| 基于全波形反演的探地雷达数据逆时偏移成像 |
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| 引用本文： | 雷林林,刘四新,傅磊,吴俊军.基于全波形反演的探地雷达数据逆时偏移成像[J].地球物理学报,2015,58(9):3346-3355. |
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| 作者姓名： | 雷林林 刘四新 傅磊 吴俊军 |
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| 作者单位： | 1. 吉林大学地球探测科学与技术学院, 长春 130026;2. 中国石油集团东方地球物理勘探有限责任公司 新兴物探开发处, 河北涿州 072751 |
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| 基金项目： | 国家自然科学基金项目(40874073,41074076),国家高技术研究发展计划项目(2013AA064603)及中石油东方地球物理公司中青年科技创新基金项目(11-06-2013)共同资助. |
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| 摘 要： | 逆时偏移成像(RTM)常用来处理复杂速度模型,包括陡倾角及横向速度变化剧烈的模型.与常规偏移成像方法(如Kirchhoff偏移)相比,逆时偏移成像能提供更好的偏移成像结果,近些年逆时偏移成像越来越广泛地应用到勘探地震中,它逐渐成为石油地震勘探中的一种行业标准.电磁波和弹性波在动力学和运动学上存在相似性,故本文开发了基于麦克斯韦方程组的电磁波逆时偏移成像算法,并将其应用到探地雷达数据处理中.时间域有限差分(FDTD)用于模拟电磁波正向和逆向传播过程,互相关成像条件用于获得最终偏移结果.逆时偏移成像算法中,偏移成像结果受初始模型影响较大,而其中决定电磁波传播速度的介电常数的影响尤为重要.本文基于时间域全波形反演(FWI)算法反演获得了更为精确的地下介电常数模型,并将其反演结果作为逆时偏移成像的初始介电常数模型.为了验证此算法的有效性,首先构建了一个复杂地质结构模型,合成了共偏移距及共炮点探地雷达数据,分别应用常规Kirchhoff偏移算法及逆时偏移成像算法进行偏移处理,成像结果显示由逆时偏移成像算法得到的偏移结果与实际模型具有较高的一致性;此外本文在室内沙槽中进行了相关的物理模拟实验,采集了共偏移距及共炮点探地雷达数据,分别应用Kirchhoff和叠前逆时偏移成像算法进行处理,结果表明叠前逆时偏移成像在实际应用中能获得更好的成像效果.
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| 关 键 词： | 逆时偏移 探地雷达 全波形反演 物理模拟实验 |
| 收稿时间： | 2014-03-14 |
Reverse time migration applied to GPR data based on full wave inversion |
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| LEI Lin-Lin,LIU Si-Xin,FU Lei,WU Jun-Jun.Reverse time migration applied to GPR data based on full wave inversion[J].Chinese Journal of Geophysics,2015,58(9):3346-3355. |
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| Authors: | LEI Lin-Lin LIU Si-Xin FU Lei WU Jun-Jun |
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| Institution: | 1. College of Geo-exploration Science and Technology, Jilin University, Changchun 130026, China;2. BGP Inc., China National Petroleum Corporation, Zhuozhou Hebei 072751, China |
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| Abstract: | Reverse-time migration (RTM) is used for subsurface imaging to handle complex velocity models including steeply dipping interfaces and dramatic lateral variations, and promises better imaging results compared to traditional migration methods such as Kirchhoff migration algorithm. RTM has been increasingly applied to seismic surveys for hydrocarbon resource explorations. Based on the similarity of kinematics and dynamics between electromagnetic waves and elastic waves, we develop a pre-stack RTM method and apply it to processing ground penetrating radar (GPR) data.#br#The finite-difference time domain (FDTD) numerical method is used to simulate the electromagnetic wave propagation including forward and backward extrapolation. The cross-correlation imaging condition is used to obtain the final image. In order to provide a velocity model with relatively higher accuracy as the initial velocity model for RTM, we apply a full waveform inversion (FWI) in the time domain to estimate the subsurface velocity structure based on reflection radar data. For testing the effectiveness of the algorithm, we have constructed a complex geological model; and synthesized common-offset radar data and common-shot profile (CSP) radar reflection data. All data are migrated with the traditional Kirchhoff migration method and pre-stack RTM method separately. The migration results from pre-stack RTM show better coincidence with the true model. Furthermore, we have performed a physical experiment in a sandbox where a polyvinyl chloride (PVC) box is buried in the sand. The obtained common-offset radar data and common-shot radar data are migrated by using the Kirchhoff migration method and per-stack RTM algorithm separately. The per-stack RTM result shows that the RTM algorithm can obtain better imaging results.In the numerical experiments, velocity variation exists in the geological model due to the irregular interface between soil and sand. The imaging result from pre-stack RTM is better than that of the traditional Kirchhoff migration algorithm because pre-stack RTM can handle the model with horizontal velocity variation. In the RTM imaging, the shape and position of the interface and their anomalies match well with the true model, while the imaging of Kirchhoff migration cannot do so. As for the physical experiment, the Kirchhoff migration algorithm and pre-stack RTM have been applied to process the measured radar data. The imaging results from RTM show its advantage compared with the Kirchhoff migration method. |
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| Keywords: | Reverse time migration GPR Full waveform inversion Physical model experiment |
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