复杂构造网格化及高精度地震波场谱元法数值模拟

High precision spectral element method based on grid discretization of complicated structure for seismic wavefield numerical simulation

深部复杂隐伏构造油气藏具有复杂的地质结构和地层条件,模拟并分析其地震波场的传播特征尤为重要。研究并提出了复杂构造条件下的网格化及其高精度谱元数值模拟方法。首先基于Delaunay三角网格剖分方法将模拟区域剖分为若干三角形网格,进而采用波前法将所有三角形网格重组,得到谱元法计算所需的四边形网格。对比常规网格剖分方法,复杂构造网格剖分方法能够灵活适应速度边界的变化且网格均匀,质量较高。应用基于复杂构造网格剖分的高精度谱元法对Marmousi速度模型和二维随机介质模型进行数值模拟,并与常规谱元法的模拟结果进行对比,可以看出高精度谱元法数值模拟结果同相轴连续,数值频散小,信噪比和分辨率较高,取得了较好的应用效果。

For seismic exploration of the deep subtle structural reservoirs with complicated geological structure and formation conditions,it is particularly important to simulate and analyze their seismic wavefield characteristics. In this paper we study the grid diseretization for complicated structure and propose a high precision spectral element method. In order to get the quadrilateral grids used for calculating spectral element method, we divide the target area into several triangular grids by Delaunay grid discretization algorithm, and then all the triangular grids are reorganized into quadrilateral grids with wavefront method. Compared with conventional grid discretization method,the grid discretization method for complicated structure is flexible and adapts to the change of velocity boundary, with fairly quality. Numerical simulation of Marmousi velocity model and 2D random medium model show that the results of high precision spectral element method based on grid discretization of complicated structure has smaller numerical dispersion and higher SNR and resolution than conventional spectral element method and the method is proved to be fairly effective.