Disclosed are an underwater ferromagnetic target detection method and system employing multiple power frequency radiation sources, pertaining to the technical field of non-acoustic underwater detection. The method includes: a power transmission network generating a power frequency electromagnetic field in a spatial range, and an underwater ferromagnetic target generating an electromagnetic field under the combined action of the power frequency electromagnetic field and seawater inside and outside the underwater ferromagnetic target; if there are multiple ships on the water serving as secondary radiation sources acting on the underwater ferromagnetic target, obtaining a secondary magnetic field generated by the underwater ferromagnetic target, and adding the secondary magnetic field and the electromagnetic field generated by the underwater ferromagnetic target under the combined action of the power frequency electromagnetic field and the seawater inside and outside the underwater ferromagnetic target to obtain a total electromagnetic field generated by the underwater ferromagnetic target; and acquiring a power frequency electromagnetic field distribution around the underwater ferromagnetic target, and performing underwater ferromagnetic target detection according to the power frequency electromagnetic field distribution. The present invention can enhance power frequency electromagnetic field signals of an underwater ferromagnetic target, and achieves underwater ferromagnetic target detection.

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.

Devices and processes provide for geophysical oil, gas, or mineral prospecting and subsurface fluid monitoring, using a controlled source electromagnetic system that transmits a designed probe wave to create images of sub-surface structures and fluids either statically or while in motion.

A method for mapping underground sensors onto a network map may include obtaining a plurality of magnetic measurements from a plurality of sensors. The method may include using the plurality of magnetic measurements for determining a plurality of sensor locations in an initial network map. The method may include generating updated network maps from the perspective of each localized sensor. The method may include merging the updated network maps into a final network map, the final network map comprising a most accurate location for each sensor. The method may include determining inner localized sensors out of the plurality of sensors in the final network map. The method may include identifying the inner localized sensors as new base station anchors. The method may include mapping the inner localized sensors onto the final network map as new base station anchors.

Sonde devices for providing magnetic field signals for use with utility locators or other devices are disclosed. In one embodiment a sonde device includes a housing, a core comprising a plurality of core sections, and one or more support structures, which may include windings. Circuit and/or power supply elements may be disposed fully or partially within the core to control generation of predefined magnetic field frequencies and waveforms.

Disclosed is a method for extracting IP information in a TEM response of a grounded-wire source, comprising the following steps: 1) obtaining subsurface resistivity through inversion of a vertical magnetic field less influenced by an IP effect; 2) obtaining an electric field response not influenced by the IP effect based on forward modeling of the obtained underground electrical structure; 3) removing the influence of the IP effect on an observed response to obtain a pure IP response; and 4) inverting the obtained IP response to obtain IP information of polarizability, a frequency dependence, and a time constant. The method of the present invention provides a new idea for further extracting IP information in a TEM response.

There is described apparatus for orienting at least one electromagnetic field sensor, a related receiver unit and method of use. The apparatus has an orientation detector having an output which is dependent upon an orientation of the electromagnetic field sensor, an actuator and a controller which is arranged in communication with the orientation detector and the actuator, the controller being configured to be operable to generate at least one instruction for operating the actuator for moving the electromagnetic field sensor into a predefined orientation, in dependence upon the output from the orientation detector.

A mobile platform for assessing and modifying pavement surfaces. An emitter generates electromagnetic waves towards a portion of a pavement surface. A condition sensor receives electromagnetic radiation from a first portion of the pavement surface and generates a first electronic signal representative of a current condition of the portion of the pavement surface. A location sensor generates a second electronic signal containing location data corresponding to the first portion of the pavement surface. A computing platform processes the electronic signals and creates a current pavement condition data point. The computing platform may compare the first electronic signal against a reference representative of a target condition, determine if there is a condition variance, and, if a condition variance exceeds a predetermined threshold, generate a condition control signal which is transmitted to and operates to modify operation of the pavement surface modification system in order to reduce the condition variance.

A disclosed downhole drilling system may include a drill bit electrically coupled to a pulse-generating circuit to generate electrical arcs between first and second electrodes during pulsed drilling operations, a sensor to record responses to electromagnetic or acoustic waves produced by the electrical arcs, and a sensor analysis system. The electrical arcs occur at different azimuthal locations between the electrodes. The sensor analysis system may obtain a plurality of measurements representing first responses recorded by the sensor during a pulsed drilling operation, generate a model of a source of the electrical arcs based on the measurements, obtain an additional measurement representing a second response recorded by the sensor during the operation, and determine a characteristic of a formation near the drill bit using an inversion based on the model and the additional measurement. The determined characteristic may be used to determine dip parameters or construct images of the formation.

The present disclosure provides an apparent resistivity-depth section generating method for short-offset electromagnetic exploration, including: determining, in field zones divided quantitatively based on the induction number, positions of a recording point for each of observation points and frequencies or a time window thereof; and taking determined positions of the recording point as the assignment point for the observation point and the frequencies or the time window thereof, where one survey line of an axial configuration generates one apparent resistivity-depth section along the survey line; and one survey line of an equatorial configuration typically generates one apparent resistivity-depth section along the survey line, and apparent resistivity-depth sections along connecting lines from the observation points to the source which are the same as observation points in the number.