Viscoacoustic reverse-time migration

Absorption decreases the amplitude of waves propagating in the earth. In ad dition, it narrows the bandwidth and modifies the phase. Obtaining true-amp litude migration and acceptable resolution in dissipative media requires a migration algorithm that corrects these effects. To achieve this, a reverse -time prestack depth migration technique is used. This uses a stable amplif ying finite-difference wavefield extrapolation that compensates for the att enuating propagation of the wavefields in the real earth. Numerical tests o n synthetic VSP data illustrate how dissipation destroys the amplitude, pha se and resolution in the migration images, and how our algorithm corrects t hese effects. The tests also show that the method is stable with respect to noise, and does not require a very detailed macro-model for dissipation.