Patent ID: 9321953
Filing Date: 2016-04-26
CPC Classification: C04B,C09K

Claim Text:
1. A method of making a fluid loss additive useful to reduce the loss of fluid from a slurry of a cementing composition in water, said method comprising the steps of: preparing a first aqueous medium comprised of water and a humate, adding a first compound, a second compound and a third compound to said first aqueous medium to produce a combination and adjusting the pH of said combination to a value greater than 7 to thereby form a second aqueous medium, heating said second aqueous medium to a reaction temperature, adding activator ingredients to said second aqueous medium to form a reaction mass and to commence polymerization reaction, said activator ingredients being comprised of a chain transfer agent and a polymerization initiator, and permitting said polymerization reaction to proceed for a suitable period of time to thereby produce an aqueous solution containing said fluid loss additive; Wherein: said first compound is the sodium salt of 2-acrylamido-2-methylpropanesulphonic acid, said second compound is N,N-dimethylacrylamide, and said third compound is maleic anhydride; the mole ratio of said first compound to said second compound in said fluid loss additive is an amount in the range of from about 1.5 to about 2.5 moles of said first compound per mole of said second compound; and the mole ratio of said first compound to said third compound in said fluid loss additive is an amount in the range of from about 4.8 to about 9.8 moles of said first compound per mole of said third compound.