CO2 Flow Characteristics in Macro-Scale Coal Sample: Effect of CO2 Injection Pressure and Buried Depth
CO2 Flow Characteristics in Macro-Scale Coal Sample: Effect of CO2 Injection Pressure and Buried Depth
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DOI：
10.3390/su15108002
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发表时间：
2023-05
期刊：
影响因子：
3.9
通讯作者：
Huping Wang;Zhao Wang;Haikui Yin;Chao Jin;Xiao-guang Zhang;Langtao Liu
中科院分区：
文献类型：
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作者：
Huping Wang;Zhao Wang;Haikui Yin;Chao Jin;Xiao-guang Zhang;Langtao Liu
实验研究证实了煤样吸附CO2后渗透率降低。然而，这些研究是在有限的实验条件下进行的。在这项研究中，CO2在宏观尺度煤样的流动行为进行了数值模拟，使用耦合的气体流动，机械变形，吸附诱导变形有限元模型。模拟结果表明，在低注入压力下，有效应力降低对渗透率的提高作用大于CO2吸附对渗透率的降低作用。由于亚临界CO2注入的平流通量增强，样品中的CO2压力发展随着注入压力的增加而增加，而对于超临界CO2注入，CO2压力发展以及样品中的浓度，与亚临界CO2注入相比，由于超临界CO2的密度和粘度更大以及超临界CO2吸附引起的煤基质溶胀，临界二氧化碳增加轴向应力（埋深）阻碍CO2迁移的样品，由于增加的有效应力，这种效果是更有影响力的低注入压力，这表明，高CO2注入压力是首选的CO2封存在深部煤层。
Experimental studies have confirmed the permeability reduction of coal samples upon the adsorption of CO2. However, these studies were carried out under limited experimental conditions. In this study, CO2 flow behaviors in a macro-scale coal sample were numerically simulated using a coupled gas flow, mechanical deformation, and sorption-induced deformation finite element model. The simulation results show that the effect of the reduction of effective stress on the enhancement of permeability is greater than the negative effect of permeability reduction due to CO2 adsorption for low injection pressures. CO2 pressure development in the sample increases with increasing injection pressure due to the enhanced advection flux for sub-critical CO2 injections, while for super-critical CO2 injections, CO2 pressure development, as well as concentrations in the sample, decreases compared to sub-critical CO2 injections because of greater density and viscosity of super-critical CO2 as well as coal matrix swelling induced by the adsorption of super-critical CO2. Increasing axial stress (buried depth) obstructs CO2 migration in the sample due to the increased effective stress, and this effect is more influential for low injection pressures, which indicates that high CO2 injection pressures are preferred for CO2 sequestration in deep coal seams.