Abstract: A marine electromagnetic sensor system includes a sensor cable having at least one electromagnetic sensor thereon. A first calibration electrode is disposed on the cable on one side of the sensor. A second calibration electrode is disposed on the cable on an opposite side of the sensor. A calibration power supply is coupled to the first and second calibration electrodes. A measuring circuit is coupled to the sensor. A method for calibrating marine electromagnetic survey electrodes includes imparting electric current between calibration electrodes disposed at spaced apart locations on a cable deployed in the water. Voltages impressed across a pair of electrodes disposed on the cable between the calibration electrodes are detected in response to the current. A change in sensitivity of the at least one pair of electrodes is determined using the detected voltages.

Abstract: A detector for a marine electromagnetic survey system includes a housing arranged to minimize turbulence when the housing is towed through a body of water, and to minimize motion of the housing in any direction other than the tow direction. The housing includes at least one of an electric field and a magnetic field sensing element associated therewith.

Abstract: A method for reducing motion induced voltage in marine electromagnetic measurements includes measuring an electromagnetic field parameter at at least one position along a sensor cable towed through a body of water. Motion of the sensor cable is measured at at least one position along the cable; Voltage induced in the cable is estimated from the motion measurements. The measured electromagnetic field parameter is corrected using the estimated voltages.

Abstract: A receiver streamer system for marine electromagnetic surveying includes a first streamer, and a second streamer disposed substantially parallel to and spaced apart from the first streamer. A first pair of electrodes is associated with the first streamer and a second pair of electrodes is associated with the second streamer. Each of the first and second pairs of electrodes is functionally associated with a voltage measuring circuit configured to measure voltage along an inline direction. At least one electrode on each of the first and second streamers is configured and associated with a voltage measuring circuit to make voltage measurements in a cross-line direction.

Abstract: A method for reducing motion induced voltage in marine electromagnetic measurements includes measuring an electromagnetic field parameter at least one position along a sensor cable towed through a body of water. Motion of the sensor cable is measured at least one position along the cable; Voltage induced in the cable is estimated from the motion measurements. The measured electromagnetic field parameter is corrected using the estimated voltages.

Abstract: An electromagnetic sensor cable includes at least one strength member configured to be coupled to a vessel for towing in a body of water and extending along the length of the cable. A jacket covers the strength member and extends along the length of the cable. At least one electrode mounting sleeve is disposed along the jacket and is coupled at its longitudinal ends to one end of a segment of the jacket. The longitudinal ends of the sleeve are configured to mate with a corresponding end of the jacket segment. The sleeve includes a passage therethrough for the at least one strength member. The sleeve includes a mounting surface for a fiber electrode material thereon disposed between the longitudinal ends of the sleeve. At least one electrical contact surface is disposed on the mounting surface. Electrically conductive fiber electrode material is disposed on the mounting surface and is in electrical contact with the electrical contact surface.

Abstract: A detector for a marine electromagnetic survey system includes a housing arranged to minimize turbulence when the housing is towed through a body of water, and to minimize motion of the housing in any direction other than the tow direction. The housing includes at least one of an electric field and a magnetic field sensing element associated therewith.