Advances in Earth Science ›› 2015, Vol. 30 ›› Issue (5): 589-601. doi: 10.11867/j.issn.1001-8166.2015.05.0589

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Sedimentary Characteristics and Accumulation Conditions of Shallow-biogenic Gas for the Late Quaternary Sediments in the Changjiang River Delta Area

Chunming Lin 1, Xia Zhang 1, Zhenyu Xu 2, Chengwen Deng 1, Yong Yin 3, Qiuquan Cheng 4   

  1. 1. State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210046, China
    2. Nanjing Central China Geological Survey, Nanjing, 210016, China
    3. Geographic and Oceanographic Sciences, Nanjing University, Nanjing, 210023, China
    4. Wuxi Research Institute of Petroleum Geology of SINOPEC, Wuxi, 214151, China
  • Online:2015-06-09 Published:2015-05-06

Chunming Lin, Xia Zhang, Zhenyu Xu, Chengwen Deng, Yong Yin, Qiuquan Cheng. Sedimentary Characteristics and Accumulation Conditions of Shallow-biogenic Gas for the Late Quaternary Sediments in the Changjiang River Delta Area[J]. Advances in Earth Science, 2015, 30(5): 589-601.

This paper deals with the characteristics, distribution pattern, and accumulation features of the late Quaternary shallowbiogenic gas in the Changjiang River delta area based on the detailed analysis of sedimentary characteristics, facies, and sequence stratigraphic framework, and organic geochemistry. The results show that there are three episodes of incised valley developing in the study area, resulting in the formation of distinct sedimentary sequences. The early two systems are incomplete due to the late strong incision and erosion, and are characterized by the superposition of fluvial sediments; while the last postglacial sequence is relatively complete with different sedimentary facies assemblages. The shallow gas in the study area has a biogenic origin, and the gas reservoir belongs to a syngenetic type of self-generating and self-reservoir. The muddy clay and silty clay of estuary-floodplain and shallow marine facies occur as both gas source and cap sediments, and the muddy clay of the shallow marine facies can be used as good regional cap beds. As main biogenic gas reservoirs, the sand sediments of estuary-floodplain and fluvial channel facies distributed within the incised valleys. The study area and its adjacent area are characterized by several times of incised valleys, in favor of the development of gas source, cap and reservoir sediments. As a consequence, the incised valley is the most favorable zone for the shallow-biogenic gas exploration, and the sand bodies of estuary-floodplain and fluvial channels especially the former within the incised valleys have the high priority of exploration.

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