| 基于逆虚折射干涉法有效提取近地表弱地震信号 |
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| 引用本文： | 乔宝平,郭平,王璞,胡天跃.基于逆虚折射干涉法有效提取近地表弱地震信号[J].地球物理学报,2014,57(6):1900-1909. |
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| 作者姓名： | 乔宝平 郭平 王璞 胡天跃 |
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| 作者单位： | 1. 北京大学地球与空间科学学院, 北京 100871;
2. 中国石油辽河油田勘探开发研究院, 盘锦 124010 |
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| 基金项目： | 国家973计划(2013CB228602);国家863计划(2013AA064202);国家科技重大专项(2011ZX05004-003)联合资助 |
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| 摘 要： | 在地震勘探中，地形起伏和近地表速度的剧烈变化会导致地震波旅行时的扰动，通常会通过折射波信息来估算和消除这些扰动.本文在虚折射的基础上提出了逆虚折射干涉法，通过虚折射波场和原始折射波场的互相关，并对所有位于固定相位点上的检波点进行叠加，重构出逆虚折射波场.通过逆虚折射与超级虚折射的叠加，保证了不同偏移距下折射波振幅恢复的一致性，显著提高折射波的信噪比，有效提取弱信号.同时，本文采用反褶积干涉法来压制由于互相关和褶积产生的子波旁瓣的影响，弥补低频和高频能量的损失，改善恢复的折射波场的稳定性和分辨率.该新方法不需要知道近地表复杂速度模型的信息，可以将虚折射的勘探孔径恢复到原始地震记录的最大孔径.合成资料和实际资料的计算结果表明，基于反褶积的逆虚折射干涉法能够从低信噪比的资料中，有效恢复出折射波信息.
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| 关 键 词： | 地震干涉 逆虚折射 固定相位 反褶积 |
| 收稿时间： | 2013-11-12 |
Effectively picking weak seismic signal near the surface based on reverse virtual refraction interferometry |
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| QIAO Bao-Ping,GUO Ping,WANG Pu,HU Tian-Yue.Effectively picking weak seismic signal near the surface based on reverse virtual refraction interferometry[J].Chinese Journal of Geophysics,2014,57(6):1900-1909. |
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| Authors: | QIAO Bao-Ping GUO Ping WANG Pu HU Tian-Yue |
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| Institution: | 1. School of Earth and Space Sciences, Peking University, Beijing 100871, China;
2. Research Institute of Exploration and Development, Petrochina Liaohe Oilfield Company, Panjin 124010, China |
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| Abstract: | Topography and severe changes of near-surface velocity can lead to travel-time perturbations in records of seismic exploration.Usually, these perturbations are estimated and eliminated by refracted wave information. In this paper, we present reverse virtual-refraction interferometry based on virtual refraction. In this approach, by summing the cross-correlation of raw refraction wavefields and virtual-refraction wavefields over all receivers positioned at stationary-phase points, we reconstruct reverse virtual-refraction wavefields.By stacking of reverse virtual refraction and super-virtual refraction, we can keep the consistency of refracted waves' amplitude recovery at different offsets, significantly improve the signal-to-noise ratio of refracted waves and retrieve weak signal effectively.Meanwhile, deconvolution interferometry is employed to eliminate the influence of wavelet side lobes generated by cross-correlation and cross-convolution. This scheme can compensate energy loses at low and high frequency, and enhance the retrieved refracted waves' stability and resolution.This new method does not need the information about complex velocity model of near surface, and can recover the exploration aperture in virtual refraction to its maximum extent in raw seismic records.The calculation results on synthetic data and field data show that the reverse virtual refraction interferometry based on deconvolution is effective to retrieve refracted wave information from seismic records with low SNR. |
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| Keywords: | Seismic interferometry Reverse virtual refraction Stationary phase Deconvolution |
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