初至波层析成像正演模拟中多发多收模式计算方法研究

Study on calculation method for multiple-transit and multiple-receive mode in the forward simulation of tomography which based on the first arrival wave

初至波层析成像正演模拟中的多发多收模式计算,常规正演模拟方法是将其简单地分解为多个单发多收模式的计算.对于发射点和接收点分别位于模型对边的情况,如井间地震层析成像,常规方法存在较多的无效计算,计算效率偏低.针对这一问题,本文基于互换原理及费马原理,提出了改进计算方法:利用少量发射点至各接收点的最小走时路径确定其他发射点至各接收点最短走时路径所在区域,减少了无效计算,提高了层析成像正演模拟的计算效率.数值算例表明:对于射线追踪算法为最短路径法的情况,改进方法的计算效率是常规正演模拟方法的2倍左右.

For the calculation of multiple-transit and multiple-receive mode in the forward simulation of tomography which based on the first arrival wave,conventional method break this mode into one source point and multi-point reception mode simply.In the case of the source point and the receive point located on the opposite side of the model,such as crosswell seismic tomography,the conventional method has many invalid calculations and the calculation efficiency is low.This paper improves the forward modeling method based on the principle of exchange and the Fermat’s principle:used ray path which from a small number of source points to each reception point to determine the area where the path travel from other source point to reception point,which reduce invalid calculation and improves the computational efficiency of the conventional method of forward simulation.Numerical examples show that,when the ray tracing algorithm is the shortest path method,the computational efficiency of the improved method is about 2 times that of the conventional forward modeling method.