Elastic waveform inversion of pressure field data

An elastic waveform inversion method for inverting crosswell pressure field data is presented. In this method a low frequency approximation is used to analytically simulate the pressure generated in the fluid filled well. The tube wave in the borehole is not simulated based on the assumption that it can be removed from the field data by median filtering. The inversion method inverts for both P- and S-velocity tomograms at the same time. Therefore it requires fewer data processing procedures and honors the original amplitude information. The field data example shows that this method can provide superior images of the P- and S-velocity structures compared to the traveltime tomogram. The correlation between the P- and S-velocity tomograms is quite reasonable. Comparisons between the tomogram velocity profiles and the sonic logs show a good match. The resolution of the S-velocity tomogram is about the twice that of the P-velocity tomogram.