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3D Traveltime Computation in Orthorhombic Media Using Layer-by-layer Wavefront Marching
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 79th EAGE Conference and Exhibition 2017, Jun 2017, Volume 2017, p.1 - 5
Abstract
Traveltime computation in orthorhombic media is important for imaging the fractured reservoir. Wavefront marching is a natural way of traveltime computation which usually solves the eikonal equation along the expanding wavefront in isotropic media. However, the position of the expanding point on the wavefront may vary rapidly in 3D space which decreases the computational efficiency. Besides, the eikonal equation in orthorhombic media contains high-order nonlinear term which is challenging to solve by finite difference method. To address these issues, we present a layer-by-layer wavefront marching method to compute traveltime in orthorhombic media. It avoids the rapid variation of position by computing traveltime from one depth to the next depth using wavefront marching. And a strategy is designed to follow the causality of wave propagation. Besides, it avoids solving the eikonal equation by marching the wavefront using Fermat’s principle. And the group velocity obtained by moveout approximation is used to describe the ray propagation during wavefront marching. This method is valid in both vertical and tilted orthorhombic media. Numerical examples on both vertical and tilted orthorhombic models demonstrate the feasibility of the proposed method.