Oil & Gas Geology ›› 2021, Vol. 42 ›› Issue (5): 1078-1088.doi: 10.11743/ogg20210506

• Petroleum Geology • Previous Articles     Next Articles

Shale oil exploration potential in central Ordos Basin: A case study of Chang 7 lacustrine shale

Bojiang Fan1(), Yue Jin1, Liang Shi1, Yating Li1, Weichang Chen2   

  1. 1. School of Petroleum Engineering and Environment Engineering, Yan'an University, Yan'an, Shaanxi 716000, China
    2. College of Geography and Planning, Jining Normal University, Ulanqab, Inner Mongolia 012000, China
  • Received:2020-06-08 Online:2021-10-28 Published:2021-10-26

Abstract:

The Chang 7 member (the seventh member of Yanchang Formation) lacustrine shale in the central Ordos Basin is largely thin and made up of either pure shale or shale interbedded with sandy laminas or thin sand layers of shallow to semi-deep lake facies.Its high content of sand seems quite ideal for achieving positive stimulation responses through fracturing.A discussion and comparison of shale oil exploration targets in the area is recommended for gaining such response.However, no such efforts have been made so far.To judge the oil potential of the shale, samples are collected from both pure shale and shale interbeded with sandy lamina to compare hydrocarbon generation and hydrocarbon expulsion capacities based on geochemical tests and analyses.The results show that shale mainly composed of sapropelic organic matter has higher organic matter abundance than shale interbeded with sandy lamina composed of mixed organic matters.Both are at a low to moderate maturity stage but shale interbeded with sandy lamina is inferior to pure shale in terms of hydrocarbon generation capacity.Both can effectively expel hydrocarbons.Shale interbeded with sandy lamina contains oil at 7.22 mg/g and pure shale 9.42 mg/g.Both can be economically developed and share similar oil saturation index, indicating great oil potential.

Key words: sandy laminas, shale, shale oil, exploration potential, Yanchang Formation, Ordos Basin

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