Progress and study on exploration and production for deep coalbed methane

According to the results of China’ s new round of CBM resource evaluation in 2006, coalbed methane (CBM) resources were mainly concentrated in the deep seams (coal seam depth in 1 000-2 000 m),but studies re- lated to deep CBM theory were limited,and exploration operations were rare. In this paper,based on the main distribu- tion of coalbed methane resources in the deep coal seams in China,the current deep coal seam mining and CBM explo- ration wells in Erdos basin and Junggar basin indicate that the exploration and development of deep CBM shows some potential,although the appraisal wells of commercial value occur only in a few pilot areas. By comparing different coal seam depth studies in Yanchuannan block in Erdos basin,it could be concluded that the key parameters such as the gas content,gas saturation,reservoir pressure and critical desorption pressure of deep coal seams were commonly high- er than in shallow coal seams. In general,it was a complex system engineering to evaluate the factors of deep CBM pro- duction,which generally include resource geology and development technology. Geological conditions of deep CBM were more complicated than those of shallow CBM,which resulted in that the development technology applied in these area was difficult. According to the experience of exploration and production in Yanchuannan pilot CBM project,it was fracturing technique adapted for deep geological condition and draining technology that responsible for favorable well production. Based on this study,it is proposed that the improved well production way of deep CBM is to do the evaluation and prediction of sweet point,to study the fracturing technology and to manage drainage working system.