Key technology progress of surface extraction project deployment based on coordinated development of CBM and coal

The surface extraction of CBM in coal mine area has the multiple effects of improving the efficiency of safe coal mining, using CBM resource cleanly and reducing gas emission. From the 11th five-year plan to the 13th five-year plan period, based on the national major oil and gas projects in coal mining areas, and based on the guiding principle of coordinated development of CBM and coal in coal mining areas, the characteristics and existing problems of surface CBM extraction and deployment in coal mining areas were studied, according to the influence of coal mining, the surface extraction of CBM in coal mining area is divided into two types: pre-extraction and mining extraction. Based on the study of the objects, time and space characteristics of the two kinds of extraction methods, the engineering deployment systems of ground pre-extraction and mining extraction are summarized respectively. Based on the analysis of the present situation of CBM development technology in non-coal mining areas, the technology system of CBM surface pre-extraction in coal mining areas is sorted out, and the characteristics of CBM extraction technology and the variation regularity of key reservoir parameters are studied based on the understanding of gas migration law of permeability control,  the extraction simulation and prediction method of mining is formed. According to the safety effect of surface extraction in coal mining area, the evaluation index of indirect economic benefit of surface drainage in coal mining area is put forward, which is the difference between the cost of gas disaster treatment before surface extraction and the cost of gas disaster treatment after surface extraction, a comprehensive economic evaluation method for CBM surface extraction engineering is established. The surface extraction project deployment and related technology are the key means to predict the low-cost and high-return effect of surface CBM and the coordinated development of CBM and coal resources in coal mining area.