地震干涉法分阶多次波逆时偏移
Reverse time migration of order-divided multiples based on seismic interferometry
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摘要: 地下介质中的盐丘高速体和高陡构造对传统成像方法构成挑战。在常规地震勘探中,多次波通常被视为噪声加以压制或消除。然而,多次波由于其地下传播路径长、反射角小,所以具备更广的成像范围和更丰富的地下构造信息。地震干涉理论能够正确预测多次波,因此基于地震干涉的多次波逆时偏移方法在复杂地下构造成像中具有重要意义。本文分析了地震干涉的基本原理,推导出相应公式并给出算法,提出了基于地震干涉的多次波预测技术。该技术避免了传统多次波处理方法,提高了成像效率,为后续多次波逆时偏移提供了研究基础。针对常规多次波逆时偏移中存在大量串扰噪声的问题,本文创新性地利用地震干涉原理进行了分阶多次波逆时偏移研究,提出了基于地震干涉的分阶多次波逆时偏移方法,有效改善了多次波成像的串扰噪声问题。数值实验表明,相较于一次波逆时偏移,多次波逆时偏移在盐丘下构造成像方面有明显改善,而基于地震干涉理论的分阶多次波逆时偏移则能进一步压制常规多次波逆时偏移中的串扰噪声,对盐下复杂构造进行准确成像,提高了成像分辨率。Abstract: High-velocity salt domes and steeply dipping structures in subsurface media pose challenges to conventional imaging methods.In conventional seismic exploration,multiples are usually treated as noise to be suppressed or eliminated.However,due to their long propagation paths and smaller reflection angles within subsurface media,multiples show a wider imaging range and richer information on subsurface structures.Since seismic interferometry enables accurate prediction of multiples,the reverse time migration(RTM) of multiples based on seismic interferometry is crucial for imaging complex subsurface structures.Based on the analysis of the fundamental principles of seismic interferometry,this study derived the corresponding equations and algorithms.Furthermore,this study proposed a multiple prediction technique based on seismic interferometry.By circumventing conventional multiple processing methods,this technique enhances imaging efficiency, providing a research basis for subsequent RTM of multiples.To address the significant crosstalk noise in conventional RTM,this study innovatively utilized seismic interferometry to explore the RTM of order-divided multiples.Finally,this study proposed a RTM method for order-divided multiples based on seismic interferometry,effectively mitigating the problem of crosstalk noise in multiple imaging.Numerical experiments show that compared to the RTM of primary waves,the RTM of multiples exhibited significant improvements in imaging pre-salt structures.The RTM of order-divided multiples based on seismic interferometry could further suppress the crosstalk noise in conventional RTM,enabling accurate imaging of complex pre-salt structures and improving imaging resolution.
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