Study on Optimization of Safe and Efficient Drilling Technology in Xihu Sag of East China Sea

Drilling speed of the exploration well in Xihu Sag of East China Sea is slow, the deep well section is frequently complicated downhole, and the operation efficiency is low. In order to increase the drilling speed and improve the drilling efficiency in Xihu Sag of East China Sea, the following methods are adopted. In the surface section, a technical scheme is adopted to reduce the hole size and establish a mechanical model to analyze the depth. The well structure was optimized to reduce operation schedule. Oil based drilling fluid was used in the middle and lower well section. The integrated drilling tool assembly was used to optimize drilling parameters. Through research on four aspects of surface speed-raising technology, casing structure, drilling fluid performance and speed-raising tools, the safe and efficient drilling technology in Xihu Sag of East China Sea has been formed, which can improve the ROP, enhance the sidewall stability and wellbore cleaning ability, shorten the drilling cycle and reduce the downhole failure rate of deep strata. The technology has been applied on-site in more than 10 Wells in several structures in Xihu Sag of East China Sea. Compared with exploration wells of East China Sea during the same period, the drilling rate of the whole well has been increased by 20% and the drilling cycle has been shortened by 23%. Results of this technology can provide effective technical ideas for improving the speed and efficiency of offshore drilling.