Rheology stabilizer for high-temperature high-pressure high-mineralized degree drilling fluids

摘要

The invention relates to a rheology stabilizer or thinner for high-temperature high-pressure high-mineralized degree drilling fluids, methods of their preparation and use. The rheology stabilizer is a copolymer synthesized by an olefinic acid, ester of an olefinic acid, a sulfonic acid containing unsaturated linkage(s), an amide or imide containing unsaturated linkage(s), a quaternary compound containing olefinic linkage(s) reacting chemically with phosphorous acid or hypophosphorous acid, more particularly, copolymer of acrylic acid, 2-hydroxypropyl acrylate, N-(4-sulfophenyl)-maleimide, allyltrimethylammonium chloride and phosphorous acid. The copolymers have very high resistance to high-temperature high-pressure high-valence ions, can high-effectively adjust the rheology and thixotropy of drilling fluids, and can be used as the rheology stabilizer, thinner, clay and shale stabilizer of drilling fluids.