临清坳陷东部高古4井煤成气藏成藏特征

Hydrocarbon accumulation characteristics of well Gaogu 4 coal-derived gas reservoir in eastern Linqing depression

  • 摘要: 为了查明临清坳陷东部上古生界煤成气藏的勘探潜力,通过多种方法对其成藏条件进行研究并对高古4井煤成气藏进行解剖。结果表明:该区主要发育煤岩和砂泥岩互层沉积,其中煤岩和泥岩可作为烃源岩,干酪根类型多为Ⅲ型和Ⅱ2型,生气为主,砂体可作为储层,与煤岩和泥岩形成储盖组合;高古4井太原组气藏中的天然气主要来源于本组煤岩,储集空间以溶蚀孔隙和微裂缝为主,上覆煤岩封盖和侧向泥岩遮挡形成断块圈闭,定型于新近纪,烃类聚集主要发生于新近纪之后,其它组段砂岩由于侧向遮挡条件不利而未成藏。高古4井煤成气成藏具有"近源自生自储、超晚期生烃成藏、断层侧向遮挡"的特点,发育类似成藏条件的区域应该成为该区今后勘探的重点。

     

    Abstract: In order to find out the exploration potential of the coal-derived gas reservoir of the Upper Paleozoic of eastern Linqing depression, many ways were used to study its reservoir-forming conditions and analyze Gaogu 4 coal-derived gas reservoir. The results show that eastern Linqing depression develops coal and sandstone-mudstone. The coal and dark mudstone could act as source rocks, whose kerogen types are mainly or Ⅲ Ⅱ2, and dominatingly generate gas. The sandstones could act as reservoirs and the coal and mudstones could act as cap rocks. The gas in Taiyuan Formation of well Gaogu 4 reservoir is mainly from the coal in the same formation, and the dissolved pores and micro-fractures are the main pore types. The gas was accumulated in Neogene-Quaternary after the shaping of the trap. The coal-derived gas pool is characterized by "near-source, self-generating, self-accumulating", "super-late hydrocarbon generating and accumulating" and "favorable lateral barrier condition". The areas developing similar conditions should be the focus for future exploration.

     

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