Methods and systems are provided that predict electromagnetic properties of drilling mud and a formation, which involve a logging tool that measures current injected into a measurement zone adjacent a sensor electrode at multiple frequencies. The measured currents at the multiple frequencies are processed to determine complex impedances for the sensor electrode at the multiple frequencies. The complex impedances are used to generate input data, which is supplied to a system of artificial neural networks (ANNs) that is configured to predict and output electromagnetic properties of the drilling mud and the formation within the measurement zone and possibly tool standoff based on the input data. The system of ANNs can employ a cascaded architecture of multiple ANNs. The electromagnetic properties or tool standoff predicted by the system of ANNs can be used to construct a borehole image over varying azimuth and depth.

Methods and systems are provided that predict electromagnetic properties of drilling mud and a formation, which involve a logging tool that measures current injected into a measurement zone adjacent a sensor electrode at multiple frequencies. The measured currents at the multiple frequencies are processed to determine complex impedances for the sensor electrode at the multiple frequencies. The complex impedances are used to generate input data, which is supplied to a system of artificial neural networks (ANNs) that is configured to predict and output electromagnetic properties of the drilling mud and the formation within the measurement zone and possibly tool standoff based on the input data. The system of ANNs can employ a cascaded architecture of multiple ANNs. The electromagnetic properties or tool standoff predicted by the system of ANNs can be used to construct a borehole image over varying azimuth and depth.

A method, drill string, bottomhole assembly, drill bit, and insert are for extending a borehole for a relief well in a subsurface. The rotary drill string is provided in the borehole and includes a bottomhole assembly. The bottomhole assembly includes a drill bit. Current is provided into the subsurface using at least one electrode on the drill string, thereby generating current in a casing of a mother well located a distance away from the borehole of the relief well. At least one component of a magnetic field associated with the current generated in the casing is detected using at least one sensor disposed on the drill string. Data is obtained from the sensor for determining either or both the proximity and direction to the mother well. The drill string is advanced into the subsurface based upon the obtained data to extend the borehole.

Disclosed is a system and a method for monitoring water inrush, including: a host terminal, a field host, at least one controller and at least one electrode array. Each electrode array is placed in one borehole and to detect electric field signals of surrounding rocks around the borehole; each controller connects with one electrode array and is to control the electrode array to carry out a high-density induced polarization measurement on the surrounding rocks; the field host connects with the controller and is to send control signals to the controller, receive and process the electric field signals output by the electrode array; and the host terminal connects with the field host and is to receive the electric field signals processed by the field host, determine changes on apparent resistivity and apparent chargeability of the surrounding rocks, and determine whether there exists water inrush according to the changes.

A method for determining mud properties may comprise taking multi-frequency measurement data with a downhole tool, selecting an injector electrode from the one or more injector electrodes for the multi-frequency measurement data, selecting data from the multi-frequency measurement data with low resistivity or a large standoff, creating a forward model based at least partially on the selected data by making initial guesses of model parameters for one or more mud properties, performing a cost function minimization with the forward model, identifying from the cost function minimization if a misfit is above or below a threshold, and identifying the one or more mud properties based at least in part on the cost function minimization. A system may comprise a downhole tool including a mandrel, one or more arms, one or more pads, and one or more injector electrodes. The system may further include an information handling system.

A method for identifying one or more imaging properties. The method may comprise identifying one or more candidate mud constants, taking one or more measurements from a borehole with a downhole tool to form an image log, inputting into a machine learning model one or more inputs such that the machine learning model outputs one or more estimated imaging properties, and inputting into a forward model at least the one or more estimated imaging properties and the one or more candidate mud constants such that the forward model outputs one or more reconstructed tool responses. The method may further comprise computing a misfit between the one or more reconstructed tool responses and the one or more measurements, picking a mud candidate from the one or more candidate mud constants based at least in part on the misfit, and producing one or more imaging properties from the picked mud candidate.

A system and method for identifying a downhole fluid. The system may include at least one electrode station that is disposed on a non-conductive material and at least two electrodes coupled to the at least one electrode station. The system may further include at least one acquisition unit that is configured to measure a voltage across the two electrodes of the at least one electrode station and an information handling system connected to the at least one acquisition unit. The method may include injecting a current into a sensing domain with at least two electrodes disposed on at least one electrode station, measuring a voltage across the at least two electrodes at the at least one electrode station using an acquisition unit, and sending the measured voltage to an information handling system connected to the acquisition unit by at least one communication line.

A technological solution for locating and evaluating resistive targets in a space between a pair of wellbores, at least one of which includes a metallic casing. The solution includes injecting an electric current into the metallic casing of one of the pair of wellbores to energize the metallic casing as a dipole transmitter and leak the current into a formation to form variable electric fields; detecting inside the other wellbore of the pair, by an electric field receiver, the variable electric fields; and measuring, by the electric field receiver, the variable electric fields as a function of time; and generating a resistivity map of the formation based on the measurements of the variable electric fields.

A method for imaging a downhole formation. The method includes combining the captured images to generate a partial image of the formation, wherein the partial image includes captured images separated by gaps representing portions of the formation not captured with sensors what were disposed downhole. The method includes locating dips in the formation within the partial image and interpolating the partial image using the located dips within the partial image.

Methods and systems are provided for conducting formation analysis. Data from borehole logging tools is used to conduct a petrophysical analysis of the formation in order to determine (quantify) total porosity and formation matrix permittivity for an interval of the formation. Noninvaded zone water saturation and flushed zone water saturation for the interval of the formation is determined using a saturation model of the interval. The noninvaded zone water saturation is compared to the flushed zone water saturation, and the results of the comparison are used to determine that the interval of the formation contains movable hydrocarbon, immobile hydrocarbon or movable formation water.