Abstract：The energy of seismic wave decreases exponentially as it propagates underground.This results in the analytical solution of conventional viscoacoustic reverse time migration (Q-RTM) increasing exponentially with frequency,and consequently instable wave field compensation,and even failed migration due to the effective wave field covered by high-frequency noise.Based on available knowledge,a stable Q-RTM method in frequency domain for undulated shallow surface is proposed.To restrain the growth of high-frequency components,a stable factor is added to the frequency domain viscoacoustic equation,and its corresponding stable expression for Q-RTM is derived.The stable factor only changes the computing sign of the high frequency outside the effective frequency band,but not bringing additional calculation.The specific process is as follows:①Establish body-fitted grids and mapping the relationship between physical space and computational space; ②In the computational space,calculate the forward and backward wave fields with Q in frequency domain and obtain corresponding wave fields in time domain through IFFT; ③Obtain the forward and backward wave fields in physical space by the mapping relationship; ④Migrate according to the cross-correlation imaging conditions for every time step.Models and raw data have demonstrated that the proposed method can compensate amplitude and high frequencies caused by attenuation,and significantly improve seismic resolution and imaging quality of shallow surface.
刘延利, 李振春, 王姣, 孙苗苗, 刘强. 起伏浅表层稳定的频率域黏声逆时偏移方法[J]. 石油地球物理勘探, 2020, 55(6): 1312-1320.
LIU Yanli, LI Zhenchun, WANG Jiao, SUN Miaomiao, LIU Qiang. Stable viscoacoustic reverse time migration in frequency domain for undulated shallow surface. Oil Geophysical Prospecting, 2020, 55(6): 1312-1320.
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