US 7,321,527 B2
Method and apparatus for controlling the acoustic output of an airgun
Jon-Fredrik Hopperstad, Petersfield (United Kingdom); Johan-Fredrik Synnevaag, Oslo (Norway); and Anneli Soppi, Svanesund (Sweden)
Assigned to WesternGeco, L.L.C., Houston, Tex. (US)
Filed on Sep. 02, 2005, as Appl. No. 11/219,273.
Claims priority of provisional application 60/607977, filed on Sep. 08, 2004.
Prior Publication US 2006/0050614 A1, Mar. 09, 2006
Int. Cl. G01V 1/37 (2006.01)
U.S. Cl. 367—144 41 Claims
OG exemplary drawing
 
1. A device for releasing compressed gas to produce an acoustic pulse in water, the device comprising:
a housing having an inside diameter defining a first chamber;
a port formed through the housing in fluid communication with the first chamber; and
a shuttle flange having a diameter, the shuttle flange moveably positioned within the first chamber during a gas-release cycle between a closed position blocking the port containing the compressed gas in the first chamber to an open position exposing an exit area of the port through which the compressed gas is discharged to produce a primary pressure pulse:
wherein the port exit area is created through the gas-release cycle at a non-linear rate.