Wavefield separation in acoustic media from normalized energy flux density

Robert James Ferguson

The analytic separation of upgoing and downgoing wavefields in acoustic media is summarized, and explicit relations are given for use in prestack-depth migration of seismic data under the acoustic assumption. The linearized wave equations for acoustic media are assumed to be valid, and planewave decomposition of pressure and displacement is used to generate a set of coupled differential equations for pressure and vertical displacement. A wavefield-separation operator is then postulated whose effect is to separate upgoing waves from downgoing waves, and time averaged (normalized) energy flux density is used to determine coefficients for this operator.