Patents Assigned to Multifield Geophysics AS
  • Patent number: 9176254
    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.
    Type: Grant
    Filed: March 16, 2009
    Date of Patent: November 3, 2015
    Assignee: MULTIFIELD GEOPHYSICS AS
    Inventor: Svein Erling Johnstad
  • Patent number: 7982465
    Abstract: A method for analyzing acquired electromagnetic measurements (R) made at or in a sea (4) over a seafloor (1) with rock formations (3) having relatively low resistivity (?3) for detecting a possibly underlying petroleum bearing reservoir formation (2) having relatively high resistivity (?2), wherein a low frequency electromagnetic transmitter (5) arranged in the sea (4) emits an electromagnetic field (P) propagating in the sea (4), in the rocks (3, 2) and in the air (0) above the sea; wherein electromagnetic sensors (6) are arranged with desired offsets (x) in the sea (4) for measuring the electromagnetic field (P(x)) while the field propagates, characterized in that one or more component of the electromagnetic field (P) is measured at least one large offset (xL) from the transmitter (5) where the field (P) essentially only has its origin from the field propagating as a field (P0) through the air (0); that the one or more components of the electromagnetic field (P) measured at the large offset (xL) is calculat
    Type: Grant
    Filed: February 12, 2007
    Date of Patent: July 19, 2011
    Assignee: Multifield Geophysics AS
    Inventors: Harald Westerdahl, Svein Erling Johnstad, Brian Anthony Farrelly
  • Publication number: 20110158043
    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.
    Type: Application
    Filed: March 16, 2009
    Publication date: June 30, 2011
    Applicant: MULTIFIELD GEOPHYSICS AS
    Inventor: Svein Erling Johnstad
  • Publication number: 20090278541
    Abstract: A method for analysing acquired electromagnetic measurements (R) made at or in a sea (4) over a seafloor (1) with rock formations (3) having relatively low resistivity (?3) for detecting a possibly underlying petroleum bearing reservoir formation (2) having relatively high resistivity (?2), wherein a low frequency electromagnetic transmitter (5) arranged in the sea (4) emits an electromagnetic field (P) propagating in the sea (4), in the rocks (3, 2) and in the air (0) above the sea; wherein electromagnetic sensors (6) are arranged with desired offsets (x) in the sea (4) for measuring the electromagnetic field (P(x)) while the field propagates, characterized in that one or more component of the electromagnetic field (P) is measured at least one large offset (xL) from the transmitter (5) where the field (P) essentially only has its origin from the field propagating as a field (P0) through the air (0); that the one or more components of the electromagnetic field (P) measured at the large offset (xL) is calculat
    Type: Application
    Filed: February 12, 2007
    Publication date: November 12, 2009
    Applicant: Multifield Geophysics AS
    Inventors: Harald Westerdahl, Svein Erling Johnstad, Brian Anthony Farrelly