LANGSTRAKT SEISMISK KILDE FOR ANVENDELSE VED OPERASJONER PAA SJOEEN

1417948 Marine seismic generators SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ BV 6 March 1974 [8 March 1973] 10060/74 Heading H4D An elongate seismic source for use in marine seismic operations, comprises a plurality of individual sound sources 6; e.g. air guns, or possibly gas exploders or sparkers; that are disposed in a plurality of arrays which are distributed over the length of the seismic source. Each individual array 4a-4e is supported below the water, e.g. on lines 8 from floats 7, and is connected by a separate cable to the vessel 3, the cables being arranged for towing the arrays in a substantially straight line and for passing activating signals between the vessel and the individual sound sources 6. The spacing between the arrays may be varied by the amount of cable paid out from its respective drum to each array. Array 4a is attached to cable 16 (Figs. 3, 5) by a hingeable clamp 19 connected by a pivoted arm 18 to frame 5, from which is suspended air gun 6 and which is attached to float 7 by eyebolt 32 via cable 8. Cables 15, 14, 13, 9 which are attached to, respectively, seismic arrays 4b, 4c, 4d and 4e pass, movably, through the channels 35 of guide means 33, attached to the top of frame 5. Each cable comprises (Fig. 6) a central high pressure air conduit 10 surrounded by signal conduits 11, which are enclosed in armoured envelope 12. Each cable is separately detachable from its respective array and details of how the complete source may be deployed, the dimensions thereof &c. are given. In other possible embodiments, several sets of arrays may be deployed in parallel by the same towing vessel. The arrays may be fired simultaneously, or with a delay, and hydrophones may be deployed thereon to receive echo signals.