China Petroleum Exploration ›› 2021, Vol. 26 ›› Issue (6): 110-124.DOI: 10.3969/j.issn.1672-7703.2021.06.008

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Gas accumulation conditions and resource potential in coal measure strata of the Permian Shanxi Formation in the eastern Ordos Basin

Zhang Chunlin1,Zhang Jiaqi2,3,Song Zezhang2,3,Jiang Fujie2,3,Fan Liyong4,Pei Yu2,3   

  1. 1 PetroChina Research Institute of Petroleum Exploration & Development; 2 State Key Laboratory of Petroleum Resources and Prospecting; 3 College of Geosciences, China University of Petroleum (Beijing);4 PetroChina Changqing Oilfi eld Company
  • Online:2021-11-15 Published:2021-11-15

Abstract: The coal measure gas resources are abundant of the Permian Shanxi Formation of the Upper Paleozoic in Ordos Basin. Therefore, it is of great signifi cance to analyze the gas accumulation conditions in coal measure strata and predict the gas resource potential, so as to deepen the exploration of unconventional gas in Ordos Basin. By taking Shanxi Formation as the study object, the geological and geochemical characteristics of source rocks and the mineral composition, pore structure, physical properties of reservoirs are studied in details in this study based on core observation and stratigraphic characteristics in single well, as well as a series of lab test results such as SEM, XRD analysis and gas adsorption experiments. Then the gas accumulation conditions of coal measure strata are analyzed and the gas resource potential is predicted. The results show that: (1) The source rocks of Shanxi Formation are characterized by relatively thin thickness of a single layer,multiple layers, thick in the east and thin in the west, high TOC, organic matter types of Type Ⅱ2 and Ⅲ, high mature to over mature with R o ranging from 1.2%-2.6%, and great gas generation potential; (2) The sandstone reservoir of Shanxi Formation is mainly composed of lithic quartz sandstone and lithic sandstone, and the reservoir space is dominated by dissolution pores of lithiclast with the porosity of 2%-10%; The mineral composition of mudstone is mainly quartz and clay mineral, and the reservoir space types include organic pores and micro fractures,with complex pore throat structure; (3) The estimated gas resource of Shanxi Formation is about 306879.79×108m3 by using the Monte-Carlomethod, among which the 2nd member of Shanxi Formation has large gas resource potential of 177001.15×108m3.

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