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煤层气是一种由煤生成，以ＣＨ４为主的非常规气。它与常规气藏不同，主要以吸附状态储集在煤岩过程中形成的三维储集网络内，其储集量远大于储存在孔隙、裂隙中的游离气和溶解气量。正是这一特点决定了煤层气的运移、扩散微弱，易于大面积成藏。在地质历史演化过程中，后期构造相对稳定、水动力系统完好、煤层处于封闭状态是形成良好煤层气藏的必要条件。成煤期具有全球意义，我国与全球有极为相似的分期特征，出现在阿尔卑斯和华力西两个构造期。我国５个构造区分属以陆块为代表的稳定区和以陆缘为代表的活动区，其中塔里木华北区和华南区为稳定区，几个成煤期都利于煤层气盆地的成生与保存。
CBM is a kind of unconventional gas that is generated from coal and mainly CH4. Unlike the conventional gas reservoirs, it mainly accumulates in the three-dimensional reservoir network formed during coal and rock adsorption in an adsorbed state, which is much larger than the free and dissolved gas stored in pores and fractures. It is this feature that determines the migration of CBM, which is weak and easy to accumulate in large areas. During the geological history evolution, the post-tectonics are relatively stable, the hydrodynamic system is intact, and the coal seam is in a closed state, which is a necessary condition for the formation of a good coalbed gas reservoir. Coal-forming period has global significance. China has very similar staging features with the whole world, appearing in two tectonic periods of the Alps and Variscan. Five structural tectonics in China belong to the stable zone represented by land mass and the active zone represented by the continental margin. Among them, North China and South China in Tarim are stable areas, and several coal-forming periods are beneficial to the formation and preservation of coalbed methane basins. .