基于格子Boltzmann方法的裂缝有效开度研究

Study on the Effective Opening Degree of Crack Based on the Lattice Boltzmann Method

以格子Boltzmann方法(LBM)为检验标准,将立方定律中的平均开度替代为有效开度,对三维裂缝渗透率计算方法进行研究。推导LBM三维动力学边界条件,构建格子单位和物理单位下的渗透率单位转换公式,对6个裂缝模型的渗透率进行计算;设想2种有效开度计算公式,替代立方定律中的平均开度,与LBM模拟结果进行对比,优选精度较高者。将平均开度替代为新的有效开度后,计算得到的渗透率下降0.05~0.5μm2,与LBM模拟结果更加接近,误差平均减小8%。后续还应从裂缝曲迈度、裂缝内部接触面积等影响因素中寻求精度提升空间。

By using the lattice Boltzmann method（LBM） as the benchmark, the average opening degree in the cubic law is replaced by the effective opening degree, and the calculation method of the threedimensional fracture permeability is studied. Through the deduction of three-dimensional dynamic boundary conditions of LBM, unit conversion formulas for permeability units in lattice unit and physical unit are constructed, and the permeabilities of 6 fracture models are calculated. 2 effective opening degree calculating formulas are assumed to replace the average opening degree in the cubic law, and by comparing with LBM simulation results, the one with higher accuracy is selected. After the average opening degree is replaced by the new effective opening degree, the calculated permeability decreases by0.05~0.5 μm2, which is closer to the LBM simulation result, and the error is reduced by 8% on average.Further, one should also seek space for the precision improvement from the factors including stride degree and internal contact area of cracks.