Evaluation of legacy coalbed methane resources and optimization of gas drainage zones within the Songzao mining area

Legacy coalbed methane (CBM) extraction holds substantial significance in advancing resource development within closed mines, fostering unconventional clean energy production, and facilitating the optimization and transformation of mining regions. The volume method was employed to estimate the legacy CBM resources in the Songzao mine area. Principles for selecting optimal legacy CBM extraction wells and their deployment strategies were proposed, and a benefit analysis of legacy CBM extraction in closed mines across various power generation scenarios was conducted. The study indicates that the total coalbed methane resources in the Songzao mine area are estimated to range between 6.553 and 6.632 billion cubic meters. The Songzao coal mine has been identified as the primary site for coalbed methane extraction from depleted zones, with its gas gathering zone in a designated level and area selected as the initial extraction site. Emission reduction benefits represent a critical economic factor influencing the viability of legacy CBM extraction in closed mines, significantly alleviating the capacity demands of individual wells. The principles of well selection and deployment for pumping and mining effectively guide the identification of optimal coalbed methane extraction sites in legacy hollow areas, offering theoretical support for exploiting legacy resources in closed mines and advancing the development of coal mining regions.