UTILIZATION OF ANIONIC DISPERSED POLYMERS AS VISCOSITY MODIFIERS FOR WATER-BASED DRILLING FLUIDS

摘要

FIELD: oil and gas production.;SUBSTANCE: invention provides water-based drilling fluid suitable for use when drilling holes through underground formations, which fluid is characterized by having pH within a range of about 7 to about 12 and viscosity from about 20 to about 80 sec (Marsh cone). Drilling fluid is prepared by mixing fresh water, brine, or sea water with one or several polymers taken in amount approximately between 0.3 and 2.5 pounds per barrel calculated for active polymer compounds. Anionic dispersed polymers are comprised of about 2 to about 98 mol % of one or several anionic monomers and from about 98 to about 2 mol % of one or several nonionic monomers. Anionic dispersed polymers have reduced specific viscosity value between about 10 and about 50 dL/g. Method of drilling hole through underground formation using above-defined drilling fluid is also claimed. Invention is further specified in depended claims.;EFFECT: increased viscosity of drilling fluid.;12 cl, 2 ex