Study on the characteristics of coal pore structure changes during hot flue gas displacement and their impact on the gas displacement effect

IF 3.3 2区工程技术 Q3 ENERGY & FUELS

Geomechanics for Energy and the Environment Pub Date : 2025-04-05 DOI:10.1016/j.gete.2025.100673

Jiahao He , Baiquan Lin , Tong Liu , Zhenyong Zhang , Shuai Le , Yajie Hu

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引用次数: 0

Abstract

Gas displacement by hot flue gas injection into the coal body is a hot spot in the research on high-gas and low-permeability coal seams. Injecting hot flue gas generated by gas power plants into coal seams will introduce water and CO₂, and the introduced CO₂ will dissolve and ionize to form an acidic environment, leading to the dissolution of minerals in coal. Therefore, it is particularly important to study the impact of coal pore structure changes on gas displacement before and after mineral dissolution. In this study, the impact of mineral dissolution in coal was explored by combining Computed Tomography (CT) and COMSOL Multiphysics numerical simulation, and the parameters of the numerical model were determined based on gas adsorption-desorption experimental results. The following conclusions were drawn at the millimeter scale: (1) Compared with the Langmuir equation, the BET equation is more competent to act as an isothermal adsorption and desorption model of coal in high-gas and low-permeability coal seams. (2) After 10.11 % of minerals dissolve, the flow velocity and outlet flow rate in the fractures formed at the original positions of minerals both increase significantly, and the model permeability grows from 7.0711 × 10⁻¹² m² to 2.2331 × 10⁻¹¹ m². (3) The time consumed for the residual gas pressure to drop from its initial value to 0.1 MPa was calculated. (4) After mineral dissolution, the coal pore structure alters, resulting in changes in the distribution of gas pressure during displacement, and the gas pressure varies obviously spatially.

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来源期刊

Geomechanics for Energy and the Environment Earth and Planetary Sciences-Geotechnical Engineering and Engineering Geology

CiteScore

5.90

自引率

11.80%

发文量

期刊介绍： The aim of the Journal is to publish research results of the highest quality and of lasting importance on the subject of geomechanics, with the focus on applications to geological energy production and storage, and the interaction of soils and rocks with the natural and engineered environment. Special attention is given to concepts and developments of new energy geotechnologies that comprise intrinsic mechanisms protecting the environment against a potential engineering induced damage, hence warranting sustainable usage of energy resources. The scope of the journal is broad, including fundamental concepts in geomechanics and mechanics of porous media, the experiments and analysis of novel phenomena and applications. Of special interest are issues resulting from coupling of particular physics, chemistry and biology of external forcings, as well as of pore fluid/gas and minerals to the solid mechanics of the medium skeleton and pore fluid mechanics. The multi-scale and inter-scale interactions between the phenomena and the behavior representations are also of particular interest. Contributions to general theoretical approach to these issues, but of potential reference to geomechanics in its context of energy and the environment are also most welcome.