摘要
通过全波形反演(FWI)在理论上可得到较高精度的深层速度模型,而在实际中相关条件却难以完全具备。究其原因主要为:FWI对初始速度模型的依赖性强;深层信号弱,在目标函数中的贡献较小。为此,提出基于一阶近似瞬时频率的时间域声波FWI方法。根据瞬时相位公式推导出一阶近似瞬时频率的目标函数和伴随震源项公式;充分发挥瞬时频率可突出低频信息和深层弱信号的特点,为FWI建立初始速度模型;同时加入梯度衰减因子以进一步提高深层反演效果、防止深浅层间互相干涉。模型和实际资料测试证明了该方法的可行性和有效性。
A deep velocity model with high accuracy can be obtained by full waveform inversion(FWI)in theory.However,it is difficult to find underground conditions in actual exploration.This is because that,on the one hand,full waveform inversion is strongly dependent on the initial velocity model;and on the other hand,deep signals are weak,and their contribution to the objective function is small.This paper proposes time-domain full waveform inversion based on first-order approximate instantaneous frequency.First,according to the instantaneous phase formula,the objective function and the adjoint source term formula of the first-order approximate instantaneous frequency are derived;Then the initial velocity model for full waveform inversion is established by making full use of the advantage of the instantaneous frequency to highlight low frequency information and deep weak signals.Finally,agradient attenuation factor is added to further improve the effect of deep inversion and prevent the interference between deep and shallow layers.The feasibility and validity of the method have been proved by model and real data.
作者
徐夷鹏
任志明
李振春
刘畅
贺紫林
陈金茂
XU Yipeng;REN Zhiming;LI Zhenchun;LIU Chang;HE Zilin;CHEN Jinmao(SWPI,School of Geosciences,China University of Petroleum(East China),Qingdao,Shandong 266580,China;Shengli Branch of Sinopec Geophysical Corporation,Dongying,Shandong 257000,China)
出处
《石油地球物理勘探》
EI
CSCD
北大核心
2020年第5期1029-1038,932-933,共12页
Oil Geophysical Prospecting
基金
国家自然科学基金项目“基于敏感核分解的弹性反射波和回折波波形反演方法研究”(41804117)
国家科技重大专项“地震与井筒精细勘探关键技术”(2016ZX05006-002)
中央高校基本科研业务费专项资金项目“弹性地震资料反射波波形反演新方法研究”(18CX02186A)联合资助
关键词
初始模型
瞬时频率
一阶近似
全波形反演(FWI)
initial model
instantaneous frequency
first-order approximation
full waveform inversion(FWI)
