Dynamic Evolution of Gas Flow during Coalbed Methane Recovery to Reduce Greenhouse Gas Emission: A Case Study

Song, Haoran; Lin, Baiquan; Zhong, Zheng; Liu, Ting

doi:10.1021/acsomega.2c03274

Cited by 9 publications

(2 citation statements)

References 43 publications

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“…Depressor mining causes small deformation of the coal reservoir matrix skeleton during the extraction and drainage of CBM, with the coal body being viewed as an elastic medium that is continuous throughout the process. Song et al [60] derived the equation governing coal deformation by considering the volumetric strain from methane and water, along with the contraction strain from methane desorption:…”

Section: Governing Equation Of Coal Deformationmentioning

confidence: 99%

A Fully Coupled Gas–Water–Solids Mathematical Model for Vertical Well Drainage of Coalbed Methane

Wang,

Zhao,

Liu

et al. 2024

Energies

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The coupling relationship between the deformation field, the diffusion field, and the seepage field is an important factor in fluid transport mechanisms in the long-term coalbed methane (CBM) exploitation process. A mathematical model of gas–water two-phase fluid–structure coupling in a double-porosity medium in coal reservoirs is established in this paper. Taking Hancheng Block, a typical production block in Qinshui Basin, as the geological background critical desorption pressure, reservoir permeability anisotropy is considered in the model. COMSOL Multiphysics (COMSOL_6.0) was used to create the model. The accuracy and rationality of the model were verified by comparing field production data with the results of the simulation. Using the simulation, the influence law of various reservoir geological characteristics parameters (Langmuir strain constant, ratio of critical desorption pressure to reservoir pressure of coal seam (CDPRP), elastic modulus, initial water saturation, Langmuir pressure, etc.) on CBM productivity, reservoir pressure, and permeability ratio was discussed, and a thorough analysis of the factors affecting productivity was obtained using the orthogonal test method. The findings of this study indicate that the change in permeability is the result of the superposition effect of many factors. Different stages of drainage have different primary regulating factors. Rock skeleton stress has a consequence on coal matrix permeability in the early drainage stage, and coal matrix shrinkage is primarily impacted in the later drainage stage. Besides the initial water saturation, other reservoir geological parameters (e.g., CDPRP, Langmuir volume, Langmuir strain constant, elastic modulus) have a strong relationship with productivity. When the value of coal geological parameters increases, the degree of productivity release is higher (as the initial water saturation increases, the production decreases correspondingly). Different coal and rock parameters have varying levels of impact on the drainage stage of CBM wells. The influences of the CDPRP, Langmuir volume, Langmuir strain constant, and elastic modulus on gas production are mainly concentrated in the initial and intermediate drainage stages and begin to fall off during the last drainage stage. Per the multi-factor analysis, the main coal–rock parameters affecting the productivity release are the Langmuir strain constant, followed by the CDPRP and other parameters. The analysis findings can offer theoretical guidance for CBM well selection and layer selection and enhance the block’s overall CBM development level. The improved productivity prediction model for CBM, which is based on fluid–structure coupling theory, can offer a new technical benchmark for CBM well productivity prediction.

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Section: Governing Equation Of Coal Deformationmentioning

confidence: 99%

A Fully Coupled Gas–Water–Solids Mathematical Model for Vertical Well Drainage of Coalbed Methane

Wang,

Zhao,

Liu

et al. 2024

Energies

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“…The migration of gas mixture in fractures follows Darcy's law, and the migration in the coal matrix follows Fick's law of diffusion [29]. Specifically, in the absence of external interference, the adsorbed gas and the free gas are in a dynamic equilibrium state.…”

mentioning

confidence: 99%

Numerical Simulation Study of High-Pressure Air Injection to Promote Gas Drainage

Zheng

Liu

et al. 2022

Sustainability

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Coal-accompanying gas is an essential resource, with numerous mining methods. The practice has proved that injecting high-pressure air into the coal seam can replace and flush the gas in the coal seam, effectively solving the problem of inadequate single gas drainage in soft and low permeability coal seams. This paper uses the finite element method to solve the model, simulate and study the gas drainage by high-pressure air injection in the bedding drilling, and establish a fluid-structure coupling model for gas drainage by high-pressure air injection. The competitive adsorption of N2, O2, and CH4, diffusion and migration of CH4 in coal matrix and fissure, matrix deformation caused by CH4 adsorption, and desorption and control of coal deformation by applied stress are considered in the model. When the fixed extraction time is 600 days (d), the optimal spacing between the extraction hole and injection hole is 12.5 m. The safe extraction effect and minimum drilling amount can be ensured. It provides a basis for guiding gas drainage by injecting high-pressure air on-site.

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Impact of methane gas diffusion in coal on elastic modulus and porosity: Modeling and analysis

Song

Zhong

Lin

2023

Energy

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Dynamic Evolution of Gas Flow during Coalbed Methane Recovery to Reduce Greenhouse Gas Emission: A Case Study

Cited by 9 publications

References 43 publications

A Fully Coupled Gas–Water–Solids Mathematical Model for Vertical Well Drainage of Coalbed Methane

A Fully Coupled Gas–Water–Solids Mathematical Model for Vertical Well Drainage of Coalbed Methane

Numerical Simulation Study of High-Pressure Air Injection to Promote Gas Drainage

Impact of methane gas diffusion in coal on elastic modulus and porosity: Modeling and analysis

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