	US 12,111,438 B2
	Repeating a previous marine seismic survey with a subsequent survey that employs a different number of sources
Magnus Wangensteen, Levanger (NO); Christian Strand, Finchampstead (GB); Bertrand Caselitz, Weybridge (GB); Edwin Hodges, Guildford (GB); and Didier Lecerf, Guildford (GB)
Assigned to PGS Geophysical AS, Oslo (NO)
Filed by PGS GEOPHYSICAL AS, Oslo (NO)
Filed on Apr. 4, 2023, as Appl. No. 18/130,751.
Application 18/130,751 is a division of application No. 17/189,128, filed on Mar. 1, 2021, granted, now 11,662,491.
Claims priority of provisional application 63/082,419, filed on Sep. 23, 2020.
Prior Publication US 2023/0236332 A1, Jul. 27, 2023
Int. Cl. G01V 1/30 (2006.01); G01V 1/38 (2006.01)

CPC G01V 1/308 (2013.01) [G01V 1/38 (2013.01); G01V 2210/1212 (2013.01); G01V 2210/612 (2013.01)]

12 Claims

1. A method of performing a marine seismic 4D monitor survey that repeats a previous survey, comprising:

towing a number of sources during the marine seismic 4D monitor survey that is greater than a number of sources that were used to perform the previous survey, such that the marine seismic 4D monitor survey employs additional sources relative to the number of sources that were used to perform the previous survey; and

activating the additional sources during the marine seismic 4D monitor survey to produce additional shot points relative to shot points that were produced during the previous survey;

wherein crossline outermost sources that were used to perform the previous survey define a previous survey crossline source spread; and

wherein some of the additional shot points are produced at crossline positions outside the previous survey crossline source spread and others of the additional shot points are produced at crossline positions inside the previous survey crossline source spread.