一种基于改进共轭梯度法的弹性波全波形反演速度分层建模方法  

A layered velocity modeling method for elastic wave full waveform inversion based on improved conjugate gradient method

作　　者：王立德 王小卫[1] 周辉[2] 吴杰[1] 张志强 王建乐 王德英 冯刚[1] WANG Lide;WANG Xiaowei;ZHOU Hui;WU Jie;ZHANG Zhiqiang;WANG Jianle;WANG Deying;FENG Gang(PetroChina Research Institute of Petroleum Exploration&Development-Northwest,Lanzhou 730020,China;China University of Petroleum(Beijing),Beijing 102249,China;Gas Production Company,PetroChina Daqing Oilfield Company,Daqing 163000,Heilongjiang,China)

机构地区：[1]中国石油勘探开发研究院西北分院,兰州730020 [2]中国石油大学(北京),北京昌平102249 [3]中国石油大庆油田有限责任公司采气分公司,黑龙江大庆163000

出　　处：《岩性油气藏》2023年第4期61-69,共9页Lithologic Reservoirs

基　　金：中国石油天然气股份有限公司科技项目“人工智能速度建模方法研究”(编号:kt2020-10-06-02);物探攻关项目“2022年塔里木盆地和田河周缘寒武系盐下地震成像攻关与目标落实”(编号:2022KKT0506)联合资助。

摘　　要：陆上地震资料由于低频信息缺失、波场复杂等问题,加剧了反演的非线性。基于改进共轭梯度法的时间域多尺度分层反演方法有效重建了纵、横波速度场。研究结果表明:(1)利用时窗筛选早至波信息,使用小炮检距早至波数据自低频至高频多尺度重建浅层速度场,可以减少中深层反射波及噪声的强非线性影响;固定浅层速度,采用全波场的全偏移距数据可重建中深层速度场。(2)整个反演过程均利用基于移动加权平均的改进共轭梯度法进行速度场的迭代更新。改进的共轭梯度法可增强反演的稳定性,提高深层速度建模质量,同时反演收敛更快;分层反演策略可兼顾浅层低速和深层高速,采用大小不同的有限差分网格,保证波场模拟精度的同时减少了计算量,提高了反演计算效率;改进共轭梯度法的多尺度分层反演策略可有效降低陆上实际资料带来的非线性影响,使共成像点道集拉平程度更好,纵、横波速度场均得到有效恢复。Due to the lack of low-frequency information and complex wave field of land seismic data,the nonlinearity of elastic wave full waveform inversion is aggravated.A layered inversion strategy of time-domain multiscale inversion was proposed to reconstruct the P-wave and S-wave velocity based on the improved conjugate gradient method.The results show that:(1)Time window was used to screen the early arrival wave information and to constrain the offset size to reconstruct the velocity field in the shallow area from low frequency to high frequency,which can reduce the strong nonlinear effects caused by the reflected waves and noises in the middle and deep layers.The shallow velocity was fixed,and the full offset data of full wave field was used to conduct multi-scale inversion for the middle and deep layer velocity.(2)The whole inversion process used the improved conjugate gradient method based on moving weighted average to update the P-wave and S-wave velocity iteratively.The improved conjugate gradient method can enhance the stability of inversion,improve the quality of deep velocity modeling,and increase the convergence speed.The layered inversion strategy can reduce the amount of calculation and ensure the accuracy of wave field simulation by using staggered grid finite difference method with different mesh size,and improve the calculation efficiency of inversion.The layered inversion strategy based on the improved conjugate gradient can effectively reduce the nonlinear impact of the onshore actual data,making the common imaging point gathers flattened better and the velocity reconstructed more precise.

关 键 词：时间域 弹性波 全波形反演 多尺度 共轭梯度 分层反演 有限差分 速度建模 

分 类 号：TE319[石油与天然气工程—油气田开发工程] P631.4[天文地球—地质矿产勘探]