OIL BASED DRILLING FLUID AND COPOLYMER BASED ON STYRENE, LAURYL METHACRYLATE AND (METH)ACRYLIC ACID

摘要

An oil based drilling fluid comprising oil, a fluid loss additive and a rheology modification agent, optionally water, optionally at least one surfactant and optionally a weighting agent characterised in that the fluid loss additive is a polymer which is formed from a monomer blend comprising, i) 50 to 90% by weight styrene, ii) 10 to 50% by weight C10-20 alkyl (meth)acrylate iii) 0 to 10% by weight (meth)acrylic acid.