1. Estimation of True (Angle-Dependent) Reflection Coefficients in 3-D Prestack Depth Migration of Seismic Data George A. McMechan, Center for Lithospheric Studies, University of Texas at Dallas
During seismic wave propagation, amplitudes are affected by many factors including geometrical spreading, transmission and estimating attenuation losses, and reflection coefficients.  Accurate recovery of reflection coefficients during seismic imaging is crucial for estimating rock and fluid properties from the  images. Thus, all the other amplitude effects need to be compensated for during imaging. That is the heart of this project.
A representative reflected propagation path for a seismic reflection. Energy is reduced during wave propa-gation everywhere (by geo-metrical spreading losses), at boundaries (by transmis-sion losses), and within layers [by attenuation (Q) losses]. These losses need to be compensated for accurate amplitude recovery in imaging.
Reflection coefficients for a single source (at 2.55 km) at the top of the model at the lower left, as recorded at a series of positions along the top. Only fully compensated amplitudes (the + symbols) match well with the correct values (the heavy solid line).
The best-fit solutions across data from 66 sources give accurate estimates of the density in the target layer of the model at the left. The partially compensated solution is very inaccurate below the salt overhang. The fully compensated estimate is the same both beneath the salt, and away from it. Other parameters in the composite solution (compressional and shear velocities and attenuations), fit similarly.
Example of a target reflector beneath a salt body. Test data are simulated for arrays of sources and receivers along the top of the model. The data contain reflected waves from each of the boundaries in the model. Reflections from the portions of the model beneath the salt overhang are of lower amplitude than those away from it because of losses associated with the salt.