Abstract: Device, system, and method embodiments provide fluid front monitoring via permanent, casing-mounted electromagnetic (EM) transducers. One or more casing strings have one or more transmit antennas that each encircle a casing string and one or more receive antennas that similarly encircle the casing string, with at least one receive antenna oriented differently from at least one transmit antenna to provide sensitivity to at least one cross-component signal. A processor unit derives an estimated distance to a fluid front, and may further determine a direction and orientation of the fluid front for display to a user. Signals from an array of transmit and receive antennas may be combined, optionally with signals from other boreholes, to locate and track multiple points on the fluid front. In response to the determined location and progress of the front, the processor unit may further provide control settings to adjust injection and/or production rates.

Abstract: Various resistivity logging tools, systems, and methods are disclosed. 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 direct coupling along the longitudinal tool axis (Czz), direct coupling along the perpendicular axis (Cxx or Cyy), and cross coupling along the longitudinal and perpendicular axes (Cxz, Cyz, Czx, or Czy). The processor performs a multi-step inversion of said transmitter-receiver coupling measurements to obtain values for model parameters. Based at least in part on the model parameters, the processor determines borehole corrections for the transmitter-receiver coupling measurements and may further provide one or more logs derived from the borehole corrected transmitter-receiver coupling measurements.

Abstract: Disclosed herein are electromagnetic logging systems and methods that provide a set of signals that robustly approximate the response of a model tool employing orthogonal triads of point-dipole antennas. One illustrative method embodiment obtains an azimuthally sensitive electromagnetic logging tool's signal measurements as a function of position in a borehole, the tool having at least two spacing distances (d1, d2) between transmit and receive antennas. Orthogonal direct coupling measurements (Vxx, Vyy, Vzz) are derived from the signal measurements and converted into a set of robust signals, the set including: a ratio between Vzz coupling components at different spacing distances, a ratio between Vxx and Vzz coupling components, a ratio between Vyy and Vzz coupling components, and a ratio between Vxx and Vyy coupling components. The set may include an additional robust signal having a ratio between a sum of cross-coupling components Vxz+Vzx or Vyz+Vzy and a sum of orthogonal direct coupling components.

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: Various embodiments include apparatus and methods to inspect casing defects in a pipe such as a casing associated with a drilling operation. Electrical connectors contacting the inside wall of the pipe can be used to generate a current in the pipe. Magnetic fields correlated to an anomaly or anomalies that alter the current can be sensed to identify the presence of the anomaly or anomalies. Additional apparatus, systems, and methods are disclosed.

Abstract: Various embodiments include apparatus and methods to operate a drilling operation relative to formation boundaries. The apparatus and methods can include operating one or more transmitters in a borehole in a formation having a thickness between two boundaries, selecting thickness models based on applying responses from operating the one or more transmitters such that the thickness of the formation is between the two thickness models, and generating a value of a distance to a nearest boundary based on linearization of the thickness models with respect to a long distance investigation parameter and a short distance investigation parameter. Additional apparatus, systems, and methods are disclosed.

Abstract: A casing segment includes a conductive tubular body and at least one transmission crossover arrangement. Each transmission crossover arrangement has an inductive adapter in communication with a coil antenna that encircles an exterior of the tubular body.

Abstract: Methods and tools for detecting casing position downhole is presented. The method utilizes electromagnetic (EM) tools with tilted antenna systems to detect casing position. Sometimes titled antenna designs also increase EM tools' sensitivity to formation parameters, which can lead to false signals for casing detection. In addition, it is very difficult to distinguish measured signals between a casing source and a formation source. The methods presented help to distinguish between the two sources more clearly. The methods and tools presented also help to minimize those environmental effects, as well as enhance the signals from a surrounding conductive casing. The methods herein provide ideas of EM tool's design to precisely determine casing position within a certain distance to casing position.

Abstract: Various embodiments include apparatus and methods to determine true formation resistivity. Such apparatus and methods may use techniques to effectively reduce or eliminate polarization horn effects at boundaries between formations of different resistivity. The techniques may use combinations of geosignals and adjustments of measurement data to evaluate true formation resistivity for formation layers investigated. Such techniques and associated analysis may be conducted real time. Additional apparatus, systems, and methods are disclosed.

Abstract: A drilling assembly includes a first tubular member supporting a first transmitter antenna and a steering assembly located beneath the first tubular member. The drilling assembly also includes an earth boring device comprising a drill bit. The drill bit has a body member, a bottommost surface and a gage surface at a stabilizing section of the drill bit. The earth boring device is supported beneath the steering assembly. The earth boring device includes a second transmitter/receiver antenna supported in spaced relation to the first transmitter antenna and within 36 inches of the bottommost surface of the drill bit, and at least one electrode generally at an outer surface of the stabilizing section of the drill bit.

Abstract: Methods and tools for detecting casing position downhole is presented. The method utilizes electromagnetic (EM) tools with tilted antenna systems to detect casing position. Sometimes titled antenna designs also increase EM tools' sensitivity to formation parameters, which can lead to false signals for casing detection. In addition, it is very difficult to distinguish measured signals between a casing source and a formation source. The methods presented help to distinguish between the two sources more clearly. The methods and tools presented also help to minimize those environmental effects, as well as enhance the signals from a surrounding conductive casing. The methods herein provide ideas of EM tool's design to precisely determine casing position within a certain distance to casing position.

Abstract: Disclosed herein are various telemetry systems and methods suitable for communicating a cylindrical volume of formation property measurements to the surface. Some system embodiments include a downhole processor coupled to a telemetry transmitter. The downhole processor determines a compressed representation of the formation property measurements and/or selects a subset of the measurements for transmission uphole. The subset selection can be based on selected radial distances having characteristics that potentially indicate features of interest to a user. Such features include bed boundaries, and the characteristics include sinusoidal variation as a function of azimuth, large changes in this sinusoidal variation versus radial distance, or inversion suggesting the presence of a bed boundary.

Abstract: Various embodiments include apparatus and methods to make resistivity measurements in a borehole using tool having an array of electrodes operable to provide focused currents, measure corresponding voltages, and measure corresponding voltage differences to determine resistivity. Tools can be configured to operate at a plurality of modes when voltage differences at some frequencies are effectively unreadable. Additional apparatus, systems, and methods are disclosed.

Abstract: Methods and tools for detecting casing position downhole is presented. The method utilizes electromagnetic (EM) tools with tilted antenna systems to detect casing position. Sometimes titled antenna designs also increase EM tools' sensitivity to formation parameters, which can lead to false signals for casing detection. In addition, it is very difficult to distinguish measured signals between a casing source and a formation source. The methods presented help to distinguish between the two sources more clearly. The methods and tools presented also help to minimize those environmental effects, as well as enhance the signals from a surrounding conductive casing. The methods herein provide ideas of EM tool's design to precisely determine casing position within a certain distance to casing position.

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: A retrievable tool for steering through an earth formation includes a first tool assembly and a tilted antenna attached to the first tool assembly. The tool also includes a second tool assembly attached to the first tool assembly and a tilted antenna attached to the second tool assembly. The first tool assembly attaches to the second tool assembly so that the antennas are tilted in predetermined directions. The tilted antennas are transmitter antennas or receiver antennas. Each tool assembly is a tubular cylinder with a longitudinal axis running the length of the cylinder, wherein the tubular cylinder has two ends, each end including a rotational attachment mechanism. The tool assemblies attach to each other through their rotational attachment mechanisms. The rotational attachment mechanism may be a screw-on mechanism, press-fit mechanism, or welded mechanism.

Abstract: In some embodiments, an apparatus includes a tool having a transmitter antenna and a receiver antenna. The transmitter antenna and the receiver antenna are arranged to substantially cancel out signals from layers between the transmitter antenna and the receiver antenna or to substantially cancel out signals from layers being outside a region between the transmitter antenna and the receiver antenna in response to the transmitter being operated downhole in a well.

Abstract: One or more non-transitory machine-readable storage media comprising program code to control activation of an arrangement of transmitting and receiving sensors attached to a tool, wherein controlling activation of the arrangement of transmitting and receiving sensors comprises activating a transmitting sensor having a first tilt angle to generate a transmission signal. The program code is to acquire an acquired signal from a receiving sensor having a second tilt angle, wherein acquiring the acquired signal from the receiving sensor having the second tilt angle is based on the transmission signal inducing at the receiving sensor a magnetic dipole perpendicular to a magnetic field corresponding to the transmission signal from the transmitting sensor having the first tilt angle. The program code is to perform an inversion operation on data to determine one or more properties of a formation.

Abstract: Various embodiments include apparatus and methods of operation with respect to well logging. Apparatus and methods can include a tool having an arrangement of spaced apart transmitter antennas and receiver antennas in transmitter-receiver antenna pairs to make shallow measurements and deep measurements. The signals acquired from the shallow measurements and deep measurements can be processed to provide a look-ahead signal in a drilling operation. The transmitter and receiver antennas can be oriented to cancel or substantially cancel out signals from layers between the transmitter antenna and the receiver antenna in response to the transmitter being operated downhole in a well. Additional apparatus, systems, and methods are disclosed.

Abstract: A drilling assembly includes a first tubular member supporting a first transmitter antenna and a steering assembly located beneath the first tubular member. The drilling assembly also includes an earth boring device comprising a drill bit. The drill bit has a body member, a bottommost surface and a gage surface at a stabilizing section of the drill bit. The earth boring device is supported beneath the steering assembly. The earth boring device includes a second transmitter/receiver antenna supported in spaced relation to the first transmitter antenna and within 36 inches of the bottommost surface of the drill bit, and at least one electrode generally at an outer surface of the stabilizing section of the drill bit.