Underground coal gasification (UCG) has a great potential to be accompanied by the technology of (enhanced) coal bed methane ((E)CBM) and carbon capture and storage (CCS), enhancing coal energy efficiency and mitigating climate change. This study aims to assess the environmental impact of three field-scale UCG hypothetical sites targeting deep-buried seams during the UCG operational stage in the combined CBM-UCG application. For this purpose, a risk assessment methodology is developed with consideration of the geomechanical and hydrogeological impact of UCG operations on the overlying strata by analogy to longwall mining operations. A series of numerical simulations are conducted to investigate the effect of variations in the saturation conditions around the UCG reactor, the change of rock permeability, and the UCG reactor operation duration on the propagation of heat, moisture and gaseous chemicals. The results demonstrate that CBM-UCG activities in the three sites are not likely to cause negative impacts on the environment during the UCG process when the behaviour of the reactor and the change of the surrounding strata are in control as expected. This work can provide insights in terms of environmental decision making, regulation and management to prevent reduction in gasification efficiency, to conduct the post-UCG (E)CBM process and to mitigate the UCG gas leakage and contamination of surrounding aquifers, highlighting where additional information is required in CBM-UCG activities.

煤炭地下气化（UCG）与（增强型）煤层气（（E）CBM）和碳捕集与封存（CCS）技术相结合，具有巨大的潜力，可提高煤炭能源效率并缓解气候变化。本研究旨在评估在联合 CBM-UCG 应用中 UCG 操作阶段针对深埋煤层的三个现场规模 UCG 假设站点的环境影响。为此，通过类似于长壁开采作业，考虑到 UCG 作业对上覆地层的地质力学和水文地质影响，开发了一种风险评估方法。进行了一系列数值模拟以研究 UCG 反应器周围饱和条件变化的影响、岩石渗透率的变化、以及 UCG 反应器在热、湿气和气态化学品传播方面的运行持续时间。结果表明，当反应堆的行为和周围地层的变化按预期得到控制时，三个站点的CBM-UCG活动不太可能对UCG过程中的环境造成负面影响。这项工作可以在环境决策、监管和管理方面提供见解，以防止气化效率降低，进行后 UCG (E)CBM 过程并减轻 UCG 气体泄漏和周围含水层的污染，突出显示其他信息在 CBM-UCG 活动中需要。结果表明，当反应堆的行为和周围地层的变化按预期得到控制时，三个站点的CBM-UCG活动不太可能对UCG过程中的环境造成负面影响。这项工作可以在环境决策、监管和管理方面提供见解，以防止气化效率降低，进行后 UCG (E)CBM 过程并减轻 UCG 气体泄漏和周围含水层的污染，突出显示其他信息在 CBM-UCG 活动中需要。结果表明，当反应堆的行为和周围地层的变化按预期得到控制时，三个站点的CBM-UCG活动不太可能对UCG过程中的环境造成负面影响。这项工作可以在环境决策、监管和管理方面提供见解，以防止气化效率降低，进行后 UCG (E)CBM 过程并减轻 UCG 气体泄漏和周围含水层的污染，突出显示其他信息在 CBM-UCG 活动中需要。