刘英昌,
李聪,
孙成禹
中国石油大学(华东)地球科学与技术学院, 山东青岛 266580
基金项目: 国家自然科学基金项目(41504097，41874153)资助
详细信息
作者简介: 唐杰, 男, 1980年生, 2008年博士毕业, 中国石油大学(华东)副教授, 主要从事微地震研究工作.E-mail: tangjie@upc.edu.cn
中图分类号: P631 收稿日期:2020-08-24
修回日期:2021-01-21
上线日期:2021-08-10
Reverse time location of microseismic source and fracture imaging with attenuation compensation in viscoelastic medium based on low rank approximation
TANG Jie,LIU YingChang,
LI Cong,
SUN ChengYu
School of Geosciences, China University of Petroleum, Shandong Qingdao 266580, China
MSC: P631
--> Received Date: 24 August 2020
Revised Date: 21 January 2021
Available Online: 10 August 2021
摘要
摘要:真实地下介质具有黏弹性，地震波在传播过程中会发生耗散与频散.忽视黏弹性介质的吸收衰减效应，逆时延拓过程中地震波将会出现振幅减弱、相位失真等现象，无法准确定位震源真实位置，因此需要对黏弹性介质中传播的波场进行衰减补偿，并通过采用合适的成像算子对微地震震源进行定位与裂缝成像.本文基于耗散与频散解耦的分数阶黏弹性波动方程模拟波场，采用low rank分解近似混合域算子，分离衰减相关项并反转耗散项符号，并在补偿的衰减项波场的波数域中进行低通滤波，压制噪声的影响；使用优化后的成像算子进行微地震震源定位，并通过分离散射波场，对散射波进行逆时反传寻找裂缝.数值实验证明，本文方法通过low rank近似有效提高了计算效率，衰减补偿算子在滤波器约束下能够稳定地补偿反向延拓的波场，优化后的成像算子能够在压制随机噪声的同时进一步提高计算效率和定位分辨率.
关键词: 黏弹性/
分数阶/
Low rank/
衰减补偿/
微地震/
逆时定位
Abstract:Due to the viscoelasticity of real underground media, dissipation and dispersion occur when seismic wave propagates. If the absorption effect of the viscoelastic medium is not considered, the backpropagation wave field will have amplitude weakening and phase distortion, making it difficult to locate the source accurately. Therefore, it is necessary to compensate for the attenuation of the wave field propagating in the viscoelastic medium, and then use the appropriate imaging operator to locate the microseismic source and image the fracture. In this paper, we simulate wavefield propagation with the fractional order viscoelastic wave equation decoupled from dissipation and dispersion, and use low rank decomposition to approximate the mixed domain operator. The dissipation sign is inverted in the separated attenuation related terms, and low-pass filtering is performed in the wavenumber domain of the compensated attenuation term. We derive the wave equation of viscoelastic medium with attenuation compensation. The optimized imaging operator is used to locate the microseismic source. By separating the scattering data, we backpropagate scattering wave to image fracture. Numerical examples show that this method can improve the calculation efficiency by low rank approximation. Under the constraint of low-pass filter, the attenuation compensation operator can stably compensate the backpropagation wavefield. The optimized imaging operator can further improve the calculation efficiency and location resolution while suppressing random noise.
Key words:Viscoelasticity/
Fractional order/
Low rank/
Attenuation compensation/
Microseismic/
Reverse time location
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