基于三角网格的有限差分法叠后逆时偏移

摘要

与其他偏移方法相比,逆时偏移基于精确的波动方程而不是对其近似,用时间外推来代替深度外推.因此,它具有良好的精度,不受地下构造倾角和介质横向速度变化的限制.采用的三角网格差分法最大限度地保持了差分法的简单性,同时兼有有限元法的精确性,可直接用于起伏地表模型的正演模拟和偏移计算而无需对模型做特殊处理.本文首次尝试将三角网格差分法应用于逆时偏移中,模型试算表明了这两种方法的结合具有较好的应用效果.%Compared with other migration methods, reverse-time migration is based on a precise wave equation, not an approximation, and performs extrapolation in the depth domain rather than the time domain. It is highly accurate and not affected by strong subsurface structure complexity and horizontal velocity variations. The difference method based on triangular grids maintains the simplicity of the difference method and the precision of the finite element method. It can be used directly for forward modeling on models with complex top surfaces and migration without statics preprocessing. We apply a finite difference method based on triangular grids for post-stack reverse-time migration for the first time. Tests on model data verify that the combination of the two methods can achieve near-perfect results in application.