Ultra-High Pressure Well Control Technology and Supporting Equipment for Ultra-Deep Carbonate Rock in Tarim Oilfield

Abstract The exploration and development of Tarim Oilfield focuses on ultra-deep formations. Since 2021, more than 100 ultra-deep wells with a depth of 8000m have been completed. Ultra-deep drilling brings risks and challenges such as ultra-high pressure, ultra-high temperature, and high H2S. The highest formation pressure tested in Tarim Oilfield is 182MPa, and the highest H2S content is 41×104ppm. Ultra-deep carbonate rock ultra-high pressure well control treatment technology and supporting equipment for Tarim Oilfield were developed. Tarim Oilfield has taken various technical measures to solve the risk of ultra-high pressure well control. Firstly, in terms of engineering design, Tarim Oilfield has formed an integrated risk identification technology for "five specials" (special surface, special lithology, special geological phenomenon, special fluid, special temperature and pressure field), and adopted a comprehensive prediction technology for "five pressures" (pore pressure, collapse pressure, loss pressure, closure pressure and fracture pressure). Secondly, in in terms of well control technology, the application of dual density drilling, direct push logging, automatic filling, remote control center technologies successfully ensured the safe drilling of ultra-high pressure wells in this block. Finally, in terms of well control equipment, a new type of 140MPa all-metal casing head, large diameter integrated four-way, overflow one-click alarm well control equipment, 175MPa ultra-high pressure Christmas Tree and Blowout preventer (BOP) have been formed to achieve the essential safety of well control. The wellbore configuration optimization technology and ultra-high pressure well control equipment technology have been applied to 51 ultra-deep wells in the Tarim Oilfield. 140MPa well control equipment is used in the drilling process, including 140MPa casing head and blowout preventer. The 140MPa well killing manifold has a throttling function and the throttling valve adopts a wedge valve and is erosion-resistant. All 140MPa throttling manifolds use 140MPa gate valves to avoid using low-level gate valves on the outermost side. Remote control consoles with special shear gate control functions are promoted in high-risk areas. Compared with the more traditional complex overflow monitoring, the comprehensive Ultra-high pressure well control risk integrated identification technology can achieve early warning of complex overflows 10 minutes in advance. The drilling process combines the managed pressure drilling (MPD), pressure return method, and choke circulation killing have been successfully applied to deal with high casing pressure and complex overflow accidents in 17 wells, The maximum shut-in pressure was 47.57 MPa, and the maximum overflow disposal pressure was 64.4 MPa. Ultra-high pressure well control technology successfully ensures well control safety in the block and achieved high oil production. The promotion and application of ultra-high pressure well control risk management technology and supporting equipment in the Tarim Oilfield have provided excellent engineering cases and experience for the development of ultra-high pressure well control. This article also discusses the development trend of well control technology under extreme conditions.