A proximity sensor includes a lead supported on an outer surface of a case structure and a sensor wire that extends from the lead and through an opening in the case structure. The sensor is formed by applying alternating layers of electrically conductive and non-conductive materials in a non-cured state. A base non-conductive layer is applied to an inner surface of the case structure around the sensor wire in a non-cured state. Once cured, a conductive layer is deposited onto the base non-conductive layer and encapsulates the sensor wire. A cover non-conductive layer is then deposited over portions of the conductive layer to insulate the conductive layer. Portions of the non-conductive layer are then removed such that an area of the conductive layer is exposed to define a sensor area.

An example calibration method for a galvanic tool may include determining an internal coupling impedance between at least two electrodes of the galvanic tool, and inputting the determined internal coupling impedances into an equation used to evaluate the response of the tool. Voltage and current measurements may be generated from the galvanic tool using a calibration device. A leakage current value through at least one of the two electrodes may be determined based, at least in part, on the voltage and current measurements and the equation. The leakage current may be stored.

An example calibration method for a galvanic tool may include determining an internal coupling impedance between at least two electrodes of the galvanic tool, and inputting the determined internal coupling impedances into an equation used to evaluate the response of the tool. Voltage and current measurements may be generated from the galvanic tool using a calibration device. A leakage current value through at least one of the two electrodes may be determined based, at least in part, on the voltage and current measurements and the equation. The leakage current may be stored.

Aspects of the disclosure can relate to simulating expected sensor values associated with a drill tool (e.g., a drill assembly) before drilling to monitor the sensor. A planned trajectory for the drill assembly is received, where the planned trajectory is associated with a borehole to be drilled by the drill assembly along a geographic path. Next, an expected position for the drill assembly is determined along the geographic path. Then, an expected sensor value for a sensor associated with the drill assembly is simulated at the expected position. Next, an actual sensor value at an actual position corresponding to the expected position is determined. Then, the expected sensor value and the actual sensor value are dynamically displayed together at a user interface.

Aspects of the disclosure can relate to simulating expected sensor values associated with a drill tool (e.g., a drill assembly) before drilling to monitor the sensor. A planned trajectory for the drill assembly is received, where the planned trajectory is associated with a borehole to be drilled by the drill assembly along a geographic path. Next, an expected position for the drill assembly is determined along the geographic path. Then, an expected sensor value for a sensor associated with the drill assembly is simulated at the expected position. Next, an actual sensor value at an actual position corresponding to the expected position is determined. Then, the expected sensor value and the actual sensor value are dynamically displayed together at a user interface.

A method for locating an object hidden beneath a surface using a locating device is disclosed. At least one coupling signal dependent on the object is received by a receiving means of the locating device. Once the locating device has been placed on the surface, a first value Ci of the coupling signal is detected and the first value Ci is defined as value CBG for a background subtraction. In particular, whilst the locating device and the surface are moved relative to one another, at least one further value C of the coupling signal is detected and the value CBG for the background subtraction is re-calibrated by the at least one further value C if the at least one further value C is lower than the value CBG for the background subtraction. The re-calibration is suspended if a valid value CBG is identified for the background subtraction.

An embodiment of a method of performing aspects of a downhole operation includes receiving a measurement value from a first sensor configured to measure a parameter related to the downhole operation, receiving measurement data from a different sensor, the measurement data related to the downhole operation, and performing, by a sensor evaluation module, an evaluation of the first sensor. The evaluation includes determining a condition of the first sensor based on the measurement data from the different sensor, selecting a rule that prescribes a set of one or more measurement values of the parameter that are plausible if the condition is met, and determining whether the measurement value from the first sensor is plausible based on comparing the measurement value to the prescribed set of one or more measurement values.

An embodiment of a method of performing aspects of a downhole operation includes receiving a measurement value from a first sensor configured to measure a parameter related to the downhole operation, receiving measurement data from a different sensor, the measurement data related to the downhole operation, and performing, by a sensor evaluation module, an evaluation of the first sensor. The evaluation includes determining a condition of the first sensor based on the measurement data from the different sensor, selecting a rule that prescribes a set of one or more measurement values of the parameter that are plausible if the condition is met, and determining whether the measurement value from the first sensor is plausible based on comparing the measurement value to the prescribed set of one or more measurement values.

Apparatuses are provided for evaluating an image quality of an image produced by an x-ray computed tomography (CT) system.

A method may include collecting measurement data using a first operational sensor and a second operational sensor of a downhole tool, standardizing optical responses of each operational sensor to a master sensor in a tool parameter space to obtain a standardized master sensor response, transforming the standardized master sensor response to a synthetic parameter space response of the master sensor, applying a fluid model with the synthetic parameter space response of the master sensor to predict a fluid characteristic, comparing a first prediction obtained with the fluid model from the first operational sensor with a second prediction obtained with the fluid model from the second operational sensor, determining a fluid characteristic from the first prediction and the second prediction, and optimizing a well testing and sampling operation according to the fluid characteristic.