Patent ID: 9410072
Filing Date: 2016-08-09
CPC Classification: C04B,C07F,C09K,E21B

Claim Text:
1. A method of retarding hardening time of a cementitious slurry introduced into a wellbore, comprising: (a) introducing into the wellbore a cementitious slurry comprising water, a cement and a cement retarder, the cement retarder comprising a borate ester complex formed from a polyhydroxy compound and a borate salt in the presence of caustic, the molar ratio of the polyhydroxy compound to boron in the borate ester complex being between from 1:1 to about 4:1; (b) disassociating the borate salt and the polyhydroxy compound from the borate ester complex at an elevated temperature to form a disassociated product; and (c) allowing the slurry to harden to a solid mass.