ADDITIVE FOR WATER-BASE DRILLING FLUID AND PROCESS

摘要

An additive for water-base drilling fluid compositions used for drilling subterranean wells is disclosed. In one embodiment, the additive is a sulfonated copolymer of recurring units of a maleimide monomer and recurring units of a vinyl monomer. In another embodiment, the additive is a sulfonated terpolymer of recurring units of a maleimide monomer, recurring units of a vinyl monomer, and recurring units of a carboxyl-containing monomer. Water-base drilling fluids compositions which contain the additive and a process for drilling subterranean wells therewith are also disclosed.