Viscoacoustic least-squares reverse-time migration of different-order free-surface multiples |
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| Authors: | Jinli Li Yingming Qu Mengjie Li Zhenchun Li |
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| Institution: | 1. School of Geosciences, China University of Petroleum, Qingdao, China;2. School of Geosciences, China University of Petroleum, Qingdao, China
Shandong Provincial Key Laboratory of Deep Oil & Gas, China University of Petroleum, Qingdao, Shandong, China |
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| Abstract: | Multiples have longer propagation paths and smaller reflection angles than primaries for the same source–receiver combination, so they cover a larger illumination area. Therefore, multiples can be used to image shadow zones of primaries. Least-squares reverse-time migration of multiples can produce high-quality images with fewer artefacts, high resolution and balanced amplitudes. However, viscoelasticity exists widely in the earth, especially in the deep-sea environment, and the influence of Q attenuation on multiples is much more serious than primaries due to multiples have longer paths. To compensate for Q attenuation of multiples, Q-compensated least-squares reverse-time migration of different-order multiples is proposed by deriving viscoacoustic Born modelling operators, adjoint operators and demigration operators for different-order multiples. Based on inversion theory, this method compensates for Q attenuation along all the propagation paths of multiples. Examples of a simple four-layer model, a modified attenuating Sigsbee2B model and a field data set suggest that the proposed method can produce better imaging results than Q-compensated least-squares reverse-time migration of primaries and regular least-squares reverse-time migration of multiples. |
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| Keywords: | Different-order least-squares reverse-time migration multiples Q-compensated |
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