复杂地表区时深转换和深度偏移中的基准面问题

The datum probleum of time-depth conversion and depth migration in complicated-surface area

在复杂地表区的资料处理中，地表起伏给静校正、速度分析、时深转换和深度偏移等带来了诸多困难。本文就基准面问题提出了一些解决方案。根据目前的处理技术，静校正可选择任一近地表的水平面作基准面，它不影响速度分析和叠加成像；但一般情况下它不应该是时深转换和深度偏移的基准面，时深转换和深度偏移应从地表或地表圆滑面开始。本文还给出了根据（静校正的）CMP基准面计算地表圆滑面的方法，统一了深度域中速度谱、时深转换和深度偏移的基准面。

In processing the seismic data taken from complicated-surface area, terrible topographic undulation brings many troubles in static correction, velocity analysis,time-depth conversion, depth migration and so on. Some schemes for solving the datum problem are put forward here. According to present data processing technique, any horizontal plane near ground surface may be taken as datum for static correction, and it has no influence on velocity analysis and stacked migration i however, in general circumstances, it should not be the datum for time-depth conversion and depth migration because time-depth conversion and depth migration must start from ground surface or smoothed ground surface. A method for deriving the smoothed ground surface from CMP datum of static correction is given to form a common datum for velocity spectrum, time-depth conversion and depth migration in depth domain.