The present disclosure discloses a distributed airborne electromagnetic detection system, and relates to an airborne electromagnetic detection technology. The distributed airborne electromagnetic detection system comprises at least one transmitting system, at least one receiving system, at least one trunk module, and an earth station, and also a plurality of Unmanned Aerial Vehicles (UAVs) for carrying the transmitting system, the receiving system, and the trunk module. The distributed airborne electromagnetic detection system does not require high performance or high economical efficiency for a single UAV; under precise synchronous flight conditions, the distance between a type I UAV and a transmitting loop structure can be greatly reduced, thereby significantly reducing the length of unwanted transmitting cable; and in addition, due to the better low-altitude low-speed performance of UAVs, the traveling speed of the entire system can be further reduced, thus obtaining higher quality data.

A method of evaluating a subterranean formation includes conveying a tool along a borehole. The tool includes a transmitter that transmits a drive pulse and a receiver that receives at least one formation response to the drive pulse. The method further includes calculating a signal-to-noise ratio of the at least one formation response and comparing the signal-to-noise ratio to a programmable threshold. The method further includes determining, based on the comparing, an adjusted drive pulse to transmit and transmitting the adjusted drive pulse. The method further includes and receiving at least one formation response to the adjusted drive pulse and deriving formation data from the at least one formation response to the adjusted drive pulse. The method further includes displaying a representation of the formation based on the formation data.

A method of evaluating a subterranean formation includes conveying a tool along a borehole. The tool includes a transmitter that transmits a drive pulse and a receiver that receives at least one formation response to the drive pulse. The method further includes calculating a signal-to-noise ratio of the at least one formation response and comparing the signal-to-noise ratio to a programmable threshold. The method further includes determining, based on the comparing, an adjusted drive pulse to transmit and transmitting the adjusted drive pulse. The method further includes and receiving at least one formation response to the adjusted drive pulse and deriving formation data from the at least one formation response to the adjusted drive pulse. The method further includes displaying a representation of the formation based on the formation data.

A semi-airborne electromagnetic survey device and a semi-airborne electromagnetic survey method based on coaxial coplanar mutual reference coil assembly are provided. The device includes a measuring coil and a reference coil with linear correlation of additive motion noise; the reference coil and the measuring coil have a same bandwidth, are coaxial and coplanar and are in hard connection or soft connection; detection resolution of the reference coil only distinguishes the additive motion noise; detection resolution of the measuring coil distinguishes real vertical magnetic field signals and motion noise simultaneously; the reference coil has a much smaller outer diameter than the measuring coil. In the method, one coil only receives the additive motion noise, and an other coil simultaneously receives the additive motion noise and the real vertical magnetic field signals; and the additive motion noise received by the two coils is cancelled to obtain the real vertical magnetic field signals.

A semi-airborne electromagnetic survey device and a semi-airborne electromagnetic survey method based on coaxial coplanar mutual reference coil assembly are provided. The device includes a measuring coil and a reference coil with linear correlation of additive motion noise; the reference coil and the measuring coil have a same bandwidth, are coaxial and coplanar and are in hard connection or soft connection; detection resolution of the reference coil only distinguishes the additive motion noise; detection resolution of the measuring coil distinguishes real vertical magnetic field signals and motion noise simultaneously; the reference coil has a much smaller outer diameter than the measuring coil. In the method, one coil only receives the additive motion noise, and an other coil simultaneously receives the additive motion noise and the real vertical magnetic field signals; and the additive motion noise received by the two coils is cancelled to obtain the real vertical magnetic field signals.

A method for forming 3D image data representative of the subsurface of infrastructure located in the vicinity of a moving vehicle. The method includes: rotating a directional antenna, mounted to the moving vehicle, about an antenna rotation axis; performing, using the directional antenna whilst it is rotated about the antenna rotation axis, a plurality of collection cycles in which the directional antenna emits RF energy and receives reflected RF energy; collecting, during each of the plurality of collection cycles performed by the directional antenna.

A method for forming 3D image data representative of the subsurface of infrastructure located in the vicinity of a moving vehicle. The method includes: rotating a directional antenna, mounted to the moving vehicle, about an antenna rotation axis; performing, using the directional antenna whilst it is rotated about the antenna rotation axis, a plurality of collection cycles in which the directional antenna emits RF energy and receives reflected RF energy; collecting, during each of the plurality of collection cycles performed by the directional antenna.

Techniques are disclosed for generating a time series representation of passive electromagnetic (EM) fields via towed streamer measurements without dependence on water-bottom measurement equipment. Such techniques may include storing records of respective time series measurements of passive EM fields measured by individual receivers as the individual receivers pass over a first measurement point, where the respective time series measurements correspond to respective measurement intervals, and where the respective time series measurements are synchronized with respect to a reference clock. The records of the respective time series measurements may be combined to generate a time series representation of passive EM fields observed at the first measurement point over a combination of the respective measurement intervals. The time series representation of passive EM fields observed at the first measurement point may, in turn, be used to identify one or more characteristics of subsurface structure.

Techniques are disclosed for generating a time series representation of passive electromagnetic (EM) fields via towed streamer measurements without dependence on water-bottom measurement equipment. Such techniques may include storing records of respective time series measurements of passive EM fields measured by individual receivers as the individual receivers pass over a first measurement point, where the respective time series measurements correspond to respective measurement intervals, and where the respective time series measurements are synchronized with respect to a reference clock. The records of the respective time series measurements may be combined to generate a time series representation of passive EM fields observed at the first measurement point over a combination of the respective measurement intervals. The time series representation of passive EM fields observed at the first measurement point may, in turn, be used to identify one or more characteristics of subsurface structure.

A method includes using an electromagnetic (EM) tracking system to track a tangible object, detecting a presence of interference with a magnetic field generated by the EM tracking system, and compensating for the interference. A system includes an EM tracking transmitter, an EM tracking receiver, and a processor based apparatus in communication with the EM tracking transmitter and the EM tracking receiver. The processor based apparatus is configured to execute steps including using the EM tracking transmitter and the EM tracking receiver to implement an EM tracking system. A storage medium storing one or more computer programs is also provided.