Affiliation:
1. 1 Institute of Geological Exploration and Development of CNPC Chuanqing Drilling Engineering Chengdu 610051 China
2. 2 Department of Railway Engineering Sichuan College of Architectural Technology Chengdu 610399 China scac.edu.cn
3. 3 Shale Gas Evaluation and Exploitation Key Laboratory of Sichuan Province Chengdu 610213 China
4. 4 School of Geoscience and Technology Southwest Petroleum University Chengdu 610500 China swpu.edu.cn
5. 5 Natural Gas Geology Key Laboratory of Sichuan Province Chengdu 610500 China
Abstract
Abstract
To identify the factors controlling high-quality deep shale gas reservoirs and the exploration and development potential of the Lower Paleozoic marine shale in the Sichuan Basin, the sedimentary environment of deep shale was comprehensively analysed using core thin sections, scanning electron microscopy, gamma ray spectrometry logging, and elemental logging data. In addition, the geological conditions of deep shale gas accumulation and the effect of tectonic processes on the preservation conditions are discussed based on the experimental data of mineral composition analysis, geochemical features, and reservoir spatial characteristics. (1) The sedimentary environment changes from an anoxic water environment to an oxygen-rich oxidizing environment from bottom to top in the Wufeng-Longmaxi Formation in southern Sichuan. The deep shale gas reservoir shows overpressure and rich gas characteristics, namely, high formation pressure (2.0~2.2), high porosity (20%~55%), and high gas content (4.0~5.0 m3/t). (2) The favourable sedimentary environment has a higher hydrocarbon generation potential and deposits of rich organic matter and siliceous particles. During the hydrocarbon generation process, the rich organic matter generates a large number of organic pores and a large specific surface area, which provides the main reservoir and adsorption space for free and adsorbed shale gas. A large number of biogenic siliceous particles provide a solid rock support framework for the shale reservoir, thereby maintaining excellent reservoir physical properties. (3) Late and small stratigraphic uplifts result in a short shale gas escape time and favourable preservation conditions. Additionally, the small-scale faults and a high-angle intersection between the fracture strike and the geostress direction are conducive to the preservation of shale gas. (4) A high formation pressure coefficient, a sedimentary environment rich in organic siliceous deep-water continental shelf microfacies, and a relatively stable tectonic structure are conducive to the accumulation of deep shale gas.
Funder
Natural Gas Geology Key Laboratory of Sichuan Province
Open Funds of Shale Gas Evaluation and Exploitation Key Laboratory of Sichuan Province
Cited by
63 articles.
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