Oil & Gas Geology ›› 2017, Vol. 38 ›› Issue (6): 1005-1018.doi: 10.11743/ogg20170601

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Mechanisms for gas accumulation and enrichment in tight sandstone reservoir in rift basins:Cases from the Songliao Basin and the Bohai Bay

Li Jian1,2, Jiang Xiaohua1,2, Wang Xiuqin1, Cheng Honggang1,2, Hao Aisheng1,2   

  1. 1. Research Institute of Petroleum Exploration and Development, Department of Gas Geology, Langfang, Hebei 065007, China;
    2. The Key Laboratory of Gas Reservoir Formation and Development, CNPC, Langfang, Hebei 065007, China
  • Received:2016-09-28 Revised:2017-08-03 Online:2017-12-28 Published:2018-01-08

Abstract: Tight sandstone gas in rift basins is a new play concept for exploration.This paper takes the Songliao Bbasin and the Bohai Bay Basin as case areas to systematically investigate the mechanisms for gas accumulation and enrichment in tight sandstones.The reservoir characteristics of tight sandstone gas in rift basins have been studied,which are different from those of craton basins.As to gas accumulation mechanism,it is demonstrated that multiple factors have accelerated the generation of gas by source rock,and multiple sediment provenance have ensured deposition of favorable reservoirs.Both the long gas migration distance and tightening of the reservoir before gas charge favors gas accumulation in multiple sections over large areas.For the enrichment controlling factors,it is concluded that the distribution of gas pools and source kitchens are located along the faulted troughs,the reservoir quality is controlled by facies and tectonic belts,while the vertical distribution of flowable gas sections is controlled by development of secondary porosity zones.Finally,the exploration potential and future exploration concepts of these two basins is analysed.

Key words: gas reservoir characteristic, accumulation mechanism, tight sandstone gas, rift basin, Songliao Basin, Bohai Bay Basin

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