Bottomhole pressure control method in pressure-control drilling

There are many problems in conventional overbalance drilling and underbalance drilling (UBD) in the actual well drill- ing engineering. To improve the drilling technologies used in actual production, the pressure-management drilling (MPD) has been developed on the basis of conventional overbalance drilling and UBD abroad in the past few years, which is named as pressure-control drilling in China and has been applied to actual production. Good results have been obtained, indicating that it has broad prospect for actual production. The core of MPD is to control the bottomhole pressure. The pressure-control methods vary from different drilling processes. In this paper, several methods to control the bottomhole pressure are emphatically introduced. Advantages and disadvantages of them are analyzed as well. This can be good reference to their further application to the ield.