Tomographic imaging of velocity and Q with application to crosswell seismic data from the Gypsy Pilot Site, Oklahoma

The centroid frequency shift method is implemented, tested with synthetic data, and applied to field data from three contiguous crosswell seismic experiments at the Gypsy Pilot Site in northern Oklahoma. The simultaneous iterative reconstruction technique is used for tomographic estimations of both P-wave velocity and Q. No amplitude corrections or spreading loss corrections are needed for the Q estimation. The estimated in-situ velocity and Q distributions correlate well with log data and local lithology. The Q/velocity ratio appears to correlate with the sand/shale ratio (ranging from an average of similar to 15 s/km for the sand-dominated lithologies to an average of similar to 8.5 s/km for the shale-dominated ones), with the result that new information is provided on interwell connectivity.