Drilling fluid additive

Patent metadata

Field	Value
Publication number	US-9475900-B2
Application number	US-201314103422-A
Country	US
Kind code	B2
Filing date	Dec 11, 2013
Priority date	Dec 11, 2013
Publication date	Oct 25, 2016
Grant date	Oct 25, 2016

Abstract

The present invention provides a drilling fluid additive comprising a specific cation-modified PVA-based resin and a drilling fluid containing the same. The drilling fluid additive can reduce hydration swelling of inorganic clay mineral such as bentonite, and provide a drilling fluid such as drilling mud capable of forming a thin and tough mud wall on the stratum during drilling operation.

First claim

What is claimed is:

1. A drilling fluid additive comprising polyvinyl alcohol-based resin containing a cationic structural unit represented by formula (1), a vinyl alcohol structural unit represented by formula (3a), and a vinyl ester structural unit represented by formula (3b), and excluding a carboxylic acid functional monomer unit,

wherein R 1 and R 2 are independently a hydrogen atom or an alkyl group having from 1 to 3 carbon atoms, and may be identical or different from each other, and R 3 and R 4 are independently an alkylene group having from 1 to 3 carbon atoms, and may be identical or different from each other, Y is a halogen, and R 5 is an alkyl group having from 1 to 18 carbons or an aromatic group,
wherein the content of the cationic structural unit is from 0.3 to 2 mol %, and wherein the polyvinyl alcohol-based resin has a saponification degree of 70 to less than 100 mol %.

2. The drilling fluid additive according to claim 1 , wherein the polyvinyl alcohol-based resin has a polymerization degree of 200 to 3000.

3. The drilling fluid additive according to claim 1 , further comprising a salt.

4. The drilling fluid additive according to claim 1 , wherein the content of the polyvinyl alcohol-based resin is in the range of 0.01 to 10% by weight based on the weight of drilling fluid.

5. The drilling fluid additive according to claim 1 , wherein each of R 3 and R 4 is a methylene group.

6. A drilling fluid comprising inorganic clay mineral, a medium, and polyvinyl alcohol-based resin containing a cationic structural unit represented by formula (1), a vinyl alcohol structural unit represented by formula (3a), and a vinyl ester structural unit represented by formula (3b), and excluding a carboxylic acid functional monomer unit,

wherein R 1 and R 2 are independently a hydrogen atom or an alkyl group having from 1 to 3 carbon atoms, and may be identical or different from each other, and R 3 and R 4 are independently an alkylene group having from 1 to 3 carbon atoms, and may be identical or different from each other, Y is a halogen, and R 5 is an alkyl group having from 1 to 18 carbons or an aromatic group,
wherein the content of the cationic structural unit is from 0.3 to 2.0 mol %, and wherein the polyvinyl alcohol-based resin has a saponification degree of 70 to less than 100 mol %.

7. The drilling fluid according to claim 6 , wherein the inorganic clay mineral is bentonite.

8. The drilling fluid according to claim 6 , wherein the medium is water.

Assignees

• Nippon Synthetic Chem Ind Co Ltd

Inventors

• Saito Masahiro
• Asai Midori

Classifications

• C08F218/08

  Vinyl acetate · CPC title

• C09K2208/12

  Swell inhibition, i.e. using additives to drilling or well treatment fluids for inhibiting clay or shale swelling or disintegrating · CPC title

• C08F216/06 Primary

  Polyvinyl alcohol {; Vinyl alcohol} · CPC title

• C09K8/24

  Polymers · CPC title

• C08F226/04

  Diallylamine · CPC title