Method for seismic exploration by vertical seismic profiling and installation for its implementation

Abstract

A seismic exploration method is disclosed for filtering the signals produced by a detector placed at different depths in a well in response to an emission of acoustic waves from a source on the surface: the signals comprising downgoing wave components and upgoing wave components. The filtering consists in sampling from among the N signals to be processed a group of n signals s 1 . . . s n detected at respective levels x 1 . . . x n , in determining the propagation time t k of the acoustic waves from the level x 1 to each level x k , in both advancing and delaying the signals s k by the time t k in relation to s 1 , in adjusting the signals for the effects of the acoustic impedance of the formation, in combining s 1 and the signals s k thus shifted and adjusted to obtain a sum z 1 ', in calculating a sum y 1 ' of s 1 and of the thus delayed and adjusted signals s k , and in generating a signal u 1 * ', defined as an optimum estimation of the upgoing wave component, from the sums y 1 ' and z 1 '.