Detection Indexes of Coalbed Methane Drainage Effect and Evaluation Method in Coal Mine Area

The ground drainage effect of coalbed methane (CBM) in Jincheng Coal Mine area was detected by using numerical simulation and measured method. It was measured that the CBM content by ground drainage after 5 years was declined from 21.58 m³/t to 10.74 m³/t and the value of declined rate of the CBM content was 50.2%. After being drained by 5 years and 10 years, the average value of the CBM content declined rate within the well group was 43.3% and 58.2% using the numerical simulation method respectively. After 15.6 months and 29.6 months by underground mine drainage, it was measured that the CBM content declined from 20.1 m³/t to 11.24 m³/t and 4.76 m³/t respectively. According to the measured CBM content and the numerical simulation results of coal reservoir, combining with the practical experiences of CBM drainage in coal mine areas and the related management stipulations in China, and considering the safety of CBM drainage and the resource benefits in coal mine area comprehensively, it is suggested that the CBM content and the reduced rate (or recovery rate) of CBM content are taken as the detection and evaluation indexes of CBM drainage effect in coal mine area, and the detection and evaluation technical methods of CBM drainage effect in coal mine area are established respectively.