Thirty years of industrial development of coalbed methane in China: Review and prospects

Background Marked by the establishment of China United Coalbed Methane Corporation Ltd. in 1996, coalbed methane development in China entered the stage of industrialized development. A systematic review of the development history, key technologies, and future trends of China’s coalbed methane industry is of great significance for deepening the understanding of coalbed methane development mechanisms and promoting high-quality industrial development. Based on a systematic investigation of relevant literature and data from China and abroad, this paper comprehensively a nalyzes the industrialization process of China’s coalbed methane industry from the perspectives of development stages, technological evolution, and future trends.

Progress  (1) Since 1996, coalbed methane development in China has generally experienced three stages: establishment of the industrial system and cultivation of commercial demonstrations, commercial operation and large-scale development, and breakthroughs in deep coalbed methane with expansion of resource types. Its evolution is characterized by a transition from technology introduction to independent innovation, from pilot demonstration to commercial operation, and from shallow coalbed methane development to deep coalbed methane exploration and development. (2) In response to the complex geological conditions of coal reservoirs, China has gradually established a technical system covering geological understanding, exploration evaluation, development engineering, drainage and production control, surface gathering and transportation, and digital-intelligent operation. This has promoted the evolution of coalbed methane development from single-technology application to multi-technology collaborative optimization. (3) Geological understanding has expanded from mine gas geology to systematic understanding of deep coalbed methane. Exploration evaluation has evolved from parameter wells and static resource assessment to sweet spot evaluation and geology–engineering integrated evaluation. Development engineering technologies have advanced from vertical-well fracturing to multi-branch horizontal wells, staged fracturing of horizontal wells, and reservoir stimulation of long horizontal sections in deep coal seams. Drainage technology has shifted from experience-based management to standardized, intelligent, and whole-process dynamic control. Surface systems have developed from dispersed single-well facilities to low-cost gathering and transportation, modular construction, and digital-intelligent operation systems. (4) China has established a complete coalbed methane development technology system, with geology–engineering integration and sweet spot prediction as the foundation, staged fracturing of horizontal wells and volumetric stimulation as key technologies, intelligent drainage and multi-layer coordinated production control as production guarantees, and low-pressure gathering and transportation and digital-intelligent operation as operational support.

Prospects  The development of China’s coalbed methane industry will show further trends of resource expansion toward deep and multiple types, technological upgrading toward integration and intelligence, and industrial development toward low cost and coordination. Future coalbed methane development will focus on five major fields: stabilizing and increasing production in mature areas, expanding deep coalbed methane development, three-dimensional development of multiple thin coal seams, integrated development of coal-measure natural gas, and roof fracturing development of coal seams in complex structural areas. The 30-year industrialization history of China’s coalbed methane industry is essentially a process of continuous deepening of resource understanding, ongoing evolution of key technologies, and gradual maturation of the industrial system, which can provide theoretical and practical references for the high-quality development of China’s natural gas industry.