Patent ID: 8687462

Claim:
A method of obtaining information about positions of seismic sources in a marine seismic source array comprising N seismic sources, wherein the marine seismic source array includes at least Nunique types of seismic sources that are nominally non-identical to one another, where 1â‰¦Nuniqueâ‰¦Nâˆ’2, the method comprising: measuring the pressure field at M locations of the N seismic sources, where M>Nunique; obtaining information about relative positions of the seismic sources in the marine seismic source array from the M pressure measurements and from a constraint that at least two of the seismic sources are nominally identical to one another, wherein obtaining information about the relative positions of the seismic sources comprises determining, on the basis of a first set of estimates of the relative positions of the seismic sources, respective notional signatures for at least first and second seismic sources that are nominally identical to one another from the M measurements of the pressure field; comparing the notional signature of the first seismic source with the notional signature of the second seismic source, wherein the seismic sources are airguns and comparing the notional signature of the first seismic source with the notional signature of the second seismic source comprises comparing the notional signature of the first seismic source with the notional signature of the seismic second source within a time window that excludes the first bubble peak of the notional signature of the first seismic source and the first bubble peak of the notional signature of the second seismic source; generating a measure indicative of a difference between the notional signature of the first seismic source and the notional signature of the second seismic source; comparing the generated measure with a predetermined threshold; and if the generated measure is greater than the predetermined threshold, calculating respective notional signatures for at least the first and second seismic sources on the basis of a second set of estimates of the relative positions of the seismic sources that is different from the first set of estimates of the relative positions of the seismic sources.