Joint PP-PS inversion at Pikes Peak oil field, Saskatchewan

Hongbo Zhang, Gary F. Margrave, R. James Brown

The method of simultaneous PP-PS inversion has recently been developed and tested on the 3D Blackfoot seismic dataset. This paper shows the application of this method on 3C-2D seismic data from Pikes Peak oil field. The inversion was accomplished with a newly installed inversion module in ProMAX. After careful prestack processing was done, five limited-offset stacked sections for each of the vertical and radial components were created, migrated, and correlated. The inversion module assumes that the data has been trace equalized and, to restore the average AVO behaviour, 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, fractional S-wave impedance, fractional -, and fractional -. 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 2D multicomponent seismic data.