Patent ID: 6681856
Filing Date: 2004-01-27
Classification: C04B,C09K

Abstract:
A method of cementing a subterranean zone penetrated by a well bore comprising the steps of:(a) preparing or providing a cement composition that comprises a hydraulic cement, sufficient water to form a slurry and a water soluble biodegradable cement dispersant comprising a polyamide graft copolymer containing at least one side chain formed from aldehydes and sulfur-containing acids or their salts, said polyamide component of said graft copolylmer being a natural polyamide selected from the group consisting of casein, gelatin, soy protein, polyaspartic acid, collagens, bone binders, blood albumins, and their degradation products; (b) placing said cement compositions in said subterranean zone to be cemented; and (c) allowing said cement composition to set into a solid mass therein.