秋里塔格构造带风险探井中秋1井安全钻井关键技术

Key technologies of safe drilling in Zhongqiu 1 Well, a risk exploration well in Qiulitag tectonic belt

中秋1井位于塔里木盆地库车坳陷秋里塔格构造带中秋段中秋1号背斜构造上,是中国石油2017年部署的1口风险探井。秋里塔格构造地面条件极其恶劣、地下复杂极其高陡,膏盐层巨厚,盐下地层、盐层、盐上地层分层构造变形,地震资料差,邻井资料少,复合盐层压力系数复杂,盐层卡层难度大。在精细研究钻井和地质设计、优化施工方案和风险防控措施、优选新型钻井工具和钻井参数的基础上,制定库车山前钻完井提速对策,全井采用定制钻头钻进,盐上地层、盐层、目的层的钻进及试油完井工作协同配合;同时针对苏维依组低压区和库姆格列木群复合盐层段发生的井漏复杂,采用不同堵漏措施,实施14次堵漏作业,地层承压能力明显提高,钻完井周期由420 d缩短至350 d。该井的钻探实践为秋里塔格构造带的油气勘探和整体评价提供了借鉴。

Well Zhongqiu 1 is located at No.1 Zhongqiu anticlinal structure in the middle section of the Qiulitage structural belt,the Kuqa depression,the Tarim Basin.It is a wildcat well deployed by PetroChina in 2017.In the Qiulitage structure,the surface conditions are extremely harsh,and underground structure is quite high and steep.Gypsum-salt layers are quite thick,subsalt layer,salt layer and suprasalt layer are structurally deformed.The seismic data is poor and the data of the neighboring wells is lack.The pressure coefficient of composite salt layer is complicated,and salt layer sticking is difficult.Drilling and geological design were studied precisely,construction scheme and risk control measures were optimized,and new drilling tools and drilling parameters were selected.Then,the countermeasures for well drilling,completion and ROP improvement in the Kuqa piedmont zone were formulated.That is to adopt the specifically tailored bit in the whole well and coordinate the well drilling,test and completion in subsalt layer,salt layer and target layer.Finally,different plugging measures were taken to deal with complex circulation loss in the low pressure zones of Suweiyi Formation and the composite salt layer interval of Kumugeliemu Group.After plugging operation was carried out by 14 times,the formation bearing pressure is increased greatly,and the drilling and completion cycle is shortened from 420 d to 350 d.The drilling practice of Well Zhongqiu 1 provides the reference for the oil and gas exploration and overall evaluation of Qiulitage structural belt.