Abstract: Systems and methods provide a mechanism to provide enhanced features for well ranging. Various embodiments may include generating a current profile for a target well, acquiring magnetic signals at a second well, and determining ranging to the target well with respect to the second well using the magnetic signals and the current profile. Additional apparatus, systems, and methods are disclosed.

Abstract: Disclosed embodiments include well ranging apparatus and systems that comprise well casing material installed in a well, well cement attached to the well casing material, and a device to conduct electromagnetic waves, the device disposed along a length of the well, substantially parallel to the well casing material, the device to be used in direct transmission or backscatter transmission of ranging signals. In some embodiments, the device comprises at least one of a conductor, an insulated conductor, a coaxial cable, a waveguide, a capacitor, or an inductor. Additional apparatus, systems, and methods are disclosed.

Abstract: A disclosed method includes acquiring ahead of bit or around bit data related to a formation from measurements by a tool. The method also includes generating a map view of the formation using the acquired data. Various map views and map view features are disclosed. An operator may select one or more of the map views and/or map view features to make steering decisions for a logging while drilling system.

Abstract: Methods and systems that compensate for magnetic interference in azimuthal tool measurements. At least some method embodiments include a downhole logging method that includes taking measurements as a function of orientation from inside a borehole. The measurements are associated with different azimuthal bins, and an azimuthal direction is determined for each azimuthal bin. Because the tool rotates at a constant rate, the relative number of measurements associated which the different bins can be used to measure the effective sizes of the different bins and to redetermine the effective angles of the bins in the presence of magnetic interference. The tool measurements may include, but are not limited to, formation resistivity, magnetic field, and formation density.

Abstract: Apparatus, systems, and methods may operate to couple a power supply to a ground point associated with a well, and to a lower portion of a conductive casing disposed within the well, where the lower portion of the conductive casing is separated by an insulating gap from an upper portion of the conductive casing, the upper portion of the conductive casing being at a higher elevation of the first well than the lower portion of the conductive casing. Further activity may include injecting an excitation signal into the lower portion of the conductive casing to induce a magnetic field in a geological formation surrounding the first well. Additional apparatus, systems, and methods are disclosed.

Abstract: Signal measurements collected by azimuthally sensitive electromagnetic logging tool as a function of position in a borehole are obtained. The signal measurements are used to identify a type of formation model. An inversion technique appropriate to the type of formation model is applied to the set of signal measurements to determine a geophysical property. The geophysical property is used to make a decision regarding drilling a well.

Abstract: Disclosed embodiments include well ranging apparatus, systems, and methods which operate to detect and determine a relative distance and/or azimuthal direction of nearby target well conductors such as pipes, well casing, etc., from within a borehole of a drilling well.

Abstract: Apparatus and methods to visualize formation properties and distances associated with formations can be implemented in a variety of applications. In various embodiments, one or more visualization schemes and systems arranged to implement such schemes can use a combination of visual structures to provide information about measured formations. Additional apparatus, systems, and methods are disclosed.

Abstract: Various embodiments include apparatus and methods to generate geosignal responses. Geosignal responses may be generated that include a representation of a determination of variation between a XX coupling component and a YY coupling component from acquired signals. Such geosignals may be used to 5 address a blindspot problem suffered in conventional geosteering in a drilling condition where the logging tool is located at layered formations with symmetric resistivity profiles. Additional apparatus, systems, and methods are disclosed.

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: 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: Methods and systems for characterizing a formation are disclosed. A tool is placed in the formation. The tool comprises a perpendicular antenna set and a parallel antenna set. The perpendicular antenna set comprises at least one transmitter antenna oriented perpendicular to at least one receiver antenna and the parallel antenna set comprises at least one transmitter antenna oriented parallel to at least one receiver antenna. Data is obtained from the tool and used to determine a compensated geosignal for each of the perpendicular antenna set and the parallel antenna set. The determined compensated geosignal is used to characterize the formation.

Abstract: Apparatuses, systems and methods for deep formation evaluations, at least some of which include LWD tool modules positioned along a drillstring with a first LWD tool module that includes a transmit antenna, a second LWD tool module that includes a receive antenna and at least one position measurement device that at least partially determines spatial locations of the transmit and receive antennas relative to each other. A formation model is then matched to a surrounding formation based at least in part on said relative spatial locations.

Abstract: Systems and methods for obtaining ranging measurements are described herein. An example method includes injecting a current 115 into a formation from a first borehole 106 to induce an electromagnetic field 120 within the formation. The current 115 may be received at a second borehole 107. The induced electromagnetic field 120 may be measured. The measurements may be taken, for example, from the first borehole 106, the second borehole 107, or another borehole 102 within the formation. The method may also include identifying the location of a third borehole 102 within the formation based, at least in part, on the measured electromagnetic field 120.

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: According to aspects of the present disclosure, systems and methods for optimizing deep resistivity measurements are described herein. The method may include obtaining one or more first multi-component measurements from a downhole tool disposed in a bore-hole. The downhole tool may comprise multi-component antennae. A relative structural dip angle, ?, of the downhole tool relative to formations may be determined, for example, through the use of an additional downhole tool, or computationally using the one or more first multi-component measurements. A tilt angle of at least one of the multi-component antenna may be adjusted, with the adjusted tilt angle being based on the dip angle. The method may further include obtaining one or more second multi-component measurements associated with the adjusted tilt angle, and determining a formation characteristic based, at least in part, on the one or more second multi-component measurements, without including or considering formation anisotropy effects.

Abstract: Apparatuses and methods are described, such as for aligning downhole measurements. Apparatuses and methods include an arrangement of at least two tilted transmitters and at least one tilted receiver along a longitudinal axis of the tool. A first and second plurality of azimuthal measurements are processed to provide a first and a second plurality of higher order mode signals configured to be time-shifted.

Abstract: Various embodiments include apparatus and methods to operate a measurement process in a borehole that uses a symmetric sensor structure or a sensor structure operable to mimic a symmetric sensor structure to provide structural compensation. Apparatus and methods can include a data processing unit to generate compensated signals based on the measurement signals and to determine formation parameters using the compensated signals. 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: Methods and systems for characterizing a formation are disclosed. A tool is placed in the formation. The tool comprises a perpendicular antenna set and a parallel antenna set. The perpendicular antenna set comprises at least one transmitter antenna oriented perpendicular to at least one receiver antenna and the parallel antenna set comprises at least one transmitter antenna oriented parallel to at least one receiver antenna. Data is obtained from the tool and used to determine a compensated geosignal for each of the perpendicular antenna set and the parallel antenna set. The determined compensated geosignal is used to characterize the formation.