Author(s)

Yuling Chen^1,2, Kai Han^1,2, Chen Yixiang^1,2, Gan Fuping^1,2,*, Zhao Wei^1,2

Affiliation(s)

^1. Institute of Karst Geology, Chinese Academy of Geological Sciences , Beijing 100091, China;

^2. Ministry of Land and Resources/Guangxi Key Laboratory of Karst Dynamics, Guangxi 541004, China.

Corresponding Author

Gan Fuping

ABSTRACT

The potential of continental shale gas resources in China is huge, and the Lower Jurassic in some parts of northeastern Sichuan has obtained industrial shale gas flow. Carrying out research on shale lithofacies division and reservoir characteristics is conducive to further exploration and development of continental shale gas. The continental shale of the Ziliujing Formation in the Northeast Sichuan Basin was carefully studied by XRD, ordinary thin section, scanning electron microscope, high-pressure mercury intrusion, N2 adsorption and CO2 adsorption. The shale is divided into 12 different lithofacies by taking the abundance of organic matter and mineral composition as classification parameters, and it is found that the shale of the Ziliujing Formation mainly develops four kinds of lithofacies, namely organic-poor siliceous shale (Ⅰ3), mixed organic matter shale (Ⅳ2), organic siliceous shale (Ⅰ2) and organic-rich clay shale (Ⅱ1). The characteristics of shale reservoirs of different lithofacies are quite different. Organic matter-rich clay shale has an organic matter content of more than 2%, the best hydrocarbon generation potential, good connectivity between organic matter pores and intercrystalline pores of clay minerals, and a relatively small specific surface area. Large and well-developed laminar structure is conducive to industrial fracturing, and is the optimal continental shale lithofacies, and is the most favorable target for exploration and development of continental shale gas; organic matter-containing mixed shale (Ⅳ2) has an organic matter content greater than 1 %, higher pore volume, better gas storage capacity, and the development of layered structures that are conducive to fracturing, it is a good continental shale lithofacies, which is a more favorable target for exploration and development; while the organic-poor siliceous shale (Ⅰ 3) and organic-containing siliceous shale (Ⅰ2) are massive, with low pore volume and specific surface area. They are poor continental shale lithofacies, and are the most unfavorable targets for exploration and development.

KEYWORDS

Northeast Sichuan; Continental shale gas; Ziliujing Formation; Shale lithofacies; Reservoir characteristics.

CITE THIS PAPER

Yuling Chen, Kai Han, Chen Yixiang, Gan Fuping, Zhao Wei. Lithofacies types and reservoir development characteristics of continental shale in the ziliujing formation in northeast sichuan basin. Academic Journal of Earth Sciences. 2023, 1(1): 1-9.

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