Vinyl alcohol-based polymer and cement slurry using the vinyl alcohol-based polymer

摘要

Provided is an additive for oil well cement, containing a vinyl alcohol polymer, the additive having good fluid loss reducing performance. The additive for oil well cement is a saponified product of a copolymer of a vinyl ester monomer and a multifunctional monomer, and has a degree of saponification of 70 to 95 mol% and a viscosity-average degree of polymerization of 1000 to 10000.