US Patent 7384892 Water-based drilling fluids

A water-based drilling fluid composition includes water and at least one rheology modifier and/or fluid loss control agent, and at least one other ingredient of polymeric additive, inorganic salts, dispersants, shale stabilizers, weighting agents, or 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) made from the baled raw cotton linters or comminuted raw cotton linters with increased bulk density.