Method for seismic monitoring of an underground zone by simultaneous use of sererval vibroseismic sources
AssigneesInstitut Francais du Petrole, Gas De France, Compagnie Generale de Geophysique
InventorJulien Meunier
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Abstract
Method and system intended for seismic monitoring of an underground zone (1), comprising simultaneously using several seismic vibrators. The system comprises for example several local units (LU) comprising each a vibrator (5), a seismic pickup antenna (2), a local acquisition and processing unit (6), and a central control and synchronization unit (8) for simultaneously controlling the various vibrators by means of orthogonal signals, local units (6) being suited, by means of particular; processing, to isolate and to reconstitute the seismograms corresponding to the contributions of the various vibrators. Applications: monitoring of a hydrocarbon reservoir during production or of a reservoir used for gas storage for example.
Claims13
A method of seismic monitoring an underground formation comprising:
- continuously emitting seismic waves in the formation by coupling with the formation at least two vibrators which emit seismic waves simultaneously and are controlled by orthogonal pilot signals, each pilot signal having a fundamental component and harmonics thereof, frequencies of the fundamental component and of the harmonics thereof being different so as to form a composite vibrational signal;
- receiving signals emanating from the formation in response to the emitted seismic waves and recording the received signals;
- and
- processing the recorded signals including discriminating respective contributions of the vibrators to the composite vibrational signal and reconstructing seismograms equivalent to seismograms that would be obtained by actuating the vibrators separately.
A system for seismic monitoring of an underground formation, comprising at least two vibrators to be coupled with the formation, an assembly for generating sinusoidal orthogonal pilot signals, each pilot signal comprising a fundamental component and harmonics thereof, respective frequencies of the fundamental component and the respective harmonics thereof being different and a connecting means for applying the orthogonal pilot signals respectively to the at least two vibrators to generate in the formation a composite vibrational signal, a seismic reception device for reception of seismic signals emanating from the formation in response to the emitted seismic waves, a recording set for recording the received signals, and a processing means including f at least one processor for discriminating respective contributions of the at least two vibrators to the composite vibrational signal and reconstructing seismograms equivalent to seismograms that would be obtained by actuating the vibrators separately.
Dependencies are inferred from the claim text.