Patent ID: 11914090
Assignee: PGS GEOPHYSICAL AS
Field: Measurement (Instruments)
Classification: CPC G  B | IPC B  G

Claim 8:
9. A method for performing a marine survey, the method comprising:
towing marine vibrators in a body of water above a subterranean formation;
activating the marine vibrators to generate orthogonal coded pseudo-random sweeps in the body of water above the subterranean formation, the orthogonal coded pseudo-random sweeps having orthogonal signatures;
detecting wavefields emitted from a subterranean formation in response to the coded pseudo-random sweeps at receivers located in a body of water; and
recording seismic data generated by the receivers in separate shot records, each shot record containing a record of a wavefield reflected from the subterranean formation following activation of one of the marine vibrators and at least a portion of the shot records containing incoherent residual noise associated with one or more previous activations of one or more of the marine vibrators, wherein activating the marine vibrators to generate orthogonal coded pseudo-random sweeps comprises:
generating binary sequences using a linear-feedback shift register in which each binary sequence is generated with seed sequences;
identifying maximum length sequences of the binary sequences with a balanced number of ones and zeros and periodic autocorrelation; and
converting the maximum length sequences into coded pseudo-random signals used to activate the marine vibrators to generate the orthogonal coded pseudo-random sweeps.