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Directional Full-Wave Scatter Source Modelling and Dip-Sensitive Target-Oriented RTM
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 79th EAGE Conference and Exhibition 2017, Jun 2017, Volume 2017, p.1 - 5
Abstract
Reverse Time Migration is now the dominant method to image complex geology. Nevertheless, illumination studies are still mostly done with ray-based methods, because wave-equation methods generally do not generate directional information, or only at considerable computational cost.
We introduce a simple way to numerically restrict the directional aperture of a full-wave source without distortion of the resulting wave front. At the location of the scatter source, a damping mask with chosen angular aperture, such as critical reflection angle, and direction, such as normal to structural dip, is applied in forward modelling time following a sine function that peaks at a small number of periods of the source wavelet.
The resulting scatter energy measured at the acquisition surface may be used in the same way as ray counts in myriad applications, such as in directional illumination or visibility analysis for survey design, and in target-oriented RTM shot selection. The main advantages of the proposed method are: implementation simplicity, computing efficiency, fidelity to the physics of wave propagation in complex geology, and stability across rugose velocity contrasts.