煤层气成因类型及其地球化学研究进展

煤层气成因研究涉及到煤层气的形成机理、运移和逸散、母质特性和形成环境等,并与盆地演化和资源评价等有密切的关系。从地球化学角度对现阶段煤层气成因研究成果进行分析,系统总结了各成因类型煤层气的地球化学研究进展,并指出了存在的问题和今后的发展趋势。研究表明:煤化作用各阶段形成的不同成因类型煤层气具有不同的成因机理、气体成分特征和δ13C(CH4),δD(CH4)和δ13C(CO2)等同位素组成差异;稀有气体在煤层气成因研究过程中能够提供丰富的地球化学信息;不同的煤层气形成机制下,煤岩饱和烃和芳香烃等生物标志化合物表现出不同的降解特征;地下水化学组成的变化和微生物的活动对煤层气的形成和运移有重要影响;微生物产气的探索将为煤制气提供新思路。最后指出,煤层气成因综合识别、复杂地质演化条件下不同成因类型煤层气的赋存特征、与煤制气相关的煤层气形成机制探索等几个方面将是今后研究中值得重视的问题。

Origin types of CBM and their geochemical research progress

Researches on the origin of Coalbed Methane (CBM) involve information mechanism，migration and dissipation，gas source rock properties and environmental factors.Besides，they have intimate relationships with basin evolution and resource assessment.From the view of geochemistry，the author analyzed the research achievements on CBM origin of this stage，summarized the geochemistry characteristics of different origins and pointed the problems and research directions.The authors consider that different genetic types not only have different characteristics in formation mechanism，but also have differences in gas composition and distribution of δ13C(CH4)，δD(CH4)and δ13C(CO2).The noble gases can provide abundant geochemistry information in discrimination of different origin types.During the coalification and generation of CBM，saturated hydrocarbon and aromatic hydrocarbon exert different degradation characteristics.Groundwater chemistry composition and microbial activity obviously influence the formation of CBM and its migration.Comprehensive recognition of CBM origin，the occurrence of different origin gas under complex evolution conditions and CBM formation mechanism research related to coal gasification are the most important research problems in the future.