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

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.