Geophysical Company of Norway A.s.

Geco A.s., Kjorbokollen N-1301

Einar Gjestrum

Inge Dragsund

Svein Selvag

Ian Rogers

Just Skog

A float for use in seismic surveys of the sea bed supports a plurality of seismic pulse transmitters (6) which are suspended on lines (7) beneath the float (1). At a distance from the front end of the float (1), on one sidewall thereof, a fastening device for a towing cable and a lead-in for control lines and lines for supplying operating medium to the pulse transmitters are provided. These lines and cables are gathered in a common line (3) which extends behind the tow ship. The line (3), at a distance away from the float (1), is connected to a line (4) which leads to a length-regulating device (12) inside the front section of the float. The float is also provided with at least one motor (10) with a drive shaft (9)leading to hoisting drums (8) for the lines (7) to the respective seismic pulse transmitters (6). Both the motors (10, 12) and the seismic pulse transmitters (6) are connected to the pneumatic supply line. The control lines leads to control devices at the separate components, permitting active steering of the system from on board the ship.

Float for use in seismic surveys of the sea bed

A device for controlling a seismic cable that is towed behind a vessel (1), so that the cable follows a path that is displaced laterally in relation to the path of the vessel, comprises a frame structure (6, 7) extending transversely to the towing direction and outwardly from the area of gun suspension from the cable having longitudinal frame members provided with intermediate transverse members extending obliquely or in a curved manner whereby the front ends of the transverse members, as seen in the towing direction, are disposed further outwards laterally than the rear ends of the transverse members. When towed, the frame will this be forced outwardly by the water flowing through the frame structure and the desired lateral displacement will be achieved.

Control device for cables with seismic equipment, especially for gun

A float for use in seismic surveys of the sea bed supports a plurality of seismic pulse transmitters (6) which are suspended on lines (7) beneath the float (1). At a distance from the front end of the float (1), on one sidewall thereof, a fastening device for a towing cable and a lead-in for control lines and lines for supplying operating medium to the pulse transmitters are provided. These lines and cables are gathered in a common line (3) which extends behind the tow ship. The line (3), at a distance away from the float (1), is connected to a line (4) which leads to a length-regulating device (12) inside the front section of the float. The float is also provided with at least one motor (10) with a drive shaft (9) leading to hoisting drums (8) for the lines (7) to the respective seismic pulse transmitters (6). Both the motors (10, 12) and the seismic pulse transmitters (6) are connected to the pneumatic supply line. The control lines lead to control devices at the separate components, permitting active steering of the system from on board the ship.

An assembly for use in seismic surveys of the sea bed is towed behind a vessel and comprises groups of seismic signal transmitters which are towed through the water, being suspended from float buoys which are combined to form one body which may be formed as a sleeve having limited flexibility. The body is formed with a head member shaped for reducing resistance to the water, and connected to a coupling point for a tow wire to the vessel, which point lies forward of the head member and at the same depth as the transmitters.

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Oslo, Norway

Einar Gjestrum