Abstract: A disclosed fracture characterization method includes: collecting three-dimensional resistivity measurements of a volume surrounding an open borehole; analyzing the measurements to determine parameters describing fractures in the volume; and providing a report to a user based at least in part on said parameters. A fluid with a contrasting resistivity is employed to make the fractures detectable by a directional electromagnetic logging tool in the borehole. Illustrative parameters include fracture direction, height, extent, length, and thickness. The resistivity measurements can be augmented using a borehole wall image logging tool. Also disclosed are fracturing methods that include: positioning a directional electromagnetic logging tool proximate to a formation; fracturing the formation; monitoring fracture progression with said tool; and halting the fracturing when measurements by said tool indicate that a predetermined set of criteria have been satisfied.

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: 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: Systems and methods for performing bed boundary detection and azimuthal resistivity logging using a logging tool with a pair of tilted receiver antennas having a midpoint on a longitudinal axis of the logging tool, a first pair of transmitter antennas symmetrically spaced from said midpoint, and a third tilted receiver antenna positioned farther from said midpoint than the transmitter antennas. Method embodiments include energizing each transmitter antenna of the first pair in a firing sequence and obtaining, responsive to the energizing, measurements with a pair of tilted receiver antennas equally spaced from said midpoint. Methods may also include obtaining, responsive to energizing of a more distant one of the first pair of transmitter antennas, measurements with a third tilted receiver antenna positioned farther from the midpoint than the transmitter antennas.

Abstract: Various embodiments include apparatus and methods to operate with respect to environmental measurements. Apparatus and methods include a processing unit to generate a ratio from signals measured relating to an underground environment and to determine parameters of the underground environment based on the generated ratio.

Abstract: Various embodiments include apparatus and methods to operate an induction measurement process in a borehole that addresses direct coupling of a signal between sensors of a measuring tool. Apparatus and methods can include a processing unit to generate formation parameters from signals received in the measurement tool. Additional apparatus, systems, and methods are disclosed.

Abstract: Various embodiments include apparatus and methods to detect and locate conductive bodies and/or provide steam-assisted gravity drainage (SAGD) steering operation. Tools can be configured with receiving sensors (310) arranged to cancel substantially a primary signal associated with a probe signal without rotating the receiving sensors to cancel the primary signal and to capture a secondary signal generated from a conductive body (301) below the earth's surface. Additional apparatus, systems, and methods are disclosed.

Abstract: Various embodiments include apparatus and methods of processing and geosteering with respect to well logging. Apparatus and methods may include acquiring signals generated from operating a tool rotating in a borehole of a well, where the tool includes a receiver antenna tilted with respect to the longitudinal axis of the tool and two transmitter antennas. The acquired signals can be processed with respect to a direction in the rotation of the tool to determine properties associated with a formation and/or to determine a geosignal for geosteering a drilling operation.

Abstract: Techniques for processing down hole information including detecting bed boundaries are disclosed. In some embodiments, a bottom hole assembly includes a down hole tool and a processing apparatus. The down hole tool includes at least one antenna pair to determine resistivity data during rotation of the down hole tool. The processing apparatus is attached to the down hole tool and includes a machine-readable medium that stores a formation model database comprising multiple formation models. The processing apparatus further includes a processor that executes program code to receive the resistivity data during down hole operation of the down hole tool, and to solve for at least resistivity formation parameters using a selected one of the formation models and a selected portion of the received resistivity data. The processor further executes program code to update the selected formation model based, at least in part, on the resistivity formation parameters.

Abstract: Various embodiments include apparatus and methods to operate a tool downhole in a well, where the tool has an optical computation element to determine different properties of downhole structures. Such an optical computation element can be structured to provide optical analysis of fluid and material composition of the downhole environment associated with a drilling operation. The data measurements from the optical computation element can be used in a geosteering operation. Additional apparatus, systems, and methods are disclosed.

Abstract: Parallel drilling systems and methods suitable for drilling wells for steam-assisted gravity drainage (SAGD). In some method embodiments, a tilted-antenna tool gathers azimuthally-sensitive electromagnetic signal measurements. Such measurements enable accurate measurement of inter-well distance and direction, thereby providing, the necessary information for drilling accurately-spaced wells having reduced vulnerability to “short-circuits” that inhibit effective reservoir exploitation. In some other method embodiments, a tilted-antenna tool transmits azimuthally non-uniform signals as it rotates. The attenuation and azimuthal variation detected by one or more receivers enables accurate direction and distance determination. The transmitter and receiver antennas can in some cases be combined into a single tool, while in other cases the transmitters and receivers are placed in separate wells to increase detection range.

Abstract: Various embodiments include apparatus and methods to land a well in a target zone with minimal or no overshoot of a target zone. The well may be directed to a target in the target zone based on the separation distance between a transmitter sensor (212) and a receiver sensor (214) being sufficiently large to detect a boundary of the target zone from a distance from the boundary of the target zone such that collected received signals from activating the transmitter sensor (212) can be processed in a time that provides minimal or no overshoot of a target zone. Additional apparatus, systems, and methods are disclosed.

Abstract: Techniques for processing down hole information including detecting bed boundaries are disclosed. In some embodiments, a bottom hole assembly includes a down hole tool and a processing apparatus. The down hole tool includes at least one antenna pair to determine resistivity data during rotation of the down hole tool. The processing apparatus is attached to the down hole tool and includes a machine-readable medium that stores a formation model database comprising multiple formation models. The processing apparatus further includes a processor that executes program code to receive the resistivity data during down hole operation of the down hole tool, and to solve for at least resistivity formation parameters using a selected one of the formation models and a selected portion of the received resistivity data. The processor further executes program code to update the selected formation model based, at least in part, on the resistivity formation parameters.

Abstract: A first broadband magnetic field is induced at a first transmitter position in a well bore drilled through a formation. A first formation magnetic field induced by the first broadband magnetic field is detected at a first receiver position. A second formation magnetic field induced by the first broadband magnetic field is detected at a second receiver position. A second broadband magnetic field is induced at a second transmitter position in the well bore. A third formation magnetic field induced by the second broadband magnetic field is detected at the first receiver position. A fourth formation magnetic field induced by the second broadband magnetic field is detected at the second receiver position. A formation property is computed using a function of the first, second, third, and fourth formation magnetic fields, wherein the function reduces the effect of a casing on the computation of the formation property.

Abstract: Borehole data presentation systems and methods that facilitate communication of volumetric logging data to a surface processing system for presentation to a driller or other user interested in visualizing the formations surrounding a borehole. The disclosed systems optionally tailor the telemetry stream to match the chosen display technique, thereby maximizing the logging system utility for the driller. Variable opacity of certain data regions or certain data discontinuities greatly facilitates data comprehension, particularly when true three-dimensional display technologies are employed. Holographic or stereoscopic display technologies may be employed to show the three-dimensional dependence of measured formation properties such as resistivity, density, and porosity. Alternatively, the radial axis can be used to represent a formation parameter value, thereby enabling cylindrical cross-plots of multiple measurements.

Abstract: Various embodiments include apparatus and methods of sensing and/or mapping a subterranean reservoir. In various embodiments, arrangements of electromagnetic sensors are disposed relative to a subterranean reservoir such that a signal received by electromagnetic sensors of one arrangement, in response to activation of an electromagnetic transmitter, can be analyzed to map the subterranean reservoir. Additional apparatus, systems, and methods are disclosed.

Abstract: Disclosed herein are multicomponent borehole radar tools and methods. At least some tool embodiments employ at least two antennas that receive reflections of electromagnetic pulses transmitted from the tool. A processor processes the receive signals to identify reflection signals and to determine a direction and/or distance to the sources of the reflection signals. Possible sources include formation boundaries, fluid boundaries, cased wells, and other features that cause contrasts in electromagnetic properties. In addition to reflection signals, the measured responses may include direct signal measurements that are useful for determining formation resistivity and permittivity. Each of the antennas may transmit and receive, and they may be collocated to reduce tool size and reduce processing complexity. Disclosed logging tool examples employ both electric and magnetic dipole antennas.

Abstract: Multi-array laterolog tool systems and methods acquire a set of array measurements sufficient to provide laterolog tool measurements of differing array sizes. Such systems and method offer multiple depths of investigation while offering greater measurement stability in borehole environments having high resistivity contrasts. In at least some system embodiments, a wireline or LWD tool body has a center electrode positioned between multiple pairs of guard electrodes and a pair of return electrodes. The tool's electronics provide a current from the center electrode to the pair of return electrodes and currents from each pair of guard electrodes to the pair of return electrodes. Each of the currents may be distinguishable by frequency or distinguishable by some other means. This novel arrangement of currents provides a complete set of measurements that enables one tool to simultaneously emulate a whole range of laterolog tools.

Abstract: Electromagnetic resistivity logging systems and methods yielding formation anisotropy and dip from a signal set that closely approximates the response of a idealized tool. One illustrative method embodiment derives from an azimuthally-sensitive tool's measurements a full set of orthogonal direct couplings (Vxx, Vyy, Vzz) and a cross-coupling sum (Vxz+Vzx) or (Vyz+Vzy). These values are converted into a signal set as a function of borehole position, the set including: a first signal representing a ratio between Vzz coupling components at different spacing distances, a second signal representing a ratio between Vxx and Vzz coupling components, a third signal representing a ratio between Vyy and Vzz coupling components, a fourth signal representing a ratio between Vxx and Vyy coupling components, and a fifth signal representing a ratio between a cross-coupling sum and a sum of the direct couplings. From this signal set, formation parameters can be accurately determined by inversion.

Abstract: In some embodiments, an apparatus and a system, as well as a method and an article, may operate to acquire input data to determine properties of a formation, using a combination of down hole transmitters and receivers, to select a portion of the input data using a formation model chosen from a plurality of down hole tool response models in a formation model database, based on a valid sensitive range for the bed boundary distance and a greatest signal-to-noise ratio (SNR), and to solve for at least resistivity formation parameters in the properties using the chosen formation model and the selected portion of the input data. The database may be updated with boundary distance and the resistivity formation parameters. Additional apparatus, systems, and methods are disclosed.