Key technologies for the directional drilling and completion of deep and ultra deep wells in the East China Sea

As the deep oil and gas resources in the East China Sea are explored and developed continuously, the drilling depth increases year by year, and the average total depth in 2019 is up to 5 713 m. Therefore, it is necessary to solve the engineering problems of deep and ultra deep directional wells, including high hole drag and torque, poor formation drillability, difficult direction, difficult cementing quality control of long open hole section and difficult cementing quality detection. To solve these problems, adaptability analysis was firstly carried out on the efficient high-temperature wear resistance and friction reduction agent. And based on its application, the wear resistance rate was reduced by 300 times and the friction was reduced by over 30%. Secondly, conical-tooth bit was designed and applied to improve the rock breaking efficiency. And combined with power steered drilling tools, the rate of penetration (ROP) was increased by over 100%. Thirdly, the wellhead reinjection cementing technology for deep and ultra deep directional wells was designed and implemented, which solves the difficulties of leakage and accurate cementing. Fourthly, the acoustic cementing quality evaluation technology while drilling was used to solve the problems of cementing quality evaluation. These technologies have been applied in 26 wells of East China Sea Oilfield, and their ROP and efficiency improvement effects are remarkable with the average ROP increasing by 23% and the average drilling cycle reducing by 38%. They can provide experience and reference for the drilling and completion of similar wells.