煤系泥页岩生烃条件分析——以临清坳陷东部上古生界为例

Analysis of Coal Measures Argillutite Hydrocarbon Generation Conditions—A Case Study of Upper Paleozoic Group in Eastern Linqing Depression

页岩气资源逐渐成为矿产能源研究的热点,目前的研究大都集中在对海相和湖相页岩气的研究,而对煤系页岩气的研究较为薄弱。临清坳陷东部地区石炭系-二叠系煤系泥页岩主要发育在滨浅海、潟湖-潮坪和浅水三角洲环境,太原组泥页岩最为发育,以东北部和西南部厚度最大;泥页岩有机质含量高-特高,整体表现为自西北向东南方向逐渐增高,且太原组最高,本溪组次之;泥页岩干酪根主要为Ⅱ-Ⅲ,泥页岩的生烃效率整体偏低,且以太原组最高,本溪组次之。泥页岩经历了四次生烃过程,生烃高峰发生在新生代,具有晚期成烃特征;泥页岩有机质热处于低成熟-成熟阶段,页岩气主要为生物气和热解混合气。总体而言,太原组泥页岩生烃条件最佳。

The shale gas resources are gradually become the mineral energy research hotspot. At present, studies are mostly concentrated on marine and lacustrine facies shale gases, while relatively weak on coal measures shale gas. In the eastern Linqing depression area, Permo-Carboniferous coal measures argillutite was mainly developed in littoral, shallow sea lagoon-tidal flat and shallow water delta environments. The argillutite has mostly developed in the Taiyuan Formation, and thickness is largest in northeastern and southwest？ern parts. The organic matter content is high-extremely high in argillutite, as a whole, gradually increasing from northwest to southeast, and highest in Taiyuan Formation, while Benxi Formation the second. Kerogen types in argillutite are mainly categories Ⅱ and Ⅲ, argillutite hydrocarbon generation efficiency overall on low side, but highest in Taiyuan Formation, then in Benxi Formation. Argillutite has experienced 4 hydrocarbon generation processes, peaked in Cenozoic with late hydrocarbon generation features. Argillutite organic matter thermal evolution is in low mature to mature stages, shale gas is mainly mixture of biogenic gas and pyrolysis gas. Overall, the Taiyuan Formation argillutite has best hydrocarbon generation conditions.