▎ 摘　　要

NOVELTY - Oil-based drilling fluid comprises white oil, organic soil, calcium chloride solution, calcium oxide, main emulsifier, auxiliary emulsifier, wetting agent, plugging agent, barite and fluid loss reducer. The plugging agent is 1250 mesh superfine calcium carbonate, 2250 mesh superfine calcium carbonate, nano plugging agent and/or bituminous plugging agent ME-CAL. The nano plugging agent is nano graphene modified by sodium dodecylbenzene sulfonate or sodium heavy alkylbenzene sulfonate. The average particle size of nano plugging agent is 80-210 nm. USE - The oil-based drilling fluid is used for drilling in deep shale formation (claimed). ADVANTAGE - The drilling fluid has reasonable particle size grading and optimal dosage and enhances plugging ability.