顺北5-7井超深层奥陶系地层油基钻井液技术

Oil-based drilling fluid technology for ultra-deep Ordovician strata of Well Shunbei 5-7

针对顺北5-7井奥陶系地层采用水基钻井液钻进时坍塌掉块严重且井下复杂情况频发的问题,开展了油基钻井液在超深层奥陶系地层的探索性应用研究。分析了奥陶系地层井壁失稳的原因,对比评价了不同配比的主乳化剂、辅乳化剂、润湿剂等自主产品以及柴油对钻井液乳化稳定性能的影响,形成了油基钻井液性能现场调控方法;采用“密度控制”与“段塞堵漏+随钻堵漏”相结合的堵漏工艺,在小井眼储层段堵漏材料类型与粒径选择受限的情况下,有效降低了油基钻井液损耗。该井油基钻井液施工井段扭矩平稳,无掉块,平均井径扩大率仅为12.22%;裂缝性储层段钻进过程中油基钻井液漏失量控制在0.44m3/h以下;酸压后自喷求产小时产油19.8m3,折合日产气136535m3,表现出良好的井筒强化效果和储层保护效果,为探索油基钻井液在超深层奥陶系地层的应用提供了有益参考。

In order to solve the problem of serious collapse and block falling when drilling with water-based drilling fluid in Ordovician strata of Well Shunbei 5-7,the exploratory application of oil-based drilling fluid in ultra-deep Ordovician strata was studied.The main causes of wellbore instability in Ordovician strata were analyzed.The influence of main emulsifier,auxiliary emulsifier,wetting agent and diesel oil with different proportions on the emulsion stability of oil-based drilling fluid was compared and evaluated,and the field control method of oil-based drilling fluid performance was formed.The plugging technology combined“density control”with“plug plugging and plugging while drilling”was adopted,which has effectively reduced the loss of oil-based drilling fluid under the limitation of the choice of plugging material type and particle size in the small hole reservoir section.During the drilling process of the section of oil-based drilling fluid,the torque was stable without any falling block.The average well diameter expansion rate was only 12.22%.The leakage of oil-based drilling fluid in the fractured reservoir formation was successfully controlled below 0.44m 3/h.After acid fracturing,the oil production of the application well was 19.8m 3/h,equivalent to the gas production of 136535m 3/d,showing good wellbore strengthening effect and reservoir protection effect,and providing a useful reference for exploring the application of oil-based drilling fluid in ultra-deep Ordovician strata.