Research on inclined wells connecting technology of multi-coalbed and multiple branches horizontal wells in Liulin District

Liulin is located at the east edge of Erdos Basin, and the medium coalbed in the region contains rich methane gas. But the ravines on loess landform restricted the application of conventional multi-branch horizontal wells. In order to improve development efficiency of the coalbed methane(CBM) drilling, the inclined well connecting technology was innovatively adopted, achieving the goal of small-size wellsite planning where the spacing between the engineering wells and drainage slant hole wellhead is 10 m. In line with that the No. 3+4 coal reservoirs have the same reservoir pressure as No. 5 coal reservoir and are suitable for comingled production, the drilling and completion technique for multi-coalbed multi-branch horizontal wells was innovatively adopted to development No. 3+4 and No. 5 coalbeds at the same time; plastic screen tubes were run in hole after completion. Now a set of multi-coalbed multi-branch horizontal wells have been drilled which connected four inclined wells; the total daily gas production is up to 50 000 m3/d. The drilling and completion technique for multi-coalbed, multi-branch horizontal wells has become the demonstration technology for efficient development of medium coal methane at east edge of Erdos Basin, which achieves remarkable economic and social benefits.