Coalbed methane diffusion and water blocking effects investigated by mesoscale all-atom molecular dynamic simulations

Zhu, Qingzhong; Li, Gang; Liu, Zhong; Luo, Yan‐Ling; Fan, Hongming; Guo, Wei; Zhang, Chen; Wang, Sanshuai; Luo, Wenjia

doi:10.1039/d0ra07967g

Cited by 6 publications

(4 citation statements)

References 52 publications

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“…Gutierrez-Rodriguez et al claimed that the trappings for water show evident relation with coal ranks. The gas diffusivity is also reduced with the impenetrable barrier formed by the presence of water, and thus, additional forces are required to mobilize fluids. , …”

Section: Understanding Gas–water Two-phase Flowmentioning

confidence: 99%

“…The gas diffusivity is also reduced with the impenetrable barrier formed by the presence of water, and thus, additional forces are required to mobilize fluids. 141,142 Hence, quantifying capillary pressure and coal wettability response to reservoir depletion would offer useful inputs for evaluating its impact on gas flow and ultimate gas recovery.…”

Section: Capillary Pressure In Coalmentioning

confidence: 99%

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Dewatering Optimization of Coal Seam Gas Production Wells: A Review and Future Perspectives

et al. 2022

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Coal seam gas (CSG), as a type of unconventional gas resource, is playing an increasingly important role in energy generation and transition to renewables, as the world takes action to meet the climate change challenge. To produce CSG, the reservoir first needs to be dewatered, but unreasonable dewatering rates can lead to various unfavorable outcomes, such as a reduction in productivity, capillary trapping, borehole instability, excessive coal fines generation, and frequent production well workovers due to particle-induced damage to pumps. Determining the optimum dewatering strategy is currently in a very primitive stage of development, and CSG operators rely on empirical and instinctive approaches to deal with this problem. This paper conducts a comprehensive literature review to (i) explain why dewatering rate optimization remains a great challenge for the CSG industry, (ii) illustrate the complexity and nature of the issue through a conceptual model, and (iii) investigate four key factors that dominate the dewatering optimization design, borehole stability, stress-dependent permeability, gas–water two-phase flow, and generation of coal fines. A detailed summary of current dewatering optimization practices in CSG reservoirs is then presented, focusing on the employed theories, methodology, key learnings, and limitations of each practice. Finally, the remaining knowledge gaps are highlighted, and recommendations for further future work are provided.

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Section: Understanding Gas–water Two-phase Flowmentioning

confidence: 99%

Section: Capillary Pressure In Coalmentioning

confidence: 99%

Dewatering Optimization of Coal Seam Gas Production Wells: A Review and Future Perspectives

et al. 2022

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“…Wang et al studied the structures of graphene-reinforced epoxy coatings and the dynamic diffusion of guest water . Zhu et al investigated the adsorption and diffusion of methane and liquid water in the mesopores of coal . Yang et al studied the effect of water volume on methane adsorption capacity under high pressure .…”

Section: Introductionmentioning

confidence: 99%

“… 25 Zhu et al investigated the adsorption and diffusion of methane and liquid water in the mesopores of coal. 26 Yang et al studied the effect of water volume on methane adsorption capacity under high pressure. 27 Urbina et al studied rotational diffusion in methanol by means of molecular dynamics simulations at several temperatures.…”

Section: Introductionmentioning

confidence: 99%

Diffusion Mechanisms of Dissolved Gases in Transformer Oil Influenced with Moisture Based on Molecular Dynamics Simulation

Jiang

Yang

et al. 2022

ACS Omega

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Dissolved Gas Analysis (DGA) of insulating oil is widely used for diagnosing transformer incipient faults. Moisture is a major contaminant and degradation byproduct of transformer insulating oil. In this paper, molecular dynamics simulation was used to study the influence of moisture on the diffusion movement of dissolved gases in the insulating oil. Cycloalkanes (C20H42), alkanes (C20H38), and aromatic hydrocarbons (C20H26) are selected as the basic structural units in the constructed transformer oil simulation system. 0%, 1%, 3%, and 5% moisture molecules are added to insulating oil, respectively, and the insulating oil generates seven kinds of gas molecules through cracking. With an anhydrous model used as a benchmark, we researched the diffusion trajectory, the diffusion coefficient (D), free volume (V F), and the moisture–gas interaction energy of each gas molecule as a function of moisture content. Through this study, we found that the increase of moisture content enlarges the V F value of dissolved gas in insulating oil, which makes the gas in oil easier to diffuse. Besides, the moisture can also alter the mean square displacement (MSD) of dissolved gases; the mutual energy of molecules is mainly affected by the electrostatic interaction energy. This study can contribute to a better understanding of the influence of different moisture contents on the diffusion movement of dissolved gas in transformer oil from the micro level.

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Macromolecule simulation studies on mechanical properties and CH4/CO2 adsorption characteristics in bituminous coal matrix based on uniaxial tension–compression effect

Zhu

Zhang

Kang

et al. 2022

Environ Sci Pollut Res

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Coalbed methane diffusion and water blocking effects investigated by mesoscale all-atom molecular dynamic simulations

Abstract: Molecular dynamics simulations of coalbed methane diffusion and water-blocking effects were performed based on mesoscale molecular models.

Cited by 6 publications

References 52 publications

Dewatering Optimization of Coal Seam Gas Production Wells: A Review and Future Perspectives

Dewatering Optimization of Coal Seam Gas Production Wells: A Review and Future Perspectives

Diffusion Mechanisms of Dissolved Gases in Transformer Oil Influenced with Moisture Based on Molecular Dynamics Simulation

Macromolecule simulation studies on mechanical properties and CH4/CO2 adsorption characteristics in bituminous coal matrix based on uniaxial tension–compression effect

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