Fremgangsmåte for seismisk prospektering og innretning som benytter samtidig utsendelse av seismiske signaler ervervet ved åkode et signal med pseudo-tilfeldige sekvenser

摘要

- method and device of seismic prospecting by simultaneous emission of seismic signals obtained by encoding a signal by the pseudorandom sequences, and in particular of a periodic signal modulated in phase by such sequences. - it emits, for example, in the ground by means of vibrators, signals such as, for example, of the periodic signals modulated in phase with a pseudo-random binary code (for example), produced by a control unit, it is picked up by the receivers coupled with the formation, the seismic signals reflected by the discontinuities of the ground under - in response to the periodic signals transmitted and recorded in an acquisition and recording system. The periodic signals are transmitted simultaneously by the vibrators. The sequences of control of the periodic signals coded adapted to all the vibrators are obtained either from the same random binary sequence with respective offsets are distributed regularly over the length of the control sequence as a function of the number of vibrators used simultaneously (first embodiment), or from different sequences, chosen in a group of sequences of intercorrelation is minimal (second), or else by combining the two preceding embodiments. The respective contributions of the various vibrators are separated by correlating signals received and recorded with signals constructed from the various sequences of control obtained by a shift. The vibrators can be divided into several groups, the vibrators of each of them being driven by a binary sequence belonging to a group of intercorrelation minimum. - application to the seismic prospecting or the seismic monitoring of the deposits, for example.