静校正对叠前时间偏移的副作用

Side-effects of static corrections to prestack time migration

静校正是复杂近地表区地震资料处理的关键步骤之一,对改善成像效果具有重要意义。但对地形起伏大的地区,静校正在对成像效果起正面作用的同时,也产生副作用。本文通过比较静校正前、后Kirchhoff叠前时间偏移旅行时计算的差异,研究静校正的副作用。静校正副作用表现在时间误差及空间误差两个方面,且误差随反射层倾角等参数变化。用一个在起伏地表上激发接收的具有典型构造特征的简单理论模型,验证了理论分析结果。最后给出能明显表现时间误差和空间误差影响的实例。

As one of the key steps for improving the seismic data imaging under complex near surface conditions,static corrections play a positive role in imaging.But they have side-effects to pre-stack migration in processing data in the area with severe topographic variations.Taking the Kirchhoff pre-stack time migration as an example,the side-effects are expounded by analyzing the difference in travel time calculation before and after static corrections.The side-effects reflect in time and space errors,and they are varied with the elevation,offset,depth,and reflector angle.Theoretical data collected from a model with rugged topography and typical subsurface structures is applied to demonstrate the side-effects.Real data example is also given in the paper.