Inspirations of typical commercially developed coalbed methane cases in China

The coalbed methane resources in China are characterized by wide geographical distribution, large time span, significant quality differences and complex coal-forming conditions, thus establishing a coalbed methane development system suitable for geological characteristics can greatly reduce the difficulty of mining and promote industrial development. Through the systematic summary of typical successful cases of commercial development of coalbed methane in China over the past 30 years, including shallow high rank coalbed methane in Panzhuang, shallow medium-low rank coalbed methane in Baode, medium deep coalbed methane in South Yanchuan, deep coalbed methane in Daning-Jixian, thin coalbed methane in Panhe, coal and coalbed methane co-mining in Huainan and Huaibei, gas drainage in four regions linkage in Jincheng and gas drainage in three regions linkage in Songzao, the main understanding is as follows:The shallow high rank coal in Panzhuang and Panhe have high gas content, high permeability, and weak hydrodynamics under the synclinal-hydrological gas control model, forming a single-layer development model of single/multiple horizontal wells for shallow high rank coal. The vertical well multi combination three-dimensional development model is formed based on the comprehensive gas bearing characteristics of thin ultra-thin coal seams in multiple layers. The low rank coal in Baode has high gas saturation, stable structure, and the presence of biogas supply under the positive structure-hydrological gas control model, forming a shallow low rank coal big platform cluster well development model. The coal seams in southern Yanchuan are relatively buried deep, with low porosity, low permeability, low pressure, and weak hydrodynamics, forming an effective support- fine drainage development model for medium-deep coal seam. The coal seam located in the west of Daning-Jixian has a deep burial depth, low porosity and permeability, high free gas content, and weak hydrodynamics, forming a deep coal volume fracturing horizontal well development model. The Huainan and Huaibei mining area have developed a group of soft, low-permeability, and high gas coal seams, forming a development model of medium-long distance “pressure relief of mining protective layer ground and underground three-dimensional drainage”; The Jincheng mining area has developed primary structure coal seam wit high permeability and gas content, forming a development model of “four zone linkage ground and underground three-dimensional drainage”; The Songzao mining area has developed a group of soft and low-permeability prominent coal seams, forming a development model of “three zone supporting three super-advanced enhanced permeability drainage”. The development of coalbed methane in China has basically realized the breakthrough of depth limit, thickness lower limit, single type gas reservoir development, and complex structural backgrounds, forming a geological theoretical understanding of coalbed methane development with Chinese characteristics. The potential for coalbed methane development in the northwest and northeast middle-low rank coal seams, complex structural areas in the south, and deep-ultra deep coalbed methane in large basin abdomen still needs to be further explored. Significant breakthroughs have been achieved in the development of coalbed methane in China under different burial depths, coal ranks, thicknesses and tectonic settings. which is expected to promote and lead a new pattern of global coalbed methane industry development.