US Patent 7388045 Cement compositions comprising lignite grafted fluid loss control additives

Novel well cement compositions are provided. Exemplary embodiments of the well cement compositions comprise water, a cement and a fluid loss control additive comprising a graft polymer. The graft polymer comprises a backbone comprising a lignite. The graft polymer further comprises grafted monomers selected from the group consisting of 2-acrylamido-2-methylpropanesulfonic acid, acrylamide, acrylic acid, vinylphosphonic acid, diallyldimethylammonium chloride and salts thereof.