Abstract: A method to minimize borehole effects upon a multi-component induction tool within a well and borehole with water-based mud includes measuring parameters of the reservoir with the induction tool to create an array of measured components. The method further includes comparing a measured component from the array of measured components with a corresponding model component from an array of model components for a reservoir model with known parameters and no borehole effects, and determining the parameters for the reservoir based upon the comparison of the measured component and the corresponding model component.

Abstract: Various embodiments include apparatus and methods that perform a homogeneous inversion processing to data or signals acquired from a multicomponent induction tool operating in a wellbore. The homogeneous inversion processing can be used to provide a quality check of results from radial one dimensional borehole correction processing. Also, the homogeneous inversion processing may be employed as a dip indicator of conventional array induction logging processing. Additional apparatus, systems, and methods are disclosed.

Abstract: In some embodiments, an apparatus and a system, as well as a method and an article, may operate to determine spatial orientations of one or more transmitters attached to a first downhole component, relative to one or more receivers attached to a second downhole component, at common points in time during rotation of the first and the second downhole components. The first downhole component may be variably, rotationally coupled to the second downhole component. Further activity may include transforming raw measurements of transmitter signals provided by the receiver(s) into calibrated measurements based on the spatial orientations at the common points in time. Additional apparatus, systems, and methods are described.

Abstract: A contactless power transmitting device is capable of contactlessly transmitting power to a power receiving device. The contactless power transmitting device includes a power transmitting unit configured to be capable of contactlessly transmitting power to the power receiving device, and a communication unit configured to send information, which relates to a magnetic flux distribution of the power transmitting unit during power transmission, to the power receiving device.

Abstract: Techniques for managing a hydraulic fracturing operation include receiving a selection of a proxy model that represents a first principles model of a hydraulic fracturing operation, the proxy model including at least one property of a plurality of properties of the first principles model associated with the hydraulic fracturing operation; simulating the selected proxy model to generate a modeled output based on the property; and determining a value of a control setpoint for hydraulic fracturing operation equipment based on the modeled output.

Abstract: Electrocrushing drills and methods for operating electrocrushing drills. Electrocrushing drill bits comprise one or more high voltage electrodes surrounded by a ground or current return structure, which can be a ring or a comprise rod shaped electrodes. Openings in the rim of the current return structure facilitate removal of drilling debris and bubbles created by the electrocrushing process out from the bottom face of the bit and up the wellbore. The high voltage electrodes can be arranged in a circle. The current return structure may partially cover the bottom face of the drill bit, thereby enclosing the high voltage electrodes in openings that may be sector shaped. The drill may comprise one or more conducting loops, in each of which pulsed current creates a pulsed magnetic field. The loops can be oriented in particular directions to provide a pulsed magnetic field with the desired configuration and orientation in space. The formation ahead of the drill can then be evaluated with the appropriate sensors.

Abstract: Evaluation of formation and fracture characteristics based on multicomponent induction (MCI) log data includes automated calculation of inverted biaxial anisotropy (BA) parameters for the formation by performing an iterative BA inversion operation based on the MCI log data and using a BA formation model that accounts for transfers by axial formation anisotropy to resistivity. The BA inversion operation can be combined with a transversely anisotropic (TI) inversion based on the MCI log data and using a TI formation model, to calculate inverted TI parameters for the formation. The inverted BA parameters and the inverted TI parameters can be used, in combination, to calculate a quantified value for an identification function, to indicate estimated presence or absence of a fracture in the formation.

Abstract: EM-telemetry remote sensing wireless systems include a plurality of downhole tools in a drilling area, an array of electrodes at the earth's surface, a noise reduction manager, and an acquisition system. Each downhole tool transmits a modulated current into the formation to generate an electromagnetic signal at the earth's surface. The array of electrodes comprises a plurality of nodes. Each node has a plurality of electrodes that receives the signal. The signal received by the node has a signal component from the tool and a noise component from the area. The noise reduction manager has a de-mixing vector that filters the noise component of the signal and increases a signal to noise ratio. The acquisition system located on earth's surface wirelessly receives signal from each node.

Abstract: A method and system for transmitting data through a transmission medium between surface and subsurface transceivers. A surface transceiver and a subsurface transceiver are each configured to selectively transmit over a plurality of transmission channels, each transmission channel having a range of frequencies within the total frequency bandwidth. The surface transceiver is adapted to initialize a channel to determine at least one parameter affecting the current maximum data rate for transmission of information through the channel using a given transmission methodology. At least one of the channels uses carrierless phase/amplitude (CAP) modulation for its transmission methodology. The surface transceiver and the subsurface transceiver adapt to cooperatively periodically test a channel by transmission of a calibration signal from the subsurface transceiver to the surface transceiver.

Abstract: An interwell tomography method includes casing a first borehole with a casing tubular having at least one transmission crossover arrangement, each transmission crossover arrangement having an adapter in communication with a coil antenna that encircles an exterior of the casing tubular. The method also includes deploying, inside the casing tubular, a conductive path that extends from a surface interface to the at least one transmission crossover arrangement. The method also includes providing a set of one or more antennas in a second borehole. The method also includes obtaining electromagnetic (EM) measurements for interwell tomography using the at least one transmission crossover arrangement and the set of one or more antennas, where said obtaining involves conveying data or power between the at least one transmission crossover arrangement and the surface interface via the conductive path.

Abstract: Illustrative logging methods, systems, and software, provide for correction of cross-coupling error via a complex-plane extrapolation technique. Frequency-dependent measurements at each given borehole position will trace out a dependence of a quadrature signal component on the in-phase component. With linear or curve-fit extrapolation to the real axis, the cross-coupling error is readily compensated, enabling more accurate formation property logs to be derived over greater range of operating environments. The technique is particularly suitable for use with laterolog resistivity tools, where cross-coupling between current and voltage conductors might otherwise be problematic.

Abstract: Systems, devices, and methods for evaluating an earth formation. Methods include conveying a tool on a carrier in a borehole, the tool comprising a conducting tubular having a transmitter and receivers disposed thereon in a spaced-apart relationship; inducing a current in the earth formation using the transmitter; measuring with the first receiver a first time-dependent transient electromagnetic (TEM) signal induced by the formation responsive to the current; measuring with a second receiver a second time-dependent TEM signal induced by the formation responsive to the current; and using at least one processor to estimate a corrected time-dependent TEM signal using the first time-dependent TEM signal, the second time-dependent TEM signal, and a correction coefficient estimated as a function of a non-exponentiated ratio of distances rb and rm between the transmitter and the respective receivers.

Abstract: Systems and methods for characterizing a spatial frequency of interface regions within a subterranean formation. A first method may include drilling a wellbore with a drilling assembly and measuring a downhole parameter during the drilling. The downhole parameter may be indicative of a lithology of a portion of the subterranean formation that is proximal to the drilling assembly. The first method also may include calculating an information entropy of the downhole parameter and characterizing the spatial frequency of the interface regions based upon the information entropy. A second method may include calculating the information entropy as a function of distance within a first wellbore and characterizing the spatial frequency of the interface regions. The second method also may include drilling a second wellbore within the subterranean formation and regulating the drilling based upon the spatial frequency of the interface regions. The systems include systems that perform the methods.

Abstract: In some embodiments, an apparatus and a system, as well as a method and an article, may operate to calculate a map that transforms fast modeled measurement results into accurate modeled measurement results within a modeled data space, to make actual measurements using a tool disposed in a borehole, to transform a plurality of modeling parameter vectors into the fast modeled measurement results via modeling, to transform the fast modeled measurement results into the accurate modeled measurement results using the map, to locate a matching modeling parameter vector as one of the plurality of modeling parameter vectors that matches the accurate modeled measurement results to the actual measurement, and to display at least a portion of the matching modeling parameter vector to represent at least one property of a geological formation. Additional apparatus, systems, and methods are described.

Abstract: An angle estimating method applied in a radar system includes receiving a first signal and a second signal reflected from a target object via a first antenna and a second antenna; obtaining a first phase difference and at least one virtual phase difference, where the first phase difference is a phase difference between the first antenna and the second antenna; and obtaining a direction of arrival (DOA) of the target object according to the first phase difference and the at least one virtual phase difference.

Abstract: Various downhole logging tools and methods of using and making the same are disclosed. In one aspect, a downhole logging tool for inspecting one or more well tubulars includes a housing adapted to be supported in the one or more well tubulars by a support cable. A first transmitter, a second transmitter and a third transmitter are positioned in longitudinally spaced-apart relation in the housing and are operable to generate magnetic fields. Driving circuitry is operatively coupled to the first transmitter, the second transmitter and the third transmitter to selectively fire the first transmitter, the second transmitter and the third transmitter in multiple transmission modes to generate magnetic fields to stimulate pulsed eddy currents in the one or more well tubulars. A first receiver is positioned in the housing to sense decaying magnetic fields created by the pulsed eddy currents.

Abstract: Methods and systems for estimating properties of formations including conveying a carrier through a borehole having a first transmitter, a second transmitter collocated with the first transmitter, a first receiver, and a second receiver, the first receiver positioned a first distance from the first transmitter and the second receiver positioned a second distance therefrom, generating a transient electromagnetic field with the first transmitter, generating a suppression signal with the second transmitter, the suppression signal configured to suppress a response received by the first and second receivers that is caused by the transient electromagnetic field interacting with the carrier, measuring a signal with suppressed pipe signal at the first and second receivers, the measured signal representing the formation response to the transient electromagnetic field, estimating a formation property from the measured signal to select a model, and adjusting a drilling operation based on the estimated property of the fo

Abstract: Systems, devices, and methods for evaluating an earth formation. Apparatus include an electrically conducting tubular; at least one transmitter configured to propagate an electromagnetic field in the earth formation; and at least one receiver configured to receive an electromagnetic signal resulting from interaction of an electromagnetic field with said earth formation. The at least one transmitter and at least one receiver may employ antenna assemblies comprising: a recess in the conducting tubular defined by at least one radially extending surface substantially perpendicular to a longitudinal axis of the conducting tubular and non-radially extending surfaces; an antenna in the recess; and conductive shielding, the conductive shielding having a conductivity significantly more than a conductivity of the conducting tubular and covering the whole of each of the plurality of radially extending surfaces.

Abstract: An electromagnetic well logging tool for a wireline logging process, includes a shaft, a transmitter coil mounted on the shaft and configured to generate primary magnetic fields for propagation into a well formation, upon excitation by a first current, a receiver coil mounted on the shaft at a predefined distance from the transmitter coil and configured to receive secondary magnetic fields generated from the well formation, and a bucking coil mounted on the shaft in a concentric arrangement with the receiver coil, wherein the bucking coil is configured to generate magnetic fields at the receiver coil upon excitation by a second current, for cancelling the magnetic fields generated at the receiver coil due to direct coupling between the transmitter and receiver coils.

Abstract: Tools, systems, and methods are disclosed for multi-component induction logging with iterative analytical conversion of tool measurements to formation parameters. At least some system embodiments include a logging tool and at least one processor. The logging tool provides transmitter-receiver coupling measurements that include at least diagonal coupling measurements (Hzz, Hxx, and/or Hyy) and cross-coupling measurements (Hxy, Hxz, and Hyz). The processor employs an iterative analytical conversion of the cross-coupling measurements into formation resistive anisotropy and dip information. The processor may further provide one or more logs of the resistive anisotropy and/or dip information.

Abstract: A method for obtaining gain compensated electromagnetic logging while drilling propagation measurements includes rotating an electromagnetic logging while drilling tool in a subterranean wellbore. The tool includes a plurality of transmitter antennas and a plurality of receiver antennas symmetrically spaced along a logging while drilling tool body with the transmitter antennas including at least one axial transmitter antenna and at least one transverse transmitter antenna and the receiver antennas including at least one axial receiver antenna and at least one transverse receiver antenna. Electromagnetic voltage measurements are acquired from the receiver antennas while rotating. The acquired voltage measurements are processed to compute harmonic voltage coefficients. Ratios of selected ones of the harmonic voltage coefficients are in turn processed to compute gain compensated quantities including symmetrized and anti-symmetrized quantities.

Abstract: An apparatus includes a helical flow tube in a formation testing tool. A current injector injects an electromagnetic current into the flow tube. A receiver coil is positioned to produce a receiver coil signal in response to the electromagnetic current. A processor is coupled to the receiver coil to calculate a conductivity of a fluid flowing through the flow tube based on the receiver coil signal.

Abstract: Systems, methods, and apparatuses to generate a crosswell data set are described. In certain aspects, a method includes producing a first electromagnetic field at the earth's surface with a transmitter at a first location, detecting in a first borehole a first field signal induced by the first electromagnetic field, detecting in a second borehole a second field signal induced by the first electromagnetic field, and generating a crosswell data set from the first field signal and the second field signal. A formation model may be created from the crosswell data set.

Abstract: Systems, tools, and methods for enhancing a measurement of a fluid in a borehole, pipe, conduit and/or the like involve an electromagnetic measurement tool that includes a transmitting antenna configured to transmit electromagnetic energy, a receiving antenna configured to receive the electromagnetic energy, and a metamaterial element comprising a negative refractive index. The metamaterial element may focus the electromagnetic energy. The electromagnetic system may comprise one or more antennas that are disposed adjacent to or in contact with the fluid, electromagnetic energy may be transmitted via the transmitting antenna, and the electromagnetic energy may be received with the receiving antenna to measure a property of the fluid.

Abstract: A downhole tool and a method for operating the downhole tool, in which the downhole tool includes a first sensing member, and a second sensing member. The first and second sensing members have a first communication status when the downhole tool is in a first configuration. The first and second sensing members have a second communication status that is different from the first communication status when the downhole tool is in a second configuration. The downhole tool is prevented from actuating prior to the first and second sensing members having the second communication status, and the downhole tool is permitted to actuate after the first and second members have the second communication status.

Abstract: A transmission assembly may include an electronics package comprising an RF generator, the electronics package having a first antenna output and a second antenna output. The transmission assembly may also include a transmission antenna formed from at least one transmission winding, the transmission antenna having a first end coupled to a first antenna output and a second end coupled to a second antenna output. In addition, the transmission assembly may include a compensation coil formed from at least one compensation winding, the compensation winding wound parallel with the transmission winding, the compensation coil having a first compensation end connected to the transmission antenna output and a second compensation end not coupled.

Abstract: A method for determining a property of a medium, wherein an excitation signal is generated and transmitted into the medium, a measuring signal is generated from the excitation signal transmitted into the medium, the measuring signal is measured, an amplitude of the excitation signal and an amplitude of the measuring signal are determined, and the property of the medium is determined using the amplitude of the excitation signal and the amplitude of the measuring signal. To provide a method in which the accuracy of determination of the property of the medium is improved, the amplitude of the excitation signal is determined by digitizing the excitation signal and applying a lock-in method to the digitized excitation signal and determining the amplitude of the measuring signal by digitizing the measuring signal and applying the lock-in method to the digitized measuring signal.

Abstract: The disclosure concerns a device for obtaining electromagnetic measurements in a wellbore. In one implementation, the device includes an electromagnetic source carried by the device and a metamaterial arranged to cover a portion of the device in order to divert electromagnetic waves from the source around the covered portion of the device. In one version, the electromagnetic radiation from the source impinging on the portion of the device covered by the metamaterial, and on the electronics carried by the devices that are covered by the metamaterial is reduced. Depending on the implementation, the electromagnetic source may be an antenna, such as a coil antenna. Also, the antenna coil may be wrapped circumferentially around the tool.

Abstract: Methods and a system for detecting through casing formation resistivity. A method may comprise inserting an inspection device inside a tube, activating the transmitter coil, recording signals with the receiver coil array, creating a transmitter matrix from an electromagnetic field produced from the transmitter coil, creating a receiver matrix from the recorded signals, and determining a through casing formation resistivity of a target from the transmitter matrix and the receiver matrix. A method may further comprise determining a casing thickness of a target from the transmitter matrix and the receiver matrix. An inspection device may comprise a sensor array comprising a transmitter coil array and a receiver coil array. The inspection device may further comprise a sensor array housing, wherein the sensor array is disposed within the sensor array housing, a memory module, and a differential amplifier.

Abstract: A method for calibrating an electromagnetic core analysis tool is disclosed. The method includes disposing a tilted test loop inside of or outside of a tool having more than one antenna. A uniform test pack, a layered test pack, and an effective media test pack are each disposed in the tool. A signal is induced in a receiver antenna in the tool when a second antenna is energized with a known current of a known frequency. The induced signal is measured and a calibration gain and offset is determined. A corrected signal is produced and compared with the determined signal based on a forward model.

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: A resistivity measuring tool used in a drillstring having a drill bit on a distal end for drilling a wellbore in a formation includes a tool body having a longitudinal axis, a sensor configured to measure the angular position of the tool body relative to the wellbore, at least one axial antenna including a wire winding for generating an axial magnetic moment parallel with the longitudinal axis, and at least one transverse antenna. The transverse antenna includes an antenna body disposed within a pocket extending radially inward from an outer surface of the tool body and one or more turns of wire wound around the antenna body, the wire winding generating a transverse magnetic moment orthogonal to the longitudinal axis.

Abstract: Embodiments of the invention are directed to a method of determining underground liquid (e.g., water) content. Embodiments of the method may include: receiving a scan of an area at a first polarization, the scan scans including first L band microwave reflections from the area. Embodiments of the invention may include receiving an optical data at a wavelength of 1 millimeter to 10 nanometers. Embodiments of the method may further include filtering electromagnetic noise from the scan using the optical data. Embodiments of the method may further include creating a water roughness map based on typical roughness values of various types of water sources and the filtered scan, identifying a first type of water sources using the water roughness map and the filtered scan and calculating the water content at locations in the area based on the identified first type of water sources.

Abstract: A drill bit for measuring the electromagnetic propagation resistivity of a subterranean formation is disclosed. The drill bit includes a shank portion and a cutting portion with a raised face. The drill bit includes a transmitter element and a receiver element disposed on the raised face. The transmitter element propagates electromagnetic waves into a subterranean formation with a frequency of at least one gigahertz. The receiver element is positioned relative to the transmitter element at a pre-determined distance, with the predetermined distance is based, at least in part, on the frequency of the electromagnetic wave.

Abstract: During drilling of an earth borehole, resistance measurements may be made at the drill bit through use of a bottom hole assembly that includes a drill bit having a sensor, such as an electrode, located generally at an exterior surface of the drill bit. The current will be induced in the formation from multiple transmitters, at least one of which will be supported on, or very close to the drill bit. Connection mechanisms are described that enable the releasable engagement of electrical conductors to circuitry within the drill bits. The obtained resistivity measurements at the drill bit can be used for many purposes, including formation imaging and geosteering of the drilling operation.

Abstract: Various embodiments include systems and methods that operate to provide reservoir imaging. The systems and methods can include a number of transmitter antennas and a number of receiving antennas arranged to operate as one or more multi-pole antennas, controlled to generate high resolution cross-well formation images. Additional apparatus, systems, and methods are disclosed.

Abstract: Systems, tools and techniques for measuring downhole parameters are provided. The techniques involve providing a downhole tool with a sensing apparatus. The sensing apparatus has at least one source positionable about the downhole tool, at least one sensor electrode positionable about a front face of the downhole tool for measuring electrical signals from the source, and a raised insulating cover positionable along the front face of the downhole tool for defining at least one contact surface. The raised insulating cover extends over at least a portion of the sensor electrode whereby the sensor electrode is positionable adjacent to the subterranean formation for electrically coupling thereto without direct contact therewith.

Abstract: An electromagnetic exploration device minimizes signal interference due to a metal body or electronic components that constitute an air vehicle by installing a transmission coil and a receiving coil in an envelope of an airship, and enables a batch arrangement of the optimized transmission coil and receiving coil in accordance with various exploration purposes using the envelope shape, thereby acquiring exploration data from one flight. The device in an airship having an envelope includes: a transmission coil along the periphery of the horizontal axial direction of the envelope, for generating a primary magnetic field; at least one receiving coil along the periphery of the envelope, for detecting a secondary magnetic field induced by the primary magnetic field; and an analyzing device for applying an electric current to the receiving coil and analyzing a measurement value of the secondary magnetic field detected by the receiving coil, thereby performing air electromagnetic exploration.

Abstract: A wellbore tool comprising a power supply, an electrical load, a receiving unit configured to passively receive a triggering signal, and a switching system electrically coupled to the power supply, the receiving unit, and the electrical load, wherein the switching system is configured to selectively transition from an inactive state to an active state in response to the triggering signal, from the active state to the active state in response to the triggering signal, or combinations thereof, wherein in the inactive state a circuit is incomplete and any route of electrical current flow between the power supply and the electrical load is disallowed, and wherein in the active state the circuit is complete and at least one route of electrical current flow between the power supply and the electrical load is allowed.

Abstract: Borehole electromagnetic exploration or tomography (EM tomography). An induction type broadband 3-component borehole magnetic measuring sensor can accurately and precisely measure a broadband magnetic field about x, y and z axes using a three-dimensional (3D) model within a borehole by monitoring natural variations in the earth's magnetic field or based on EM tomography using the borehole. The measuring sensor is applicable to energy resource fields such as petroleum and coal, mineral resources fields and civil engineering and environmental fields.

Abstract: A method for making downhole electromagnetic logging while drilling measurements includes rotating an electromagnetic logging while drilling tool in a subterranean wellbore. The logging tool includes a plurality of transmitter antennas and a plurality of receiver antennas symmetrically spaced along a logging while drilling tool body, the plurality of transmitter antennas including at least one axial transmitter antenna and at least one transverse transmitter antenna. The plurality of receiver antennas includes at least one axial receiver antenna and at least one transverse receiver antenna. The receiver antennas are used to acquire electromagnetic voltage measurements while rotating. The voltage measurements are processed to compute harmonic voltage coefficients, selected ratios of which are processed to compute gain compensated symmetrized and anti-symmetrized quantities and angles.

Abstract: An apparatus for estimating at least one parameter of interest of an earth formation includes a first sub and a second sub positioned along the conveyance device. The first sub and the second sub cooperate to generate at least one main component measurement and only the second sub is configured to generate at least one cross-component measurement. A method includes conveying a first sub and a second sub along a wellbore formed in the earth formation using a conveyance device, using the first sub and the second sub to generate at least one main component measurement, and using only the second sub to generate at least one cross-component measurement.

Abstract: Systems, devices, and methods for evaluating an earth formation. Methods may include inducing a current in the formation; measuring a time-dependent transient electromagnetic (TEM) signal induced by the formation responsive to the current; and estimating apparent resistivity values for each of a plurality of samples derived from the TEM measurement, wherein each sample corresponds to a discrete time window of the TEM measurement. Estimating the apparent resistivity values for each of the samples includes determining for each sample a simulated homogeneous formation that provides a best fit for the sample. The apparent resistivity values may be used to estimate distance to an interface. The apparent resistivity values or the estimated distance may be logged and the log displayed. The apparent resistivity values, the estimated distance, or the log may be used to conduct further operations in a borehole, including geosteering.

Abstract: Systems and methods for performing bed boundary detection and azimuthal resistivity logging with a single tool are disclosed. Some method embodiments include logging a borehole with an azimuthally-sensitive resistivity logging tool; deriving both a resistivity log and a boundary detection signal from measurements provided by said tool; and displaying at least one of the boundary detection signal and the resistivity log. The resistivity log measurements may be compensated logs, i.e., logs derived from measurements by one or more symmetric transmitter-receiver arrangements. Though symmetric arrangements can also serve as the basis for the boundary detection signal, a greater depth of investigation can be obtained with an asymmetric arrangement. Hence the boundary detection signal may be uncompensated.

Abstract: For some embodiments, a software application for correcting sensor data in a remote database (114, 118) according to magnetic correction parameters obtained from a geophysical survey service, the sensor data obtained from directional instruments on a well tool (107, 108, 110). The remote database resides in a field computer (112) at a well site, and a copy of the remote database may also reside in a real time operations computer system. For some embodiments, the sensor data for particular depths and measurement times are stored as rows in a table (FIG. 3). The correction software may write new rows in the remote database with the corrected sensor data, or may write new rows in a second database for storing corrected sensor data (FIG. 1).

Abstract: The present disclosure provides an apparatus and method for measuring electrical properties of an underground formation surrounding a borehole. The apparatus preferably comprises a downhole tool positionable in the borehole, a sensor pad positionable on the downhole tool, and a plurality of electrodes mounted on the sensor pad and configured to face a wall of the borehole. The apparatus further comprises an insulating layer extending over at least a portion of the plurality of electrodes facing the wall of the borehole.

Abstract: A drill string is disposed in the borehole having a BHA and a drill bit advancing the borehole. Among other BHA components, including a telemetry unit and a data acquisition unit, in a surface-to-borehole configuration a receiver (or receiver array) is positioned immediately proximate the drill bit in the borehole, while a source (or source array) is positioned at the Earth's surface. Alternatively, in a borehole-to-surface configuration the source may be positioned immediately proximate the drill bit in the borehole while a receiver (or receiver array) is positioned at the surface. The surface-to-borehole, or borehole-to-surface, system enables an electromagnetic look about while drilling operations are underway.

Abstract: In some embodiments, an apparatus and a system, as well as a method and an article, may operate to obtain a dip angle in a formation; to generate a model, using a model generation algorithm, of the formation using the dip angle; to generate a dip correction based on the model using at least two dip correction methods, at least one of which is affected more by the presence of an invasion in the formation than the other of the at least two dip correction methods; to determine existence of a fluid invasion of the formation based on comparison of results of the at least two dip correction methods; and to correct a log of parameters associated with the formation based on the existence of the fluid invasion. Additional apparatus, systems, and methods are disclosed.

Abstract: A method of processing electromagnetic signal data includes: receiving transient electromagnetic (TEM) signal data from a downhole tool disposed in an earth formation, the downhole tool including at least one conductive component; estimating an initial bucking coefficient based on relative positions of the at least two receivers; combining the TEM signal data using the initial bucking coefficient to estimate an initial formation signal; selecting a plurality of bucking coefficient values based on the initial bucking coefficient and estimating a plurality of formation signals, each formation signal corresponding to one of the plurality of bucking coefficients; and selecting an optimal bucking coefficient from one of the initial bucking coefficient and the plurality of bucking coefficients based on the plurality of formation signals, the optimal bucking coefficient providing suppression of parasitic signals due to the at least one conductive component.

Abstract: A transmitter on a bottomhole assembly (BHA) is used for generating a transient electromagnetic signal in an earth formation. A processor estimates the distance to a resistivity interface using a signal produced by a receiver on the BHA. The transmitter-receiver distance may be less than 1 m. The estimation of the distance is done in real time using a thin conductive sheet approximation.