起伏地表条件下的波场上延法叠前深度偏移

Wave-field upward continuation pre-stack depth migration based on irregular topography

直接从起伏地表开始的叠前深度偏移方法是分析复杂地表和复杂地质体成像的有效手段。借鉴Beasley和Lynn提出的“零速层”的概念与Reshef提出的“逐步累加”法的思路,根据地震波在真实介质中的传播特性及波的可叠加性,利用“波场上延”法,实现基于相移(时间域)法上延和频率空间域有限差分(深度域)法(ω-xFD)上延的波动方程法叠前深度偏移成像。理论分析和模型试算结果表明,深度域“波场上延”法是解决起伏地表和地下复杂构造双重成像的一种有效方法,实现了波动方程基准面校正和深度域成像的有机结合,其有效性和准确性使该方法可用于实际资料的处理,有较好的应用前景。

Pre-stack depth migration which starts directly from undulating earth surface turms out to be a valid way to deal with irregular topography and complex geologic structures. According to zero velocity layer brought out by Beasley and Lynn, and the method of summation step by step put forward by Reshef, and the characteristics of wave propagation in real media and wave stacking, the method of wave field upward continuation to realize wave-equation pre-stack depth migration and imaging based on phase shift （in time domain） and finite difference （in depth domain） was put forward. Theoretical analysis and model tests show that the method of wave fidd upward continuation in depth domain is a valid method to solve the problems of the dual-imaging of irregular topography and complex geological structures, and can effectively combine wave equation redatuming with depth imaging, whose effectiveness and accuracy make it apply to actual data processing with a good prospective.