Patent ID: 7384892

Claim:
A water-based drilling fluid composition comprising water and at least one rheology modifier and/or fluid loss control agent, and at least one other ingredient selected from the group consisting of polymeric additive, inorganic salts, dispersants, shale stabilizers or inhibitors, weighting agents, and finely divided clay particles, depending upon the desired attributes, wherein the rheology modifier and/or the fluid loss control agent comprises carboxymethylated raw cotton linters (CM-RCL) and/or salts thereof, wherein the polymeric additive and/or dispersants exclude polycarboxylic selected from the group consisting of a homopolymer of acrylic acid, a homopolymer of methacrylic acid, a copolymer of acrylic acid and methacrylic acid, and a water-soluble salt of any of the foregoing acids, wherein the polycarboxylic acid has a number average molecular weight not exceeding 3,000, and wherein the CM-RCL is prepared from raw cotton linters containing about 80-85% cellulose, about 1.5-2.5% lignin and about 2.5-3.5% hemicellulose.