DRILLING LIQUID Russian patent published in 1995 - IPC

FIELD: drilling of oil and gas holes. SUBSTANCE: drilling liquid has clay, carboxymethylcellulose, polymeric flocculant and water. The source of polymeric flocculant: copolymer of acrylamide and sodium vinyl sulfonate or copolymer of acrylamide and sodium 2-acrylamido-2-methylpropane-3-sulfonate at intrinsic viscosity 6.2 dl/g, not less. Copolymer has 70-99.6 mole acrylamide and 0.4-30 mole vinyl sulfonate or sodium 2-acrylamido-2-methylpropane-3-sulfonate. Copolymer is prepared by polymerization in aqueous alkaline solution at pH 11.0 (not less) in the presence of peroxide initiating agents and at heating at the total comonomer concentration from 3.5 to 4.0 mole/l. Copolymer is used at concentration from 0.15 to 0.75% of drilling liquid mass. EFFECT: improved method of drilling liquid preparing. 2 tbl