Common‐shot Fresnel beam migration based on wave‐field approximation in effective vicinity under complex topographic conditions |
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| Authors: | Jianping Huang Wenyuan Liao Xin Wang Zhenchun Li |
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| Institution: | 1. Department of geophysics at China University of Petroleum, China;2. Department of Mathematics and Statistics, University of Calgary, Calgary, AB, Canada |
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| Abstract: | Gaussian beam migration is a versatile imaging method for geologically complex land areas, which overcomes the limitation of Kirchhoff migration in imaging multiple arrivals and has no steep‐dip limits of one‐way wave‐equation migration. However, its imaging accuracy depends on the geometry of Gaussian beam that is determined by the initial parameter of dynamic ray tracing. As a result, its applications in exploration areas with strong variations in topography and near‐surface velocity are limited. Combined with the concept of Fresnel zone and the theory of wave‐field approximation in effective vicinity, we present a more robust common‐shot Fresnel beam imaging method for complex topographic land areas in this paper. Compared with the conventional Gaussian beam migration for irregular topography, our method improves the beam geometry by limiting its effective half‐width with Fresnel zone radius. Moreover, through a quadratic travel‐time correction and an amplitude correction that is based on the wave‐field approximation in effective vicinity, it gives an accurate method for plane‐wave decomposition at complex topography, which produces good imaging results in both shallow and deep zones. Trials of two typical models and its application in field data demonstrated the validity and robustness of our method. |
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| Keywords: | Fresnel beam migration Wave‐field approximation Effective vicinity Complex topographic conditions |
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