Abstract: Managed pressure drilling technology is an effective technical guarantee to solve the well control problem of narrow density window formation drilling,and has been successfully applied in land,shallow sea and deep water all over the world. Deepwater is an important replacement area for oil and gas exploration and development in China. The South China Sea is rich in oil and gas resources,but it faces difficulties such as high temperature and high pressure,narrow density operating window and so on. It is difficult to control wellbore pressure,which brings great troubles to safe and efficient operation. Under the background that the deepwater MPD equipment and technology are almost monopolized by foreign countries,the volume of deepwater drilling operations is increasing and the drilling risk level is rising,it is an inevitable choice to have China’s independent deepwater MPD technology and equipment. Due to the great difference between surface and underwater wellhead managed pressure drilling technology and equipment system,the existing surface wellhead managed pressure drilling technology cannot be directly transplanted to deep water. Therefore,based on the current situation of deepwater drilling operations in China,this paper proposes an independent supporting construction scheme for key equipment of subsea wellhead managed pressure drilling. The managed pressure drilling system of annulus back pressure is taken as the main line of independent construction,and the process adaptability of the managed pressure drilling system of surface wellhead is transplanted. Through comprehensive comparison and analysis,the ATR configuration scheme of the underwater wellhead managed pressure drilling system is recommended.

Key words: ocean, deep water, managed pressure drilling, rotary blowout preventer, narrow density window