Shale oil drilling technology for leakage control and ROP enhancement of absorption wells in upper and lower formation
Domestic shale oil drilling technology is becoming more mature than ever.However,such challenges are still present in drilling process,including severe drilling fluid leakage,low rate of penetrate,and longer drilling cycle,which seriously restricts the efficient development of shale oil.In order to solve these challenges,through analysis of drilling data of earlier 6 shale oil wells,this article clarifies the complex geological characteristics and leakage characteristics in Qinghai shale oil formations.The wellbore configuration is simplified to two spud from conventional four spud to reduce casing programme and solidify the thief formation.The drilling fluid system is selected based on leakage type,and the formula of key agent of BH-WEI drilling fluid is modified to improve the stability,inhibition,and sealing of drilling fluids,thereby lowering the leakage and achieving effective prevention of leakage.Meanwhile,the distance between the upper and lower centralizers of screwdrill is adjusted to 12 m,thus reducing the sliding footage ratio.ROP is enhanced by optimizing PDC drill bit arrangement and adopting high build-up ratio rotary steering tool ATC and low-speed straight screw rod,which shapes the shale oil drilling technology for leakage control and ROP enhancement.This technology was applied in 8 wells in Qinghai shale oil block,compared with 6 earlier drilling wells which shows the leakage of single well has been reduced from 335.02 m3 to 21.08 m3,ROP increased from 4.45 m/h to 7.36 m/h,and the average drilling cycle shortened to 68.26 days from 94.77 days.The field application demonstrates that this technology is a solution to shale oil drilling challenges in Qinghai oilfield and offers technical foundation for the efficient development of shale oil in this region.
万方数据
维普
