Development of domestic fine controlled pressure drilling technology and equipment and evaluation on their application effect

In order to effectively overcome the problem of narrow density window drilling, increase drilling efficiency and reduce drilling cost, a set of fine controlled pressure drilling equipment has been developed domestically with proprietary right, which has realized the goal of accurately controlling down-hole annular pressure. This equipment mainly includes automatic throttle manifold system, backpressure pump system and remote automatic control center, and is capable of providing additional flow-rate and backpressure compensation required by constant pressure at hole bottom when making up connections, starting or shutting down the pump, changing the drilling fluid density and drill-string moving. The application of near-balanced and under-balanced controlled pressure drilling technology in Sichuan, Chongqing and Tarim regions show that under-balanced controlled pressure drilling technology can control the bottom pressure to be below the formation pore pressure, allowing gas to flow from the formation at a controlled rate, which helps protect and discover the reservoirs and is a viable technology with development potential.