| 摘要 |
Drilling fluid compositions and methods of using such compositions in oil, gas and water well drilling fluid operations to reduce fluid loss from the composition to the formation are disclosed. Such compositions incorporate a terpolymer formed from (a) a vinyl containing alkyl or aromatic substituted sulfonate selected from the group consisting of 2-acrylamido, 2-methyl propane sulfonic acid (AMPS), sodium vinyl sulfonate or vinyl benzene sulfonate, and method salts thereof at about 10 to 75 weight percent in the polymer; (b) an unsaturated polybasic acid such as itaconic acid at about 1 to 60 weight percent; and metal salts thereof and (c) a nonionic monomer selected from the group consisting of acrylamide, N, N-dimethylacrylamide, N-vinyl pyrrolidone, N-vinyl acetamide, or dimethylamino ethyl methacrylate and metal salts thereof at about 10 to 76 weight percent. The terpolymer should have a molecular weight between 200,000 to 1,000,000. The preferred terpolymer comprises AMPS, acrylamide and itaconic acid. The polymers are used as fluid loss control additives for aqueous drilling fluids and are particularly advantageous when used with lime or gypsum based drilling muds containing soluble calcium ions.
|
