GB1348463A - Device for generating acoustic waves in a liquid medium - Google Patents

Abstract

1348463 Seismic energy generators INSTITUT FRANCAIS DU PETROLE DES CARBURANTS ET LUBRIFIANTS 4 May 1972 [7 May 1971] 20876/72 Heading H4D An acoustic source for use in a liquid medium, e.g. for marine seismic prospecting, comprises two chambers with a constriction providing communication between their interiors, a valve for closing off the communication, and an arrangement for expelling liquid from a first chamber with pressurized gas, then lowering the fluid pressure of the second chamber while the valve is closed, then opening the valve to allow the gas to pass into the second chamber so that the liquid rushes into the first chamber and causes an impact against the constriction, thereby generating acoustic waves. In the Fig. 3 embodiment water is initially forced out of chambers 1 and 2 by compressed air from a pump 5, valve 4 being open as shown. The valve 4 is then closed and air is evacuated from chamber 2 through a hose 9 connected with the suction side of pump 5. To "fire" the acoustic source, valve 4 is opened so that water rushes into chamber 1 and the water movement is braked by the valve constriction and, optionally, by a spring-and-ball valve 13, 14. In alternative embodiments a slack sealing membrane may be fixed across the outer end of chamber 1 (Figs. 4, 5, 6, none shown) so as to move with the water mass while keeping the inside of the acoustic source dry, a tubular chamber 1 may be arranged at each end of tubular chamber 2 to double the source output power (Fig. 5), and an hydraulic piston-andcylinder system may be used instead of the suction arrangement for evacuating chamber 2 (Fig. 7, not shown).