Reliable prediction of methane emission sources and dynamics from adjacent strata of longwall coal mining is critical for developing efficient methane capture designs to maximise emission reduction and improve mining safety. This paper presents an integrated field monitoring study that has resulted in many new insights into mine methane emissions and dynamics in a relatively high permeability, multi-seam mining environment. The field study comprised of measuring gas content pre- and post-mining at three different locations across the longwall panel, and continuous monitoring of seam pore pressure using fibre optic piezometers.

The gas content profile pre- and post-mining enabled delineation of the gas emission zone. The lateral extent of the gas emission zone was found to be far beyond the goaf vicinity, which contradicts the baseline assumption of the conventional Flugge model used at the mine. Significant discrepancies were also found in the degree of gas emission between the measurement and the predictive modelling. For instance, the coal seam 62 m below the mining seam had no discernible gas released, whereas the Flugge model predicts a 24% gas emission. The causes underlying these discrepancies were analysed, and the methods to improve gas emission prediction were discussed. The monitored pore pressure change in different seams validates the gas content measurement results, and is also invaluable for characterising gas emission dynamics from seams in the roof and floor. Monitoring seam pore pressure change can therefore be an effective means to guide methane capture planning and design.

可靠地预测长壁煤矿邻近地层的甲烷排放源和动态对于开发高效的甲烷捕集设计以最大限度地减少排放和提高采矿安全性至关重要。本文介绍了一项综合现场监测研究，该研究对相对高渗透性、多煤层采矿环境中的煤矿甲烷排放和动力学产生了许多新的见解。现场研究包括在整个长壁板的三个不同位置测量开采前和开采后的气体含量，以及使用光纤测压计连续监测煤层孔隙压力。

开采前和开采后的瓦斯含量分布图能够划定瓦斯排放区。发现气体排放区的横向范围远远超出采空区附近，这与矿山使用的常规 Flugge 模型的基线假设相矛盾。测量和预测模型之间的气体排放程度也存在显着差异。例如，矿层以下 62 m 的煤层没有可识别的气体释放，而 Flugge 模型预测 24% 的气体排放。分析了造成这些差异的原因，并讨论了改进气体排放预测的方法。监测的不同煤层孔隙压力变化验证了含气量测量结果，并且对于表征屋顶和地板接缝的气体排放动态也是非常宝贵的。因此，监测煤层孔隙压力变化可以成为指导甲烷捕集规划和设计的有效手段。