STUDY ON DIRECTIOANL CONTROL TECHNOLOGY FOR XIJIANG EXTENDED-REACH WELLS IN SOUTH CHINA SEA

Great advantages have been made by the Extended-Reach Wells (ERW) in Xijiang Oilfield in South China Sea. The directional drilling technology used in these ERWs has very important reference value. An intensive research has been made into the well trajectory control technology. The results show that it’s virtually a combination of the steering technologies of modulated or non-modulated slid-steering BHA and of rotary steerable system. An ERW with displacement of beyond 8 km can be drilled with the slide-steering BHA, but of great difficulty. A simulation should be made and the borehole enlargement should be taken into account to make a reasonable design of BHA. The steerable rotary system can be used to control the wellbore trajectory accurately, however it is determined by the technical and economic factors, that the slide-steering technology should be used when the horizontal displacement is smaller and the rotary steering technology should be used when the displacement is larger.