Acoustic wavefield imaging using the energy norm

Wavefield energy can be measured by the so-called energy norm. Using this norm, we propose an imaging condition that represents the total reflection energy and accounts for wavefield directionality in space-time, thus enabling us to attenuate backscattering artifacts in reverse-time migration (RTM). This imaging condition has the flexibility to attenuate any selected angle, and by exploiting this property, we develop a procedure to emphasize events such as backscattered, diving and head waves, with application to full waveform inversion (FWI). This application involves filtering the FWI gradient to preserve its tomographic term consisting of waves propagating along the same path, while attenuating the migration term consisting of waves crossing at arbitrary propagation directions.