Abstract: Systems and methods of the present disclosure relate to calibration of resistivity logging tool. A method to calibrate a resistivity logging tool comprises disposing the resistivity logging tool into a formation; acquiring a signal at each logging point with the resistivity logging tool; assuming a formation model for a first set of continuous logging points in the formation; inverting all of the signals for unknown model parameters of the formation model, wherein the formation model is the same for all of the continuous logging points in the first set; assigning at least one calibration coefficient to each type of signal, wherein the calibration coefficients are the same for the first set; and building an unknown vector that includes the unknown model parameters and the calibration coefficients, to calibrate the resistivity logging tool.

Abstract: Disclosed is a system and a method of transient electromagnetic advanced detection. The system includes a detection host, an electromagnetic signal transmitter, a probe, and a communication device. The system and method of transient electromagnetic advance detection disclosed by examples of the present disclosure can realize an early-warning through a transient electromagnetic advance detection in a borehole while drilling the borehole in a tunnel or a roadway.

Abstract: Downhole ranging from multiple wellbores. In one example, multiple transmitters and multiple receivers are disposed in multiple wellbores to exchange electromagnetic signals. By implementing a full compensation technique, a computer system determines multiple compensated signals. A compensated signal is determined from a signal received from a first wellbore and a second signal received from a second wellbore. In another example, a first transmitter is disposed in a first wellbore, a first receiver is disposed in a second wellbore, and either a second transmitter or a second receiver is disposed in either the first wellbore or the second wellbore. By implementing partial compensation techniques, a computer system determines compensated signals. Using the compensated signals, the computer system determines a position of a first wellbore relative to a second wellbore, and provides the position.

Abstract: A system for looking ahead of a drill bit includes a plane wave generator (PWG) tool deployed downhole inside a wellbore for formation evaluation and generation of reflection data, a power source providing electric power to the PWG tool for the formation evaluation and the generation of the reflection data, a surface control system receiving the reflection data from the PWG tool and generating image data of a subsurface rock formation based on the received reflection data, and a wireline that electrically couples the PWG tool to the power source and communicatively couples the PWG tool to the surface control system. The PWG tool includes a beam forming network (BFN) architecture and a plurality of antenna elements mounted to a base of the PWG tool to transmit and receive electromagnetic signals.

Abstract: The subject disclosure relates to a method for determining a volume fraction of water and water salinity in organic shales and other geological formations. The method includes a knowledge of complex formation permittivity at several frequencies and minimizes or excludes dependency on external parameters, such as the permittivity of the formation mineral phase.

Abstract: A communication system using vector and scalar potential is disclosed. The system uses field-free potentials signaling for many applications where the absence of shielding effects in sea water, plasma or other dense media due to the fact that the absence of (E,B) fields eliminates the possibility of induced charge and current response in the media being transited.

Abstract: A magnetic susceptibility and conductivity tool (10) which incorporates a transmitter coil (4) energized with a time-varying current from a transmitter coil drive (13). The transmitter coil drive receives a clock signal and induces a data signal (99) including a primary mutual coupling signal and a formation coupling signal. A receiver coil (1) outputs a receiver coil voltage induced by the data signal. A transmitter coil current sense circuit (15) receives current from the transmitter coil and outputs a digital coil current voltage signal. A synthetic null circuit (14) receives the digital current voltage signal and multiplies the digital current voltage signal with a predetermined constant (28) for amplitude of a base primary mutual coupling signal and shifts phase with a predetermined phase offset (27) to output a synthetic null signal (104).

Abstract: Pipe]parameter determinations from electromagnetic logs can be improved, in accordance with various embodiments, by weighting signals with frequencies below a threshold associated with resolution degradation lower than signals with frequencies above the threshold. The threshold frequency may be determined based on a spatial resolution associated with the logging tool and a logging speed. Further embodiments are described.

Abstract: A phase-shift unit includes: a first substrate and a second substrate provided opposite to each other; a medium layer provided between the first substrate and the second substrate; a microstrip line disposed at a side of the second substrate facing towards the first substrate; and a grounding layer provided at a side of the first substrate facing towards the second substrate and formed with a via hole; wherein a projection of the via hole onto the second substrate and a projection of the microstrip line onto the second substrate have an overlapped area therebetween; and wherein the via hole is configured to feed a phase-shifted microwave signal out of the phase-shift unit, or feed a microwave signal into the phase-shift unit such that the microwave signal is phase-shifted.

Abstract: A solution for evaluating a medium using electrical signals is described. A plurality of electrical signals having different frequencies are transmitted through the medium and signal data corresponding to the electrical signals after having traveled through the medium is acquired. A complex impedance and a complex permittivity and/or complex conductivity can be calculated for the medium. A set of characteristics of the medium can be computed using mixing models and/or known information of the medium. A level of one or more attributes of the medium can be determined from the characteristics using nonparametric Bayesian inference. One particular application is directed to determining a nitrate level of soil.

Abstract: Methods to operate an NMR tool, methods to simulate a numerically-controlled oscillator of an NMR tool in real time, and downhole NMR tools are presented. A method to operate an NMR tool includes determining a phase shift of a sinusoidal wave, determining a number of look-up tables and a number of terms of Taylor Expansions performed to obtain a value corresponding to a phase angle of the phase shift, and separating the phase angle into a first component and a second component. The method also includes obtaining a first value corresponding to the first component from the number of look-up tables, performing the number of terms of Taylor Expansions on the second component to obtain a second value corresponding to the second component, combining the first value and the second value to obtain the value of the phase angle, and generating the sinusoidal wave having the phase shift.

Abstract: A method for estimating all five transversely-isotropic (TI)-elastic constants using borehole sonic data obtained from at least one subterranean borehole in a transversely isotropic formation. In an embodiment, the method includes: solving for a quasi-compressional qP-wave velocity VqP using inversion algorithms based on exact solutions of the Kelvin-Christoffel equations for plane wave velocities in arbitrarily anisotropic formations, where the five TI-elastic constants may include C11, C13, C33, C55, and C66.

Abstract: An electromagnetic tool using slotted dipole antennas is presented. The dipoles may be placed in slots on a drill collar. A receiver or transmitter antenna consists of one or more slots. A dipole consists of a ferrite rod with electric wires placed above and below the ferrite. Wires may be connected such that wire current forms a loop around the ferrite rod. When a group of slots are used for an antenna, wire holes are constructed between slots. Effectively a single wire may be used to go above all ferrite rods in the group and then turn to go below all the rods. Two wire segments are in a wire hole connecting two adjacent slots. Currents in the two segments are the same in magnitudes and flow in opposite directions. There is no net current in wires in a wire hole.

Abstract: The disclosure presents processes to generate look ahead data to guide borehole operations, such as drilling operations. The processes can array collected resistivity data around a representation of an active borehole. The array can be in various patterns, such as an interleaved helix pattern. Each slice of data from the collected resistivity data can be positioned and oriented corresponding to the central point depth parameter for each slice of data. A selection of one or more card views can be enabled to display details of the collected resistivity data corresponding to the selected slice of data. An analysis of the resistivity data can generate an identification of a boundary, such as an object or a subterranean formation change, in the subterranean formation look ahead portion of the active borehole. The boundary identification can be used as inputs to a borehole operation plan or to a geo-steering system.

Abstract: A method comprises determining a plurality of responses at a plurality of tilted angles for multiple coils of a collocated antenna assembly based on at least one coil parameter of the collocated antenna assembly, wherein the at least one coil parameter comprises at least one of a number of coil turns, a coil size, and a number of coils. The method includes determining crosstalk between the multiple coils at each of the plurality of tilted angles from the plurality of responses. The method includes determining a signal-to-noise ratio for each of the plurality of tilted angles based on the crosstalk. The method also includes selecting a tilted angle for the collocated antenna assembly corresponding to an optimal signal-to-noise ratio of the determined signal-to-noise ratios.

Abstract: Systems and methods of the present disclosure relate to calibration of a resistivity tool. A method for in-situ calibration of a resistivity logging tool, comprises transmitting signals with transmitters of the resistivity logging tool; measuring voltages at two or more receivers located at different distances to the transmitters of the resistivity logging tool; decoupling two or more sets of multi-component tensors at two or more receivers based on the measured voltages; calculating a ratio signal from two or more sets of multi-component tensors; obtaining an apparent resistivity based on the ratio signal; simulating a dipole response tensor at the first receiver based on the apparent resistivity; comparing the first set of multi-component tensor with the dipole response tensor to acquire an in-situ calibration factor; and applying the in-situ calibration factor to multi-components for an inversion input.

Abstract: Systems and methods of the present disclosure relate to calibration of a resistivity tool. A calibration method comprises deploying a transmitter in a known formation with a known resistivity property with a physical tilted angle ? relative to a longitudinal axis of the tool; deploying receivers in the known formation, wherein a physical tilted angle of a first receiver is ? relative to the longitudinal axis of the tool, and wherein a physical tilted angle of a second receiver is ??, relative to the longitudinal axis of the tool; transmitting signals with the transmitter and measuring the signals at the receivers; combining measurements at two receivers with respect to a transmitter signal in the known formation; producing synthetic responses of the tool in the known formation using forward modeling; and calculating an effective tilted angle ?? from real measurements and the synthetic responses.

Abstract: A method for making a log of material properties in a plurality of beds from an instrument utilizes steps such as estimating material properties for said plurality of beds and/or estimating positions for a plurality of bed boundaries and/or estimating orientations for said plurality of bed boundaries wherein the bed boundary orientations are individually variable. The estimated positions, orientations, and/or material properties can be utilized to compute the log.

Abstract: The present disclosure describes various antenna assemblies, each antenna coil being disposed about a tool body section in an antenna pathway. The antenna pathway passes through alternating grooves and lands. In each embodiment, at least one of the grooves is disposed in the tool body section at a non-axial direction relative to the longitudinal axis of the tool body section. In an embodiment, the antenna coil is an axial coil or a tilted coil. Additional grooves oriented at axial direction may be disposed on the tool body section. Each of the antenna assemblies disclosed may be employed in an electromagnetic logging tool for providing directional measurements while drilling.

Abstract: Raw signal measurements can be received by sensors in a wellbore. Borehole effects can affect the raw signal measurements. The raw signal measurements can be converted into ratio signals having attenuation and phase shift. An apparent resistivity can be determined from the ratio signals. Mud resistivity can be determined based on apparent resistivity, at least part of the raw signal measurements, and the borehole size. A true resistivity can be determined based on the mud resistivity and at least part of the ratio signals. The raw signal measurements and the ratio signals can be updated based on the true resistivity. Steps can be repeated to determine a corrected true resistivity. Based on the true resistivity value and updated raw signal measurements and ratio signals, an operating characteristic of a well tool can be caused to be adjusted.

Abstract: A method of drilling a wellbore to a target includes measuring attitudes at two adjacent survey stations along a wellbore using a downhole surveying tool. An actual change in wellbore position over a survey leg linking the two survey stations is determined. Corrections are applied to the measured attitude at one or both of the survey stations such that a modeled well path joining the survey stations reflects the determined actual change in wellbore positon between the two survey stations.

Abstract: Systems, methods, and computer-readable media for in-situ calibration of magnetic field measurements. In some examples, a method can involve generating a magnetic field via a magnetic field source that is coupled to a downhole tool. The magnetic field source can be located within a fixed distance from one or more sensors coupled to the downhole tool. The method can also involve obtaining respective field measurements of the known magnetic field from the one or more sensors, and comparing the respective field measurements from the one or more sensors with respective reference measurements previously obtained from the one or more sensors to yield respective comparisons. The method can then involve determining, based on the respective comparisons, a respective sensitivity drift for each of the one or more sensors.

Abstract: Systems and methods for determining formation properties are disclosed. In some embodiments, a multi-component induction tool is utilized to measure a set of triaxial resistivities at each of a plurality of borehole depths. Differences among the sets of triaxial resistivities are correlated with a compaction-dependent property determined for one or more borehole depths. Depth-dependent laminate resistivity models are generated based on the correlating. A formation property is determined by processing the sets of triaxial resistivities using a formation tensor model that incorporates the depth-dependent laminate resistivity models.

Abstract: A decoding device is used to securely send corresponding data gathered from multiple underground sources to multiple users. The device comprises a signal receiving port connected to multiple bandwidth filters and further connected to internet access points that are assigned to end users for secure data access. The invention facilitates allowing the signal and data being transmitted through the formation of the earth to reach end users located nearby and significant distances away from the source of the transmission. A system and method utilizing the decoding device is provided.

Abstract: A compact sub assembly and well measurement system. The compact sub assembly may comprise a deep transmitter disposed about one end of the compact sub assembly, a shallow dual transmitter disposed on the compact sub assembly between the deep transmitter and a second end of the compact sub assembly, a shallow dual-collocated receiver disposed on the compact sub assembly between the deep transmitter and a second end of the compact sub assembly, and a deep receiver disposed about the second end of the compact sub assembly. A well measurement system for decoupling a component signal may comprise a logging tool. The logging tool may comprise a first sub assembly and a conveyance attached to the logging tool. In examples the first sub assembly is a compact sub assembly comprising a deep transmitter, a shallow dual transmitter, a shallow dual-collocated receiver, and a deep receiver.

Abstract: The systems and methods provide a universal bottom hole assembly node module. The universal bottom hole assembly node module comprises an azimuthal resistivity module, an azimuthal gamma module, a pressure while drilling module, or any combination thereof. The universal bottom hole assembly node module includes a communication system configured to provide two way communication between a rotary steerable system and a measurement while drilling system.

Abstract: A compact sub assembly and a method for forming a deep antenna. The assembly may comprise a look-ahead deep transmitter is attached at about one end of the compact sub assembly, and a shallow transmitter is attached to the compact sub assembly and positioned adjacent to the look-ahead deep transmitter. A method of forming a deep antenna may comprise positioning a look-ahead deep transmitter adjacent to a shallow transmitter at about one end of a compact sub assembly, and connecting the look-ahead deep transmitter to a switching module through one or more deep switches, connecting the shallow transmitter to the switching module through one or more shallow switches, and closing the one or more deep switches and the one or more shallow switches to activate the look-ahead deep transmitter and the shallow transmitter to form the deep antenna.

Abstract: A method for selecting initial models or inversion solutions during an inversion process from electromagnetic measurements may comprise disposing an electromagnetic well measurement system into a wellbore, transmitting electromagnetic fields into a formation with the electromagnetic transmitter, measuring the electromagnetic fields with the electromagnetic receiver as measurements at a depth in the wellbore, forming initial models for the inversion process based on the measurements and performing an inversion, filtering an inversion solution, forming a solution database from the filtered inversion solutions, building a reference model, calculating a similarity between the reference model and one or more models in the solution database, selecting one or more results from the solution database with the similarity larger than a threshold, and generating a final inversion model image from the one or more results.

Abstract: Methods capable of determining a depth of investigation of a logging tool can include generating an error distribution model for a logging tool. The methods can also include defining a detection threshold above which a measured signal from a measurement channel of the logging tool can be considered reliable based on output from the error distribution model, and generating a simulated formation model to determine the depth of investigation. The depth of investigation can be biased by the detection threshold.

Abstract: System and methods for geosteering inversion are provided. A downhole tool's response along a path of a wellbore to be drilled through a formation is predicted over different stages of a downhole operation, based on each of a plurality of initial models of the formation. Each initial model represents a different number of formation layers over a specified range. The tool's actual response with respect to one or more formation parameters is determined, based on measurements obtained during a current stage of the operation. The actual response is compared with that predicted from each of the initial models. At least one of the models is selected as an inversion model, based on the comparison and a selection criterion. Inversion is performed for subsequent stages of the operation along the wellbore path, based on the selected model. The wellbore path is adjusted for the subsequent stages, based on the inversion results.

Abstract: A recessed antenna that includes a recessed plane formed in a conductive surface. An antenna is disposed on the recessed plane. A cavity is formed beneath the recessed plane. A circuit board is disposed in the cavity. The circuit board is electrically coupled to the antenna. A cover is disposed over the antenna, the cover protecting the antenna from abrasion.

Abstract: A technique for measuring properties of a material includes measuring the electromagnetic radiation scattered by one or more scattering points associated with the material, and adjusting the radiation according to the respective sensitivities of the scattering points to changes in material properties at that scattering point for several pairs of radiation sources and receivers. The material properties are determined using the updated measurements and corresponding simulated measurements.

Abstract: A sensor system for sensing the contents of a bore including a plurality of coils disposed behind a non-metallic lining. An oscillator circuit may be used to drive the coils to generate oscillating electromagnetic fields, and a detection circuit generates output signals from each coil representing a parameter of the electrical oscillations that depends on the contents of the bore. The coils may include a primary coil and a one secondary coil, wherein the oscillating electromagnetic field generated by the secondary coil has a lesser degree of interaction with the contents of bore than the oscillating electromagnetic field generated by the primary coil. The sensor system may use the output signal from the secondary coil to compensate the output signal from the primary coil for environmental effects.

Abstract: A phase-shift unit includes: a first substrate and a second substrate provided opposite to each other; a medium layer provided between the first substrate and the second substrate; a microstrip line disposed at a side of the second substrate facing towards the first substrate; and a grounding layer provided at a side of the first substrate facing towards the second substrate and formed with a via hole; wherein a projection of the via hole onto the second substrate and a projection of the microstrip line onto the second substrate have an overlapped area therebetween; and wherein the via hole is configured to feed a phase-shifted microwave signal out of the phase-shift unit, or feed a microwave signal into the phase-shift unit such that the microwave signal is phase-shifted.

Abstract: A system and method of evaluating and correcting for the effects of a near-surface anomaly on surface-to-borehole (STB) measurement data in a geological halfspace includes transmitting electromagnetic radiation from an EM source located on a ground surface which is positioned over the near-surface anomaly, measuring EM fields at a plurality of remote EM receivers located on the surface at a far distance from the EM source, obtaining vertical STB measurement data downhole, determining an orientation and moment of a secondary source equivalent dipole associated with the near-surface anomaly excited by the radiation transmitted by the EM source based on measurements of the EM fields at the plurality of remote receivers, determining a correction factor for the secondary source equivalent dipole on the EM field measurements at the plurality of remote receivers, and removing the effects of the near surface anomaly on the vertical STB measurement data using the correction factor.

Abstract: A sensing system adapted to determine changes in phase when a capacitive object enters into the phase detection zone created by a pair of transmitting conductors. One of the transmitting conductors has a receiving conductor located proximate to it and transmits a signal at a certain frequency. The other transmitting conductor transmits a signal that is phase shifted from the signal transmitted by the other transmitting conductor. Capacitive objects entering the space between the two transmitting conductors impacts the phase. Measurements of the change in phase are used to determine the position of an object between the two transmitting conductors.

Abstract: Methods and systems of correcting operation of multiple modules are described. The methods include generating a first dual-tone signal in a first module and transmitting the first dual-tone signal to a second module. A second dual-tone signal is generated in the second module and transmitted to the first module. The first module determines a first phase of the received second dual-tone signal and the second module determines a second phase of the received first dual-tone signal. Operation of one or both of the first and second modules is corrected based on the determined first phase and the determined second phase.

Abstract: A solution for evaluating a medium using electrical signals is described. A plurality of electrical signals having different frequencies are transmitted through the medium and signal data corresponding to the electrical signals after having traveled through the medium is acquired. A complex impedance and a complex permittivity and/or complex conductivity can be calculated for the medium. A set of characteristics of the medium can be computed using mixing models and/or known information of the medium. A level of one or more attributes of the medium can be determined from the characteristics using nonparametric Bayesian inference. One particular application is directed to determining a nitrate level of soil.

Abstract: Methods to configure a downhole electromagnetic tool and downhole electromagnetic tool calibration systems are disclosed. A method to configure a downhole electromagnetic tool includes obtaining a first calibration measurement of a first tool configuration and a second calibration measurement of a second tool configuration of a downhole electromagnetic tool, and determining a first ratio of the first calibration to the second calibration. The method further includes obtaining a first synthetic response of the first tool configuration from a first model of the downhole electromagnetic tool, and obtaining a second synthetic response of the second tool configuration from a second model of the downhole electromagnetic tool, and determining a second ratio of the first synthetic response to the second synthetic response.

Abstract: A shield assembly for logging tool sensors includes a single piece cylindrical shield and first and second cylindrical end clamps deployed about opposing axial ends of the cylindrical shield. The cylindrical shield is deployed about a logging sensor disposed on a logging tool collar. At least one of the first and second end clamps includes one or more keys for engaging a corresponding slot in the shield and a corresponding pocket in an outer surface of the tool collar. Engagement of the key with the corresponding slot and the corresponding pocket is operative to prevent relative rotational and relative axial motion between the cylindrical shield, the first and second end clamps, and the tool collar.

Abstract: A logging system includes an electromagnetic logging tool that collects at least one measurement of a subterranean formation at a borehole. The logging system also includes a processing system that generates a plurality of earth models of the subterranean formation based on the at least one measurement of the subterranean formation. The processing system projects at least one second earth model upon a well path of the borehole, and selects a model of the plurality of models based on a spatial correlation between at least one parameter of the selected model and a corresponding at least one parameter of the at least one second earth model.

Abstract: Systems, methods, and devices for evaluation of an earth formation intersected by a borehole using a logging tool. Methods include performing EM logging in a borehole intersecting an earth formation using a measurement signal from an antenna system in the borehole, the measurement signal dependent upon a parameter of interest of the formation and at least one antenna system parameter of the antenna system, comprising feeding a calibration signal into a signal path of the antenna system to generate a resultant signal; estimating at least one value of the at least one antenna system parameter by using the resultant signal; and performing further logging operations in dependence upon the at least one value of the at least one antenna system parameter. The calibration signal comprises at least two calibration subsignals with a first calibration subsignal having a first frequency and a second calibration subsignal having a second frequency.

Abstract: A logging tool includes a mandrel having an axis, a bobbin positioned about the circumference of the mandrel, and defining a first cross slot at a first slot angle and a second cross slot at a second slot angle opposite the first slot angle. The first and second cross slots intersect each other. The tool includes a first antenna in the first slot and including a first plurality of windings wrapped about the mandrel, a second antenna co-located with the first antenna and in the second slot, and an antenna shield secured to the tool mandrel and in each of the first and second slots. The first antenna is arranged in a first orientation and at a first winding angle. The second antenna is arranged in a second orientation and at a second winding angle.

Abstract: A method of subterranean drilling comprising monitoring at least one drilling criteria at the surface; communicating a marker signal to a bottom hole assembly of a drill string upon meeting a condition of the at least one drilling criteria; and repeating the marker signal at least two consecutive times the condition is met. In an embodiment, the marker signal can be repeated every time the condition is met. A system for subterranean drilling comprising a drill rig adapted to monitor at least one drilling criteria at the surface; a communication element adapted to communicate a marker signal to a bottom hole assembly of a drill string upon meeting a condition of the at least one drilling criteria, wherein the communication element is adapted to communicate the marker signal to the bottom hole assembly at least two consecutive times the condition is met.

Abstract: A logging tool includes a mandrel having a tool axis, a first loop antenna including first windings wrapped about the mandrel, a second loop antenna co-located with the first loop antenna and including second windings wrapped about the mandrel, and a shield secured to the mandrel. The first loop antenna is in a first orientation and the first windings are wrapped at a first angle. The second loop antenna is in a second orientation opposite the first orientation and the second windings are wrapped at a second angle. The shield includes first slots overlapping and along the first loop antenna and second slots overlapping and along the second loop antenna. The first slots define a first trace angle with respect to the tool axis and different from the first angle. The second slots defines a second trace angle with respect to the tool axis and different from the first angle.

Abstract: A rotary steerable bottom hole assembly includes a drill bit disposed at a distal end thereof, and azimuthal resistivity antennas and electronics configured to measure a distance to a formation boundary.

Abstract: A transmitter unit is provided for transmitting a continuous waveform in a magnetic field, the continuous waveform being an unmodulated electromagnetic waveform. The transmitter unit typically comprises a transmitting solenoid for transmitting the continuous waveform, and an oscillator for generating the continuous waveform. A receiver unit is also provided, the receiver unit having receiving circuitry, such as a receiving solenoid, for receiving the continuous waveform. The receiver unit also provides an output for outputting an indication of proximity between the transmitter unit and the receiver unit, where a characteristic of the indication of proximity depends on the strength of the magnetic field generated by the transmitter unit at the location of the receiving solenoid. Also provided is a method for using a system having a transmitter unit and a receiver unit.

Abstract: An electrically conductive proppant coating and a method for applying the coating to the proppant, whereby the coated electrically conductive proppant can determine formation characteristics, such as dimensions, orientation, and conductivity.

Abstract: An apparatus for measuring resistivity downhole in a well includes a tool having at least one transmitter antenna and receiver antenna. The transmitter antenna and the receiver antenna are tilted at angles such that signals from layers between the transmitter antenna and the receiver antenna are at least reduced. Alternatively, the transmitter antenna and the receiver antenna are tilted at angles such that signals from layers being outside a region between the transmitter antenna and the receiver antenna are at least reduced. Signals from multiple collocated antennas are combined to produce synthetical tilt angles. Tilted transmitter and receiver pairs are used to focus resistivity measurements ahead of the bit or around the tool, based on which region of signals are at least reduced.

Abstract: A downhole electrical logging tool includes a mandrel, and a pad coupled to and radially extendable from the mandrel. The pad includes an isolated power supply configured to receive DC or AC power via the mandrel and convert the DC or AC power into one or more DC voltages for powering electronic components on the pad. The pad further includes a digital data processor (e.g., a microcontroller, field programmable gate array, or digital signal processor) powered by the isolated power supply, a transmitter electrode, and a sensing electrode. The pad also includes a housing in which the controller and isolated power supply are located, and a pad body coupled to the mandrel. Components inside the housing are electrically isolated from the pad body. The tool further includes a signal generator electrically coupled to the transmitter electrode to drive the transmitter electrode.