三维偏移距平面波有限差分叠前时间偏移

本文提出了中点-半偏移距域内的三维偏移距平面波(offset plane-wave)方程,并给出了其有限差分解法.偏移距平面波可通过对CMP道集进行平面波分解(倾斜叠加或线性Radon变换)生成,然而这样做会产生严重的噪音干扰.本文提出了局部倾斜叠加方法(local slant-stacking)来消除离散线性Rado...

3D offset plane-wave finite-difference pre-stack time migration

Based on the double-square-root equation, a 3D offset plane-wave equation for pre-stack time migration is derived and its finite-difference scheme is put forward. Offset plane waves can be generated by applying a plane-wave decomposition (slant-stacking or Linear Radon Transform) to CMP gathers. However, the resulting offset plane waves will be contaminated by coherent noise. We then present a local slant-stacking method to eliminate the noise. Meanwhile, an azimuth-independent 3D slant-stacking approach is developed to address the issue of uneven azimuth distribution and irregular offset distribution in CMP gathers. High-quality offset plane-wave datasets can be produced by the offset plane-wave decomposition approach proposed in this paper. Besides, residual curvature velocity analysis can be implemented in the offset ray-parameter common-image gathers. 3D offset plane-wave migration will be a practical solution for prestack time migration.