Patent ID: 8685900
Filing Date: 2014-04-01
Classification: C09K

Abstract:
1. A drilling fluid comprising an aqueous base fluid and a fluid loss control additive that comprises at least one at least partially spherical, non-fibrous polymeric micro gel that comprises a reaction product formed by a polymerization reaction of a polymer or copolymer and a crosslinking agent, wherein the polymer or copolymer comprises at least one unit based on at least one compound selected from the group consisting of polybutylene succinate, polybutylene succinate-co-adipate, polyhydroxybutyrate-valerate, polyhydroxybutyrate-covalerate, polyester amides, polyethylene terephthalates, sulfonated polyethylene terephthalate, aliphatic aromatic copolyester, chitins, chitosans, poly(hydroxy ester ethers), poly(hydroxybutyrates), poly(orthoesters), poly(phosphazenes), a copolymer thereof, a homopolymer thereof, a tetrapolymer thereof, and any derivative thereof, and wherein the aqueous base fluid is a high density brine with a density of at least about 9 lb/gal.