地震立体层析成像的实现方法及效果分析

Implementation Methods of Stereotomography and Analysis of Influence Factors on Its Results

立体层析成像是一种新的地震反射波层析成像方法,能为叠前深度偏移提供较为精确的宏观速度模型。本文研究了立体层析成像的实现方法,包括斜率与走时数据的拾取、离散速度模型构建和初始化、射线参数的确定、斜率和走时及射线计算以及反演问题解法等,建立立体层析成像的算法流程。并通过对Marmousi模型试验,对立体层析成像运行所需的主要参数,如初始速度模型、拾取数据量、离散网格尺寸、速度平滑权重等进行测试和分析,总结这些不同参数对立体层析反演结果的影响规律,用以指导生产实践。

Stereotomography is a new reflection tomography method based on the slopes of locally coherent seismic events. It can provide accurate velocity macromodels for prestack depth migration. We study the implementation methods for picking travel times and slopes using hyperbolic stack in common midpoint gather and common offset gather, representing the discrete velocity model using B-spline function, tracing rays with the numerical solution of ray equation, calculating picked data based ray theory, determining ray parameters, solving the inverse problem, etc., and then provide the algorithm flow of stereotomography. Based on the experiments with Marmousi model, we test and analyze the main factors of stereotomography like the initial velocity model, the amount of picked data, discrete grid scale, smoothing weight for velocity model, and summarize their influences on the results of stereotomography.