Effect of graphitization of organic matter on shale gas reservoirs: Take the marine shales in the southern Sichuan Basin as examples

被引：0
|
作者：
Zhang Q. [1 ,2 ]
Zhao Q. [1 ,2 ]
Luo C. [3 ]
Liang F. [1 ,2 ]
Zhou S. [1 ,2 ]
Wang Y. [1 ,2 ]
Lu B. [1 ,2 ]
Qiu Z. [1 ,2 ]
Liu H. [1 ,2 ]
Liu W. [1 ,2 ]
机构：
[1] PetroChina Research Institute of Petroleum Exploration & Development, Beijing
[2] National Energy Shale Gas R & D <Experimental> Center, Hebei, Langfang
[3] Shale Gas Institute, PetroChina Southwest Oil & Gasfield Company, Sichuan, Chengdu
来源：
Natural Gas Industry | 2022年 / 42卷 / 10期
关键词：
Graphitization of organic matter; Laser Raman Spectroscopy; Lower Silurian Longmaxi Formation; Lower Cambrian Qiongzhusi Formation; Reservoir characteristics; Shale; Southern Sichuan Basin;
D O I：
10.3787/j.issn.1000-0976.2022.10.003
中图分类号：
学科分类号：
摘要：
Shale gas is an important transitional energy source for China to achieve carbon neutralization and energy transformation in the future. However, previous exploration and development practices show that graphitization of organic matter can bring risks to shale gas exploration. In order to clarity the effect of graphitization of organic matter on shale gas reservoirs, we take the Lower Silurian Longmaxi Formation and the Lower Cambrian Qiongzhusi Formation in the Southern Sichuan Basin as examples. The Laser Raman Spectroscopy, high-resolution transmission electron microscopy (HRTEM), gas adsorption, high-pressure mercury injection (HPMI) and nuclear magnetic resonance (NMR) were used to systematically test and analyze the graphitization of organic matter in shale. The reservoir characteristics of graphitized and non-graphitized samples were compared and analyzed, and the mechanism of graphitization of organic matter on reservoir was discussed. The following research results are obtained. (1) Longmaxi shale samples from Well W202 in Weiyuan and Well L205 in Luzhou, and Qiongzhusi shale samples from Wells W201 and W207 in Weiyuan have not yet entered the graphitization stage, while there is an obvious G' peak in Raman spectrum of Qiongzhusi shale samples from Well N206 in Changning, which demonstrates that organic matter of N206 samples has been graphitized. (2) The porosity of the graphitized shale samples is generally lower than 3%, which is manifested in the significant decrease of the micro, meso and macro pore volumes. And the specific surface area of the graphitized samples also significantly decreases with mesopores contributing the most to the total specific surface area, accounting for 89.25%. (3) After the graphitization of organic matter, the development degree of organic pores is greatly reduced, and the inorganic pores become the main component of the graphitized samples, accounting for up to 91.8% of the total shale porosity. (4) The graphitization of organic matter leads to the depletion of hydrocarbon generation capacity, the shedding of side chains and heteroatoms, the condensation of aromatic nuclei and further directional arrangement, which destroys the mechanical and chemical mechanisms of pore preservation. It's concluded that graphitization of organic matter has a destructive effect on shale gas reservoirs. In future exploration, it's necessary to further clarify the spatial distribution range of graphitization in favorable shale intervals to avoid exploration risks. © 2022 Natural Gas Industry Journal Agency. All rights reserved.
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页码：25 / 36
页数：11
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