基于有限元分析的页岩气扩散数值模拟

本文基于Fick扩散定律,结合页岩气赋存形式和运移特点,针对干酪根有机质中溶解气扩散形式,建立干酪根中页岩气扩散数学模型。利用有限元分析方法进行数值求解,得到不同时刻干酪根内部页岩气浓度分布,分析干酪根内部不同位置浓度变化规律,内边界气体平均扩散通量变化规律,并通过计算得出给定符合页岩储层有机干酪根存在条件下干酪根扩散通量。同时在该扩散模型基础上改变边界条件,可以理论上计算多孔介质中气体有效扩散系数,为今后关于页岩气渗流理论和数值模拟研究奠定了基础。

Shale Gas Diffusion Simulations in Porous Organic kerogen MediaUsing Finite Element Analyses

The Development of shale gas has become a hotspot in today"s society, while the research on shale gas percolation theory and numerical simulation is still in its infancy. Based on Fick"s diffusion law, combined with the characteristics of shale gas occurrence, establishing a gas diffusion mathematical models for the dissolved gas in the organic kerogen which is solved using the finite element method to analyze the concentration distribution inside kerogen at different moments, the concentrations at different points inside the kerogen, the average diffusion flux variation within the boundaries of the gas, calculated the diffusion flux for a given shale reservoirs under the presence of organic kerogen. Also introducing the approach of theoretically reverse the effective diffusion coefficient about gas in porous media by numerical simulations. Laying for the future shale gas percolation theory and numerical simulation research basis.