Joint PP-PS inversion at Pikes Peak oilfield, Saskatchewan

The method of simultaneous PP-PS inversion has recently been developed and tested on the 3-D Blackfoot seismic data set. This paper shows the application of this method on 3C-2D seismic data from Pikes Peak oilfield. The inversion was accomplished with a newly installed inversion module in ProMAX. After careful prestack processing, five limitedoffset stacked sections for each of the vertical and radial components were created, migrated and correlated. The inversion module assumes that the data have been traceequalized and, to restore the average AVO behaviour, it requires the input of scalar RMS amplitude estimates for each offset. These were obtained by creating elastic synthetic seismograms for P-P and P-S from well control and calculating the RMS amplitudes for each offset. Then the ten datasets, together with the RMS amplitude values and a background velocity model, were input into the joint PP-PS AVO inversion module in ProMAX. The weighted stacking requires estimation of the P-P and P-S incidence angles at each depth level and this is done by raytracing through the background velocity model. Four attributes were determined: fractional P-wave impedance I I ∆ , fractional S-wave impedance J J ∆ , ( ) λρ λρ ∆ and ( ) ( ) μ λ μ λ ∆ . Good correlation of these parameters from seismic inversion and those calculated from well logs shows that simultaneous PP-PS AVO inversion can be used to indicate anomalous lithology and pore-fluid changes in the subsurface. Therefore it should be helpful in detecting hydrocarbons using 2-D multicomponent seismic data.