Electromagnetic and seismic streamer cable and method for using such a streamer cable
AssigneeMultifield Geophysics AS
InventorSvein Erling Johnstad
Life of this patent
Estimating the term…
Abstract
A geophysical sensor cable has one or more sensor cable sections. Each of the sensor cable sections is provided with seismic and electromagnetic sensors arranged along said cable. The seismic sensors include a hydrophone and a seismic component receiver for seismic vector measurements while the sensor cable is at the sea-floor. The electromagnetic sensors include both E-field sensors and H-field sensors. The E-field sensors include pairs of first and second electrodes arranged with different positions along the cable and connected to a voltage amplifier. The H-field sensors include three mutually orthogonally arranged H-field component sensors.
Claims20
A marine geophysical streamer, comprising:
- one or more sensor cable sections connected to one another and configured to have adjustable buoyancy enabling said one or more sensor cable sections to be placed stationary on the sea-floor at different survey positions and to be towed between the survey positions during a marine survey;
- seismic and electromagnetic sensors arranged along said sensor cable sections and configured to detect seismic and electromagnetic waves while said one or more sensor cable sections are placed stationary on the sea-floor;
- and
- a lead-in cable having a first end attached to the sensor cable sections and a second end on a continuously moving ship, the lead-in cable being extended while said one or more sensor cable sections are stationary on the sea-floor, and shortened while said one or more cable sections are towed from one of the survey positions to another of the survey positions.
A marine geophysical survey system comprising:
- a ship configured to tow at least one of an electromagnetic source and a seismic signal source;
- and
- a streamer having
- one or more sensor cable sections connected to the ship and configured to have an adjustable buoyancy enabling said one or more sensor cable sections to be towed and to be placed stationary on the sea-floor at different survey positions and to be towed between the survey positions during a marine survey;
- and
- seismic and electromagnetic sensors arranged along said sensor cable sections and configured to detect seismic and electromagnetic waves while said one or more sensor cable sections are placed stationary on the sea-floor,
- wherein said ship tows the electromagnetic source or the seismic source continuously, while the one or more sensor cable sections are stationary on the sea-floor and while said one or more cable sections are towed from one of the survey positions to another of the survey positions.
A method for acquiring seismic and electromagnetic data related to a geological structure under sea-floor, the method comprising:
- placing a streamer carrying seismic and electromagnetic sensors configured to detect seismic and electromagnetic waves, at a first survey position on the sea-floor;
- acquiring seismic and electromagnetic data while the streamer is stationary at the first survey position;
- towing the streamer between the first survey position and a second position on the sea-floor;
- and
- towing continuously a seismic source and an electromagnetic source, while said streamer is stationary on the sea-floor and while said streamer is towed,
- wherein said seismic sources and said streamer are towed by a same ship.
Dependencies are inferred from the claim text.