1887

Abstract

Seismic pressure point sources have been simulated near the surface of sand dunes in Oman. Real topographic elevation data was assembled from recorded field data in the region, in-filled with necessary interpolated data, to form the surface topography implemented. Recent results describing seismic sand curves for the region are employed in the near-surface medium definition, and a constant half space of realistic seismic velocities and densities are used for the simulated sub-sand medium. Topographic effects in the form of scattering and reflections from prominent sand dune topography are confirmed, showing differences between scattering from elongated and normally oriented sand dunes to the excited source orientation. 8th order Finite-Differences (F-Ds) are used to discretize full elastic wave equations in the velocity-stress formulation, reducing gradually the F-D order when approaching all numerical grid boundaries. At the free surface, I employed boundary conditions for arbitrary surface topography derived for the particle velocities, discretized by 2nd order F-Ds, and at the side and bottom boundaries exponential damping is applied for non-reflective boundaries. A rectangular grid is used to model the Cartesian wave equations from a curved grid by adding in the equations extra terms that depend on the arbitrary surface topography and its spatial derivatives. The curved grid is adapted to an arbitrary surface topography with gradually less curvature with depth towards the bottom of the grid, which is planar. The code is parallellized by domain decomposition through MPI (Message Passing Interface) parallellization between processors. This makes possible the time domain modelling of higher frequencies (even relevant for exploration) and larger areas than could be done otherwise. Only in the last 3-5 years has such complex modelling been commercially viable in hydrocarbon exploration.

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/content/papers/10.3997/2214-4609.20146395
2008-09-08
2020-09-27
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http://instance.metastore.ingenta.com/content/papers/10.3997/2214-4609.20146395
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