全球煤层(岩)气形成分布、富集模式及发展前景OA

China has made significant breakthroughs in the exploration of coal-rock gas.By the end of 2025,the proven reserves of coal-rock gas have exceeded 1×1012 m3,and a coal-rock gas field with an annual output of 300×104 t oil and gas equivalent has been built in the Daning-Jixian Block of the Ordos Basin.Globally,the development of coalbed methane(CBM)is mature,but the resource potential of coal-rock gas remains to be confirmed.To get a deep insight into the distribution characteristics and enrichment patterns of coal-rock gas,this paper reviews the main coal-forming periods,coal distribution characteristics,and cases of coal-rock gas development in typical coal-bearing basins worldwide,and then systematically discusses the enrichment conditions,resource potentials,and development prospects of coal-rock gas in different types of basins.The following results are obtained.First,the formation and distribution of coals globally are controlled by the evolution of plants,paleoclimates and regional tectonics.The three major coal-forming periods are the Late Carboniferous–Permian,the Jurassic–Cretaceous,and the Paleogene–Neogene.There are two major coal-bearing belts,i.e.,the east-west coal-forming belt in Eurasia(dominantly the Carboniferous–Permian coals),and the north-south coal-forming belt in America(dominantly the Jurassic–Cretaceous coals).Second,the distribution of global coal and coal-rock gas resources shows significant differences in geological age,coal rank,and burial depth.The proportion of coals in the Paleozoic,Mesozoic,and Cenozoic is approximately 60%,35%,and 5%,respectively,while the proportion of coal-rock gas is 74%,21%,and 5%,respectively.Third,the Mesozoic is dominated by low-to medium-rank shallow CBM,while the Paleozoic coals have a high degree of thermal metamorphism and good preservation conditions,with great resource potential of coal-rock gas.Fourth,the enrichment of coal-rock gas can be classified into two patterns,i.e.,the detained"original"pattern,and the transformed"mixed"pattern.In the detained"original"pattern,thermogenic gas is dominant,the gas is enriched in situ after partially escaping,and the enrichment process is controlled by reservoir conditions.The transformed"mixed"pattern is evolved from the original gas reservoir after water invasion and transformation,secondary biogenic gas supply,or exogenous gas charging.In conclusion,key factors such as coal rank,gas source and preservation conditions shall be considered comprehensively in the exploration and development of coal-rock gas in different coal-bearing basins worldwide.The research results further enrich and deepen the understanding on global coal-rock gas resources,and provide theoretical guidance for the reserve and production increase of coal-rock gas in China.