| 基于Low-rank分解的复杂TI介质纯qP波正演模拟与逆时偏移 |
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| 引用本文： | 黄金强,李振春.基于Low-rank分解的复杂TI介质纯qP波正演模拟与逆时偏移[J].地球物理学报,2017,60(2):704-721. |
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| 作者姓名： | 黄金强 李振春 |
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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地球物理系, 青岛 266580 |
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| 基金项目： | 国家重点基础研究发展计划（2014CB239006），国家自然基金（41274124），中央高校科研业务费专项基金（R1401005A），中国石油大学（华东）研究生创新工程资助项目基金（YCXJ2016005）联合资助. |
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| 摘 要： | 近年来,面向实际应用的TI介质准P波正演模拟与逆时偏移成像技术受到空前的关注.基于常规耦合型传播方程的正演模拟方法不仅存在伪横波及频散假象干扰,而且还遭受模型参数限制(η0)和不稳定影响;而纯qP波方程的推导繁琐,且由于方程中包含拟微分算子造成求解难度大且精度有限.为此,本文首先构建了一种适用于任意TI介质的纯qP波传播算子,然后借助Low-rank分解求取该算子中的空间-波数域矩阵,同时引入Cerjan衰减边界条件来压制边界反射干扰,最终实现了一种间接的纯qP波波场外推方案,并将其成功应用于复杂TI介质正演模拟与逆时偏移成像中.通过开展数值模拟,并与其他方法对比表明:①该方法既避免了纯qP波方程的繁琐推导,又克服了耦合型方程对模型参数的限制;②还彻底消除了残余伪横波噪音及数值频散;③且能适应较大时间或空间步长及高频震源,是一种相对准确且稳定的各向异性纵波正演与成像策略.
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| 关 键 词： | 正演模拟 逆时偏移 TI介质 纯qP波 Low-rank分解 |
| 收稿时间： | 2016-06-13 |
Modeling and reverse time migration of pure quasi-P-waves in complex TI media with a low-rank decomposition |
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| HUANG Jin-Qiang,LI Zhen-Chun.Modeling and reverse time migration of pure quasi-P-waves in complex TI media with a low-rank decomposition[J].Chinese Journal of Geophysics,2017,60(2):704-721. |
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| Authors: | HUANG Jin-Qiang LI Zhen-Chun |
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| Institution: | Department of Geophysics, School of Geosciences, China University of Petroleum(East China), Qingdao 266580, China |
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| Abstract: | Forward modeling and reverse time migration (RTM) of quasi-P-waves (qP) in TI medium for practical application draw great attention in recent year. Modeling based on conventional coupled equations may exist SV-wave artifacts and numerically dispersion,also suffer from strict limitations on the media parameter (η>0) and instabilities. For decoupled qP wave equation,it requires many tedious mathematical deduction,causing its numerical calculation to be very challenging,and its accuracy is limited,due to containing a pseudo-differential operator in this equation.
To overcome these defects,Firstly,we derived a pure qP-wave propagator suitable for arbitrary TI media. Then the Low-rank decomposition algorithm was employed to solve the space-wavenumber domain matrix in propagator. In addition,the Cerjan's attenuation boundary condition was adopted to eliminate boundary reflections. Finally,an indirect pure qP-wave evolution scheme was implemented,which is successfully applied to perform modeling and RTM.
Numerical experiments on modeling and RTM validate that,compared to the traditional approaches,the proposed scheme is more accurate and stable for anisotropic qP-wave modeling and RTM. Specifically,our method presented here include three aspects:① it cannot only avoid the complicatedly mathematical deduction of decoupled equations,but also break the restrictions (η>0) on media parameters for coupled equations; Besides,② SV-waves artifacts and numerical dispersion can be eliminate completely by this strategy; ③ Synthetic results remain high quality even for large temporal and spatial intervals or high-frequency sources,which proves better adaptability of the proposed method. |
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| Keywords: | Forward modeling Reverse time migration TI medium Pure quasi-P-wave Low-rank decomposition |
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