CA1275345C

CA1275345C - Clay stabilizing agent preparation and use

Info

Publication number: CA1275345C
Application number: CA000539301A
Authority: CA
Inventors: Paul S. Brown, Jr.; Keith H. Hollenbeak
Original assignee: Halliburton Co
Current assignee: Halliburton Co
Priority date: 1986-06-25
Filing date: 1987-06-10
Publication date: 1990-10-16
Anticipated expiration: 2007-10-16
Also published as: US4693639A; NO872585D0; NO872585L; EP0251558A3; EP0251558A2

Abstract

Abstract of the Disclosure Methods of preparing and using a clay stabilizing agent are provided. The agent is prepared by polymerizing dial lyldimethylammonium chloride with sulfur dioxide in the pre-sence of a polymerization reaction rate retarder to form a solid cationic copolymer having a high sulfur content. When dissolved in an aqueous carrier fluid, the copolymer is par-ticularly effective in preventing clay swelling and/or fines migration.

Description

~ !~ r~ r rd CLAY STABILIZING AGENT PRE:I?ARATION AND USE
Background of the Invention 1. Field o the Invention The present invention relates generally to clay stabi-lizing agents useful in subterranean formation treating, and more particularly, to the preparation and use of a water 5 soluble clay stabilizing agent.

2. Descrlptlon of the Prior Art The production of hydrocarbons from subterranean forma-tions is often troubled by the presence of clays and other finesl which can migrate with produced fluids and plug off 10 or restrict the flow of such fluidsO The migration of fines in a subterranean formation is generally the result of clay swelling and/or the disturbance of normally quiescent fines by the introduction of water foreign to the formation there- -; in. Typically~ the foreign water is introduced into the 15 formation in completing and/or txeating the formation to stimulate production of hydrocarbons therefrom such as frac-turing, acidizing and other treatments utilizing aqueous fluids.
A variety of clay stabilizing agent~ have been developed 20 and used heretofore to control ~he ill affects of water on clay and/or other fines in subterranean ormations contain-ing hydrocarbons. For example, inorganic polycationic poly-mers or complexes have been utilized as clay stabilizing agents. Ions contained in the clay are replaced by th~
25 inorganic polycationic polymers or complexes thereby trans-forming the clays into relati~ely non-swelling forms. Such - ~ , ' ' a ;~

irlorganic polycationic polymers or complexes have been suc-cessful in controlling swelling clays, but have various limitations. For example, two commonly used inorganic poly-cationic polymers are zirconyl chloride (ZrOCl~) and alumi-5 num hydroxychloride (Al(OH)xCly). Aluminum hydroxychloriderequires a cure time after it is placed in the presence of the clay. Also, aluminum hydroxychloride can tolerate only a limitPd amount of carbonate material in the formation and is removed by contact with acids such as when a subsequent 10 acid treatment of the formation i5 necessary. Zirconyl chloride is limited in the pH range of the placement fluid and can also be removed by acid under certain conditions.
organic polycationic polymers have also been utilized or stabiliæing clays or migrating fines or combinations 15 thereof. For example~ United States Patents Nos. 4,366,071;
4,366~072; 4,366,073; 4,366,074; 4,374,739; 4,460,483; and 4,462,718, all assigned to the assignee of this present invention, disclose the use of organic polycationic polymers as clay stabilizing agents. U.S. Patent Nos. 4,497,596 and 20 4,536,305, also assigned to the assignee of this invention, disclose water soluble organic polycationic polymers con-; taining two or three quaternary ammonium moieties in the monomer repeat units.
Organic cationic polymers have achieved great success as 25 clay stabili~ing agents in that they are effective when dis-solved in aqueous treating fluids in small concentrations, they resist removal by most subsequent acid and other treat-;.
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ments and result in long life stabilization of formation clays and fines. However, all of the heretoEore used ~rga-nic cationic polymers are hygroscopic and are available for use only as dilute aqueous solutions. Thus, there is a need 5 for a highly e~fective clay stabilizing agent which can be prepared and used as a concentrated aqueous solution or a non-hygroscopic solid which can be readily dissolved in aqueous fluids.
By the present invention, methods of preparing a concen-10 trated aqueous solution of a highly effective clay stabi-lizing agent or such agent in a solid non-hygroscopic form are provided as well as methods of using such agent for reducing clay swelling and fines migration in subterranean formations.

Summary of the Invention A method of preparing a water soluble clay stabilizing agent comprising polymerizing diallyldimethylammoni~m chlo~
ride with sulfur dioxide in the presence of a polymerization reaction rate retarder is provided. The resulting copolymer has a high sulfur content, i.e~, a nitrogen-to-sulfur mole 20 ratio of about 1 and is a highly effective clay stabilizing agent. A method of reducing clay swelling and fines migra-tion in a clay containing subterranean formation using the copolymer clay stabilizing agent is also provided~
The cationic copolymers prepared and used in accordance 25 with this invention are very effective in treating swelling 4~

clays such as clays in the smectic group including clay rninerals such as montmorillonite, beidellite~ nontromite, saponite, hectorite and sauconite, and fines such as silica and iron minerals, e~g., hematite, magnetite, lepidocrocite, 5 wuestite, akaganeite and siderite. Also, alkaline earth metal carbonates such as calcite and dolomite are effective-ly treated. The cationic copolymer clay stabiliziny agent of this invention is effective when added to aqueous treat-ing fluids in small concentrations, is essentially permanent 10 and is very resistant to being removed by brines, oils and acids. Permeable structures 9 such as subterranean forma-tions, exhibit high permeabili~y retention after being treated with the cationic copolymer stabilizing agent of this invention and no well shut in time is required after 15 treatment.

Detailed Description of the Preferred Embodiment The present invention involves the preparation and use of a water soluble clay stabilizing agent comprised of a copolymer of diallyldimethylammonium chloride and sulfur 20 dioxide to prevent or reduce clay swelling and fines migra-tion in permeable subterranean formations. The method of use is carried out by contacting swellable clays and migra-table fine~ or combinations thereof with an effective amount of the aforesaid copolymer having a molecular weight in the 25 range of from about 1000 to about 100,000, and preferably from about 3000 to about 20lO00l having a nitrogen-to-sulfur mole ratio o about 1 f and having the structural formula:

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N ~ Cl-_ CH3 CH3 _ n The water soluble copolymer clay stabilizing agent is prepared by polymexizing diallyldimethylammonium chloride with sulfur dioxide. ~he polymerization reaction is carried out in an aqueous solution containing a polymerization reac-tion xate retarder whereby the resulting copolymer has a 10 high sulfur content, i.e., a nitrogen-to~sulfur mole ratio in the range of from about 1.0 to about 1.4, preferably about 1~ -Particularly suitable polymerization reaction retarders are erythorbic acid salts such as sodium erythorbate and 15 sodium ascorbate. Of ~hese, sodium erythorbate is the most pre~erred. Other polymeri~ation reaction retarders which can be utilized are erythorbic acid and ascorbic acid.
In carrying out the polymerization reaction, an aqueous solution of diallyldimethylammonium chloride, the polymeriza-20 tion reaction rate retarder used and an initiator such asammoniurn peroxydisulate is first prepared The solution is then contacted with sulfur dioxide gas under controlled tem-perature conditions whereby the polymeri2ation reaction takes place. Prefexably, the cationic copolymer product is 25 precipitated and then dried in a vacuum oven ~o produce a solid product. It is to be understood, however, that the concentrated li~uid reaction product can be utilized direct-7~

ly as a liquid additive to a treatment fluid.
The solid copolymer product is a white powder which isnon-hygroscopic and can be stored and transported in bags or other convenient containers. The copolymer has a high sul-5 fur content, i.e., a nitrogen~to sulfur mole ratio in therange of from about 1.0 to about 1.4, and is an excellent clay stabilizing agent as shown by the examples which fol-low. The most preferred clay stabilizing agent of this invention has a nitrogen-to-sulfur mole ratio of about 1.
In using the cationic copolymer clay stabilizing agent of the present invention for preventing or reducing clay swelling and fines migration in a clay containing subterra-; nean formation, the formation and the clays and fines there-in are contacted with the agent in any suitable mannerO The 15 cationic copolymer agent attaches to clay surfaces in the formation and converts the clays into relatively non-swelling forms thereby preventing or reducing swelling and fines migration.
In a preferred m thod of using the water soluble clay 20 stabili~ing agent of the present invention, the agent is dissolved in an aqueous carrier fluid in an effective amount, and the fluid is then introduced into the formation.
The particular amount of the agent required to be effective will vary according to, for example, the size and porosity 25 of the particular formation and the types of fines present ; therein. ~owever, the agent is generally dissolved in the caxrier fluid in a concentration within the range of from .

about 0.1~ to about 2.0~ by weight of the carrier fluid.
While lower or high~r concentrations can be used, they are generally not practical. The preferred concentration of the clay stabilizing agent in an aqueous carrier fluid is in the 5 range of from ab~ut 0.15% to about 0.5% and most preferably of from about 0.17~ to about 0~35% by weight of the carrier fluid.
Examples of suitable carrier fluids which can be uti-lized include water, brine, a~ueous mixtures oE low molecu-10 lar weight alcohols, ketones and monoethers of glycol. Theaqueous carrier fluid can contain other ingredients which do not substantially interfere with the dissolution of the sta-bilizing agent in the carrier fluid. Furthermore, the carrier fluid can be gelled or thickened for certain appli-15 cations using gelling agents such as natural gums~ cellulosederivatives and polymersO Other ingredients include salts, mineral acid~ such as hydrochloric acid or hydrofluoric acid or mixtures thereof, low molecular weight organic acids, cationic or nonionic surfactants, and wetting agents.
A particularly suitable aqueous carrier fluid is a saline solution containing about 0 1 to about 40.0 percent by weight salt. The preferred salt concentration is about 2 to about 12 perc~nt by weight of the solution. The salt can be an alkali meta~ salt, an alkaline earth metal salt, an 25 ammonium salt or mixtures thereof. Suitable anions include halides, fluorides, sulfa~es, carbonates, hydroxides, or mixtures thereof. Aqueous acids having a concentration in " ' ' ~,7~

the range of from about 0.1 to about 40.0 percent by weight of the solution can also be utilized as carrier fluids.
Examples of sui table acids include hydrochloric acid, hydro-fluoric acid, phosphoric acid, acetic acid, formic acid, 5 citric acid, and mixtures thereof. Preferred acid carrier fluids include from about 3% to about 15% by weight of hydrochloric acid and a mixture of about 3% by weight of hydrofluoric acid and about 12~ by weight hydrochloric acid.
When the carrier fluid is a saline aqueous treating 10 fluid containing a gelling agent, the solid cationic copo-lymer clay stabilizing agent is preferably dissolved therein in an amount in the range of from about 0.2% to about 0.3%
by weight of the fluid. When the aqueous treating fluid contains an acid, the clay stabilizing agent is preferably 15 dissolved therein in an amount in the range of from about 0.2% to about 0.4~ by weight of the fluid.
The method of the present invention can be used in a number of subterranean formation ~reating operations. For example, the method can be used in conjunction with well 20 completion procedures, sand consolidation procedures, gravel packing procedures, secondary recovery operations, and aci-dizing, ~racturing and other similar operations. In these oper~tions, the stabilizing agent is used to prevent or reduce th~ swelling of clays and/or migration of fines or 25 combinations thereof, This in turn results iD a greater permeability ;n the subterranean formations involved.
The use of the clay stabilizing agent of ~he present :

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invention, i.e., the cationic copolymer of diallyldimethyl-~mmonium chloride and sul~r dioxide having a high sulfur content, preferably a nitrogen-to-sulfur mole ratio of about - 1, is particuarly advantageous in carrying out treatments in 5 subterranean formations. Because the agent is a non-hygro scopic solid, it can be transported to the well site and stored in bags or other convenient containers until used.
When used, the solid agent is readily dissolvable in aqueous carrier or treating fluids using conventional equ:ipment.
In order to furthex illustrate the invention and facili-tate a clear understanding thereof, the following examplesare given.

Example 1 A solid clay stabiliziny agent of the present invention is prepared as follows. A 250 milliliter graduated cylinder ]-5 containing a magnetic stirring bar, a thermometer, and a gas dispersion tube connected to a nitrogen source is placed in an ice-water bath. To the cylinder are added 150 grams of a 64~ by weight aqueous solution of diallyldimethylammonium chloride, 0.15 gram of sodium ery~horbate retarder, and 0.60 20 gram o~ ammonium peroxydisulfate initiator. The mixture is stirred and sparged with nitrogen while the temperature is lowered to about 10C. The gas tube is disconnected from the nitrogen source and reconnected to a sulfur dioxide source and the liquid volume ln the cylinder is noted. Sul-25 fur dioxide gas is passed into the cylinder very slowly so . .

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that at no time does the temperature exceed 25C. When theliquid volume has increased by 30 milliliters, gas introduc-tion is stopped. The reaction mixture is transferred to a jacketed beaker containing a magnetic stirxing bar and a 5 thermistor which is connected to a temperature controller.
The temperature controller functions to regulate a solenoid valve controlling the circulation of chilled water through the jacket of the beaker whenever the reaction te~perature reaches 40C. With this arrangement, a reaction temperature 10 variation of 2C is maintained during the exothermic stage.
The reaction mixture is warmed and at about 25C, the poly-merization reaction exotherm commences and continues for several hours as the viscosity of the reaction mixture increases. After the e~otherm has subsided, the chilled 15 water is replaced with tap water and the reaction is allowed to continue for about 12 additional hours. The product is then precipitated by pouring the reaction mixture into a blender containing a 1:1 methanol-acetone mixtur~. After drying in a vacuum oven at 35-40C, a 90% yield of copolymer 20 is obtained as a white powder. An analysis of the powder indicates the copolymer contains 5.45% nitrogen and 12.42~
sulfur which corresponds to a nitrogen-to-sulfur mole ratio of about 1.
The procedure described above is repeated except that 25 the sodium exythorbate retarder is omi~ted~ The polymeri-zation exotherm begins soon after sulfur dioxide is first introduced into the graduated cylinder and the product pro : , ' ~ ' ' ` , .' ' ' ~ ` ~

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~11--duced has a low sulfur content, i.e., a nitrogen-to-sulfur mole ratio of 1.425.

Example 2 Tests are performed to determine the effectiveness of the cationic copolymer formed in accordance with the proce-5 dure described in Example 1 as a swelling clay stabilizer.
The test equipment is comprised of a TEFLON~-sleeved test chamber of a design and shape which insures that fluid injected into the chamber flows through particulate material therein rather than around the material. A 100 U~S. mesh 10 screen is placed at the base of the chamber to hold parti-culate material therein. The material contained in the chamber is comprised of 10 grams oE Oklahoma No. 1 sand ~70-170 U.S. mesh); 60 grams of a mixture of 85.0~ Oklahoma No. 1 sand (70-170 U.S. mesh), 10.0% silica (Ca.270 U.S.
15 mesh), and 5.0% Wyoming bentonite; 10 grams of Oklahoma No.
1 sand (70-170 ~.S. mesh); and 20 grams of a coarse sand (20-40 U.S. mesh)O Fluids are forced through the chamber at 145~F using an applied pressure of 50 psig.
A standard laboratory brine is prepared by mixing 7.5 20 weight percent sodium chloride, 0.55 weigh~ percent calcium chloride, 0.42 weight percent magnesium chloride hexahy-drate, and 91.53 weight percent fresh water. The brine is injected through the test chamber lln~il a stable flow rate is achieved. The chamber is then treated with 200 millili-25 ters o~ 2% ammonium chloride water con~aining the desired - . .
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concentration of clay stabilizing agent to be tested. A
filtered API brine is next flowed through the chamber until a stable flow rate is achieved. This step determines the effectiveness ~f the clay stabilizing agent in stopping clay 5 swelling and/or migrating. Fxesh water is next flowed through the chamber until a stable flow rate is achieved.
~his step also determines the effectiveness of the clay sta-bilizing agent in stopping the clay (bentonite) from swelling and/or migrating. 400 milliliters of 15% by weight 10 hydrochloric acid are next flowed through the chamber fol-lowed by the injection of fresh water until a stable flow rate is achieved. The purpose of ~he acid and fresh water injections is to determine if acid treatment detrimentally affects the clay stabilization ability of the clay stabi 15 lizing agent tested.
- The percent flow rate retentions of the sand and clay to brine, fresh water and fresh water after acid are calculated based upon the initial flow rate of filtered standard brine.
The results of these tests are given in Table I for various 20 concentrations of clay stabilizing agent. Also given in Table I for comparison purposes are standard specifications for an values achievable using an organic polycationic poly-mer type of clay stabilizing agent at a concentration of 0.39% by weight in 2% ammonium chloride water. The results 25 of these tests are given in Table I below.

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, ~13 TABLE I

Clay % Flow ~ Flcw % F1CW
Stabilizing Rate ~ate Rate Agent Con- Retention ~etention Retention centrat.ion to to to 5in 2 wt.~ Erine ~rine Fresh NH4C1 Solu- Water Cl~Stabilizin~ ent tion (wt.%) P~ter Acid Standard Specifications for Organic Cationic 10 P~lymer Type o~ Clay Stabilizing Agent 0.39 100 100 75 cationic Cbpolymer of Present Invention with N:S Mole Ratio of 1.004 0.40 106 118 120 15 Cationic Copolymer o~
Æesent I~ven~ion with N:S Mole Ratio of 1.004 0.35 lOU 115 l12 Cationic Cbpolymer of Pres~nt Invention with 20 N:S M~le ~atio of 1.004 0.30 107 115 117 Cationic Cbpolymer of present Invention with N:5 M~le ~atio of 1.004 p.25 105 117 121 ~ Cationic Copolymer of ; 25 Pr~sent Invention wnth N:S MQle Ratio oE 1.004 0.20 95 105 109 Cat.ionic CopolymEr of Present Invention wi~h ~:S M~le Ratio of 1.004 0.175 95 98 98 30 Cationic Oopolymer of Present In~ention with N:S Mole Ratio of 1.004 0.15 102 86 70 ..

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: : , ` ' ': . ' ' -~ ~t~,3 From Table I it can be seen that the clay stabilizins agent of the present invention very effectively prevents the swelling of clay.

Example 3 The procedure set forth in Example 2 above is repeated 5utilizing clay stabilizing agents of the present invention, one of which has a higher sulfur content than the other.
The results of these tests are given in Table II below~

- TABLE II

Clay~ Elow % ~low % Flow S~ilizingRate Rate Rate Agent Con-Retention R~tention Retention :~ centration to to ~
in 2 wt.~ Erine FreshEresh NH4Cl Solu- Water~ater ~:Cla~bilizing Agent tion (wt.%?_ __ _ After Acid ~:15cationic Copol~ of Present Invention with : N:S M~le Ratio of 1.004 0.425 97.6 109.4 96.5 : Cationic Cbpol~ of Present Invention with 0N:S Male Ratio of 1.159 00425 87.4 99.7 77.3 ~: .
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~ rom Table II it can be seen that the cationic copolymer of diallyldimethylammonium chloride and sulfur dioxide having the highest sulfur content achieves the best clay stabilization flow test results~ .

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Claims

1. A method of preparing a water soluble clay stabi-lizing agent comprising polymerizing diallyldimethylammonium chloride with sulfur dioxide in the presence of a polymeri-zation reaction rate retarder to form a copolymer having a nitrogen-to-sulfur mole ratio in the range of from about 1.0 to about 1.4.

2. The method of claim 1 wherein said copolymer has the structural formula:

3. The method of claim 1 wherein said polymerization reaction retarder is comprised of an erythorbic acid salt.

4. The method of claim 3 wherein said polymerization is carried out in an aqueous solution having said erythorbic acid salt dissolved therein.

5. The method of claim 3 wherein said erythorbic acid salt is sodium erythorbate.

6. In a method of preparing a copolymer of diallyldi-methylammonium chloride and sulfur dioxide, the improvement whereby said copolymer has a high sulfur content and utility as a clay stabilizing agent comprising carrying out said reaction in the presence of a polymerization reaction rate retarder.

7. The method of claim 6 wherein said copolymer has the structural formula

8. The method of claim 6 wherein said polymerization reaction retarder is comprised of an erythorbic acid salt.

9. The method of claim 8 wherein said polymerization is carried out in an aqueous solution having said erythorbic acid salt dissolved therein.

10. The method of claim 8 wherein said erythorbic acid salt is sodium erythorbate.

11. A method of reducing clay swelling and fines migra-tion in a clay containing subterranean formation comprising contacting said formation with a clay stabilizing agent comprised of a copolymer of diallyldimethylammonium chloride and sulfur dioxide.

12. The method of claim 11 wherein said copolymer has a nitrogen to sulfur mole ratio of about 1 and the structural formula:

13. The method of claim 11 wherein the step of con-tacting said formation with said clay stabilizing agent comprises dissolving said clay stabilizing agent in an aqueous treating fluid followed by introducing the aqueous treating fluid containing said dissolved clay stabilizing agent into said formation.

14. The method of claim 13 wherein said clay stabiliz-ing agent is dissolved in said aqueous treating fluid in an amount in the range of from about 0.15% to about 0.5% by weight of said fluid.

15. The method of claim 13 wherein said aqueous treat-ing fluid contains a gelling agent and said clay stabilizing agent is dissolved therein in an amount in the range of from about 0.2% to about 0.3% by weight of said treating fluid.

16. The method of claim 11 wherein said aqueous treat ing fluid contains an acid and said clay stabilizing agent is dissolved therein in an amount in the range of from about 0.2% to about 0.4% by weight of said fluid.

17. The method of claim 11 wherein said clay stabi-lizing agent is a solid and is prepared by polymerizing diallyldimethylammonium chloride with sulfur dioxide in the presence of a polymerization reaction rate retarder to form a water soluble solid copolymer having a nitrogen-to-sulfur mole ratio of about 1.

18. The method of claim 17 wherein said polymerization reaction retarder is comprised of an erythorbic acid salt.

19. The method of claim 18 wherein said polymerization is carried out in an aqueous solution having said erythorbic acid salt dissolved therein.

20. The method of claim 18 wherein said erythorbic acid salt is sodium erythorbate.