【摘要】 网格剖分程度直接影响着地震波正演数值模拟的计算精度及其计算量。以均匀介质模型为例,分析不同网格大小对波场模拟精度和计算量的影响,得出精细化网格剖分是实现高精度地震波正演模拟的有效方法,然而其计算量较大。以均匀倾斜介质模型为例,探讨倾斜地层网格剖分问题,数值实例分析不同震源频率对不同网格剖分方案引起的波场传播精度的影响,同时给出网格剖分的合理选取准则,并建立差分阶数和调节因子的近似函数关系。结合理论分析和数值试算表明,网格步长越大,倾斜界面网格剖分引起的台阶效应越严重,在网格步长满足合理的频散关系(精度)情况下,选择合理的非均匀网格剖分策略可以减小计算量,尤其是可以压制由倾斜地层网格剖分造成的虚假波场,并保证计算波场具有较高的信噪比和可信度,同时指出在适当减小网格剖分步长和提高差分近似阶数可以在保证计算精度的前提下提高计算效率。更多还原

【Abstract】 Mesh Generation level can directly affect the accuracy and memory of seismic wave numerical simulation.The paper takes isotropic medium model as example to analyze the effect of different grid sizes on wave field simulating precision and calculated amount,and concludes that the fine grid can achieve the purpose of high-precision,but with disadvantage of calculated amount,then takes isotropic tilted medium model as another example to discuss the mesh generation problems on the tilted formation,uses numerical examples to analyze the wave field propagating effect of the different source frequency caused by different mesh generation strategy,and at the same time puts forward the rational mesh generation,and builds the approximating relationship between difference order and adjusted factor.The theoretical analysis and numerical experiments shows that the larger the grid step,the greater step effect induced by mesh generation of the tilted formation,under the condition of the grid size satisfying the rational dispersion relationship,selecting rational heterogametic mesh generation strategy can reduce the calculated amount,especially suppresses the bogus wave field raised by the mesh generation on the tilted formation,which ensures the numerical wave field with high S/N and credibility,and at the same time,points out that properly reducing the grid step and improving the difference order can improve the computational effect under the condition of ensuring the computational precision.更多还原