Time reversal focusing for velocity estimation: Cross-well acquisition

In this study, we utilize time reversal focusing as a tool for velocity model estimation. Demonstrated on a cross-well acquisition, we show the usefulness of focusing as a measure for velocity model quality. It can be therefore used as an objective function for an inversion problem, solved in this study by a global optimization method - simulated annealing. In addition, we show the validity of significantly reducing computation time by time-reversal of a summation of all shot records instead of time-reversing each shot separately. Then, we study a 2-D field-data SH-waves cross-well example, where a conventional travel-times tomography model is compared to the time-reversal inverted model, and show the advantages of the latter.