Abstract: A ranging system calculates the distance, direction and orientation of a target well through rotationally invariant analysis of triaxial electric and magnetic field measurements from a bottom hole assembly (“BHA”) having electromagnetic sensors. The triaxial electric and magnetic field sensors can be deployed in any downhole device without explicitly needing to process or retrieve rotational information about the downhole BHA or wireline device. Also, the distance, direction and orientation of the target well can be retrieved from a single measurement position.

Abstract: An illustrative casing coupler for a permanent electromagnetic (EM) monitoring system, the casing coupler includes a tubular body having threaded ends for connecting casing tubulars together, and a wire coil that encircles the tubular body and transmits and/or receives EM signals.

Abstract: Electromagnetic (EM) measurement systems and methods for a downhole environment are described herein. An example system includes an optical fiber, an EM source to emit an EM field, and a magnetic induction sensor. The magnetic induction sensor comprises a coil and an electro-optical transducer coupled to the coil and the optical fiber. The electro-optical transducer generates a light beam or modulates a source light beam in the optical fiber in accordance with a voltage induced in the coil by the EM field. An example method includes positioning an optical fiber and magnetic induction sensor in the downhole environment, the magnetic induction sensor having a coil and an electro-optical transducer coupled to the coil and the optical fiber. The method also includes emitting an EM field and generating a light beam or modulating a source light beam, by the electro-optical transducer, in the optical fiber in accordance with a voltage induced in the coil by the EM field.

Abstract: In some embodiments, an apparatus and a system, as well as a method and article, may operate to model electromagnetic data to provide modeled electromagnetic data by solving a first set of surface integral equations that include earth model parameters corresponding to an earth model of a geological formation. Additional activity may include publishing at least some of the modeled electromagnetic data in human-readable form, and/or controlling drilling operations in the geological formation based on the earth model when error between the modeled electromagnetic data and measured electromagnetic data is less than a selected threshold. Additional apparatus, systems, and methods are disclosed.

Abstract: An apparatus and method may operate to mount one or more communication assemblies relative to the exterior of a casing being placed in a borehole. Each communication assembly is configured to cause electrodes of a fluid sensing assembly to inject currents into fluids in one or more regions of the annulus surrounding the casing, and to obtain excitation responses from electrodes of the fluid sensing assembly, where the excitation responses vary based on electrical properties of fluids in one or more regions of the annulus surrounding the casing. Control is provided to control which electrodes of the fluid sensing assembly will inject currents and generate excitation responses and to control which electrodes of the fluid sensing assembly will sense the currents. Additional apparatus, systems, and methods are disclosed.

Abstract: A magnetic field sensor unit for a downhole environment includes an optical fiber, a magnetic field sensor, and an optical transducer. The sensor unit also includes a sealed housing that encloses the magnetic field sensor and the optical transducer. The optical transducer is configured to generate a light beam or to modulate a source light beam in the optical fiber in response to a magnetic field sensed by the magnetic field sensor. Related magnetic field measurement methods and systems deploy one or more of such magnetic field sensor units in a downhole environment to obtain magnetic field measurements due to an emitted electromagnetic field.

Abstract: A disclosed electromagnetic (EM) interferometry system includes a first EM field sensor at a first position in a downhole environment. The system also includes a second EM field sensor at a second position in the downhole environment. The system also includes a processing unit that receives a first EM field measurement from the first EM field sensor and a second EM field measurement from the second EM field sensor. The processing unit derives a response of the first EM field sensor to a virtual EM field source at the second position by cross-correlating the first EM field measurement with the second EM field measurement. The processing unit also performs an inversion process based at least in part on the derived response to obtain a model of subsurface formation properties.

Abstract: Illustrative permanent electromagnetic (EM) monitoring systems and methods have a casing string positioned inside a borehole and equipped with one or more EM transducer modules having a layer of soft magnetic material that substantially encircles the casing string to amplify a signal response of a magnetic field transmitting and/or sensing element. The layer preferably has an axial dimension at least twice an axial dimension of the magnetic field sensing element, with a relative permeability at least twice that of the casing material. The magnetic field transmitting element can be a coil. The magnetic field sensing element can be a coil or a piezoelectric or magnetostrictive element that applies stress to an optical fiber. A well interface system communicates with the one or more EM transducer modules to transmit and/or collect EM signals over time. Additional casing strings may be provided in other nearby boreholes to enable tomographic mapping and monitoring of fluid interfaces in the reservoir.

Abstract: An apparatus and method provides for nondestructive inspection of a generally tubular target structure (such as a wellbore casing) by rolling contact engagement of one or more rolling probe devices with the target structure. Each rolling probe device carries electromagnetic (EM) measurement instrumentation to capture measurement data during rolling contact engagement with the casing. Each rolling probe device may comprise an instrumentation carrier (e.g., a roller or a wheel) having an endless tread surface to engage the target structure, with the EM measurement instrumentation extending along the endless tread surface and being located at or adjacent an exterior of the instrumentation carrier. A plurality of such rolling instrumentation carriers can be mounted at azimuthally spaced positions on a tool body configured for axial movement along a wellbore.

Abstract: A time-lapse electromagnetic (EM) monitoring system for a formation includes at least one EM source and at least one EM field sensor to collect EM survey data corresponding to the formation in response to an emission from the at least one EM source. The EM survey data includes first EM data collected at a first time and second EM data collected at a second time. The time-lapse EM monitoring system also includes a processing unit in communication with the at least one EM field sensor. The processing unit determines time-lapse EM data based on the first EM data and the second EM data, and performs an analysis of the time-lapse EM data to determine an attribute change in an earth model.

Abstract: A passive system for ranging between two wellbores where a distributed acoustic sensor system is deployed in a first wellbore and a drill bit in a second wellbore being drilled is utilized and an acoustic source to generate an acoustic signal for measurement by the distributed acoustic sensor system. The dynamic strain along the distributed acoustic sensor system is detected with an optical interrogation system and utilized to determine direction and distance between the first wellbore and the second wellbore.

Abstract: A wellbore ranging system and method utilized between first and second wellbores includes an electromagnetic field sensing instrument disposed in the second wellbore, a conductive casing in the first wellbore, an electric current source exciting current flow in the conductive member, and a fiber optic sensor disposed adjacent the conductive member. The current flow along the conductive member results in a magnetic field which is measured by the sensing instrument. The fiber optic sensor includes a core that is responsive to the magnetic field in which it is disposed. The responsive core alters the optical property of an optical wave guide forming the sensor, which altered optical property can be utilized to measure the magnitude of the electrical current at the position of the sensor. The magnitude of the current and the measured magnetic field can be utilized to determine a range between the first and second wellbores.

Abstract: A well having optically controlled switching, the well including a power cable run along a tubular string in a borehole, one or more downhole devices attached to the tubular string, one or more optically-controlled switches arranged downhole, where each switch is coupled between the power cable and one of the one or more downhole devices to enable or disable a flow of power to the downhole device, and a switch controller coupled to the one or more optically-controlled switches via an optical fiber, where each of the one or more optically-controlled switches are independently controllable.

Abstract: A disclosed electromagnetic (EM) interferometry system includes a first EM field sensor at a first position in a downhole environment. The system also includes a second EM field sensor at a second position in the downhole environment. The system also includes a processing unit that receives a first EM field measurement from the first EM field sensor and a second EM field measurement from the second EM field sensor. The processing unit derives a response of the first EM field sensor to a virtual EM field source at the second position by cross-correlating the first EM field measurement with the second EM field measurement.

Abstract: A spontaneous (SP) monitoring system includes a plurality of EM field sensors positioned in a downhole environment. The SP monitoring system also includes a processing unit in communication with the plurality of EM field sensors. The processing unit determines SP data for the downhole environment using a multi-frequency SP model and EM field measurements collected by the plurality of EM field sensors. The processing unit performs an inversion process based at least in part on the SP data to obtain a model of subsurface fluid.

Abstract: A method for the real time volume imaging of geological structures and/or man-made objects having electrical conductivity is described, using electromagnetic (EM) sources and/or EM sensors mounted from at least one moving platform. The EM sources may include natural EM sources and/or man-made inductive sources and/or man-made galvanic sources. The EM sensors may measure at least one component of the EM field at the at least one sensor position. The EM fields measured for each combination of EM source and EM sensor may be volume imaged in real time using a moving sensitivity domain that captures the finite spatial sensitivity of each combination of EM sources and EM sensors. At least one desired property, such as conductivity, dielectric permittivity and/or induced polarization parameters, may be derived from the volume image, providing a reconstruction or classification of the physical properties of the geological structures and/or man-made objects.

Abstract: A ranging system calculates the distance, direction and orientation of a target well through rotationally invariant analysis of triaxial electric and magnetic field measurements from a bottom hole assembly (“BHA”) having electromagnetic sensors. The triaxial electric and magnetic field sensors can be deployed in any downhole device without explicitly needing to process or retrieve rotational information about the downhole BHA or wireline device. Also, the distance, direction and orientation of the target well can be retrieved from a single measurement position.

Abstract: Illustrative permanent electromagnetic (EM) monitoring systems and methods have a casing string positioned inside a borehole and equipped with one or more EM transducer modules having a layer of soft magnetic material that substantially encircles the casing string to amplify a signal response of a magnetic field transmitting and/or sensing element. The layer preferably has an axial dimension at least twice an axial dimension of the magnetic field sensing element, with a relative permeability at least twice that of the casing material. The magnetic field transmitting element can be a coil. The magnetic field sensing element can be a coil or a piezoelectric or magnetostrictive element that applies stress to an optical fiber. A well interface system communicates with the one or more EM transducer modules to transmit and/or collect EM signals over time. Additional casing strings may be provided in other nearby boreholes to enable tomographic mapping and monitoring of fluid interfaces in the reservoir.

Abstract: An apparatus and method may operate to mount one or more communication assemblies relative to the exterior of a casing being placed in a borehole. Two communication assemblies can be placed in longitudinally spaced relation to one another along the casing, wherein each communication assembly is configured to obtain excitation responses from electrodes of a fluid sensing component, where the excitation responses vary based on properties of fluids in one or more regions of the annulus surrounding the casing. Additional apparatus, systems, and methods are disclosed.

Abstract: A method for the real time volume imaging of geological structures and/or man-made objects having electrical conductivity is described, using electromagnetic (EM) sources and/or EM sensors mounted from at least one moving platform. The EM sources may include natural EM sources and/or man-made inductive sources and/or man-made galvanic sources. The EM sensors may measure at least one component of the EM field at the at least one sensor position. The EM fields measured for each combination of EM source and EM sensor may be volume imaged in real time using a moving sensitivity domain that captures the finite spatial sensitivity of each combination of EM sources and EM sensors. At least one desired property, such as conductivity, dielectric permittivity and/or induced polarization parameters, may be derived from the volume image, providing a reconstruction or classification of the physical properties of the geological structures and/or man-made objects.