Stable attenuation-compensated reverse time migration and its application to land seismic data
Xinru Mu, Qiang Mao, Jianping Huang
Abstract
Intrinsic attenuation of the earth causes energy loss and phase distortion in seismic wave propagation. To obtain high-resolution imaging results, these negative effects must be considered during reverse time migration (RTM). We can easily implement attenuation-compensated RTM using the constant Q viscoacoustic wave equation with decoupled amplitude attenuation and phase dispersion terms. However, the nonphysical amplitude-compensation process will inevitably amplify the high-frequency noise in the wavefield in an exponential form, causing the numerical simulation to become unstable. This is due to the fact that the amplitude of the compensation grows exponentially with frequency. In order to achieve stable attenuation-compensated RTM, we modify the analytic expression of the attenuation compensation extrapolation operator and make it only compensate for amplitude loss within the effective frequency band. Based on this modified analytic formula, we then derive an explicit time-space domain attenuation compensation extrapolation operator. Finally, the implementation procedure of stable attenuation-compensated RTM is presented. In addition to being simple to implement, the newly proposed attenuation-compensated extrapolation operator is superior to the conventional low-pass filter in suppressing random noise, which will further improve the imaging resolution. We use two synthetic and one land seismic datasets to verify the stability and effectiveness of the proposed attenuation-compensated RTM in improving imaging resolution in viscous media.