基于变差分系数的变网格弹性波全波形反演

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国家科技期刊平台
NETL
NSTL
万方数据

中文摘要：全波形反演充分利用地震波传播的振幅、相位和旅行时等信息,相较于旅行时层析能够获得分辨率和精度更高的反演结果.当浅层介质速度较低时,为了保证正演模拟精度,通常需要使用较细的网格对低速层进行采样.然而,对整个模型用细网格剖分会导致巨大的计算量以及存储量,同时模型的高速区域也会产生过采样现象,这些问题会在全波形反演过程中被进一步放大.为了避免这些问题,引入了一种基于变差分系数的变网格弹性波动方程有限差分正演模拟方法.首先,基于Taylor展开式推导了变网格波场模拟的差分系数,实现了变网格波场模拟;其次,将变差分系数正演模拟方法应用于全波形反演中的正演模拟、残差反传和波场重构中,实现了基于变差分系数的变网格弹性波全波形反演.在全波形反演时,分别采用多尺度反演策略和常规的共轭梯度法迭代求解.使用细网格剖分速度较低的浅部低速层和粗网格剖分速度较高的中深层,既可以保证浅层的反演精度,又可以避免中深层的过采样.模型数据反演结果表明,基于变差分系数的变网格全波形反演相较于均匀粗网格全波形反演可以更有效实现低速异常体的准确刻画.含噪数据测试表明,提出的全波形反演方法具有较强的抗噪性.

外文标题：Full-waveform inversion of elastic waves in variable grids based on variable difference coefficients

外文摘要：Full-waveform inversion fully utilizes all the information of seismic wave propagation,including am-plitude,phase,and travel time,which can obtain inversion results with higher resolution and accuracy com-pared with travel time tomography.When the velocity in the shallow layer of the medium is low,fine grids are usually used to sample the low-velocity layer,so as to ensure the accuracy of forward modeling.However,sub-dividing the entire model into finer grids will increase computational complexity and storage requirements,and oversampling will occur in the high-velocity regions of the model.These problems are further amplified in the process of full-waveform inversion.To address these issues,this study introduced a finite difference forward modeling method of the elastic wave equation in variable grids based on variable difference coefficients.Firstly,the difference coefficient of variable grid wave field simulation was derived based on Taylor expansion,and the variable grid wave field simulation was realized.Secondly,the forward modeling method of variable difference coefficients was applied to the forward modeling,residual backpropagation,and wave field reconstruction of the full-waveform inversion,and the full-waveform inversion of elastic waves in variable grids based on the variable difference coefficient was realized.In the full-waveform inversion,the multi-scale inversion strategy and the conventional conjugate gradient method were used for the iterative solution.The fine grids were used to divide shallow low-velocity layers,and coarser grids were used to divide the middle and deep layers with high ve-locity,which ensured the accuracy of inversion for the shallow layers while avoiding oversampling in the middle and deep layers.The inversion results of the model data demonstrate that the full-waveform inversion in variable grids based on variable difference coefficients can effectively characterize the low-velocity anomalies compared with full-waveform inversion in uniform coarse grids.The test of noisy data shows that the proposed full-waveform inversion method has strong noise resistance.

外文关键词：

elastic wavefull-waveform inversionvariational difference coefficientforward modeling of variable gridsfinite difference

作者：

张红静、贺慧丽、孙文博、孙鹏远、李红辉、周辉

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作者单位：

东华理工大学核资源与环境国家重点实验室,江西南昌 330013

东华理工大学地球物理与测控技术学院,江西南昌 330013

东方地球物理公司物探技术研究中心,河北涿州 072751

中海油研究总院有限责任公司勘探开发研究院,北京 100028

海洋油气勘探国家工程研究中心,北京 100028

中国石油大学(北京)油气资源与工程全国重点实验室,北京 102249

中国石油大学(北京)CNPC物探重点实验室,北京 102249

中国石油大学(北京)地球物理学院,北京 102249

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关键词：

弹性波全波形反演变差分系数变网格正演有限差分

基金：

核资源与环境国家重点实验室开放基金东华理工大学博士科研启动基金中国石油前瞻性基础性项目

项目编号：

2022NRE16DHBK20190832021DJ3506

出版年：

2024

DOI：

10.13810/j.cnki.issn.1000-7210.2024.03.014

石油地球物理勘探

东方地球物理勘探有限责任公司

石油地球物理勘探

CSTPCD北大核心

影响因子：1.766

ISSN：1000-7210

年,卷(期)：2024.59(3)