Abstract: A system includes an electromagnetic transmitter disposed in a first borehole. The system further includes an optical fiber disposed in a second borehole. The system further includes an array of electromagnetic transducers coupled to the optical fiber in the second borehole. The transducers are able to operate simultaneously with each other. The system further includes one or more processors to generate a tomographic image of at least a partial formation between the first and second borehole based on measurements of tomography signals, transmitted by the electromagnetic transmitter, collected by the array.

Abstract: A method of forming a short-hop communications transceiver includes creating, in a conductive tool body, an annular cavity that is electromagnetically coupled to an external tool surface by a surface gap that encircles the tool body. The method further includes positioning material having high magnetic permeability in the annular cavity. The method further includes coupling electrical leads from an electronics module to opposite sides of the surface gap. The method further includes operating the electronics module to perform short-hop telemetry by driving or sensing a voltage signal across the surface gap.

Abstract: A system for locating water floods, in some embodiments, comprises: multiple transducers for coupling to a borehole casing to inject current into a formation within which the casing is disposed; and multiple electrodes, each of the electrodes coupled to a different one of the multiple transducers when coupled to the casing, wherein each of the multiple transducers is used to determine a potential between the casing and a corresponding one of the multiple electrodes to which the transducer is coupled, wherein the potentials from the multiple transducers are used to determine a water flood location.

Abstract: A well monitoring system includes a plurality of transmitter coils coupled to an exterior of a casing positioned within a wellbore, wherein one or more first transmitter coils are positioned at a first location and one or more second transmitter coils are positioned at a second location axially offset from the first location. At least one receiver coil is coupled to the exterior of the casing and positioned at the second location. A power source is communicably coupled to the one or more first and second transmitter coils. The one or more first transmitter coils generates a magnetic field detectable by the at least one receiver coil, and the one or more second transmitter coils generates a bucking signal that minimizes a direct coupling between the one or more first transmitter coils and the at least one receiver coil.

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.

Abstract: An antenna assembly includes a tool mandrel having a tool axis, and a coil including a plurality of windings wrapped about the tool mandrel at a winding angle offset from the tool axis. A soft magnetic band radially interposes the coil and the tool mandrel and extends about a circumference of the tool mandrel at a band angle orthogonal to the winding angle. The soft magnetic band includes a plurality of inserts, and a gap is defined between each laterally adjacent insert and the gap extends parallel to the tool axis.

Abstract: A first magnetic cavity transmitter is in the conductive tool body. A first magnetic cavity receiver is in the conductive tool body. A first transmit module is coupled to the first magnetic cavity transmitter. A first receiver module is coupled to the first magnetic cavity receiver.

Abstract: A disclosed formation monitoring system includes a casing that defines an annular space within a borehole. A distributed magnetomotive force sensor is positioned in the annular space and configured to communicate with the surface via a fiber-optic cable. A computer coupled to the fiber-optic cable receives said measurements and responsively derives the location of any fluid fronts in the vicinity such as a an approaching flood front to enable corrective action before breakthrough. A disclosed formation monitoring method includes: injecting a first fluid into a reservoir formation; producing a second fluid from the reservoir formation via a casing in a borehole; collecting magnetic field measurements with a distributed magnetomotive force sensor in an annular space between said casing and said borehole, communicating measurements to a surface interface via one or more fiber-optic cables; and operating on said measurements to locate a front between the first and second fluids.

Abstract: A metal cylinder defines a longitudinal axis and has a plurality slots. Each slot has the same dimensions along two perpendicular axes through a centroid of the slot. The plurality of slots is azimuthally periodic relative to the longitudinal axis of the metal cylinder and axially periodic relative to the longitudinal axis of the metal cylinder.

Abstract: An antenna assembly includes a tool mandrel having a tool axis, and a plurality of coils are collocated about the tool mandrel and each include a plurality of windings wrapped about the tool mandrel. A soft magnetic band radially interposes the plurality of coils and the tool mandrel and includes a plurality of inserts that form two or more annular arrays axially spaced from each other and extend about the tool mandrel at an angle orthogonal to the tool axis. The inserts in each annular array are circumferentially spaced from each other.

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: Systems and methods for formation evaluation and reservoir monitoring that use electromotive force measurements. A well monitoring system may comprise: a power supply that generates an electromagnetic field in a subterranean formation; and a distributed electromotive force sensor for measuring electromotive force at one or more points along a length of the distributed electromotive sensor, wherein the distributed electromotive force sensor comprises an optical waveguide and an electro-optical transducing layer coated on one or more lengths of the optical waveguide.

Abstract: Systems and methods for optimized geosteering using real-time geological models that are updated with LWD measurements containing data such as, for example, layer boundaries and formation properties.

Abstract: An electromagnetic (EM) telemetry system with capacitive electrodes for use with downhole equipment is described. Embodiments of the EM telemetry system with capacitive electrodes include a downhole transceiver comprising an encoded signal transmitter, a downhole sensor disposed to monitor the downhole equipment, and an encoded signal receiver comprising one or more capacitive counter electrodes. The one or more capacitive counter electrodes receives a first encoded signal from the downhole transceiver, the encoded signal corresponding to a voltage measured between the counter electrode and a wellhead. A decoder and demodulator of the encoded signal receiver recovers information in the first encoded signal. A second encoded signal, which may include instructions for the downhole equipment, may be similarly encoded, modulated, and transmitted from the encoded signal receiver to the downhole transceiver.

Abstract: Systems, methods and apparatuses for measuring properties of a borehole formation and generating an image of the formation. The method comprises selecting a direction for transmission of an electromagnetic signal, wherein the selection includes altering an electromagnetic coupling between an active element of a first device and at least one passive element of the first device. An electromagnetic signal can be transmitted, by the active element of the first device, into a borehole formation. The electromagnetic signal can subsequently be received by a second device. Formation properties can be determined from the received signal and an image of the formation can be generated.

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 method of obtaining an equivalent tool model includes obtaining a set of known well data, in which the known well data includes sensor data measured by a logging tool and an actual dispersion response, and the logging tool has an actual tool size. The method also includes obtaining one or more well parameters from the known well data, and inputting the one or more well parameters and a model tool size into a rigid tool model. The method further includes obtaining an estimated dispersion response from the rigid tool model, and fitting the estimated dispersion response to the actual dispersion response by adjusting the model tool size.

Abstract: A system includes a drillstring with an electromagnetic (EM) transmitter in a first borehole. The system also includes at least one fiber optic sensor deployed in a second borehole. The system also includes a processor configured to determine a distance or direction of the EM transmitter relative to the at least one fiber optic sensor based on EM field measurements collected by the at least one fiber optic sensor in response to an EM field emitted by the EM transmitter.

Abstract: A communication system can include a first subsystem of a well tool that can include a first cylindrically shaped band positioned around the first subsystem. The first cylindrically shaped band can be operable to electromagnetically couple with a second cylindrically shaped band. The communication system can also include a second subsystem of the well tool. The second subsystem can include the second cylindrically shaped band positioned around the second subsystem. The communication system can further include an intermediate subsystem positioned between the first subsystem and the second subsystem. The intermediate subsystem can include an insulator positioned coaxially around the intermediate subsystem.