Drilling fluid additive

摘要

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.

主权项

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 R1 and R2 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 R3 and R4 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 R5 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 %.