Uncertainties exist on the efficiency of CO₂ injection and storage in deep unminable coal seems due to potential reduction in the permeability of coal that is induced by CO₂ adsorption into the coal matrix. In addition, there is a limited knowledge about the stability of CO₂ stored in coal due to changes in gas partial pressure caused by potential leakage. This paper presents an experimental study on permeability evolution in a high rank coal from South Wales coalfield due to interaction with different types of gases. The reversibility of the processes and stability of the stored CO₂ in coal are investigated via a series of core flooding experiments in a bespoke triaxial flooding setup. A comprehensive and new set of high-resolution data on the permeability evolution of anthracite coal is presented.

The results show a considerable reduction of permeability above 1.5 MPa CO₂ pressure that is correlated with the coal matrix swelling induced by CO₂ adsorption. Notably studied in this work, the chemically-induced strain due to gas sorption into coal, that has been isolated and quantified from the mechanically-induced strain as a result of changes in effective stress conditions. The results of post-CO₂ core flooding tests using helium (He), nitrogen (N₂) and methane (CH₄) demonstrated a degree of restoration of the initial permeability. The injection of N₂ showed no significant changes in the coal permeability and reversibility of matrix swelling. The initial permeability of the coal sample was partially restored after replacing N₂ by CH₄. Observation of permeability evolution indicates that the stored CO₂ has remained stable in coal under the conditions of the experiments.

在深部不可开采的煤中，CO ₂注入和储存效率存在不确定性，这似乎是由于CO ₂吸附到煤基质中引起的煤渗透性的潜在降低。另外，由于潜在的泄漏引起的气体分压的变化，关于储存在煤中的CO ₂的稳定性的知识有限。本文提出了一项实验研究，该实验研究了南威尔士煤田的高品位煤由于与不同类型的气体相互作用而产生的渗透率演化。的过程和所存储的CO的稳定性的可逆性₂在煤进行了研究通过定制三轴驱油装置中的一系列岩心驱油实验。提出了关于无烟煤渗透性演变的一套全面的高分辨率高分辨率数据。

结果表明，在1.5 MPa CO ₂压力以上，渗透率显着降低，这与CO ₂吸附引起的煤基质膨胀有关。在这项工作中特别要研究的是，由于有效应力条件的变化，由于气体吸附到煤中而产生的化学诱导应变已经从机械诱导应变中分离出来并进行了量化。使用氦气（He），氮气（N ₂）和甲烷（CH ₄）进行的CO _2后岩心驱油测试的结果表明，初始渗透率得到了恢复。注入N ₂煤的渗透率和基质膨胀的可逆性没有显着变化。用CH ₄代替N ₂后，煤样品的初始渗透率得以部分恢复。渗透性演变的观察表明，在实验条件下，煤中储存的CO ₂保持稳定。