某复杂超深井非常规井身结构设计

Unconventional Wellbore Structure Design of a Complex Ultra-deep Well

某井是部署在南黄海崂山隆起带上的一口参数井,钻探地层自下而上主要发育震旦系、寒武系、奥陶系、志留系、泥盆系、石炭系、二叠系、三叠系以及第四系,设计井深7308 m。邻井资料最深钻达地层为志留系,志留系以下地层存在不确定性,且存在异常高压层、易垮塌地层、易漏失地层和含H2S地层,预测井底温度达到188.4℃,预测最高地层压力达到84 MPa,钻井风险高,给井身结构设计带来了很大的挑战。为此,借鉴国内超深井的成功经验,在分析钻井面临的难点和风险的基础上,结合该井地层特点,优化井身结构,确定井身结构必封点4个、套管层次6层,并为灯影组专门设计一层套管,以实现灯影组储层专打。

The well is a parameter well deployed on the Laoshan uplift belt in the South Yellow Sea.The drilled strata mainly develop from bottom to top in the Sinian,Cambrian,Ordovician,Silurian,Devonian,Carboniferous,Permian,Triassic and Quaternary systems.The designed depth of the well is 7308 m.The Silurian strata with the deepest drilling data of adjacent Wells are Silurian strata.There are uncertainties in the strata below Silurian,and there are abnormal high pressure strata,collapsible strata,leak-prone strata and H2Scontaining strata.The predicted bottom hole temperature reaches 188.4℃and the predicted maximum formation pressure reaches 84 MPa,which brings great challenges,to the well structure design.Based on the successful experience of ultra-deep wells in China,based on the analysis of the diff iculties and risks faced by drilling,and combined with the characteristics of the formation of the well,the well structure was optimized.It was determined that the well structure must have 4 sealing points and 6 layers of casing,and a layer of casing was specially designed for the Dengying formation to realize the special drilling of the reservoir in the Dengying formation.