Method of improving an estimate of seismic wave propagation velocities by focusing analysis

摘要

The invention relates to a method of processing seismic data in which a volume of raw focusing data is constituted by downwards extrapolation of seismic data obtained by means of at least one seismic source and of sensors disposed at the surface at regular abscissas along a prospecting section. For a subset of said volume corresponding to a given extrapolation depth and for a contiguous set of abscissas along the prospecting section, zero offset downwards migration is performed to a first set of depths greater than said extrapolation depth in order to constitute a first block of focusing analysis migrated data, and similarly inverse zero offset migration is performed upwards to a second set of depths less than said extrapolation depth in order to constitute a second block of focusing analysis migrated data. The first and second blocks of data are united for each extrapolation depth, and a focusing panel is constructed which is subsequently processed by focusing analysis in order to obtain a better estimate of the seismic wave propagation velocities underground.