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.

A method for detecting a beacon signal using an above-ground tracker. The tracker comprises an antenna assembly comprising a plurality of antennas. Each antenna is oriented in a different direction. During operation, if the beacon signal is interrupted due to a local noise source, transmission of the beacon signal is stopped. The tracker then detects radiation from the local noise source and the processor determines a direction from which peak ambient noise arrives at the tracker. The beacon signal is then resumed. A processor included in the tracker excludes any signals generated by the antenna assembly that are representative of radiation that arrived at the tracker from the same direction the peak ambient noise arrived at the tracker. The tracker then detects the beacon signal using the non-excluded signals.

An exemplary inventive optimization model delineates a three-dimensional geometric environment for situation therein of electromagnetic sources and an electromagnetic sensor array used for measuring electric and magnetic fields emanating from the electromagnetic sources. Based on measurements and computations relating to electrical, magnetic, and structural physical properties, the geometric environment is stratified into air, sea, and seafloor regions as well as into electromagnetically distinct zones. The design of the electromagnetic sensor array is optimized through an iterative process involving successive determinations as to how well the electric and magnetic fields emanating from the electromagnetic sources may be calculated based on measurements taken in the geometric environment by the electromagnetic sensor array. Every instance of the electromagnetic sensor array in the iterative process is uniquely located and/or uniquely configured vis-à-vis every other instance. Design optimization can be performed with respect to various frequencies or frequency ranges.

A system and techniques for detecting near-subsurface voids in the earth use a controlled source electromagnetic transmitter and a plurality of controlled source electromagnetic receivers. Signals received by the plurality of controlled source electromagnetic receivers corresponding to signals generated by the controlled source electromagnetic transmitter are analyzed. Bi-static doublets detected in the received signals are used to identify the location of the near-subsurface voids.

Provided is a metal detector capable of quickly and accurately ascertaining a noise generating situation. A metal detector generates a magnetic field in an inspection region and detects a change in the magnetic field in the inspection region to detect a foreign substance in an inspection object passing through the inspection region. The metal detector measures the change in the magnetic field of the inspection region while changing an inspection frequency, performs frequency analysis of the measurement result, and displays an obtained frequency distribution diagram on the display unit as a noise diagnosis result. In the frequency distribution diagram, target foreign substance reference lines are displayed.

Provided are systems and methods for mapping hydrocarbon reservoirs. Operations include disposing an electromagnetic (EM) transmitter and an EM receiver into first and second wellbores of first and second wells, respectively, penetrating a resistive layer of a subsurface formation bounded by first and second conductive layers. The EM transmitter and receiver each being disposed at depths proximate to intersections of the first and second wellbores and the resistive layer, respectively. The operations further including transmitting an EM signal between the EM transmitter and receiver via the resistive layer, determining transport properties associated with propagation of the EM signal from the EM transmitter to the EM receiver via the resistive layer, and determining the presence of an anomaly in at least one of the conductive layers based on the travel time.

Systems and methods for acquiring and processing electromagnetic data in subsurface formations. In one example, a system includes an electromagnetic source, a plurality of electromagnetic receivers, and an electromagnetic data processor. The electromagnetic source is configured to generate an electromagnetic pulse that induces electromagnetic energy in subsurface formations. The electromagnetic receivers are configured to detect the electromagnetic energy reflected by the subsurface formations, and to output signals corresponding to detected electromagnetic energy reflected by the subsurface formations. The electromagnetic data processor configured to process, based on differences in travel times of the electromagnetic energy between the subsurface formations and the electromagnetic receivers, the signals output by the electromagnetic receivers. The electromagnetic data processor is further configured to produce a representation of the subsurface formations based on processed signals output by the electromagnetic receivers.

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.

This disclosure may relate to a system and method for calculating the mud angle from a downhole device. A method for estimating a mud angle may comprise: disposing a downhole tool into a borehole; extending an arm of the downhole tool to a first location, wherein a pad is disposed on the arm; taking a first impedance measurement with at least one button electrode, wherein the button electrode is disposed in a button array, wherein the button array is disposed on the pad; extending the arm to a second location; taking a second impedance measurement with the at least one button electrode; transmitting the first measurement and the second measurement to an information handling system; and estimating the mud angle from the first impedance measurement and the second impedance measurement with an information handling system.

Electromagnetic streamer cables and methods of use. Example systems include: a first electrode, the first electrode at a first location along the streamer cable; a second electrode at a second location along the streamer cable; a first sensor module electrically coupled to the first electrode and second electrode, the first sensor module configured to measure a voltage across the first and second electrodes; a third electrode at a third location between the first and second electrodes; a fourth electrode at a fourth location along the streamer cable, the fourth location distal to the second location; and a second sensor module electrically coupled to the third electrode and fourth electrode, the second sensor module configured to measure a voltage across the third and fourth electrodes.