Claims
- 1. In a water based drilling fluid suitable for circulating in a bore hole while drilling the bore hole into subterranean formations which include water, a weighting agent and a fluid-loss controller, the improvement which comprises that said fluid loss controlling agent is the product made by the process comprising
- (a) adding to a rotating continuous reactor to form a mixture
- (i) solid particles of polyvinyl alcohol,
- (ii) an aldehyde, and
- (iii) an aqueous salt solution adjusted to have an acidic pH;
- (b) mixing the mixture of step (a) in the reactor until a polyvinyl alcohol-aldehyde reaction product is obtained; and
- (c) drying the polyvinyl-aldehyde material, said product being present in said fluid in from about 0.1 to 15 percent by weight based on the weight of the water present in said fluid and said fluid is maintained at a pH of from 8 to 12.
- 2. A water based drilling fluid according to claim 1, wherein said product is made from an aldehyde which is either formaldehyde or glutaraldehyde.
- 3. In a process of drilling a bore hole into a subterranean formation using conventional bore hole drilling equipment, the improvement comprising circulating in the bore hole while drilling the drilling fluid of claim 2.
- 4. A method of inhibiting fluid loss from an aqueous drilling fluid in subterranean formations comprising adding the dried product made by the process comprising
- (a) adding to a rotating continuous reactor to form a mixture
- (i) solid particles of polyvinyl alcohol,
- (ii) an aldehyde, and
- (iii) an aqueous salt solution adjusted to have an acidic pH;
- (b) mixing the mixture of step (a) in the reactor until a polyvinyl alcohol-aldehyde reaction product is obtained; and
- (c) drying the polyvinyl alcohol-alehyde material, to said aqueous drilling fluid in an amount of from about 0.1 to 15 percent by weight based on the weight of the water present in said drilling fluid and maintaining said system at a pH of from 8 to 12.
- 5. A method according to claim 4, wherein the product is the product made from an aldehyde which is either formaldehyde or glutaraldehyde.
- 6. In a process of drilling a bore hole into a subterranean formation using conventional bore hole drilling equipment, the improvement comprising circulating in the bore hole while drilling the drilling fluid of claim 1.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a division of U.S. application Ser. No. 553,510, filed Nov. 21, 1983, which is now U.S. Pat. No. 4,472,552 and which is a continuation-in-part of U.S. application Ser. No. 423,798, filed Sept. 27, 1982 now abandoned.
US Referenced Citations (3)
Foreign Referenced Citations (1)
Number |
Date |
Country |
2073228 |
Oct 1981 |
GBX |
Divisions (1)
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Number |
Date |
Country |
Parent |
553510 |
Nov 1983 |
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Continuation in Parts (1)
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Number |
Date |
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Parent |
423798 |
Sep 1982 |
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