Process for improving the estimated seismic propagation velocity by focussing analysis

摘要

The invention relates to a method for processing seismic data, in which a volume of raw focusing data (20) is constructed on the basis of back-extrapolation of seismic data obtained by means of at least one seismic source and sensors arranged on the surface along a prospecting section at regular baseline separations. For a subassembly of the said volume which corresponds to a given extrapolation depth (Ze), and for a connected set of baseline points on the prospecting section, a downward shift is carried out, with zero offset, until reaching a first set of depths which are greater than the said extrapolation depth, in order to construct a first block of shifted focusing-analysis data, as well as a reverse shift, with zero offset, upwards to a second set of depths which are less than the said extrapolation depth, in order to construct a second block of shifted focusing-analysis data. The first and second data blocks are combined for each extrapolation depth and a focusing panel is constructed, which is subsequently processed by focusing analysis, with a view to obtaining a better estimation of the propagation velocities of the seismic waves in the substratum. IMAGE