Prestack time migration from 3D irregular surfaces with near-surface-related deabsorption
| Autor: | Linong Liu, Wei Zhang, Hui Yang, Jianfeng Zhang, Jincheng Xu |
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| Rok vydání: | 2020 |
| Předmět: | |
| Zdroj: | GEOPHYSICS. 85:S21-S32 |
| ISSN: | 1942-2156 0016-8033 |
| DOI: | 10.1190/geo2019-0259.1 |
| Popis: | We have developed a 3D prestack time migration (PSTM) approach that can directly migrate nonplanar data with near-surface-related deabsorption using three effective parameters. The proposed scheme improves the so-called topography PSTM approach by adding a near-surface effective [Formula: see text] parameter that compensates for the absorption and dispersion of waves propagating through near-surface media. The two effective velocity parameters above and below the datum can be estimated by flattening events in imaging gathers, and the additional near-surface effective [Formula: see text] parameter can be obtained using scanning technology. Hence, no knowledge with respect to near-surface media is needed in advance for implementing the proposed scheme. The proposed topography-deabsorption PSTM method can be applied to seismic data recorded on a 3D irregular surface without statics corrections. Consequently, traveltimes are obtained with improved accuracy because the raypath bends away from the vertical in the presence of high near-surface velocities, and the absorption and dispersion caused by strong intrinsic attenuation in near-surface media are correctly compensated. Moreover, we attenuated the migrated noise by smearing each time sample only along the Fresnel zone rather than along the entire migration aperture. As a result, an image with a higher resolution and superior signal-to-noise ratio is achieved. The performance of the proposed topography-deabsorption PSTM scheme has been verified using synthetic and field data sets. |
| Databáze: | OpenAIRE |
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