Abstract: To perform marine electromagnetic (EM) surveying of a subterranean structure, a marine cable system is provided including a tow cable, a plurality of electromagnetic (EM) sources coupled to the tow cable, and a plurality of EM receivers coupled to the tow cable. The system is configured for deployment in a body of water to perform marine EM surveying of a subterranean structure.

Abstract: To perform marine electromagnetic (EM) surveying of a subterranean structure, a marine cable system is provided including a tow cable, a plurality of electromagnetic (EM) sources coupled to the tow cable, and a plurality of EM receivers coupled to the tow cable. The system is configured for deployment in a body of water to perform marine EM surveying of a subterranean structure.

Abstract: To fully characterize the inductive response of an isolated conductive object, such as buried unexploded ordinance, one needs to measure its response to stimulation by primary magnetic fields in three linearly independent (e.g., approximately orthogonal) directions. In one embodiment this is achieved by measuring the response to magnetic fields of three independent transmitters arranged to have magnetic fields that are linearly independent. According to the apparatus and methods employing the system of this invention, multiple transmitters and receivers of known relative position and orientation on a single platform are used. In a preferred embodiment, matched sets of receiver pairs connected in gradient mode are positioned adjacent to closely spaced pairs of transmitting coils, such that a minor displacement of one or both of the receiver coil pairs relative to the paired transmitting coils will not affect the detected secondary signals emitted by a buried metallic object.

Abstract: To perform marine electromagnetic (EM) surveying of a subterranean structure, a marine cable system is provided including a tow cable, a plurality of electromagnetic (EM) sources coupled to the tow cable, and a plurality of EM receivers coupled to the tow cable. The system is configured for deployment in a body of water to perform marine EM surveying of a subterranean structure.

Abstract: To fully characterize the inductive response of an isolated conductive object, such as buried unexploded ordinance, one needs to measure its response to stimulation by primary magnetic fields in three linearly independent (e.g., approximately orthogonal) directions. In one embodiment this is achieved by measuring the response to magnetic fields of three independent transmitters arranged to have magnetic fields that are linearly independent. According to the apparatus and methods employing the system of this invention, multiple transmitters and receivers of known relative position and orientation on a single platform are used. In a preferred embodiment, matched sets of receiver pairs connected in gradient mode are positioned adjacent to closely spaced pairs of transmitting coils, such that a minor displacement of one or both of the receiver coil pairs relative to the paired transmitting coils will not affect the detected secondary signals emitted by a buried metallic object.