Decomposition and inversion of elastic reflection data; first-order angular dependence and applications (Q1902683)

This is an interesting paper presenting and demonstrating elastic inversion of seismic data. After discussing the advantages and drawbacks of the principal classes of seismic inversion methods, from ray tracing based travel time inversion, to full waveform inversion the author discusses his approach to inversion based on the elastic wave equation in two dimensions. He applies the Born approximation to obtain relations between four reflectivity functions and three medium parameters: density, bulk and shear moduli. An interesting aspect of the derivation is the separation of the signal into various components, that generates the four reflectivity functions. A full procedure is described to perform all the necessary steps leading to the inversion, and then it is exemplified and compared with some simple synthetic data and with some real two-dimensional seismic sections. The new procedure is more accurate in recovering reflectivity than any of the other methods, namely, Stolt-Benson migration-inversion, Kirchhoff finite difference, \(f\)-\(k\) and phase-shift migration. In the real data (which have been collected with great care to preserve amplitudes) it shows its ability to map density, bulk and shear moduli giving direct (bright spot) indication of the presence of hydrocarbon deposits. All in all, a very complete, well written paper.