| 黏声介质最小平方逆时偏移 |
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| 引用本文： | 李振春,郭振波,田坤.黏声介质最小平方逆时偏移[J].地球物理学报,2014,57(1):214-228. |
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| 作者姓名： | 李振春 郭振波 田坤 |
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| 作者单位： | 中国石油大学(华东)地球科学与技术学院, 青岛 266580 |
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| 基金项目： | 国家自然科学基金（40974073），国家863课题（2011AA060301），中央高校基本科研业务费专项资金（13CX06014A）联合资助. |
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| 摘 要： | 介质的黏滞性是普遍存在的.黏滞性介质中的真振幅成像需要校正由介质的黏滞性引起的振幅衰减与速度频散，然而常规的反Q偏移方法存在不稳定问题.本文在反演的框架下求解黏声介质成像问题，在有效避开不稳定的同时实现真振幅成像.首先将波动方程线性化，并依此建立黏声介质最小平方逆时偏移（LSRTM）的目标函数；然后推导波动方程伴随算子，并在此基础上借助伴随状态法推导迭代求解的具体算法；最后通过引入动态相位编码技术将计算量降至与常规逆时偏移相同的数量级.该方法在真振幅成像过程中考虑了介质黏滞性的影响，更接近实际情况，具有更好的振幅保持性.相对于常规逆时偏移，该方法能够自动压制成像噪声，具有更高的成像分辨率及精度.通过模型试算验证了方法的正确性.
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| 关 键 词： | 黏滞性吸收 真振幅 最小平方偏移 逆时偏移 |
| 收稿时间： | 2013-01-17 |
Least-squares reverse time migration in visco-acoustic medium |
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| LI Zhen-Chun,GUO Zhen-Bo,TIAN Kun.Least-squares reverse time migration in visco-acoustic medium[J].Chinese Journal of Geophysics,2014,57(1):214-228. |
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| Authors: | LI Zhen-Chun GUO Zhen-Bo TIAN Kun |
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| Institution: | School of Geosciences, China University of Petroleum, Qingdao 266580, China |
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| Abstract: | The viscosity of the subsurface medium is widespread. It's necessary to compensate absorption and correct dispersion of seismic wave in true-amplitude pre-stack imaging. The instability problem hinders the wide application of conventional inverse-Q migration. In this paper, seismic imaging is treated as a linear inverse problem which is often called Least-Squares Reverse Time Migration(LSRTM). Firstly, we linearize the wave equation and define the cost function. Then based on the derived equations of adjoint wave propagation operator, iterative solution is derived using adjoint-state method. At last, dynamical phase encoding technology is used to reduce computation cost. We propose a new method for imaging in visco-acoustic medium while avoid the instability problem. The true-amplitude imaging results can be obtained after compensating absorption and correcting dispersion automatically. It's also a good method to suppress the imaging noise and correct amplitude unbalance caused by geometrical spreading or uneven illumination. Compared with conventional Reverse Time Migration(RTM), this method can provide results with higher resolution and lower imaging noise. Numerical tests on synthetic data demonstrate the validity of the proposed method. |
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| Keywords: | Viscous absorption True-amplitude Least-squares migration Reverse time migration |
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