CHEMICALLY MODIFIED LIGNITE

摘要

A method of improving high temperature fluid loss and rheology stabilization of high calcium brine clay-containing oil well drilling fluids which comprises adding thereto a stabilizing amount of a water-soluble terpolymer composition comprising: said composition containing brown coal or modified brown coal in an amount ranging between 5-95% with the brown coal or modified brown coal having been present during the polymerization of the water-soluble polymer.