基于CMP域的山地表层速度模型构建  

CMP-based near surface velocity model building for mountainous areas

作　　者：彭文 赵尧 曹中林 张亨 张华[1] PENG Wen;ZHAO Yao;CAO Zhonglin;ZHANG Heng;ZHANG Hua(BGP,CNPC,Chengdu 610213,China)

机构地区：[1]中国石油东方地球物理公司物探技术研究中心,成都610213

出　　处：《物探化探计算技术》2020年第2期212-216,共5页Computing Techniques For Geophysical and Geochemical Exploration

基　　金：国家项目(2017ZX05018005-004)。

摘　　要：对于山地地震勘探而言,地形起伏,不能直接使用Herglotz-Wiechert公式反演近地表速度模型,这里采用不同于前人在炮域处理的思路,而是在CMP域建立了一组基于CMP浮动基准面对起伏地表上的炮检对走时和偏移距进行校正的公式,首先用本文提出的公式去除起伏地表对初至波的影响,然后应用Herglotz-Wiechert公式快速反演地形起伏地区近地表速度模型。该方法采用地震反射波的CMP浮动基准面校正思路,包含三个关键步骤:①产生CMP浮动基准面;②实测时距曲线的校正;③计算射线参数和速度-深度函数的计算。此方法无需射线追踪,无需初始模型,计算速度快,反演得到的模型具有和地震数据相同的水平分辨率,该模型可用于计算基准面静校正量,或用于叠前深度偏移速度场的表层建模,也可以作为回转初至波层析反演或全波形反演的初始模型。Regards to mountain seismic exploration with undulating topography the Herglotz-Wiechert formula can't be directly applied to invert the near-surface velocity structure.This paper introduces a fast algorithm to estimate the near-surface velocity-depth function associated with the rugged topography,which utilizes the traveltime-distance curve of first arrivals in CMP domain.This method employs the concept of CMP floating datum corrections of seismic reflection,consisting of four steps:CMP floating datum construction,traveltime-distance curve corrections,instantaneous ray parameter estimation,and velocity-depth function estimation.This method does not require ray tracing and initial velocity model,but it has a fast computational speed.The inverted result has the same horizontal resolution as the seismic data,allowing it to be used for the calculation of datum statics,near surface velocity model building of prestack depth migration,as well as the initial velocity model building of the refraction tomography or full waveform inversion.

关 键 词：近地表模型 时距曲线 CMP域 射线参数 山地 

分 类 号：P631.4[天文地球—地质矿产勘探]