of Claim 1 or 2, wherein R2 is selected from the group consistinq of a .beta.,.gamma.-unsaturated alkyl group having less than 7 aliphatic carbon atoms, a hydroxyalkyl group having 2 to 6 carbon atoms, an aralkyl group and mixtures thereof.

8. The gellant of Claim 1 or 2, wherein R3 and R4 are individually selected from the group consisting of a .beta.,.gamma.-unsaturated alkyl group having less than 7 aliphatic carbon atoms, a hydroxyalkyl group having 2 to 6 carbon atoms, an aralkyl group, an alkyl group having from 1 to 22 carbon atoms and mixtures thereof.

9. The gellant of Claim 1 or 2 wherein the amount of said organic anion is from 5 to 100 milli-equivalents per 100 g of said clay, 100% active clay basis.

The gellant of Claim 1 or 2 wherein the amount of said organic cation is sufficient to satisfy the cation exchange capacity of the smectite-type clay and the cationic exchange capacity of the organic anion.

11. The gellant of Claim 1 or 2 wherein the smectite-type clay is selected from the group consisting of hectorite, bentonite and mixtures thereof.

12. The gellant of Claim 1 or 2 wherein R2 is selected from a group consisting of a .beta.,.gamma.-unsatu-rated cyclic alkyl group, .beta.,.gamma.-unsaturated acyclic alkyl group having less than 7 carbon atoms, an acyclic .beta.,.gamma.
-unsaturated alkyl group substituted with aromatic groups, an aromatic .beta.,.gamma.-unsaturated group substituted with aliphatic groups, and mixtures thereof.

13. The gellant of Claim 1 or 2 wherein R2 is a hydroxyalkyl group selected from a group consisting of cyclic groups, acyclic groups and mixture thereof, and said hydroxyl substitution is on C2 to C6.

14. The gellant of Claim 6 wherein R1 is a fatty acid group.

15. The gellant of Claim 1 or 2 wherein the amount of said organic cation is from 100 to 130 milli-equivalents per 100 grams of said clay, 100% active clay basis.

16. The fluid of Claim 1 wherein said fluid comprises additionally dispersed aqueous phase comprising from about 2 to about 50% by volume water.

17. The fluid of Claim 16 wherein said fluid comprises additionally a water-in-oil emulsifier.

18. The fluid of Claim 17 wherein said fluid comprises 2 to 30 lbs. per barrel water-in-oil emulsifier.

19. The packer fluid of Claim 2 wherein said fluid comprises additionally dispersed aqueous phase compris-ing from about 2 to about 50% by volume water.

20. The packer fluid of Claim 19 wherein said fluid comprises additionally a water-in-oil emulsifier.

21. The packer fluid of Claim 20 wherein said fluid comprises additionally from about 2 to 30 pounds per barrel water-in-oil emulsifier.

22. The fluid of Claim 1 wherein said fluid is non-aqueous.

23. The fluid of Claim 2 wherein said fluid is non-aqueous.