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Elastic Forward Modelling Method for an Irregular Surface in the Curvilinear-Polar Coordinates
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 81st EAGE Conference and Exhibition 2019, Jun 2019, Volume 2019, p.1 - 5
Abstract
The polar-coordinate forward modelling can simulate the seismic wavefield propagation in some special geological environments such as tunnel-, log- and borehole- spaces (polar spaces) more accurately than the traditional rectangular-grid-based methods in the Cartesian coordinates. To handle a polar space including irregular surface topography, we develop a transitional coordinate system to improve the accuracy of the finite-difference modelling method in the polar coordinates. In this method, the topographic polar-space model is firstly meshed into curvilinear-polar grids and then the wavefields are calculated in curvilinear-polar coordinates, where the topographic surface is mapped to a flat one. A full staggered grid (FSG) numerical discretization scheme is introduced to solve the wave equations in the curvilinear-polar coordinates. In addition, the polar-coordinated boundary conditions are developed to absorb unwanted reflections surrounding the curvilinear-polar coordinates. The numerical examples on polar-space models indicate that our curvilinear-polar-coordinate modelling method can obtain accuracy, stable and excellent results.