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: 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: 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, systems, and methods which operate to detect and determine a relative distance and/or azimuthal direction of nearby target well conductors such as pipes, well casing, etc., from within a borehole of a drilling well.

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 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: 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: An electromagnetic telemetry system may include an electrically conductive member, a transmitter coupled to the electrically conductive member, the transmitter configured to induce an alternating current along the electrically conductive member, the alternating current representing encoded information, a first receiver coupled to the electrically conductive member, the first receiver configured to receive electromagnetic waves resulting from the alternating current, a second receiver positioned at a location apart from the first receiver, the second receiver configured to receive the electromagnetic waves resulting from the alternating current, and a receiver processing system communicatively coupled to the first receiver and the second receiver, the receiver processing system configured to process the electromagnetic waves received by the first receiver and the second receiver into a combined signal, and decode the combined signal.

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 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: 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: Disclosed embodiments include well ranging apparatus, systems, and methods which operate to detect and determine a relative distance and/or azimuthal direction of nearby target well conductors such as pipes, well casing, etc., from within a borehole of a drilling well.