Patent ID: 6807508
Filing Date: 2004-10-19
Classification: G01V

Abstract:
A method of prospecting or monitoring an underground formation by elastic waves, comprising:simultaneously emitting, in the ground, seismic waves from seismic sources each controlled by a signal comprising either an elementary sequence formed by coding of a signal by pseudo-random sequences, a length of each elementary sequence being at least equal to a product of a number of seismic sources vibrating simultaneously by a listening time, or with the elementary sequence extended, before and after, with parts whose length is at least equal to the listening time; receiving and recording the signals reflected by subsoil discontinuities in response to the emitted signals; and processing the recorded signals; and wherein a respective contribution of each one of the seismic sources is separated by correlating the received and recorded signals either by signals constructed from either the elementary sequence, extended, before and after, with parts whose length is at least equal to the listening time, obtained by circular permutation, or of the elementary sequence, the signals applied to the vibrators being formed from a periodic signal having an amplitude and derivatives with respect to time are equal to zero at a beginning and at an end of each period of the periodic signals such that an integral of the periodic signals over a period of the periodic signals is zero.