The stability and efficiency, especially the stability, are generally concerned issues in Q compensated reverse time migration (Q-RTM). The instability occurs due to the exponential amplitude increasing during the forward or backward wavefield propagation. The regularization and low-pass filtering method are two effective strategies to overcome the instability of the wave propagation in Q-RTM. However, the regularization parameters are determined experimentally, and the wavefield cannot be recovered accurately. The low-pass filtering method cannot balance the selection of cutoff frequency for varying Q values, and may dam the effective signals. In this paper, we present a stable Q-RTM algorithm based on the excitation amplitude imaging condition, which can compensate both the amplitude attenuation and phase dispersion. Unlike the existing Q-RTM algorithms enlarging the amplitude, our new algorithm attenuates the amplitude again during both the forward and backward wavefield propagation. Therefore, the new Q-RTM algorithm is absolutely stable. We test our Q-RTM using a realistic BP gas model, and compare the Q-RTM images to the reference images obtained by the acoustic RTM with acoustic seismic data. The new Q-RTM results match the reference images quite well.
Presentation Date: Wednesday, September 27, 2017
Start Time: 1:50 PM
Presentation Type: ORAL