非椭圆各向异性介质高阶优化走时计算方法及应用

A High Oredr Optimized TravelTime Computing Algorithm and It's Applications in Anelliptic AnisotropicC Media

随着地震勘探的深入,对勘探精度的要求越来越高,目前,提高勘探精度的主要方法之一就是提高地震波走时计算的精度,地震走时精度直接影响如动校正、静校正和偏移成像质量.根据地质模型假设条件的不同,有不同的走时计算方法,常用的有各向同性介质假设和各向异性介质假设条件下的走时计算方法,各向异性假设具有比各向同性假设更好的适用性,具有更高的走时计算精度,能够满足大偏移距和高陡构造情况下成像的要求.本文根据Alkhalifah的VTI介质中走时计算方法,以Fomel的TI介质中群速度的计算为基础,利用各向异性介质中Snell定律,提出了在非椭圆各向异性介质中的高阶优化走时计算方法,通过理论和实际数据的应用,表明该方法克服了常规各向异性走时方法中不能够计算大偏深比情况下地震波走时的缺点,具有走时计算精度高、便于实际应用等特点,对叠加和偏移成像有广阔的应用.

With the progress in seismic exploration, the need for accuracy is more essential. One of the methods in improving the accuracy of the exploration is to improve the accuracy of traveltime, which affacts the stack, statics and migration in the seismic data processing. According to the assumption of the medium, such as the isotropic medium and the anisotropic medium, there are different methods in calculating traveltime. The algorithm of traveltime based on the anisotropic medium is more applicable and accurate than the algorithm based on the isotropic medium, and it can settle with the traveltime for the deep dip or the large offset seismic easily. This paper, using the group velocity of anisotropy from Fomel＇ s and Snell＇s law in anisotropy, deals with the traveltime based on the method of Alkhalifah, and develops a new high-order optimized algorithm for the anelliptical anisotropic medium. After application for the theoretical model and raw seimic data, the method in this paper succeeds in dealing with the weakness of the conventional method not computing the taveltime in the large-offset-deepth ratios seismic data, and it is more accurate and useful in the stack and imaging.