ESSAI DE DETERMINATION AUTOMATIQUE DES VITESSES SISMIQUES PAR MESURES ENTRE PUITS*

Abstract

A bstract Large memory computers create new possibilities for seismic interpretation in well‐drilled areas, and more generally in problems involving deep sources. Records obtained by well‐to‐surface, surface‐to‐well and/or well‐to‐well propagation contain a large amount of information, owing to the great number of seismic rays travelling throughout the subsurface. This paper considers two successive steps: — direct case: computation of the first arrival times of seismic rays propagating through a two‐dimensional subsurface with given vertical and horizontal velocity variations; — inverse case: computation of a two‐dimensional velocity distribution, knowing the travel times of seismic rays through the subsurface. A computer program has been elaborated to solve both direct and inverse problems. There are no difficulties with the direct case; a certain number of uncertainties remain with the inverse case.