Methods of marine to borehole measurement may include dispersing one or more borehole receivers in one or more boreholes; distributing one or more marine receivers in marine water at a seabed; immersing an electromagnetic dipole source in the marine water above the seabed; energizing the electromagnetic dipole source; measuring one or more borehole signal measurements using the one or more borehole receivers and one or more seabed signal measurements using the one or more marine receivers; and determining a three-dimensional property distribution of a reservoir of interest by processing the one or more borehole signal measurements and the one or more seabed signal measurements.

An electromagnetic (EM) sensor includes a front end module generating an EM signal using electromagnetic waves transmitted from an external source, a sensor memory storing a portion of a plurality of machine learning models used to recognize the EM signal, and a microcontroller unit for recognizing the external electronic device emitting the electromagnetic waves by inputting feature values extracted from the EM signal to the machine learning models. If the machine learning models stored in the sensor memory are not able to recognize the external device, the feature values may be transmitted to a main processor, and the main processor may compare the feature values to another set of machine learning models.

A geophysical surveying method and assembly applying transient pulses of electric current to an airborne time-domain electromagnetic transmitter to generate a primary controlled electromagnetic field; measuring, using an airborne receiver, a secondary controlled electromagnetic field to generate controlled field data; measuring, using the airborne receiver, a magnetic component of a natural electromagnetic field at an above-ground position to generate first natural field data; measuring, using a ground receiver at a ground station, telluric electrical currents induced by the natural electromagnetic field and/or a magnetic component of the natural electromagnetic field at a ground position to generate second natural field data; merging the first natural field data and the second natural field data into combined natural field data; extracting, from the combined natural field data, off-time natural field data recorded between the pulses; and generating geophysical survey data based on the controlled field data and the off-time natural field data.

The disclosed embodiments include systems and methods for multi-frequency focusing signal processing in wellbore logging. In one embodiment, the method includes obtaining a harmonic frequency set to evaluate a resistivity of a formation at a wellbore location, where the harmonic frequency set includes at least one harmonic frequency of a fundamental frequency. The method also includes selecting a waveform from a library of waveforms based on the obtained harmonic frequency set, where the library of waveforms includes a plurality of waveforms having different frequency spectrums. The selected waveform corresponds to a predicted conductivity of the formation. The method further includes generating, based on the selected waveform, a binary waveform for use in evaluating the resistivity of the formation at the wellbore location.

Techniques are disclosed relating to electrical safety systems that may be useful, for example, in electromagnetic geophysical prospecting. Electromagnetic streamer systems often include a number of electrical loads in series that are powered by a constant-current power supply unit. Known techniques for detecting electrical faults have various drawbacks in such an arrangement. Embodiments of this disclosure may be used to mitigate some or all of such drawbacks.

Marine survey data resulting from a first signal comprising a signal representing a flat spectral far-field pressure generated by a marine vibrator source swept over a frequency range according to a time function of motion such that acceleration of the marine vibrator source is a flat function in a frequency domain can be used to improve full waveform inversion. For example, full waveform inversion can be performed using the marine survey data received from the first signal and from a second signal generated by an impulsive seismic source to estimate a physical property of a subsurface location.

An electromagnetic (EM) receiver system for measuring EM signals. The EM receiver system includes a survey EM transmitter for generating survey EM signals within a first frequency range; a calibration EM transmitter for generating a calibration signal; a receiver section, including a receiver housing and a receiver, that measures both the survey EM signals and the calibration signal; and a calibration device connected to the calibration EM transmitter and to the receiver, the calibration device configured to control a frequency and waveform of the calibration signal. The calibration device is further configured to calculate a response function of the receiver, based on the calibration signal.

There is disclosed a method of performing a controlled source electromagnetic survey, which includes in one embodiment deploying a receiver and an electric dipole source. The source defines a dipole axis. An electromagnetic field is transmitted from the electric dipole source. First and second horizontal components of an electromagnetic field response are detected using the receiver. A vertical component of the electromagnetic field response is then estimated using the detected first and second horizontal components of the electromagnetic field response.

A system and method allows determining the movement of subsurface fluids, gases or solids in the subsurface structure of interest. This allows quantitatively determining the results of surface and subsurface equipment and materials changes. These simple observations may result in significant improvements in field efficiency.

The invention discloses a node multi-electrode resistivity measurement system provided with a transmitter, a PC terminal, acquisition nodes, transmitting electrodes and receiving electrodes. The transmitter, acquisition nodes and PC terminal are connected by Wifi, and the transmitter and acquisition nodes are connected in series by a five-core cable. So the weight of the cable is greatly reduced, and each core can be wrapped by shielding layer, reducing the influence of electromagnetic coupling and ensuring the quality of collected data. The weight of the system is very light so that work efficiency has been improved. Synchronization between transmitter and acquisition nodes is carried out by GPS.