Two-dimensional multi-phase numerical simulations based on detailed laboratory experiments are used to provide insight into the key processes of methane migration in porous media and to analyze the suitability of a continuum approach for modelling gas migration at the intermediate bench-scale. The simulations were conducted using the multi-phase numerical model DuMu^x, including groundwater flow, transport of free-phase methane subject to capillary and buoyancy forces, kinetic-controlled dissolution of methane into the flowing groundwater, and advective-diffusive transport of dissolved-phase methane. Mass transfer kinetics are controlled by the water-gas interfacial area, avoiding the assumption of thermodynamic equilibrium which was shown not applicable under these conditions of high aqueous velocity in sandy materials.

The model is applied to a series of 2D laboratory experiments in which gas-phase methane was injected near the bottom of a 1.5 m square vertical flow cell under a background flow gradient and with homogeneous and heterogeneous configurations. Simulations are compared to the observed behavior with respect to gas-phase mass distribution over time, gas-phase saturations, and to breakthrough of the dissolved-phase methane at selected monitoring points. In this first comparative study (simulations vs real data), insights are provided into the role of spatial property distributions on methane migration, in particular gas-phase pooling below low-permeability layers. Similar to the laboratory results, the simulations confirmed that the concentrations of dissolved-phase methane are strongly dependent on the structure of the gas-phase plume which in turn is influenced by the geology. We show that at the local metre-scale, kinetic-controlled mass transfer is needed to reproduce the dissolved-phase methane concentrations. Nevertheless, an assessment of capillary parameter values typically encountered in sandy aquifer materials suggests that an equilibrium approach could still be suitable for field-scale simulations.

基于详细实验室实验的二维多相数值模拟用于深入了解多孔介质中甲烷运移的关键过程，并分析连续介质方法在中间实验规模模拟气体运移的适用性。模拟是使用多相数值模型 DuMu ^x进行的，包括地下水流、自由相甲烷在毛细管力和浮力作用下的传输、甲烷在流动地下水中的动力学控制溶解以及溶解的平流扩散传输。相甲烷。传质动力学由水-气界面面积控制，避免了热力学平衡的假设，该假设在砂质材料的高水流速度条件下不适用。

该模型应用于一系列二维实验室实验，其中在背景流动梯度下以均质和非均质配置将气相甲烷注入 1.5 m 方形垂直流动池底部附近。将模拟结果与观察到的行为进行比较，包括气相质量随时间的分布、气相饱和度以及选定监测点溶解相甲烷的突破。在第一项比较研究（模拟与真实数据）中，深入了解了空间属性分布对甲烷运移的作用，特别是低渗透层下方的气相池。与实验室结果类似，模拟证实溶解相甲烷的浓度强烈依赖于气相羽流的结构，而气相羽流的结构又受到地质的影响。我们表明，在局部米尺度上，需要动力学控制的传质来重现溶解相甲烷浓度。然而，对砂质含水层材料中通常遇到的毛细管参数值的评估表明，平衡方法仍然适用于现场规模模拟。