Application of 3D Statics Technology and Seismic Interferometry to Engineering Geophysics

This paper presents the application of 3D statics used in oil exploration industry to Engineering Geophysics, and an attempt to prove the unicity of inverted solutions with an analysis of amplitudes of refracted first arrivals. The principle of one of the most renowned method, the Plus-Minus method (Hagedoorn (1959)) , has been improved by Dereck Palmer (1981) with the General Reciprocal method (GRM). Later on, the same author (reference needed) outlined a problem of non-unicity of inversions which can be supported with the following question; is the interface of a refractor dipping or is the velocity varying laterally? Palmer (2001) proposed a solution through the analysis of refracted amplitudes, with a technique alled Refraction Convolution section, or RCS. Different cases show that the smaller is the amplitude, the higher is the impedance contrast between layers on top and beneath a same refractor. If the amplitude remains constant along a delineated refractor, change in time-depth is related to a change in depth of the refractor. On the other hand, if amplitude varies laterally along a same delineated refractor, the change in time-depth is related to a lateral change in velocity.