Abstract: A method may comprise: inserting into a wellbore penetrating a subterranean formation an apparatus comprising: a transmitter sub comprising a transmitter coil; a first receiver sub comprising a first receiver coil; a second receiver sub comprising a second receiver coil; and a third receiver sub comprising a third receiver coil; generating an electromagnetic wave at the transmitter coil; propagating the electromagnetic wave through the subterranean formation; receiving the electromagnetic wave in the first receiver coil, the second receiver coil, and the third receiver coil; generating a plurality of response signals, wherein the plurality of response signals comprises a first response signal in the first receiver coil, a second response signal in the second receiver coil, and a third response signal the third receiver coil; solving a series of linear equations defined by an orientation of the transmitter sub in the wellbore, orientation in the wellbore for each of the first receiver coil, the second receiver

Abstract: A transmitter of a downhole tool inserted in a borehole of a geological formation transmits a first signal. A receiver of the downhole tool receives a second signal, where the second signal is induced by the first signal in the geological formation. A simple response matrix is determined based on the second signal, where the simple response matrix includes a plurality of response components. One or more of the response components are combined and a modified response matrix is formed by replacing one or more of the plurality of response components in the simple response matrix with a linear combination of the response components of the simple response matrix. The modified response matrix is inverted and an indication of formation properties in the geological formation is output.

Abstract: Numerical and/or semi-analytical methods are leveraged to decouple a complete set of nonzero electromagnetic field tensor components (118) from detected signal data (119). Nine nonzero components can serve as inputs for a three-dimensional inversion process to determine formation properties. A resistivity tool (100) containing at least one transmitter (111) and at least one receiver (108, 109) at tilted angles receives an electromagnetic signal throughout a rotation. A difference in the azimuthal positions of the transmitter(s) and receiver(s) during rotation of the resistivity tool can result in an azimuthal offset between resistivity tool subs. The components (118) are decoupled from the detected signal data (119) numerically or semi-analytically according to whether the azimuthal offset angle is known. If the azimuthal offset angle is known, the nine components are determined numerically through curve fitting.

Abstract: A method for calibrating a resistivity-logging tool using air-hang calibration is provided. The method may include performing an air-hang measurement using the resistivity-logging tool and performing a first measurement decoupling operation on the air-hang measurement. The first measurement decoupling operation may include generating correcting factors based on a physical model and calculating an air-hang calibration matrix based on the correcting factors. Additionally, the method may include performing a formation measurement using the resistivity-logging tool and performing a second measurement decoupling operation on the formation measurement to generate a decoupled formation measurement matrix. Further, the method may include calibrating the resistivity-logging tool to generate a calibrated formation measurement matrix by subtracting the air-hang calibration matrix from the decoupled formation measurement matrix.

Abstract: A method may comprise: inserting into a wellbore penetrating a subterranean formation an apparatus comprising: a transmitter sub comprising a transmitter coil; a first receiver sub comprising a first receiver coil; a second receiver sub comprising a second receiver coil; and a third receiver sub comprising a third receiver coil; generating an electromagnetic wave at the transmitter coil; propagating the electromagnetic wave through the subterranean formation; receiving the electromagnetic wave in the first receiver coil, the second receiver coil, and the third receiver coil; generating a plurality of response signals, wherein the plurality of response signals comprises a first response signal in the first receiver coil, a second response signal in the second receiver coil, and a third response signal the third receiver coil; solving a series of linear equations defined by an orientation of the transmitter sub in the wellbore, orientation in the wellbore for each of the first receiver coil, the second receiver

Abstract: A method and system for electromagnetic ranging of a target wellbore. A method may comprise disposing an electromagnetic ranging tool in a wellbore, energizing a conductive member disposed in the target wellbore to create an electromagnetic field, measuring at least one component of the electromagnetic field from the target wellbore, performing at least two non-axial magnetic field measurements, performing at least one axial magnetic field measurement, calculating a processed non-axial magnetic field measurement using the at least two non-axial magnetic field measurements, calculating an end-of-pipe ratio with the processed non-axial magnetic field measurement and the at least one axial magnetic field measurement, and altering a course of the electromagnetic ranging tool based at least in part from the end-of-pipe ratio. A well ranging system may comprise a downhole assembly, a sensor comprising a first component and a second component, a drill string, and an information handling system.

Abstract: A system for ranging between a target well and a ranging well using unbalanced magnetic fields. The system comprises a current injection path associated with a target well casing. The current injection path is configured to generate a first magnetic field. A return path is coupled to the current injection path. The return path is configured to generate a second magnetic field such that the first and second magnetic fields are unbalanced with respect to each other. The unbalanced magnetic fields can be measured and used to range with the target well.

Abstract: Methods and systems for determining conductivity of a reservoir formation based on skin effect correction and an analytical model for admittance of the reservoir formation are presented in this disclosure. At least one analytical model of admittance of the formation can be initially built as a function of conductivity of the formation. A plurality of samples for the admittance of the formation can be generated, and one or more parameters of the at least one analytical model can be determined based on the plurality of samples and the at least one model. Then, admittance of the formation can be measured, and conductivity of the formation can be calculated from the measured admittance based on the analytical model with the parameters.

Abstract: Disclosed embodiments include well ranging apparatus and systems that comprise well casing material installed in a well, well cement attached to the well casing material, and a device to conduct electromagnetic waves, the device disposed along a length of the well, substantially parallel to the well casing material, the device to be used in direct transmission or backscatter transmission of ranging signals. In some embodiments, the device comprises at least one of a conductor, an insulated conductor, a coaxial cable, a waveguide, a capacitor, or an inductor. Additional apparatus, systems, and methods are disclosed.

Abstract: Apparatus, systems, and methods may operate to couple a power supply to a ground point associated with a well, and to a lower portion of a conductive casing disposed within the well, where the lower portion of the conductive casing is separated by an insulating gap from an upper portion of the conductive casing, the upper portion of the conductive casing being at a higher elevation of the first well than the lower portion of the conductive casing. Further activity may include injecting an excitation signal into the lower portion of the conductive casing to induce a magnetic field in a geological formation surrounding the first well. Additional apparatus, systems, and methods are disclosed.

Abstract: A system for electromagnetic wellbore surface ranging to determine the location of a second wellbore relative to a first wellbore utilizing i) a current source configured to directly inject electrical current into a conductive member disposed in each wellbore and ii) an electromagnetic senor positioned on the surface of a formation, the sensor configured to measure electromagnetic fields at the formation surface emanating from the conductive member within each wellbore.

Abstract: The disclosed embodiments include systems and methods for multi-frequency focusing signal processing in wellbore logging. In one embodiment, the method includes obtaining a harmonic frequency set to evaluate a resistivity of a formation at a wellbore location, where the harmonic frequency set includes at least one harmonic frequency of a fundamental frequency. The method also includes selecting a waveform from a library of waveforms based on the obtained harmonic frequency set, where the library of waveforms includes a plurality of waveforms having different frequency spectrums. The selected waveform corresponds to a predicted conductivity of the formation. The method further includes generating, based on the selected waveform, a binary waveform for use in evaluating the resistivity of the formation at the wellbore location.

Abstract: Methods to accurately plan and optimize clamped source excitation in ranging or telemetry operations approximate a well having a complex pipe structure as a simple solid pipe (“effective model”) with an effective pipe cross-section and resistance. The simple solid pipe is then treated as a thin wire and analyzed using a FAST Code.

Abstract: A method includes cementing a target well with a target well cement comprising resistive cement having resistivity that is greater than a resistivity of a subsurface formation through which the target well passes. The method includes injecting an injected signal into a conductive casing material at least partially surrounded by the target well cement. The method also includes receiving a resulting signal that results from the injecting at a signal receiver disposed within at least one of the target well and a drilling well separated from the target well.

Abstract: A telemetry and communication system and method. The system may comprise a well production system, which may comprise a telemetry sensor disposed in a production well below a highly conductive layer and a transmitter. The system may further comprise a well assist system comprising a sensor which is operable to receive information from the transmitter. A method for providing telemetry and communication may comprise determining a location of a well assist system for a well production system, deploying the well assist system to the location, disposing a sensor from the well assist system below a highly conductive layer, and receiving information with the sensor, the information being transmitted from a transmitter of the well production system disposed below the highly conductive layer.

Abstract: An electromagnetic telemetry system can be used for determining a resistivity of a portion of a wellbore drilled through a subterranean formation. For example, the electromagnetic telemetry system can include a computing device and a downhole transceiver positioned on a well tool in the wellbore. The computing device can receive, from the downhole transceiver, a signal indicating a load impedance across an electrically insulating segment of the downhole transceiver. The computing device can determine a resistivity associated with a portion of the wellbore based on the load impedance. The computing device can determine a corrected resistivity by modifying the resistivity associated with the portion of the wellbore using a correction factor.

Abstract: Disclosed embodiments include methods and apparatus for ranging techniques to detect and determine a relative distance and azimuthal direction of nearby target well conductors such as pipes, well casing, etc., from within a borehole of a drilling well. A nearby casing string of a target well can be detected by transmitting an electromagnetic signal from an excitation source located along the target well and measuring a response signal with an antenna on a downhole logging tool in the drilling well. Several different excitation sources for various target wells are utilized to distinguish nearby conductor signals from formation signals. Joint]inversion algorithms are utilized to identify multi]well locations on the basis of measured signal responses from the different excitations sources. The joint]inversions may be implemented in real]time or during post]processing, and used in applications such as SAGD, anti]collision, and relief well development.

Abstract: A first transceiver positioned in a wellbore can transmit an electromagnetic signal. The electromagnetic signal can include encoded data. A second transceiver can be positionable at a surface of an adjacent wellbore and can include a computing device communicatively coupled to electrodes positionable in the adjacent wellbore. The electrodes can receive the electromagnetic signal and generate respective voltages in response to the electromagnetic signal. The computing device can determine a decoded version of the encoded data based on a voltage difference between the electrodes.

Abstract: A system includes an electromagnetic logging tool that transmits an electromagnetic signal as the tool is conveyed along a borehole through a formation. The system further includes a processing system that measures a first signal level in response to the tool being at a first measured depth, determines a first conductance based on the first signal level, measures a second signal level in response to the tool being at a second measured depth greater than the first measured depth, the second measured depth and the first measured depth defining a formation interval there between, determines a second conductance based on the second signal level, and assigns a uniform resistivity value to the formation interval based on the first conductance and the second conductance.

Abstract: The disclosed embodiments include systems and methods for multi-frequency focusing signal processing in wellbore logging. In one embodiment, the method includes obtaining a harmonic frequency set to evaluate a resistivity of a formation at a wellbore location, where the harmonic frequency set includes at least one harmonic frequency of a fundamental frequency. The method also includes selecting a waveform from a library of waveforms based on the obtained harmonic frequency set, where the library of waveforms includes a plurality of waveforms having different frequency spectrums. The selected waveform corresponds to a predicted conductivity of the formation. The method further includes generating, based on the selected waveform, a binary waveform for use in evaluating the resistivity of the formation at the wellbore location.