Abstract: An electromagnetic geophysical exploration system includes transmitter-receiver pairs configured to transmit waveforms and sense signals in different frequency bands. A controller directs the transmitters of the transmitter-receiver pairs to transmit the waveforms at different moments while the electromagnetic geophysical exploration system is flown over a subsurface formation. The signals sensed by the receivers enable geophysical exploration of the subsurface formation.

Abstract: A device and method for calculating electrical properties of a surveyed underground formation. The method includes selecting a waveform having multiple current transition rates; placing a time-domain electromagnetic (TEM) system above the underground formation while generating with a transmitter a transient primary magnetic field during an on-time period and no magnetic field during a following off-time period, due to the waveform; and recording with a receiver magnetic related data generated by the earth as a result of the transient primary magnetic field. The receiver records the magnetic related data during the on-time period using plural on-time gates sampling.

Abstract: An electromagnetic geophysical exploration system includes a first transmitter-receiver pair that includes a first transmitter configured to transmit a first waveform in a first spectrum and a first receiver configured to sense signals in the first spectrum; and a second transmitter-receiver pair that includes a second transmitter configured to transmit a second waveform in a second spectrum, the second spectrum having a frequency higher than a frequency of the first spectrum, and a second receiver configured to sense signals in the second spectrum; and a control portion. The control portion controls the first transmitter to transmit the first waveform with a first given strength or shape in the first spectrum, and controls the second transmitter to transmit the second waveform with a second given strength or shape in the second spectrum, after a specified time delay.

Abstract: An electromagnetic geophysical exploration system includes a first transmitter configured to transmit a first waveform in a first spectrum, a first receiver configured to sense signals in the first spectrum, a second transmitter configured to transmit a second waveform in a second spectrum, the second spectrum having a frequency higher than a frequency of the first spectrum, a second receiver configured to sense signals in the second spectrum, the second receiver configured to be minimum-coupled to the second transmitter, wherein a transmitter coil of the second transmitter is disposed between an inner receiver coil and an outer receiver coil of the second receiver, and the inner receiver coil and the outer receiver coil of the second receiver surround the transmitter coil of the second transmitter, and a control portion configured to control the first transmitter and the second transmitter.

Abstract: A device and method for calculating electrical properties of a surveyed underground formation. The method includes selecting a waveform having multiple current transition rates; placing a time-domain electromagnetic (TEM) system above the underground formation while generating with a transmitter a transient primary magnetic field during an on-time period and no magnetic field during a following off-time period, due to the waveform; and recording with a receiver magnetic related data generated by the earth as a result of the transient primary magnetic field. The receiver records the magnetic related data during the on-time period using plural on-time gates sampling.

Abstract: A computing device and method for removing noise associated with an excitation signal and its odd harmonics. A computing system for processing electromagnetic (EM) signals includes an interface that receives raw data indicative of a time rate of change of a magnetic field as recorded with a receiver coil while airborne, wherein the magnetic field includes a primary source excitation; and a processor connected to the interface. The processor is configured to calculate a rotation of the receiver coil relative to a desired orientation; derotate the raw EM data based on the rotation of the receiver coil relative to the desired orientation and on the primary source excitation, to obtain derotated EM data; and generate an image of a surveyed subsurface based on the derotated EM data.

Abstract: There are systems and methods for performing a geophysical survey using a hybrid aircraft which includes an apparatus configured to perform the geophysical survey. The system including: three mutually orthogonal transmitters configured to transmit electromagnetic (EM) waveforms towards the ground which creates a secondary magnetic field, wherein the three mutually orthogonal transmitters are attached to the hybrid aircraft; three mutually orthogonal null-coupled receivers configured to obtain measurements associated with the secondary magnetic field, wherein the three mutually orthogonal null-coupled receivers are attached to the hybrid aircraft; and three mutually orthogonal gradient receivers configured to obtain measurements, wherein the three mutually orthogonal gradient receivers are attached to the hybrid aircraft.

Abstract: Systems and methods for a composite magnetic field sensor is disclosed. The electromagnetic survey system includes a first receiver configured to sense signals in a first spectrum based on sensing a magnetic field. The system includes a second receiver configured to sense signals in a second spectrum based on sensing a time rate of change of the magnetic field. The second spectrum has a frequency range higher than the first spectrum. The system further includes a transmitter configured to transmit a specified waveform and a control system configured to control the transmitter to transmit the specified waveform. The control system is also configured to receive signals sensed by the first receiver, receive signals sensed by the second receiver, and store the signals received from the first receiver and the signals received from the second receiver.

Abstract: A system and method for electromagnetic geophysical exploration is provided. The system includes a first transmitter (210) configured to transmit a first waveform in a first spectrum and a first receiver (212) configured to sense signals in the first spectrum. The system also includes a second transmitter (220) configured to transmit a second waveform in a second spectrum, and a second receiver (222) configured to sense signals in the second spectrum and minimum-coupled to the second transmitter. The second spectrum has a frequency higher than a frequency of the first spectrum. The system further includes a control portion configured to control the first transmitter to transmit the first waveform, and control the second transmitter to transmit the second waveform after a specified time delay. The control portion is configured to receive signals sensed by the first receiver in the first spectrum, and receive signals sensed by the second receiver in the second spectrum.

Abstract: A device and method for estimating an apparent chargeability of a surveyed underground formation. The method includes receiving a total response of the underground formation from an airborne time domain electromagnetic (TDEM) survey system; separating, in two stages, the total response into an inductive response and an induced polarization response; and calculating (308) the apparent chargeability based on the induced polarization response.

Abstract: There are systems and methods for performing a geophysical survey using a hybrid aircraft which includes an apparatus configured to perform the geophysical survey. The system including: three mutually orthogonal transmitters configured to transmit electromagnetic (EM) waveforms towards the ground which creates a secondary magnetic field, wherein the three mutually orthogonal transmitters are attached to the hybrid aircraft; three mutually orthogonal null-coupled receivers configured to obtain measurements associated with the secondary magnetic field, wherein the three mutually orthogonal null-coupled receivers are attached to the hybrid aircraft; and three mutually orthogonal gradient receivers configured to obtain measurements, wherein the three mutually orthogonal gradient receivers are attached to the hybrid aircraft.