Research and Application of Drilling Technology of Extended-reach Horizontally-intersected Well Used to Extract Coalbed Methane

The extended-reach horizontally-intersected well used to extract coalbed methane (CBM)can increase reservoir contact area, extend the influence scope of drainage-pressure drop and the district of CBM desorption. Furthermore, the extended-reach horizontally-intersected well can enhance unit well output and create favorable conditions for future workover. With the support of Major Projects of National Science and Technology, the research on key technologies of extended-reach horizontally-intersected well is done through theoretical analysis and experiment, the concrete research content includes selection of target formation and design of casing program, choice of survey instruments, research on the bottom hole assembly design and technique of steering wellpath, research on drilling fluid and extended-reach horizontally-intersected technology. As engineering examples of popularization and application of extended-reach horizontally-intersected well, a “U” shape well group located in Sihe mine field of Qinshui Basin and a “V” shape cluster well group located in Dafosi coal mine of Binchang mining area have been constructed successfully by using the integrated technologies.