Selection of favorable areas for coalbed methane development based on economic benefit evaluation: A case study of Yangjiapo block in eastern margin of Ordos Basin

The selection of favorable areas for coalbed methane（CBM） development provides critical assurance for reducing investment risks. Taking the No. 4+5 coal seam in the Shanxi Formation and the No. 8+9 coal seam in the Taiyuan Formation of the Yangjiapo block in the eastern margin of the Ordos Basin as research objects, a development potential evaluation system was established by optimizing influencing factors for combined layer development. Based on CBM development characteristics, production capacity equations were used to predict daily gas production. Economic benefit evaluation was conducted considering geological and engineering features, and favorable areas for single-seam and combined layer CBM development were ultimately delineated. The results showed that the favorable areas for combined layer development in the Yangjiapo block were located in the central and northeastern parts of the block. The economic threshold daily gas production for single-seam development of the No. 4+5 and No. 8+9 coal seams and their combined layer development were 982, 1,063, and 1,270 m3, respectively. A small portion in the northwest was suitable for single-seam development, where sequential development of the No. 4+5 and No. 8+9 coal seams could enhance production. The central and southern parts of the block were suitable for combined layer development, where optimizing drainage and production schedules could improve gas yield. For reserve areas, further clarification of geological conditions and optimization of construction techniques were needed before evaluating development feasibility. These findings enrich the methodology for selecting favorable areas in multi-seam CBM zones and provide guidance for future development planning in the study area.