Patent ID: 6180689
Filing Date: 2001-01-30
Classification: C04B,C09K

Abstract:
A fluid loss control agent in a cement slurry, comprising a micro-gel obtained by chemical cross-linking of a polyvinyl alcohol, said cross-linking performed by reacting the polyvinyl alcohol in solution with agents which can condense with at least two alcohol functional groups at a pH of less than 10, the molar concentration of the cross-linking agent with respect to the monomer units of the polyvinylalcohol being in the range about 0.1% to 0.5%, characterized in that it further comprises a surfactant selected from among the group consisting of polyvinylpyrrolidone, N-alkyl pyrrolidones, with an alkyl chain of less than 12, alkoxylated alcohols, with an alkyl chain less or equal to 14, and water soluble copolymers of vinyl pyrrolidone.