基于快速匹配法的VTI介质走时计算

doi:10.13278/j.cnki.jjuese.20180198

摘要/Abstract

摘要： 地震波全波形反演是当今地质构造反演的潮流。在层析成像等为其提供初始模型的预处理中，地震波初至走时是一个非常重要的物理量。因而，高效高精度且稳定的走时计算方法对于各向异性建模具有重要的研究意义。为实现高效高精度且稳定的走时计算，首先利用扰动理论及泰勒公式将具有垂直对称轴的横向各向同性（VTI）介质程函方程展开，得到走时解；然后引入各向同性快速推进法（fast marching method，FMM），运用改进后的迎风差分格式求取差分格式黏滞解获取单点走时。结合窄带推进技术，得到了一种新的基于快速匹配法的VTI介质走时计算方法。通过对均匀弱各向异性模型计算结果和解析值的对比，评估了其误差，相对误差稳定于0.5%以下。针对该方法的有效性和稳定性，对层状介质模型和盐丘模型反射波走时进行了试算，取得了较好的效果。理论分析和模型试算表明，该方法对VTI介质走时计算具有较高的精度，能够应用于各向异性层析成像和全波场偏移等研究中。

关键词: 各向异性, 快速匹配法, 窄带技术, 走时计算

Abstract: Full-wave seismic inversion is a trend of geological structure interpretation. Seismic first-arrival travel time is an important parameter in processes of providing initial models like tomography. An efficient, accurate and stable method for travel time computation is very important for anisotropic modeling. Firstly, we use the perturbation theory and Taylor's theorem to expand the eikonal equation of the VTI media, by which we achieve the analytical solution of the homogeneous media (Alkhalifa2012); next, we introduce a fast marching method of isotropic media, and use the upwind difference to obtain the single point travel time. Combining with narrowband propulsion technique, we set a new travel-time computation method in VTI media based on the fast matching method. The calculated result is evaluated by comparing with the analytical values of the weak anisotropic homogenous model. The effectiveness and stability of the method is verified through calculating the travel time of the reflected waves in the layered medium model. The theoretical analysis and model trial show that this method is efficient and precise, and can be applied to anisotropic tomography and full wave field migration.

Key words: anisotropy, fast marching method, narrow band technique, travel time calculation

中图分类号:

P631.4

肖汉, 王德利. 基于快速匹配法的VTI介质走时计算[J]. 吉林大学学报(地球科学版), 2019, 49(4): 1160-1168.

Xiao Han, Wang Deli. Travel-Time Computation in VTI Media Based on Fast Marching Method[J]. Journal of Jilin University(Earth Science Edition), 2019, 49(4): 1160-1168.

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