沙12井钻井液技术及复杂情况处理

A Drilling Fluid Technology and Its Use in Dealing with Complex Conditions in Sha #12 Well

沙12井是位于准噶尔盆地中拐凸起东斜坡的一口重点探井,设计井深5450m.该井地质构造复杂,钻遇地层多.上部地层存在大段水敏性泥岩,易造成起下钻阻卡;侏罗系发育超压,应力性垮塌及硬脆性垮塌严重;三叠系及二叠系断层发育,地层破碎,施工中易垮塌.通过使用胺基成膜防塌钻井液体系,配合相应的现场维护处理工艺和井壁稳定措施,满足了工程施工的要求.

Sha #12 Well is an important exploratory well located on the east slope of the Zhongguai Uplift Area in Junggar Basin, and its designed depth is 5 450 m. The geologic structure is complex with many drilling strata at the well. A large segment of water- sensitive shale exists at the upper formation, which may cause blockage during tripping easily. Stress instability occurs frequently because of overpressure in Jurassic Systerm, and therefore severe stress collapse and hard and brittle collapse may be incurred. Mature faults and stratum breaking exist in Triassic System and Permian System, which may cause collapse during construction. Engineering construction requirements were satisfied by using an amine based film forming anti-collapse drilling fluid system while taking relevant on-site maintenance and borehole stabilization measures.