沙特阿拉伯QATIF-894井钻井液工艺技术

QATIF-894井是沙特阿拉伯QATIF区块一口具有代表性的水井,完钻井深为1568.59 m.该井表层以沙石和红色粘土为主,地层松软,易发生井壁坍塌;下部地层以页岩和泥岩为主,多为砂石胶结,裂缝发育,地层压力系数低,易发生井漏、井喷等复杂事故.QATIF-894井针对不同的地层采用了不同的钻井液体系.一开采用膨润土钙处理高切力钻井液,有效地解决了携带钻屑、清洁井眼的问题;二开和三开继续使用膨润土钙处理钻井液,在漏失的情况下,采用清水钻进,高粘度钻井液携砂;四开采用无固相聚合物钻井液.现场应用表明,该套钻井液体系满足了沙特阿拉伯QATIF区块钻井施工需要,起下钻、下套管和固井顺利.

Drilling Fluid Technology of Well QATIF-894 in Saudi Arabia

Well QATIF-894 is a typical water well drilled in QATIF Block of Saudi Arabia, with a total depth of 1568.59 m. The soft surface layer is mainly composed of sand and red clay, and hole collapse is easy to occur. The lower layer is mainly shale and mudstone, most of which are of sand-stone gelation type. Due to the well developed fractures and low formation pressure factor, complex accidents such as lost circulation and well blowout often occur. Different drilling fluids were used for different intervals in this well. The spud mud made of bentonite and lime was used to carry the surplus sand out, and it also was used in the second and the third intervals. When the well was in lost circulation, clean water was used to drill on and high viscosity drilling fluid was employed to carry cuttings. Solid free polymer drilling fluid was used in the fourth interval. Field using showed that the drilling fluid system is suitable for drilling in this area and the tripping, casing and cementing operations were all smooth.