Study on drilling and extraction technologies for U-shape CBM wells

The high steep structure coal-bed methane（CBM）resources are abundant and widely distributed in high steep structures in China, so there is great potential for development. According to the characteristics of coal seams in high steep structures, a new technology, namely U- shape well drilling and completion technology, is proposed, and it is suitable for developing the CBM in high steep structure. Based on the geologic features of low-rank CBM in Huolinhe Basin, the U-shape well drilling and completion technology, the under-balanced drilling technology, and the surface acquisition technology, etc., are also introduced in details. It comes to conclusion that the U-shape drilling and extraction technology has the advantages of both vertical wells and directional wells, it could implement the dewatering and gas producing with the geologic features and the energy of position, and it could also prevent the coal seams from pollution with the under-balanced drilling technology. By using the combined U-shape drilling technology, gas could be produced from the common vertical well for several U-shape wells, it could save a lot of surface facilities.