Molecular simulation of methane adsorption characteristics in illite nanopores of deep shale reservoirs

被引：0

作者：

Huang L. ^{[1
,2
]}

Chen Q. ^{[2
]}

Wu J. ^{[3
]}

Yang Q. ^{[2
]}

Zhang J. ^{[3
]}

Huang S. ^{[3
]}

Zhou W. ^{[1
,2
]}

Zou J. ^{[1
,2
]}

机构：

[1] State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu

[2] College of Energy, Chengdu University of Technology, Chengdu

[3] Shale Gas Research Institute, Southwest Oil & Gas Field Company, PetroChina, Chengdu

来源：

Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | 2022年 / 53卷 / 09期

基金：

中国国家自然科学基金;

关键词：

adsorption; chemical potential; deep shale gas; illite; methane; molecular simulation;

D O I：

10.11817/j.issn.1672-7207.2022.09.018

中图分类号：

学科分类号：

摘要：

Molecular simulation was performed to explore the adsorption behaviors of methane in illite nanopores under in-situ conditions of deep shale gas reservoirs. Firstly, a set of type curves of methane chemical potential was constructed by coupling grand canonical Monte Carlo and molecular dynamics methods. A prediction model for methane chemical potential was established. Secondly, the adsorption behaviors of methane in illite nanopore models were simulated by using the determined methane chemical potential. The simulations were conducted under high-temperature and high-pressure conditions, and the characteristics of methane adsorption isotherms at various temperatures and pore sizes were analyzed. Fianlly, the microscopic adsorption characteristics of methane in illite nanopores were studied, and the effects of pressures, temperatures and pore sizes on them were discussed. The results show that the total gas content in nanopores is not saturated under the deep shale reservoir conditions. Compared with the middle-deep shale reservoirs, the adsorbed gas content is lower, the free gas content is higher, and the effect of temperature on gas adsorption is not pronounced in deep shale reservoirs. The effect of pore size on methane excess adsorption is more significant in small pore size ranges and high-pressure conditions. There is an exclusive methane adsorption layer in pores with diameter of 1 nm, while double-layer adsorption is observed on each wall of pores with diameter of 2 nm. In pores with diameter of more than 4 nm, methane is single-layer adsorbed on each wall, and there is a transition zone between adsorption phase and free phase. The microstructure of the transition zone can be attributed to three factors, including the adsorbed force of pore walls towards the methane molecules of the transition zone, the repulsive force between the methane molecules of the adsorbed layers and that of the transition zone, and the irregular arrangement of the methane molecules of the adsorbed layers. © 2022 Central South University of Technology. All rights reserved.

引用

页码：3522 / 3531

页数：9

共 22 条

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