Research On Improving Drilling Speed Technology In Deep Wells In Xiachuan East Area

The fractured carbonate gas reservoirs in Under Eastern Sichuan are China's major natural gas producing areas, the distribution area is about 55,000 square kilometers. Most of the formation in this area is high-steep structure, and the maximum inclination is about to 87°. There are several pressure systems coexist in this area, and the formations have strong abrasiveness. In the process of drilling practice, the underground complex accidents come frequently, and the rate of penetration in deep well is very slow. In order to speed up the Under Eastern Sichuan's deep gas exploration and development process, this paper researched the improvement measures of ROP in Under Eastern Sichuan's deep well.Based on the geological conditions and deep drilling data in Under Eastern Sichuan, it analyzed the difficulties of drilling in this area. This paper optimized the well structure of Wubaiti, Shaping chang, Shaguanping, combined with the engineering technical requirements. Some technical measures, such as high-pressure jetting drilling, hydraulic thrusters, aerated drilling, personalized PDC bits, were researched to improving the ROP of Under Eastern Sichuan. It established a solid model of bottom hole flow field of high pressure jetting drilling by conducting high pressure jetting drilling speed mechanism analysis, using the finite element method to simulate the bottom hole flow field of high pressure jetting drilling, and analyzing the influence of different pump pressure, flow rate, nozzle combination to bottom hole velocity field and pressure field. According to the structure and working principle of hydraulic thrusters, it established a BHA mechanical model and discussed the effect of flow rate and equivalent diameter of nozzle to the behavior of hydraulic thrusters. Based on the aerated drilling's basic principles, it established an optimize model of gas injection quantity, and analyzed the impact of gas injection quantity to wellbore pressure field and velocity field. According to the relationship between drill type and formation hardness, it formulated the principle of optimizing personalized PDC bits in Under Eastern Sichuan and optimized PDC bits for the next drilling deep layers in this area. It analyzed the mechanism of underground complex accident in Under East Sichuan, and promoted the corresponding underground complex accidents'prevention and treatment measures.This paper optimized the quarto well structure for different formations. It formed a technical series to improve the ROP in Under Eastern Sichuan:using high pressure jetting drilling to increase ROP in the upper sand-shale formations, using hydraulic thruster to avoid well deviation in the upper high-steep structures, using aerated drilling to avoid circulation loss and increase ROP in the leak formation, using personalized PDC bits improve ROP and single speed drill footage in the abrasive formations. It proposed the prevention and treatment measures for underground complex accidents in the terms of engineering and management. Based on these studies, a matching technical, including optimize well structure, increase ROP technical measures and underground complex accident prevention and treatment measures, were built up to effectively improve the area's deep well drilling technology.