Inverse Q migration

Abstract

An inverse Q migration method is proposed to image the subsurface structure from seismic reflection data in anelastic media. The downward extrapolation of surface data is based on a highly accurate numerical solution for a wave system in the spacefrequency domain in an inhomogeneous viscoacoustic medium. The velocity dispersion and the energy dissipation are compensated .n the extrapolation procedure according to the anelastic properties of the rocks through which the seismic waves propagated. Numerical experiments on noise-free or noise-contaminated synthetic data show that this method produces more accurate nigrated sections in which the image of reflectors are sharper and of higher amplitudes, especially for deep reflection events, than those produced by not considering the effects of anelasticity. High frequency noise tend to be amplified in the extrapolation as depth increases, but it can be controlled by adjusting the working frequency band and/or modifying the attenuation coefficient. where i = p is the pressure; vx and vz are, respectively, the horizontal (x-direction) and vertical (z-direction) components of the particle velocity; is the density and K is the viscoacoustic modulus which is a complex function of spatial position and the frequency. Introduction Eliminating vx from equations (1) and (3) we obtain