EMULSIFYING ADDITIVE FOR OIL BASE DRILLING FLUIDS AND METHOD

Abstract: Stabilization of oil continuous phase well fluids, particularly to oil base drilling fluids, against contamination with water-soluble alkaline earth salts such as calcium chloride and lignosulfonate contaminants. Stabilization is accomplished by the addition of a sulfonamide additive which is the product of the reaction of a sulfonic acid chloride and a water soluble amine selected from the group consisting of alkylated amines and dialcohol amines. The additive controls the water wettable solids in an oil based well fluid in the presence of alkaline earth salts and lignosulfonate contaminants for extended periods at temperatures over 700<o>F, keeping such solids in the oil-wet state.

Description: EMULSIFYING ADDITIVE FOR OIL BASE DRILLING FLUIDS AND METHOD BACKGROUND OF THE INVENTION ' The term "oil base drilling fluid" or "oil base mud" is applied to a special type of drilling fluid where oil is the continuous phase and water, if present, is the dis¬ persed phase. Oil base muds commonly contain blown asphalt and usually a small mount of water emulsified into the sys¬ tem with caustic or lime and emulsifying agents. Another type of oil continuous phase muds are the so called "invert emulsion" muds. Invert emulsion muds have a continuous oil phase and contain substantial amounts of water to form a water-oil emulsion. Whereas oil base muds generally con¬ tain lower amounts of water and can be used effectively as drilling fluids even when waterless, invert emulsion muds require the presence of some water as an emulsified or dis¬ persed phase. « It is essential in oil continuous phase drilling fluids whether oil base fluids or inverts, that the dispersed sol¬ ids, i.e. the weighting solids, clays, shale and cuttings, be dispersed in an oil-wet condition and that the aqueous phase be dispersed .as a discontinuous phase in the oil. The dispersed solids are typically water-wettable, and in the presence of oil and water will preferentially exist in the water-wet state. The development of the emulsion and the hydrophobic condition of dispersed solids is accomplished using known emulsifying additives and techniques. In actual field use, however, oil continuous phase drilling fluids* can become contaminated with the water phase of alkaline earth salts. Such contamination tends to adversely affect the stability of the emulsion and the hydrophobic condition of the wet- ting agents. Substantial contamination of oil-continuous phase drilling fluids with water-soluble alkaline earth salts such as calcium chloride results in fluid breakdown, particularly at high temperatures and pressures such as encountered in deep wells. Water soluble alkaline earth salt contamination usual¬ ly results from contamination with calcium salts, in most cases calcium chloride. In this discussion, reference to calcium salt contamination will be understood to encompass stabilization against other alkaline earth salts. On occa¬ sions, calcium salt contamination may be intentionally add- ed to oil base fluids. This sometimes happens with tech¬ niques for controlling swelling of shale in those strata adjacent the borehole. In such cases, the oil continuous drilling fluids are treated with sater-soluble calcium salts to alter the "water activity" of the aqueous phase of the oil base fluid. When such techniques are utilized, it is necessary to stabilize the drilling fluid against fluid breakdown resulting from the addition of water-soluble calcium salts. Prior emulsifying agents used to stabilize oil con- tinuous phase driling fluids from water contamination, lig¬ nosulfonate contamination, and the like, have not proved effective in stabilizing against calcium ion contamination over prolonged time periods. In addition, high temperatures such as those encounted in deep wells aggrevate the problem, resulting in recurrent breakdown of desirable fluid prop¬ erties of fluids contaminated with calcium salts. Prior agents which have proved effective in stabilizing muds from calcium salt contamination at salt concentrations up to about 15% by volume and at temperatures up to about 300°F, have proved ineffective in the presence of calcium salt concen¬ trations of 25% by volume at a temperature of 700°F and higher. SUMMARY OF THE INVENTION The novel emulsifying additive for oil base well drill¬ ing fluids of this invention is especially useful in stabil¬ izing the fluids in the presence of alkaline earth salt con¬ tamination at temperatures as high as 700-800°F and at salt concentrations upwards of 25% by volume. The emulsifying additive is a linear sulfonamide having an oil soluble end and a water soluble end and is the reaction product of an alkyl aryl sulfonyl chloride and a water soluble amine se¬ lected from the group consisting of alkylated amines and dialcohol amines. - The novel additive is used in an oil base fluid suit¬ able for use in oil and gas wells under adverse borehole conditions. The oil base fluid comprises a continuous oil phase containing oil wet weighting material supported in fluid, a discontinuous water phase, and from about 1 to 20 pounds per barrel of fluid of a linear sulfonamide additive having an oil soluble end and a water soluble end, said additive being the reaction product of an alkyl aryl sul¬ fonyl chloride and as water soluble amine selected from the group consisting of alkylated amines and dialcohol amines. In the method of the invention, an oil base drilling fluid containing weighting materials is prepared for use in oil and gas wells under adverse borehole conditions where contamination with water-soluble alkaline earth salts is encountered. The sulfonamide additive is added to the fluid while circulating* through the borehole in an amount sufficient to maintain the emulsion integrity of the fluid. The sulfonamide additive is a linear sulfonamide having an oil soluble end and a water soluble end and is the reaction product of an alkyl aryl sulfonyl chloride and a water sol¬ uble amine selected from the group consisting of alkylated amines and dialcohol amines. Additional objects, features, and advantages of the invention will become apparent in the following description. DETAILED DESCRIPTION OF THE INVENTION The novel emulsifying additive of the present inven¬ tion is a linear sulfonamide having an oil-soluble end and a water-soluble end. The sulfonamide of this inven¬ tion is made by reacting an alkyl aryl sulfonyl chloride with a water soluble amine selected from the group con¬ sisting of alkylated amines and dialcohol amines. Aromatic sulfonic acids are commonly prepared by di¬ rect sulfonation, usually by fuming sulfuric acid. If the acid chloride is desired, the -SO-Cl group can be intro- duced by treatment of the aromatic compound with chloro- sulfonic acid, CISO^H: ArH + 2 C1S0 3-H > ArS02Cl + HC1 + H2_S04. In this invention, an alkylbenzene s reacted with chlorosulfonic acid to produce an alkyl aryl sulfonyl chloride. Suitable alkylbenzene starting materials in¬ clude those having a pendant alkyl group with from about 6 to 28 carbon atoms, preferably from about 9 to 18 car- bon atoms. The preferred alkylbenzene has a molecular weight and structure of the order of magnitude of dodecyl benzene. In the next step in preparing the emulsifying additive of the invention, the alkyl aryl sulfonyl chloride is re- acted with a primary, secondary, or tertiary water soluble amine selected from the group consisting of alkylated a- mines and dialcohol amines to produce a linear sulfona¬ mide. Suitable dialcohol amine constituents include di- ethanolamine, diisopropanol amine, and diethylethanolamine. Water soluble alkylated amines such as diethylamine can also be used. Preferably, a dialcoholamine is reacted with the alkyl aryl suifonyl chloride. The preferred amine reactant is diethanolamine which can be used in the commercial form. In such state, the diethanolamine can contain small or minor proportions of other alkanolamines. These other alkanolamines are pre- ferably present, if at all, in amounts less than about 10 percent by weight of the diethanolamine. In preparing the additive of this invention, it is preferred to react about 0.5 moles of alkylbenzene with 1.5 moles of chlorosulfonic acid. VThen diethanolamine is utilized as the amine constituent, the preferred amount of diethanolamine is about 1.0 mole for every 0.5 moles of sulfonyl chloride. In order to vary the water solubility of the result¬ ing sulfonamide additive, 1 to 6 moles of normal ethylene oxide can be added. The novel emulsifying additive of this invention is added to an oil base drilling fluid in amounts sufficient to maintain fluid integrity and to stabilize the system against loss of properties due to contamination with water- soluble alkaline earth salts. Pretreatment of an oil base drilling fluid can be desirably accomplished by addition of the additive of this invention in amounts corresponding to from about 1 to 20 pounds per barrel of driling fluid. The amount of additive used depends in part upon the con- centration of water in the discontinuous water phase, e.g., at a water content of 5% by volume about 1 pound per barrel of additive is sufficient while about 10 pounds per barrel of additive are needed with concentrations of 25% by. vol¬ ume water. Of course, greater amounts can be provided in the drilling fluid even as a pretreatment when the particu¬ lar oil base drilling fluid being treated is contemplated for use under conditions of severe calcium contamination or high temperature. After pretreatment, it is often necessary to continue the addition of additive during circulation of the fluid in the borehole as additional calcium salts are encountered. or as the temperature and pressure to which the fluid is subjected in the presence of calcium salts continues over long periods of time or increases as the borehole becomes deeper. Post- reatment can be effected by adding addi- 5 tional additive, usually in amounts in the range of about 1 to 10 pounds per barrel. It should be understood, how¬ ever, that amounts as large as 25 pounds per barrel can be employed, especially when post treating a severely con¬ taminated fluid containing none of the pre-treatment addi- 10 tive. The present inventive additive is intended to be used along with other conventional additives employed with oil base fluids to control water, brine, lignosulfonate mud, and alkaline earth salt contamination. Such known addi- 15 tives include alkyl aryl sulfonates, long chain fatty acids, and other anionic, cationic, nonionic, or ampho- teric surface-active agents which might be desirably em¬ ployed in oil base drilling fluids in accordance with procedures known in the prior art. -*-* *0 In order to better illustrate the invention, the following specific examples are given, but it is to be understood that the invention is not to be limited to the specific details thereof: 25 I. Preparation of P-N-DOPECYLBENZOL-SULFONIC-ACID- ,N-B1S [2-HYDROXYETHYL3-AMIDE A linear sulfonamide of the type used to stabilize oil base muds against water soluble alkaline earth salt contamination 30 is prepared in the following manner. Approximately 100 milliliters (ML) (1.5 ol) chlorosulfonic acid is placed in a 500 ML three-necked flask with a mixer, backflow cooler and drip funnel. The flask is also equipped with a calcium chloride drying tube, a thermometer, and a discharge hose. 35 The chlorosulfonic acid is then cooled to approximately 2°C by means of an ice bath. Next, 140 ML (0.5 mol) of dodecylbenzene is placed in the drip funnel and allowed to drip into the chlorosϋlfonic -Pl¬ acid at such a rate that the internal temperature does not exceed about 10°C. The * mixture in the reaction vessel is stirred constantly during the addition of the docecylben- zene. The dripping time for the dodecylbenzene is approxi- mately 45 minutes during which time HCL gas escapes from the mixture. It is necessary that the mixture be stirred at a constant rate to prevent the formation of foam. After the alkylbenzene has been added, the ice-bath is removed and the reaction mixture is then left at room temperature for one hour. After standing for one hour, the reaction mixture is poured on crushed ice and the resulting watery suspension is placed in a 1-liter separa¬ tion funnel. The watery phase is separated from the re¬ maining organic emulsion and extracted with 100 ml of car- bonetrachloride and the obtained extract is diluted further with 100 ml of carbontetrachloride. The organic phase is now extracted with this mixture to form an emulsion. To separate this emulsion, 100 ml of methanol are added to the mixture in the separatory funnel. At this stage, work should proceed expeditrously due to the possible formation of an ester. The resultant carbon tetrachloride phase is now washed with 100 ml of sodium bicarbonate saturate and then with another 100 ml of methanol. In order to insure that the internal temperature of the re- sultant mixture does not exceed about 150°C, the carbon- tetrachloride is removed -under reduced pressure. The pro- * duct -which is obtained -is the alkyl aryl sulfonyl chloride, . in this case, dodecylbenzolsμlfonyl chloride. The dodecylbenzolsulfonyl chloride is next placed in a dripping funnel which is located over a 500 ml beaker equipped with a stirring device. Approximately 100 ml (1.0 mol) of diethanolamine and 100 ml of chloroform (not carbon tetrachloride)are placed in the beaker. Then 140 ml (0.5 mol) of the alkyl aryl sulfonyl chloride are drip- ped ' into the reaction mixture at such a rate that the tem¬ perature remains constant within the range of about 60-65°C. After this, the mixture is left at room temperature for about 30 minutes and is then extracted twice with 100 ml . ... -a- portions of methanol. The solvent of the combined meth¬ anol extracts is removed as in the previous step by means of reduced pressure and the internal temperature is in¬ creased briefly to 150°C while the vacuum is being held constant. The product contains approximately 120 to 130 ml of a viscous brown liquid which is identified as P-N-DODECYL BENZOL-SULFONIC ACID-N,N-BlS (2 HYDROXYETHYL)- AMIDE. The following examples are illustrative: II. EXAMPLES Drilling mud samples used in the following examples were prepared by admixing 100 grams of an asphalt cutback, consisting of 60 grams of blown asphalt and 40 grams of diesel oil, with 11 grams of lime, 1 gram of napthenic acid and 3.5 grams of stearic acid. Five percent by vol¬ ume of water was then blended with the mixture, and diesel oil in an amount of about 240 mi, was added to form one standard laboratory barrel of unweighted oil base drill- ing fluid. Drilling fluid weighted to the desired density in pounds per gallon is prepared from the standard unweighted fluid by adding barite and blending the mixture. Typical¬ ly, some additional diesel oil is required to be added with the barite. For example, to prepare an 18 pound per gallon (ppg) mud, 85 parts of unweighted mud as above are admixed with 15 parts diesel oil prior to barite a ' ddition. SAMPLES 1-2 To test the efficiency of the novel additive of the invention in stabilizing oil base drilling fluids against calcium salt contamination, a series of samples were pre¬ pared as above and weighted to 16 ppg with barites. The first sample was treated with 2 1/2 pounds per barrel of an emulsifying system described in U.S. Patent No. 3,642,623 to Bennett et al, entitled "Oil Base Well Drilling Fluid Composition and Method" issued February 15, 1972, sold un¬ der the trade name "Additive SA-81" by OBI-Hughes Inc. oj Houston, Texas. The additive is a two component system, one component of which is a water-insoluble akyl phenol, and one component of which is a water-soluble condensation product of a mononuclear aromatic polycarboxylic acid and a fatty acid lower-alkanolamide, described in U.S. Patent No. 3,575,883, entitled "Surfactant Compositions; issued April 20, 1971 to Foley. The second sample was treated with 2 1/2 pounds per barrel of the linear sulfonamide additive of this inven- tion. Each sample was agitated at room temperature. Test¬ ing was then carried out to determine apparent viscosity (Va) , plastic viscosity (Vp) , yield point (YP) and 10 second - 10 minute gel strength on a Fann Meter ( odel 35) at 150°F and 175°F. The samples .were then hot-rolled for 16 hours at 550°F and tested. Electrical stability (ES) indicates the breakdown voltage of the emulsion and hence is a measure of strength of the emulsion. A stability of over at least about 400 volts is considered satisfactory. The results are shown in Table I. Before Hot Rolling After Hot Rolling Table I Sample No. Sample No. 1 2 1 2 Sulfon- Sulfon- dditive SA-81 amide SA-81 amide Fann, 150°F: Va, cps 74.5 90 Vp, cps 67.0 84 41 36 YP, p.c.s.f.— 15 12 11 12 10"-lO'gel,p.c.s.f. 3-5 3-5 ' 5-5 4-5 ES (volts) 1200 1380- 1600 1800 Fann, 175°F: Va, cps 50 49 Vp, cps 42 48 29 30 YP, p.c.s.f.— 16 1 6 6 10 w -10'gel.p.c.s.f. 3-3 3-3 3-3 4-5 The tests show that in non-contaminated muds the linear sul¬ fonamide additive of the invention gives improved electrical stability both before and after hot rolling, indicating improved stability of the emulsion. -ια- SAMPLES 3-4 An oil base drilling mud sample prepared as above and weighted to 16 ppg was then contaminated with 35 ml (10% by volume) of a 12.1 ppg calcium chloride brine. Sample 3 was treated with 2 1/2 ppb of SA-81 and Sample 4 was treat¬ ed with 2 1/2 ppb of linear sulfonamide. The contaminated, mud was again tested at 150°F and 175°F both before and after hot rolling at 550°F for 16 hours. The results are given in Table II. Before Hot Rolling After Hot Rolling Table II Sample No. Sample No. 3 4 3 4 Sulfon¬ Sulfon¬ Additive SA-81 amide SA-81 amide Fann, 150°F: 96.5 81 79 64 v Pr Cps — 84.0 64 57 53 YP, p.c.s, .f.— 2-5 34 26 . 22 10"-10'gel,p.c. .s.f. 7-10 12-22 13-15 13-14 ES (volts) - 1540 +2000 1040 1060 Fann, 175°F: 65 48.5 49 51 42.0 44 YP, p.c.s. .f.~ 28 17.0 10 IC'-lO'gel.p.c.s.f. 10-38 6-9 7-8 The tests show improved electrical stability with linear sulfonamide treated muds. The lower yield point after hot rolling of the sulfonamide treated mud indicates improved emulsifying characteristics. SAMPLES 5-6 An oil base drilling mud sample prepared as above and weighted to 16 ppg was then contaminated with 35 ml (10% by volume) of an 18 ppg chrome lignosulfonate mud. Sample 5 was treated with 2 1/2 ppb of SA-81 and Sample 6 was treated with 2 1/2 ppb of the linear sulfonamide. Tests were then run at 150°F and 175°F before and after hot rolling at 550°F for 16 hours. The test results are given in Table III. Before Hot Rolling After Hot Rolling Table III Sample No. Sample No. 5 6 5 6 ' Sulfon¬ Sulfon¬ Additive SA-81 amide SA-81 amide Fann, 150°F: Va, cps 86.5 96.0 66 55.5 Vp, cps 77.0 87.0 59 49.0 YP, p.c.s.f.— 19 18.0 14 13.0 10"-10'gel,p.c.s.f. 5-7 2-5 4-6 7-7 ES (volts) +2000 700 2000 480 Fann, 175°F: Va, cps 58.5 62.5 48.5 43 Vp, cps 54.0 56.0 45.0 38 YP, p.c.s.f.— 9.0 13.0 • 7.0 10 10"riθ*gel.p.c.s.f. 3-6 • 3-3 3-3 7-8 Tests results show the favorable effects of the linear sul¬ fonamide on muds contaminated with lignosulfonates. The electrical stability, while lower than that for the mud treated with SA-81, is within acceptable ranges. Both samples were soft and uniform before and after hot rolling. SAMPLES 7-8 An oil base drilling mud sample was prepared as before and weighted to 18 ppg. Sample 7 was treated with 2 1/2 ppb SA-81 and sample 8 was treated with 2 1/2 ppb of linear sulfonamide. The results are shown in Table IV. Before Hot Rolling After ' Hot Rolling Table IV Sample No. Sample No. 7 8 7 8 Sulfon- . Sulfon- Additive— —- SA-81 amide SA-81 amide Fann, 150°F: s Va, cps 94.5 108 Vp, cps 85 100 54 53 YP, p.c.s.f.— 19 16 10 6 10"-10 , gel,p.c.s.f. 4-6 5-5 4-8 5-8 ES (volts) +2000 +2000 1500 +2000 Fann, 175°F: Va, cps 61.6 58 VD, cps 56 56 39 38 YP, p.c.s.f.— 11 4 1 10"-10'gel.p.c.s.f. 4-6 2-3 3-4 4-7 The linear sulfonamide shows improved electrical stability after hot rolling .at 550°F for 16 hours. - SAMPLES 9-10 An oil base mud was next prepared and weighted to 18 ppg. The mud was then contaminated with 35 ml (10% by vol¬ ume) of a 12.1 ppg calcium chloride brine. Sample 9 was treated with 2 1/2 ppb of SA-81 and Sample 10 was treated with 2 1/2 ppb of the sulfonamide additive of the inven¬ tion. Tests were carried out as before and the results reported in Table V. Before Hot Rolling After Hot Rolling Table V Sample No. Sample No. 10 10 Sulfon¬ Sulfon¬ Additive SA-81 amide SA-81 amide Fann, 150°F: Va, cps 122.5 91.5 84 Vp, cps 99 79 76 YP, p.c.s.f.— 47 25 16 10"-10 , gel,p.c.s.f. 13-20 0-12 10-10 ES (volts) 1400 +2000 800 810 Fann, 175°F: Va, cps 78.5 81.5 54.5 72 Vp, cps 64.0 65.0 51.0 71 YP, p.c.s.f.— 29 33.0 7.0 2 10"-10'gel.p.c.s.f. 8-16 11-31 5-6 4-5 The results again show " improved electrical stability with the sulfonamide additive. The sulfonamide treated mud has de¬ sirable gel and yield point characteristics before and after hot rolling. -lϋ- SAMPLES.11-12 An oil base mud was prepared and weighted to 18 ppg. The mud was then contaminated with 35 ml (10% by volume) of an 18 ppg chrome lignosulfonate mud. Sample 11 was treated with 2 1/2 ppb of SA-81 and sample 12 was treated with 2 1/2 ppb of the linear sulfonamide. The results are given in Table VI. Before Hot Rolling After Hot Rolling Table VI Sample No. Sample No. 11 12 11 12 Sulfon¬ Sulfon¬ Additive SA-81 amide SA-81 amide Fann, 150°F: Va, cps 123.5 130.5 79 • 72 Vp, cps 113 120 74 64 YP, p.c.s.f.— 21 21 10 16 10"-10'gel,p.c.s.f. 5-8 4-6 3-8 8-10 ES (volts) 880 1220 660 640 Fann, 175°F: Va, cps 77.5 76 56.5 53 Vp, cps 71.0 70 53.0 50 YP, p.c.s.f.— 13.0 12 7.0 6 10"-10'gel.p.c.s.f. 5-7 4-6 3-7 7-7 The sulfonamide additive .gives acceptable results in the presence of chrome lignosulfonate contamination. Both samples were soft and uniform before and after hot rolling, SAMPLES 13-14 An oil base mud was prepared and weighted to 18 ppg. The mud was contaminated with 88 ml (25% by volume) of an 18 ppg chrome lignosulfonate mud. Sample 13 was treated with 2 1/2 ppb of SA-81 and sample 14 was treated with 2 1/2 ppb of the linear sulfonamide. The results are shown in Table VII. Before Hot Rolling After Hot Rolling Table VII Sample No. Sample No. 13 14- 13 14 Sulfon- Sulfon¬ Additive SA-81 amide SA-81 amide Fann, 150°F: Va, cps 147 210 92 110 Vp, cps 120 177 84 103 YP, p.c.s.f.— 36 66 16 14 10"-10'gel,p.c.s.f. 6-8 12-21 3-5 6-8 ES (volts) 420 400 100 280 Fann, 175°F: Va, cps 104 107 72.5 78 Vp, cps 88 90 66 70 YP, p.c.s.f.— 32 33 13 16 10"-10'gel.p.c.s.f. 5-8 8-7 3-5 δ-6 At a 25% by volume concentration of. chrome lignosulfonates, the mud treated with SA-81 had noticable settling after hot rolling. The mud treated with the sulfonamide was soft and uniform. -36- SAMPLES 15-16 An oil base mud was prepared and weighted to 18 ppg. The mud was contaminated with 88 ml (25% by volume) of a 12.1 ppg calcium chloride brine. Sample 15 was treated with 2 1/2 ppb of SA-81 and Sample 16 was treated with 2 1/2 ppb of the linear sulfonamide. The results of the tests are in Table VIII. Before Hot Rolling After Hot Rolling Table VIII Sample No. Sample No. 15 16 15 16 Sulfon¬ Sulfon¬ Additive SA-81 amide SA-81 amide Fann, 150°F: Va, cps 175 155 Vp, cps 139 114 YP, p.c.s.f.— 72 82 10"-10'gel,p.c.s.f. 8-13 11-15 ES (volts) 640 800 380 360 Fann, 175°F: Va, cps 116 93.5 126 102.5 Vp, cps 91 81.0 90.0 90 YP, p.c.s.f.— 50 25 73.0 28 lO-'-lO'gel.p.c.s.f. " 7-9 8-8 10-13 5-6 The tests results show that at 25% by volume concentration of calcium chloride brine, the linear sulfonamide treated mud improved electrical stability prior to hot rolling. The- sul--- fonamide treated mud shows improved yield point and gel properties over the mud treated with a conventional addi- tive after hot rolling at 550°F for 16 hours. - J 7 - SAMPLES 17- j 8 An oil base mud was prepared and weighted to 18 ppg. The mud was contaminated with 88 ml (25% by volume) of a Zechstein brine of the type encounted in Europe and the North Sea. The composition of Zechstein brine is approxi¬ mately 60% MgCl-, 12% KC1, 10-12% MgSO., and the remainder NaCl. Sample 17 was treated with 2 1/2 ppb of SA-81 and Sample 18 was treated with 2 1/2 ppb of sulfonamide. The results are in Table IX. Before Hot Rolling After Hot Rolling Table IX Sample No. Sample No. 17 18 17 18 Sulfon¬ Sulfon¬ Additive SA-81 amide SA-81 amide Fann, 175°F: Va, cps 92 103.5 HARD 115 Vp, cps 73 85.0 HARD 100 YP, p.c.s.f.— 38 37.0 HARD 30 10"-10'gel.p.c.s.f. 9-13 11-15 HARD 9-2 ES (volts) 540 220 520 The mud treated with a conventional additive became hard and dry after hot rolling at 550°F for 16 hours. The mud treat¬ ed with the linear sulfonamide was workable before and after hot rolling. Further tests have shown that SA-81 breaks up after hot rolling at 550°F for 32 hours. The linear sulfonamide has - not shown a change after 100 hours at 500-800°F. High tem¬ perature, high pressure fluid loss tests conducted at 350°F and 500 psi pressure after hot rolling at 550°F for 16 hours gave consistent readings of less than 1 ml. An invention has been provided with significant ad¬ vantages. The novel oil base drilling fluid of this in¬ vention maintains emulsion integrity, a dispersed oil-wet solids condition, and proper viscosity and gel strength under adverse borehole conditions. The novel oil-continuous phase additive of the invention results in a fluid which prevents fluid breakdown at high temperatures encounted in deep wells and in the presence of contaminants. In par¬ ticular, the present fluid remains stable in the presence of water-soluble alkaline earth salts and chrome lignosul¬ fonates in a concentration of about 25% by.volume and at temperatures in the " range of 700-800°F, and even higher. OMPI

Claims: WE CLAIM: 1. An emulsifying additive for oil base well drilling fluids especially useful in stabilizing said fluids in the presence of water-soluble alkaline earth salts, com¬ prising: a linear sulfonamide having an oil soluble end and a water-soluble end, said sulfonamide comprising the re¬ action product of an alkyl aryl sulfonyl chloride and a water soluble amine selected from the group consisting of alkylated amines and dialcohol amines. 2. The emulsifying additive of Claim 1, wherein said alkyl aryl sulfonyl chloride is a compound having ' the formula: 0 1 where R' is alkyl having 6 to 28. carbon atoms 3. The emulsifying additive of claim 2, wherein said R' has 12 to 18 carbon atoms. 4. The emulsifying additive of claim 1, wherein said alkyl aryl sulfonyl chloride is dodecylbenzolsulfonyl chloride. OMPI 5. The emulsifying additive of claim 1, wherein said alkylated amine is diethyla ine. 6. The emulsifying additive of claim 1, wherein said dialcohol amine is diethanolamine. The emulsifying additive of claim 1, wherein 0.5 mole of alkyl aryl sulfonyl chloride is reacted with 1.0 mole of water soluble amine. OMPI 8. The emulsifying additive of claim 1, wherein said additive is P-N-DODECYLBENZOL-SULFONIC-ACID-N,N-BIS [2-HY- DROXYETHYL] -AMIDE. 9. An oil base fluid suitable for use in oil and gas wells under borehole conditions wherein contamination is encountered, which comprises a continuous oil phase con¬ taining oil-wet weight material supported in said fluid, a discontinuous water phase, and a stablizing additive comprising; a linear sulfonamide having an oil soluble end and a water soluble end, said sulfonamide comprising the reaction product of an alkyl aryl sulfonyl chloride and a water sol- uble amine selected from the group consisting of alkylated amines and dialcohol amines. 10. The oil base fluid of claim 9, wherein said alkyl aryl sulfonyl chloride is a compound of the formula: 0 / \ R' r Cl 1 0 where R' is alkyl having 6 to 28 carbon atoms, 11. The oil base fluid of claim 10, wherein said R' has 12 to 18 carbon atoms. 12. The oil base fluid of claim 9, wherein said alkyl aryl sulfonyl chloride is dodecylbenzolsulfonyl chloride. 13. The oil base fluid of claim 9, wherein said alkylated amine is diethylamine. 14. The oil base fluid of claim 9, wherein said dialcohol amine is diethanolamine. 15. The oil base fluid of claim 9 , wherein said additive is present in the range of 1 to 10 pounds of additive per barrel of drilling fluid . 16. A method of treating an oil base fluid containing weighting materials for use in oil and gas wells under borehole conditions where contamination with a water soluble calcium salt is encountered which comprises ad¬ ding to said fluid an amount sufficient to maintain the emulsion integrity of said fluid of an additive which comprises the reaction product of an alkyl aryl sulfonyl chloride and a water soluble amine selected from the group consisting of alkylated amines and dialcohol amines. 17. The method of claim 16 , wherein said additive is added in the. range of 1 to- 10 pounds of additive per barrel of oil base fluid . OMPI 18. The method of claim 16, wherein said alkvl aryl sul¬ fonyl chloride is dodecylbenzolsulfonyl chloride and said water soluble amine is diethanolamine. OMPI

Inventors: BARTHEL HORST K F, SCOGGINS CHRYS
Applicants: BARTHEL HORST K F, OBI HUGHES INC, SCOGGINS CHRYS
Application year: 1981
Main classification: C07C143
IPC codes: B01F17