Managed pressure drilling (MPD) equipment is a crucial equipment to effectively solve the drilling problems of narrow pressure margin between the pore (or collapse) and fracture pressures, such as well kick, well loss, well collapse and well struck. A new-style MPD equipment is developed to accurately control the pressure in annular and effectively solve the various complex problems caused by the narrow pressure window. The MPD equipment comprises manifold system, backpump system and auto-control center, which can provides additional flowrate and back pressure to compensate for the reduction of bottom hole pressure while making a connection, reduction in rig pump rate, change in mud weight or drill pipe movement and so on. And in order to do MPD equipment development and technology research, a new MPD laboratory and simulation system have also been established which can simulate the various drilling conditions in the MPD operation, including run in hole, pull out of hole, trip, start mud pump, stop mud pump and so on.
After many experiments, the new-style MPD equipment was improved gradually, and then moved to Sichuan oilfield in Sichuan & Chongqing district of China to do the functional experiments, including equipment performance, near-balanced MPD application and a new MPD application of under-balanced drilling. Especially, the MPD technology of underbalanced drilling is different from the conventional MPD technology because the controlled bottom-hole pressure is lower than pore pressure of formation and the gas can be allowed to come out from formation at a controlled rate.
The test results prove that the MPD equipment can control the bottom-hole pressure in an exact range and the managed pressure technology of underbalanced drilling is feasible. We trust that the new-style MPD equipment and technology will be more successful in the oil or gas well with narrow pressure margin in the future.