Importance

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Abstract

Cementing compositions and methods of using such compositions in oil, gas and water well cementing operations to reduce fluid loss from the composition to the formation are disclosed. Such compositions incorporate a terpolymer formed from (a) an acid monomer selected from the group consisting of 2-acrylamido, 2-methyl propane sulfonic acid (AMPS), sodium vinyl sulfonate or vinyl benzene sulfonate, and metal 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 comprise AMPS, acrylamide and itaconic acid. The polymer is used as a fluid loss agent in oil well cementing in conjunction with dispersants, like naphthalene sulfonate formaldehyde condensate alkali salt, a polymer of ketone aldehyde sulfonate alkali salt, or lignosulfonate. At the same time, all of the above can be used in freshwater to saturated NaCl or seawater cement slurries where HEC fluid loss additive does not work.

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First Claim