Application of Connectivity Technology of U-shape Well in CBM Exploration

CBM extraction through horizontally connected wells realizes the connection of two wells by controlling well trajectory in coal seam, can effectively increase CBM flowing area, and improve CBM recovery of single well. It involves guiding while drilling, cavity making in seam, distant accurate connection, reservoir protection and other advanced technologies. The horizontal connected well engineering carried out by Xi’an Research Institute of China Coal Technology & Engineering Group Corp in Panzhuang block of Qinshui basin, which has successfully realized the distant connection of two wells by using wireless MWD, rotary magnetic distance and other tools as well as reasonable drilling technology, subsequent drainage and extraction effect was remarkable. The paper presents in detail the design, construction, drilling and development result of the connected wells.