Abstract: Coal serves as the bedrock and stabilizer in China’s energy supply system, and coalbed methane(CBM), which co-occur with coal, is a crucial alternative resource for continuously increasing reserve and production. To elucidate the geological conditions for the coordinated development of coal and CBM, this study systematically reviews the types of prototype basins in major coal-forming periods and evaluates their controls over the occurrence and distribution of CBM. Based on geological history analysis, tectonic evolution comparisons, and basin classification, combine with a comprehensive study of coal-forming plants, coal-forming periods, sedimentary environments, and coal-seam geological characteristics, the paper establishes coal-forming models under different tectonic settings in China. The results indicate that the amalgamation, extension, and subsequent transformation processes of three tectonic domains, namely the Paleo-Asian Ocean, Paleo-Tethys Ocean, and Paleo-Pacific Ocean, control the sediment provenance, accommodation space, and burial evolution of coal-bearing basins in China. Four main types of coal-forming basins are identified as below. (1) The Carboniferous-Permian cratonic depression-type basins in North China were characterized by the development of marine-continental transitional sedimentary systems. Benxi and Taiyuan formations were deposited during a transgressive-regressive cycle, promoting the continuous development of coal seams. The subsequent deposition of Shanxi Formation occurred under regressive conditions, with coal accumulation predominantly in fluvial-deltaic systems while exhibiting overall seam continuity. (2) The Late Permian cratonic depression-type and intracontinental rift-type basins in South China were characterized by frequent sea-level fluctuations and paleoland distribution controlling sedimentation, coexistence of tidal flat and delta systems, and numerous coal seams with thin individual layers. (3) The Early-Middle Jurassic intracontinental rift-type and intermontane depression-type basins in Northwest China were characterized by the development of medium- to low-rank thick coal seams in lake deltas, with significantly tectonic deformation. (4) The Early Cretaceous continental faulted sag-type basins in Northeast China were characterized by relatively independent depressions in the basin, with well-developed and numerous thick coal seams. In North China, coal seams within the Benxi, Taiyuan, and Shanxi formations exhibit continuous and stable distribution, and the spatial heterogeneity of CBM is primarily controlled by the maximum burial depth (which determines the coal vitrinite reflectance), later tectonic uplift, and preservation conditions. In South China, coal seams generally exhibit high thermal maturity and significant hydrocarbon generation potential, but individual coal seam is relatively thin. The study should focus on high-quality resources of individual coal seam and three-dimensional development of multi-seams. In Northwest China, the relatively low thermal maturity and extensive weathered-oxidized zones necessitate a focus on basin slope belts, deep-to-middle uplift zones, and structural trap areas. In Northeast China, coal seams are dominated by low-rank coals, where the regions with thick coal seams and the secondary biogenic gas recharge zones represent key areas for realizing future development potential. The geological characteristics and polycyclic tectonic evolution of coal-forming basins in China collectively control the distribution patterns of CBM. Therefore, it is essential to develop basin-specific, high-efficiency development models for multiple types of CBM resources, tailored to the geological characteristics of each basin type.

Key words: coal-forming period, coal-forming model, prototype basin, coalbed methane, coal-rock gas

摘要： 煤炭是中国能源供应的压舱石与稳定器,与之共生的煤层气是天然气持续增储上产的重要接替资源。为阐明中国煤与煤层气协同开发的地质基础,系统梳理了中国主要成煤期的原型盆地类型及其对煤层气赋存与分布的控制作用。基于地质历史分析、构造演化对比和盆地类型划分,综合成煤植物、成煤时代、沉积环境和煤层地质特征,建立了中国不同构造背景下的成煤模式。研究结果表明,古亚洲洋、古特提斯洋和古太平洋3大构造域的拼贴—伸展—改造进程控制了中国成煤盆地的物源输入、沉积空间和埋藏演化,并可划分为4类主要成煤盆地:①华北地区石炭纪—二叠纪克拉通内坳陷型盆地发育海陆过渡相沉积体系,在本溪组—太原组沉积期处于海侵—海退过渡环境,煤层连续性好,在山西组沉积期海退背景下以河流—三角洲沉积体系成煤为主,煤层整体保持连续;②华南地区晚二叠世克拉通内坳陷—陆内裂陷型盆地受海平面频繁波动与古陆分布控制,潮坪与三角洲沉积体系并存,煤层的单层薄、层数多;③西北地区早—中侏罗世陆内裂陷—山间坳陷型盆地在湖泊三角洲中发育中—低煤阶厚煤层,受构造变形影响显著;④东北地区早白垩世陆相断陷湖盆凹陷型盆地内部凹陷相对独立,厚煤层发育且层数较多。华北地区本溪组—太原组煤层和山西组煤层连续稳定,煤层气的差异分布受控于历史最大埋深(其决定了煤岩的镜质体反射率)、后期构造抬升和保存条件;华南地区煤层总体的热演化程度高、生烃量大,但单层较薄,需重点关注单层优质资源及多层立体开发;西北地区煤层的热演化程度偏低且风化氧化带厚度大,应聚焦盆地斜坡带、深部—中部隆起区和构造圈闭发育区;东北地区的煤层以低煤阶煤为主,厚煤层区域和次生生物气补给区是未来开发的潜力区。中国成煤盆地的地质特征及其多旋回构造演化过程共同决定了煤层气的分布规律,需依据不同盆地类型,构建与之相适应的多类型煤层气资源高效开发模式。

关键词: 成煤时代, 成煤模式, 原型盆地, 煤层气, 煤岩气