Composition for use in sealing a porous subterranean formation, and methods of making and using

• US 20030104949A1
• Filed: 12/03/2002
• Published: 06/05/2003
• Est. Priority Date: 12/03/2001
• Status: Active Grant

• Current Assignee: Wyo-Ben, Inc.
• Original Assignee: Wyo-Ben, Inc.
• Inventors: Brown, Richard K., Krause, Stewart W., Myers, Kent R., Stichman, Robert W., Parekh, Shobha B.
• Granted Patent: US 6,777,377 B2
• Time in Patent Office: Days
• US Class Current: 507/100
• CPC Class Codes: C04B 20/0048 Fibrous materials
• CPC Class Codes: C04B 20/1033 obtained by reactions only involving carbon-to-carbon unsaturated bonds
• CPC Class Codes: C04B 24/2623 Polyvinylalcohols; Polyvinylacetates
• CPC Class Codes: C04B 28/001 containing unburned clay polymer binder - clay mixtures used in well cementing C09K8/44
• CPC Class Codes: C04B 40/0633 Chemical separation of ingredients, e.g. slowly soluble activator
• CPC Class Codes: C09K 8/44 containing organic binders only
• CPC Class Codes: C09K 8/46 containing inorganic binders, e.g. Portland cement
• CPC Class Codes: C09K 8/5045 containing inorganic compounds
• CPC Class Codes: C09K 8/5083 obtained by reactions only involving carbon-to-carbon unsaturated bonds
• CPC Class Codes: E21B 21/003 Means for stopping loss of drilling fluid plastering the borehole wall E21B33/138
• CPC Class Codes: Y10S 507/902 Controlled release agent
• CPC Class Codes: Y10T 428/2989 Microcapsule with solid core [includes liposome]

Abstract

A composition for sealing porous subterranean formations comprises a mixture of a water-swellable clay and a water insoluble, water absorbent, water-swellable polymer, wherein the mixture is coated with a material that is resistant to penetration by water. The water penetration resistant material helps the delay the onset of swelling of the clay and polymer until it reaches the formations intended for sealing. Mixing the clay with the water-swellable polymer prior to coating assists in coating of the water-swellable polymer with the water penetration resistant material. The coated mixture can be suspended in an aqueous liquid, and then pumped into a subterranean cavity to seal porous formations therein.

Claims

1. A composition for use in sealing a porous subterranean formation comprising a mixture of effective amounts of water swellable clay and a water-insoluble, water-absorbent, water-swellable polymer, both having an external coating consisting of an effective amount of a material capable of retarding the rate of penetration of water through the coating.

2. The composition of claim 1, wherein the material capable of retarding the rate of penetration of water through the external coating comprises a liquid high molecular weight water soluble polymer.

3. The composition of claim 1, wherein a mixture of the water swellable clay and the water insoluble, water absorbent, water swellable polymer of the composition comprises between 0.1 and 99.9% by weight of the clay and between 0.1 and 99.9% of the water swellable polymer.

4. The composition of claim 3, wherein the clay ranges between 80 and 99% and the water swellable polymer ranges between 1 and 20%.

5. The composition of claim 1, wherein the water-insoluble, water-absorbent, water-swellable polymer is a cross linked polyacrylamide polymer.

6. The composition of claim 2, wherein the effective amount of the external coating is based on 0.01 to 15 gallons of the water penetration resistant liquid material per 2000 pounds of a dry mixture of the clay and water swellable polymer.

7. The composition of claim 1, wherein the clay is selected from the group consisting of bentonite, montmorillonite, hectorite, nontronite, saponite, beidellite, attapulgite, and sepiolite.

8. The composition of claim 2, wherein the liquid high molecular weight water soluble polymer is a polyacrylamide or a polyacrylamides-polyacyrlate co-polymer or a mixture of the two.

9. The composition of claim 1, wherein the clay and the water swellable polymer have a particle size of 200 mesh (ASTM) or greater.

10. The composition of claim 1, wherein the coated mixture contains an effective amount of water insoluble fibrous material to enhance integrity of a seal formed by use of the coated mixture in a subterranean formation.

21. A method of sealing a porous formation in a subterranean cavity comprising:

a) suspending an effective amount of the coated mixture of claim 1 in an aqueous-based liquid to form a fluid suspension;

b) introducing the fluid suspension into a subterranean cavity wherein the clay and water swellable polymer seal the porous formation.

22. The method of claim 21, wherein the aqueous based liquid is one of water or a water-based drilling fluid.

23. The method of claim 22, wherein the drilling fluid comprises water and bentonite.

24. The method of claim 21, wherein the fluid suspension is introduced either generally vertically or generally horizontally in subterranean cavity.

25. The composition of claim 6, wherein 1.0 to 6.0 gallons of the water penetration resistant liquid material are used per 2000 pounds of the dry mixture.

26. The composition of claim 9, wherein the clay and the water swellable polymer have a particle size of about 100 mesh (ASTM) to 0.25 inch.

27. The composition of claim 26, wherein the clay and the water swellable polymer have a particle size of about 40 mesh (ASTM) to 8 mesh (ASTM)

28. The composition of claim 10, wherein the fibrous material is comprised of one or more of polyethylene, polypropylene, nylon, rayon, polyester, hemp, cotton, wool, disassociated wood fibers and fiberglass.

11. A method of making a coated mixture for use in sealing a porous subterranean formation comprising:

a) forming a dry mixture of an effective amount of a particulate water swellable clay with an effective amount of a particulate water insoluble, water absorbent, water swellable polymer; and

b) coating the clay and water-swellable polymer particles with an effective amount of a material capable of retarding the rate of water penetration through the coating to form the coated mixture.

12. The method of claim 11, wherein the material capable of retarding the rate of water penetration through the coating comprises a liquid high molecular weight water soluble polymer.

13. The method of claim 11 wherein the effective amount of the external coating is based on 0.01 to 15 gallons of the water penetration resistant liquid material per 2000 pounds of the dry mixture.

14. The method of claim 11, wherein the mixture of the water swellable clay and the water insoluble, water absorbent, water swellable polymer of the composition comprises between 0.1 and 99.9% by weight of the clay and between 0.1 and 99.9% of the water swellable polymer.

15. The method of claim 14, wherein the clay ranges between 80 and 99% and the water swellable polymer ranges between 1 and 20%.

16. The method of claim 11, further comprising adding an effective amount of water insoluble fibrous material to the coated mixture to enhance the integrity of a seal formed a use of the coated mixture in a subterranean formation.

17. The method of claim 11, wherein the water swellable polymer is a cross linked polyacrylamide polymers.

18. The method of claim 11, wherein the clay and the water swellable polymer have a particle size of 200 mesh (ASTM) or greater.

19. The method of claim 12, wherein the liquid high molecular weight water soluble polymer is a polyacrylamide or a polyacrylamides-polyacyrlate co-polymer or a mixture of the two.

20. The method of claim 11, wherein the clay is selected from the group consisting of bentonite, montmorillonite, hectorite, nontronite, saponite, beidellite, attapulgite, and sepiolite.

29. The method of claim 13, wherein 1.0 to 6.0 gallons of the water penetration resistant liquid material are used per 2000 pounds of the dry mixture.

30. The method of claim 16, wherein the fibrous material is comprised of one or more of polyethylene, polypropylene, nylon, rayon, polyester, hemp, cotton, wool, disassociated wood fibers and fiberglass.

31. The method of claim 18, wherein the clay and the water swellable polymer have a particle size of about 100 mesh (ASTM) to 0.25 inch.

32. The method of claim 31, wherein the clay and the water swellable polymer have a particle size of about 40 mesh (ASTM) to 8 mesh (ASTM).