초록

The instant invention is directed to an aqueous drilling fluid comprising an aqueous clay dispersion and a carboxylic functional polyampholyte, or the salt thereof. The instant invention is also directed to the use of the drilling fluid.

대표청구항 ▼

An aqueous drilling fluid comprising: (a) an aqueous clay dispersion; and (b) a water loss reducing amount of a carboxylic functional polyampholyte, or the salt thereof, having an intrinsic viscosity of at least 0.5 dl/g, prepared from: (i) at least one carboxylic functional monomer; of the formula:

An aqueous drilling fluid comprising: (a) an aqueous clay dispersion; and (b) a water loss reducing amount of a carboxylic functional polyampholyte, or the salt thereof, having an intrinsic viscosity of at least 0.5 dl/g, prepared from: (i) at least one carboxylic functional monomer; of the formula: [Figure] wherein R is hydrogen, a phenyl group or an alkyl group of from 1 to 3 carbon atoms, R1 is a branched or straight chain of from 0 to 12 carbon atoms, and X is hydrogen or an alkali or alkaline earth metal (ii) at least one cationic-containing monomer containing an ion selected from the group consisting of a quaternary ammonium, phosphonium or sulfonium having one of the following structures: [Figure] [Figure] [Figure] wherein R3 is a phenyl or an alkyl group of from 1 to 3 carbon atoms, R4 is a hydrogen or an alkyl group of from 1 to 3 carbon atoms, R5 is a straight or branched chain of from 1 to 12 carbon atoms, and X is an anion; and (iii) optionally, non-ionic monomer.