Method of reducing fluid loss in cement compositions which may contain substantial salt concentrations

Abstract From the Canadian patent

Abstract of the Disclosure, Cementing compositions having improved fluid loss capabilities for use in oil, gas, water and other well cementing operations are disclosed. Such compositions are comprised of water, hydraulic cement and a fluid-loss additive comprising a graft polymer comprised of a backbone of lignin, lignite, derivatized cellulose and various synthetic polymers selected from the group consisting of polyvinyl alcohol, polyethylene oxide, polypropylene oxide and polyethyleneimine. The grafted pendant groups comprise at least one member selected from the group of homopolymers copolymers and terpolymers of 2-acrylamido-2-methylpropanesulfonic acid, acrylonitrile, …