Claims
- 1. A water-based drilling mud composition comprising in combination
- (a) sufficient aqueous solution of mineral salts having greater than 10,000 ppm dissolved solids content to maintain the mud as a fluid,
- (b) sufficient clayey material to form a filter cake on the wall of a well,
- (c) at least one water dispersible polymeric viscosifier selected from the group consisting of carboxyalkyl hydroxyalkyl cellulose ethers, carboxyalkyl cellulose ethers, hydroxyalkyl cellulose ethers, polyacrylamides, cellulose sulfate esters, guar gum, and heteropolysaccharides produced by fermentation of carbohydrates by bacteria of the genus Xanthomonas, and
- (d) a polyethylene glycol component having a molecular weight ranging from about 6,000 to about 20,000 wherein the weight ratio of (c) to (d) ranges from about 3:1 to about 1:3, and the combined amount of (c) and (d) being sufficient to reduce water loss due to filtration through said filter cake.
- 2. The drilling mud of claim 1 wherein said amount is in the range of about 0.25 to about 3 lbs/bbl of said mud.
- 3. A drilling mud according to claim 1 wherein (c) is a cellulose ether selected from the group consisting of carboxymethylhydroxyethyl cellulose (CMHEC), carboxymethyl cellulose (CMC), and hydroxyethyl cellulose (HEC).
- 4. A drilling mud according to claim 1 wherein (c) is guar gum.
- 5. A drilling mud according to claim 1 wherein (c) is cellulose sulfate.
- 6. A drilling mud according to claim 1 wherein (c) is (1) a mixture of a polyacrylamide and guar gum or (2) a mixture of polyacrylamide and a heteropolysaccharide.
- 7. A drilling mud according to claim 1 wherein (c) is a heteropolysaccharide produced by fermentation of carbohydrates by bacteria of the genus Xanthomonas.
- 8. A drilling mud according to claim 1 wherein the total amount of (c) and (d) present ranges from about 0.75 to about 2.0 lb/bbl of mud and wherein the weight ratio of (c) to (d) is about 1:1.
- 9. A composition according to claim 1 which is a brine containing from about 0.75 to about 2.0 lbs of a mixture of (c) and (d) per barrel of mud.
- 10. A composition according to claim 9 wherein there are approximately equal weights of (c) and (d).
- 11. In a method of drilling a well with drilling tools, the steps of circulating through the well during said drilling, a water-based drilling mud according to claim 1 which forms a filter cake on the wall of said well.
- 12. The method of claim 11 wherein the amount of (c) plus (d) in said mud is in the range of about 0.25 to about 3 lb/bbl of said mud.
- 13. The method of claim 11 wherein the amount of (c) plus (d) in said mud is in the range of about 0.75 to about 2.0 lbs/bbl of mud.
- 14. The method according to claim 12 wherein there are about equal weights of (c) and (d) present in said mud.
- 15. A method for preparing an aqueous drilling fluid composition containing clay, mineral salts dissolved in said fluid composition to provide greater than 10,000 ppm dissolved solids content and, optionally, weighting, suspending and conditioning agents exhibiting improved rheological properties which comprises incorporating therein
- (a) a first-water dispersible polymeric viscosifier selected from the group consisting of carboxyalkyl hydroxyalkyl cellulose ethers, carboxyalkyl cellulose ethers, hydroxyalkyl cellulose ethers, polyacrylamides, cellulose sulfate esters, guar gum, and heteropolysaccharides produced by fermentation of carbohydrates by bacteria of the genus Xanthomonas, and
- (b) a polyethylene glycol having a molecular weight ranging from about 6,000 to about 20,000 in a weight ratio of (a) to (b) ranging from about 3:1 to about 1:3, the combined amount of (a) and (b) being sufficient to reduce water loss of said drilling fluid composition and
- (c) adding a yield point improving amount of a second polymer selected from said polymeric viscosifiers which is different from the first polymeric viscosifier incorporated into said drilling fluid composition.
- 16. A method according to claim 15 wherein the amount of the second polymeric viscosifier is sufficient to provide a total weight ratio of polymeric viscosifiers to polyethylene glycol ranging from about 3:1 to about 1:3.
- 17. A method according to claim 16 wherein said first polymeric viscosifier is carboxymethyl hydroxyethyl cellulose, carboxymethyl cellulose or hydroxyethyl cellulose and said second polymeric viscosifier is guar gum.
- 18. A method according to claim 17 wherein said first polymeric viscosifier is carboxymethyl hydroxyethyl cellulose.
- 19. A method according to claim 16 wherein said first polymeric viscosifier is carboxymethyl hydroxyethyl cellulose, carboxymethyl cellulose or hydroxyethyl cellulose and said second polymeric viscosifier is a heteropolysaccharide.
- 20. A method according to claim 19 wherein said first polymeric viscosifier is carboxymethyl hydroxyethyl cellulose.
- 21. A method according to claim 17 wherein said (a) and (b) is about a 50:50 mixture of carboxymethyl hydroxyethyl cellulose and polyethylene glycol having a molecular weight of about 8,000.
- 22. A method according to claim 18 wherein said (a) and (b) is about a 50:50 mixture of carboxymethyl hydroxyethyl cellulose and polyethylene glycol having a molecular weight of about 8,000.
Parent Case Info
This application is a continuation-in-part of my copending application having Ser. No. 235,485, filed Feb. 18, 1981, now abandoned.
US Referenced Citations (18)
Foreign Referenced Citations (3)
Number |
Date |
Country |
1645283 |
Jun 1965 |
DEX |
2036055 |
Jun 1980 |
GBX |
1591313 |
Jun 1981 |
GBX |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
235485 |
Feb 1981 |
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