Correlation analysis of injection parameters for low-medium pressure injection of liquid CO2 for CH4 displacement in coal seams

Mi, Wansheng; Wen, Hu; Fan, Shixing; Wang, Shibin; Xue-ming, WU; Wei, Gaoming; Liu, Bocong; Li, Rijun; Cheng, Xiaojiao; Liu, Mingyang

doi:10.1016/j.energy.2023.127760

Cited by 7 publications

(3 citation statements)

References 16 publications

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“…A coal body is a typical fractured porous medium. CBM seepage mainly occurs in the fracture network, and its seepage capacity is mainly affected by the gas pressure gradient, external load, and fracture structure characteristics [3][4][5]. Therefore, exploring the seepage characteristics of coalbed methane in fractures has important engineering practical significance for efficient extraction of coalbed methane.…”

Section: Introductionmentioning

confidence: 99%

An Experimental Study on the Seepage Characteristics of Rough Fractures in Coal under Stress Loading

Luo,

Zhu,

Huang

2024

Processes

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Fracture and stress environments significantly affect the flow of coalbed methane. Under stress, fracture deformation and damage occur, which change the original fracture characteristics and lead to changes in gas flow characteristics. The change in gas pressure gradient makes the fluid flow obviously nonlinear. Using linear flow theory to describe the fracture flow leads to a large error in predicting coalbed methane productivity. In this study, seepage tests on fractured coal are carried out under different stresses and gas pressure gradients, the nonlinear flow and changes in related parameters are analyzed, and the applicability of the nonlinear flow equation is evaluated. The resulting seepage of the gas flow in the fracture under stress is obviously nonlinear, which gradually increases with increasing effective stress and gas pressure gradient. When the Forchheimer equation is used to characterize the nonlinear seepage in fractures, the coefficients increase with increasing effective stress. The permeability, nonlinear factor, and critical Reynolds number decrease with increasing effective stress. When the Izbash equation is used for this case, the linear coefficient ranges from 1015 to 1016, and the nonlinear coefficient ranges from 1.064 to 1.795. The coefficients are related to the effective stress through a power function. Both the Forchheimer and Izbash equations can characterize the flow in rough fractures in coal during stress loading. However, the Forchheimer equation better reveals the mechanism of flow transformation from linear to nonlinear in fractures.

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Section: Introductionmentioning

confidence: 99%

An Experimental Study on the Seepage Characteristics of Rough Fractures in Coal under Stress Loading

Luo,

Zhu,

Huang

2024

Processes

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“…and variation ratio of its surface or internal area, especially coal permeability and mechanical characteristic response. Additionally, deep analysis using mathematical models or software to comparatively investigate the evolution laws of coal microstructures and permeability coefficients that are quantitatively described by a threedimensional (3D) visualization method is still required [29,30]; even the visualization and meticulous quantification of the deformation-failure characteristics of coal microstructures before and after LCO 2 cryogenic freezing has become one of the hotspots in related research fields [31,32].…”

Section: Introductionmentioning

confidence: 99%

Deformation-Failure Characteristics of Coal with Liquid CO2 Cryogenic-Freezing Process: An Experimental and Digital Study

Wei,

Ma,

Wen

et al. 2023

Energies

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The aim of this paper is to analyze the deformation-failure degree and microstructure variations in coal under the cryogenic-freezing effect of liquid CO2. In this paper, X-ray CT scanning technology is adopted to measure the microscopic-morphological parameters of coal. Drawing support from the image processing and three-dimensional (3D) visualization functions of Avizo software, 3D spatial structure variation rules, as well as the deformation and permeability parameters, are quantitatively calculated. Under the effect of LCO2 cryogenic freezing, the macroscopic mechanical properties and deformation-failure degree of coal are thoroughly analyzed. The results show that fracture-scale parameters of treated coal are significantly increased, resulting in spatial structure parameters including the coal plug total volume (Vt), fracture network volume (V0), and proportion of fracture network (μ0) to increase by 17.11%, 56.57%, and 55.59%, respectively. A comparison analysis indicates that the coverage area of a single value function from the percolation theoretical model for treated coal plugs becomes larger, and its percolation curves are more intensive; the quantitative coal permeability coefficients are increased to more than 40% on average, which further proves that the permeability of coal by using LCO2 cryogenic freezing is significantly improved. Under the same uniaxial stress loading rate, the peak stress threshold value required by treated coal in the compaction and elastoplastic deformation stage is decreased. The corresponding output acoustic emission energy is apparently increased, owing to the increased brittleness of coal, and deformation failure of coal occurs more easily. Simultaneously, the fracture network and matrix surface of treated coal are more complex, and the corresponding fractal characteristic is obvious. It could be thus concluded that the coal plugs have deformation-failure changes under cryogenic freezing by using LCO2, increasing the proportion of coal microstructure and enhancing coal permeability. Therefore, the capability of gas migration through the coal microstructure becomes easier, which is favorable for coalbed methane recovery.

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“…Finally, the effect of energy saving and consumption reduction is achieved by reducing the number of jet fans in the original ventilation system (Zhang et al, 2018). When the tunnel construction passes through the complex stratum containing coal seams, the tunnel will often face the risk of gas accidents (Liu et al, 2023a;Liu et al, 2023b;Mi et al, 2023;Wen et al, 2023). Therefore, it is very important to choose the appropriate ventilation mode.…”

Section: Introductionmentioning

confidence: 99%

Numerical analysis and control technology of gas accumulation in a large-scale specially-shaped tunnel passing through coal bearing strata

Shu

Fan

et al. 2023

Front. Earth Sci.

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To solve the construction ventilation problem of super long (length greater than 10000 m) tunnel passing through discrete lenticular gas bag tunnel under complex working conditions in carbonaceous shale stratum, relying on the construction of Banzhulin tunnel of the new Xuyong-Bijie Railway (Sichuan-Yunnan). Using the finite element analysis software, the flow field distribution of the tunnel return air flow in the case of simultaneous excavation of multiple working faces is simulated, and the formation position and influence range of the vortex area which is easy to form gas accumulation are analyzed. On this basis, the technical team developed the PLC uninterruptible self starting ventilation power supply control program. By comparing the changes in the time required for ventilation power supply failure before and after the adoption of this technology, and the comparison of the gas concentration in the return air flow within a relatively short time of the failure, it is proved that this technology reduces the fault response time to 15.74% of the original time, and can well avoid gas accumulation within the failure time, It provides some reference for similar engineering construction.

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Correlation analysis of injection parameters for low-medium pressure injection of liquid CO2 for CH4 displacement in coal seams

Cited by 7 publications

References 16 publications

An Experimental Study on the Seepage Characteristics of Rough Fractures in Coal under Stress Loading

An Experimental Study on the Seepage Characteristics of Rough Fractures in Coal under Stress Loading

Deformation-Failure Characteristics of Coal with Liquid CO2 Cryogenic-Freezing Process: An Experimental and Digital Study

Numerical analysis and control technology of gas accumulation in a large-scale specially-shaped tunnel passing through coal bearing strata

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