Cement set retarding additives, compositions and methods

摘要

The present invention provides set retarding additives, set retarded hydraulic cement compositions including such additives and methods of using the cement compositions for cementing zones in wells. The set retarding additives are graft copolymers or terpolymers comprised of the condensation polymer product of a ketone, aldehyde and a compound which introduces acid groups into the polymer having grafted thereto a monomer selected from the group consisting of acrylic acid, vinyl phosphonic acid, methacrylic acid, maleic acid and itaconic acid or one of the foregoing monomers and a second monomer of 2-acrylamido-2-methylpropane sulfonic acid.