Magnetic field measurement via streamer cables
AssigneeConocoPhillips Company
InventorsPeter M. Eick, Joel D. Brewer
Life of this patent
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Abstract
A method of generating a magnetic anomaly map and a system to develop a magnetic anomaly map are described. The method includes obtaining magnetic compass data recorded by two or more magnetic compasses disposed along a seismic streamer that traverses a first area and obtaining measurements from one or more navigation systems over the first area. The method also includes determining a correct position of each of the two or more magnetic compasses based on the measurements from the one or more navigation systems, and comparing the magnetic compass data with theoretical magnetic field data at the correct positions to generate a magnetic anomaly map.
Claims16
A method of generating a magnetic anomaly map, the method comprising:
- towing a seismic streamer behind a vessel so the seismic streamer traverses a first area behind the vessel;
- recording magnetic compass data measured by two or more magnetic compasses disposed along the seismic streamer while the vessel tows the seismic streamer at a speed;
- obtaining measurements from one or more navigation systems over the first area;
- determining a correct position of each of the two or more magnetic compasses based on the measurements from the one or more navigation systems;
- comparing the magnetic compass data with theoretical magnetic field data at the correct position of each of the two or more magnetic compasses to yield a magnetic declination and inclination map;
- processing the magnetic declination and inclination map using overlap data and/or sampling data to improve the magnetic declination and inclination map, the processing including removal and compensation of any diurnal variations and removal of any sampling effects;
- generating a magnetic anomaly map based on the processing of the magnetic declination and inclination map;
- and
- displaying the magnetic anomaly map.
A system to generate a magnetic anomaly map, the system comprising:
- a seismic streamer configured to be towed behind a vessel;
- two or more magnetic compasses disposed along the seismic streamer and configured to traverse a first area behind the vessel, the two or more magnetic compasses configured to obtain magnetic compass data while the vessel tows the seismic streamer at a speed;
- one or more navigation systems configured to obtain measurements over the first area;
- and
- a processor configured to:
- determine a correct position of each of the two or more magnetic compasses based on the measurements from the one or more navigation systems,
- compare the magnetic compass data with theoretical magnetic field data at the correct position of each of the two or more magnetic compasses to yield a magnetic declination and inclination map,
- process the magnetic declination and inclination map using overlap data and/or sampling data to improve the magnetic declination and inclination map,
- generate a magnetic anomaly map based on processing of the magnetic declination and inclination map, the processing of the magnetic declination and inclination map including removal and compensation of any account for diurnal variations, and
- display the magnetic anomaly map.
Dependencies are inferred from the claim text.