Quantitative characterization of pore-fracture system of organic-rich marine-continental shale reservoirs: A case study of the Upper Permian Longtan Formation, Southern Sichuan Basin, China

FUEL

卷:200

Article

Zhang, Jizhen^1,2  Li, Xianqing^1,2  Wei, Qiang^1,2  Gao, Wenjie^1,2  Liang, Wanle^1,2  Wang, Zhe^1,2  Wang, Feiyu^3,4 

[1] China Univ Min & Technol Beijing, State Key Lab Coal Resources & Safe Min, D11,Xueyuan Rd, Beijing 100083, Peoples R China

[2] China Univ Technol Beijing, Coll Geosci Grad Surveying Engn, Beijing 100083, Peoples R China

[3] China Univ Petr, State Key Lab Petr Resource & Prospecting, Beijing 102249, Peoples R China

[4] China Univ Petr, Coll Geosci, Beijing 102249, Peoples R China

关键词: Quantitative characterization;    Pore-fracture system;    Marine-continental shale;    Longtan Formation;    Matrix porosity;    Petrophysical model;   

DOI  :  10.1016/j.fuel.2017.03.080

来源: Elsevier

【 摘 要 】

Although significant progress has been achieved in characterizing marine shale reservoirs, studies that are associated with marine-continental shale reservoirs, particularly quantitative characterizations of shale pore-fracture, remain rare. In this study, 12 black organic-rich marine-continental shale samples were collected from seven wells that were recently drilled in the Upper Permian Longtan Formation in the Southern Sichuan Basin of southern China. X-ray diffraction revealed that clay minerals are the most prevalent component of shale, followed by quartz and calcite. Various pore types were classified and morphologically characterized from images that were obtained with field emission scanning electron microscopy. Shale total porosity, which was measured via mercury injection porosimetry, was between 3.1% and 7.5%. In addition, a pore-fracture interpretation model was built to calculate fractures and matrix porosity, including organic matter porosity, interparticle porosity of brittle minerals, and intraparticle porosity of clay minerals. The model was highly consistent with the measured porosity. Three key parameters were obtained to characterize the development of different types of matrix pores (V-TOC > V-Bri > V-Clay).Low-pressure N-2 and CO2 gas adsorption experiments were conducted to analyze pore volume, special surface area (SSA), and pore-size diameter. The results of the analyses revealed that micropores and macropores (including micro-fractures) are the dominant pores of the Longtan shale reservoir and that micropores provide the dominant shale gas adsorption space. Furthermore, the effects of shale components on pore development, as well as the correlation among different pore structural parameters, were discussed. The results showed that the enrichment of total organic carbon and clay mineral content will benefit the development of the Longtan shale pore fracture system. Moreover, a good positive linear relationship existed among matrix porosity, pore volume, SSA, average pore diameter, and surface porosity. (C) 2017 The Authors. Published by Elsevier Ltd.

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