AVO Inversion by Simultaneous P-P and P-S Inversion

Jeffrey A. Larsen

This thesis presents a method to simultaneously invert P-P and P-S pre-stack seismic data to derive estimates of compressional and shear impedance values. These estimates of compressional and shear impedance can thus be used to correlate anomalous lithology and pore-fluid content changes in the subsurface. The simultaneous inversion method utilizes a model-based, weighted stacking approach similar to established P-P methods. The primary difference with this method is the inclusion of P-S seismic data and thus a different set of model-based weights. These weighted stacking methods are compared using synthetic data, as well as data from a three-component, threedimensional (3C-3D) survey from the Blackfoot field in Alberta, Canada.

The simultaneous inversion method has been shown to give similar results to standard P-P weighted stacking methods using synthetic noise-free data. Further results show the simultaneous inversion method performs significantly better in areas of high noise or weak P-P reflectivity than comparable methods using P-P seismic data only.