Cement set retarding additives, compositions and methods

A method of cementing a subterranean zone penetrated by a well bore comprising the steps of:

• forming a pumpable cement composition comprised of hydraulic cement, sufficient water to form a slurry, and a water soluble additive consisting of a polymer having grafted thereto at least one acid monomer selected from the group consisting of a first acid monomer or said first acid monomer and a second acid monomer wherein:
• said polymer is the condensation polymer product of an aliphatic ketone, an aliphatic aldehyde and an acid contributing compound wherein the molar ratio of said ketone to said aldehyde to said acid contributing compound in said polymer is in the range of from about 1 mole of said ketone to about 1 to 18 moles of said aldehyde to about 0.25 to 3.0 moles of said acid contributing compound;
• said first acid monomer is selected from the group consisting of acrylic acid, vinyl phosphonic acid, methacrylic acid, maleic acid and itaconic acid and said second acid monomer is 2-acrylamido-2-methylpropane sulfonic acid;
• the weight ratio of said acid monomer to said polymer in said additive is in the range of from about 0.05 to 1 to about 5 to 1;
• pumping said cement composition into said zone by way of said well bore;
• and
• allowing said cement composition to set.