3D frequency-domain finite-difference modeling of acoustic wave propagation using a massively parallel direct solver: a feasibility study

International audienceWe present a frequency-domain finite-difference method for modeling 3D acoustic wave propagation based on a massively parallel direct solver. This method was developed as a tool for frequency-domain full-waveform inversion of 3D global offset data that requires an efficient modeling code for multiple shots and few frequencies.We have first implemented a finite-difference stencil for the 3D acoustic frequency-domain wave equation in pressure. The method is based on the parsimonious mixed-grid formulation which linearly combines several second-order accurate staggered-grid stencils on different rotated coordinate frames to minimize the numerical anisotropy. Accuracy of the stencil is improved by using an average of the mass acceleration term at the collocation point. Our approach leads to a 27-point stencil. The resultant system of linear equations is solved with the massively parallel solver MUMPS based on a multifrontal method.We have computed multi-shot simulations in the 3D SEG/EAGE overthrust model to assess whether representative seismic imaging problems can be tackled with the frequency-domain approach. The 5 Hz frequency has been modeled in a portion of the overthrust model of dimension 20 × 11.4 × 4.5 km using a PC cluster of 20 bi-processor nodes with 4Go of memory each.We conclude that, using larger clusters, 3D frequency-domain fullwaveform modeling and inversion applied to dense global offset acquisition geometries may provide a reliable tool for imaging the large to middle- wavelengths of geological structures