桩西滩海中生界地层水平井钻井液技术

桩西滩海地区实施全井小循环泥浆不落地工艺，上部地层快速钻进固相控制难度大，东营组泥岩和沙河街油泥岩掉块坍塌严重，中生界水平段钻进润滑防塌要求高，分别采取了针对性的措施。现场试验表明，中上部地层采用氯化钙强抑制钻井液体系，抑制了粘土造浆和钻屑分散，满足了快速钻进阶段小循环泥浆不落地的工程要求；中下部地层采用了低活度强抑制钻井液体系，钻井液活度控制在0.96以下，高温高压滤失量＜12 mL，保证了泥岩地层的井壁稳定；三开水平段应用了油基钻井液回收循环利用工艺，性能优化后的钻井液乳化稳定性好，破乳电压＞460 V，解决了水平井钻进中生界地层摩阻扭矩大、易坍塌等问题。

Horizontal well drilling fluid technology at Mesozoic formation of Zhuangxi beach area

The whole well small circulation technology with zero-discharge of drilling fluid is implemented in Zhuangxi beach area, solid control is difficult at upper strata with rapid drilling; for there are serious block falling and collapse in mudstone of the Dongying formation and the oil mudstone of the Shahejie formation and high requirements in lubrication and collapse prevention for Mesozoic horizontal section, some targeted measures are taken respectively. The field test shows that by the use of calcium chloride high-inhibition drilling fluid system at upper formation, the dispersion of clay and cuttings is inhibited to meet the engineering requirements of the rapid drilling with small circulating and mud zero-discharge; low-activity and strong-inhibition drilling fluid system is used at lower formations, the drilling fluid activity is controlled below 0.96 and HTHP filtration loss is less than 12mL, which ensures the well stability of mudstone formation. The oil-base drilling fluid recycling technology is applied at the third horizontal section, the emulsification stability of the optimized drilling fluid performs well, demulsification voltage is greater than 460 v, which solves the problems such as big friction torque and collapse in horizontal well drilling in the Mesozoic formation.