Supercomputer finite-difference algorithms for use in seismic tomography as applied to oil sands projects

Algorithms for finite difference methods of modelling the entire elastic waveform will be discussed. They are implemented on the Cyber 205 supercomputer as it is configured at the University of Calgary. They are set up to handle SH and P-SV cases for sources and receivers in any geometric configuration consistent with the memory limitations of the system. A hyperbolic system of equations is modelled for a heterogeneous two-dimensional medium. A (2,2) Lax-Wendroff scheme forms the main basis of the current algorithms. A line source having a Gaussian time-dependence has been used and also a point source with 2-D spreading to illuminate two-dimensional models. Current implementations appear to be sufficiently efficient so that fully 3-dimensional algorithms appear to be feasible. The results from the supercomputer simulation are used to model seismic cross hole experiments before and after steam injection in the mode carried out by ESSO Resources near Cold Lake, Alberta. The results should allow us to simulate realistic physical models giving the size, shape, and anomalous attenuation present in steam injected areas.