High production indexes and key factors influencing coalbed methane (CBM) horizontal well productivity

摘要

To evaluate the development effects systematically, the coalbed methane (CBM) production performance of 58 horizontal wells in the Fanzhuang block of the Qinshui Basin was tracked and correlations between the gas rate per 100 m and the influencing factors were discussed by single and multiple factor analysis. The grey correlation analysis (GRA) was then applied to quantitatively evaluate the key geological factors influencing CBM horizontal well productivity. The results show that the order of geological factors influencing horizontal well productivity is burial depth, gas production capacity (C), gas production potential (P), ratio of critical desorption pressure to initial reservoir pressure (p_c/p_i), gas content, and thickness, where the gas production potential and capacity can reflect the comprehensive impacts of thickness, gas content, and permeability. The larger the gas production potential or capacity is, the better the gas productivity is. The high production indexes are the depth of 300～500m, p_c/p_i >0.6, P>130m~4/t, C>60 mD×m~4/t, and far away from the faults.