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: Apparatus, systems, and methods for ranging operate to use a wireline active ranging system to initially determine a relative distance and relative direction from a first well (e.g., ranging well) to a second well (e.g., target well) and an EM azimuthal logging tool to maintain or adjust the distance from the target well while drilling the ranging well. Additional apparatus, systems, and methods are disclosed.

Abstract: A method of processing data from an electromagnetic resistivity logging tool which includes a transmitter coil and a receiver coil is disclosed. The electromagnetic resistivity logging tool is placed at a desired location. The transmitter coil and the receiver coil are positioned at a first azimuthal angle. A signal is transmitted from the receiver coil. The receiver coil then receives a signal. The signal at the receiver coil, a tilt angle of the transmitter coil, a tilt angle of the receiver coil and the first azimuthal angle are then used to calculate a first complex voltage representing at least one component of the received signal.

Abstract: Disclosed embodiments include methods and apparatus for ranging techniques to detect and determine a relative distance and azimuthal direction of nearby target well conductors such as pipes, well casing, etc., from within a borehole of a drilling well. A nearby casing string of a target well can be detected by transmitting an electromagnetic signal from an excitation source located along the target well and measuring a response signal with an antenna on a downhole logging tool in the drilling well. Several different excitation sources for various target wells are utilized to distinguish nearby conductor signals from formation signals. Joint]inversion algorithms are utilized to identify multi]well locations on the basis of measured signal responses from the different excitations sources. The joint]inversions may be implemented in real]time or during post]processing, and used in applications such as SAGD, anti]collision, and relief well development.

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: Disclosed embodiments include well ranging apparatus, systems, and methods which operate to receive normal components of electromagnetic field strength azimuthal measurements within a first well at different tool azimuth angles in the first well. Further activities include determining an approximate range from the sensors to a second well that serves as a source of an electromagnetic field, via direct transmission or backscatter transmission, using the normal components of the electromagnetic field strength azimuthal measurements. In some embodiments, the approximate range can be determined without introducing sensor azimuthal separation into range calculations. 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: An example logging tool includes a tool body characterized by a longitudinal axis and an antenna coupled to the tool body. The logging tool further includes a ferrite element coupled to the tool body proximate at least a portion of the antenna and in a non-parallel orientation with respect to a normal of a plane defined by the antenna.

Abstract: Methods to accurately plan and optimize clamped source excitation in ranging or telemetry operations approximate a well having a complex pipe structure as a simple solid pipe (“effective model”) with an effective pipe cross-section and resistance. The simple solid pipe is then treated as a thin wire and analyzed using a FAST Code.

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 borehole. 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: 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: 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: 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: Disclosed embodiments include well ranging apparatus, systems, and methods which operate to acquire a series of electromagnetic field strength measurements from a single sensor at multiple depths in a first well, responsive to an electromagnetic field originating at a second well, via direct transmission or backscatter transmission. Further activities include determining a drilling phase associated with drilling operations conducted in the first well, selecting a sensor separation depth associated with the drilling phase, and calculating an approximate range between the first well and the second well, based on the series of electromagnetic field strength measurements and the sensor separation depth. Additional apparatus, systems, and methods are disclosed.

Abstract: Embodiments include well ranging apparatus, systems, and methods which operate to measure a total magnetic field strength at each of three sensors attached to a down hole tool housing, wherein each sensor is to provide normal, tangential, and longitudinal field strength component amplitude values, and wherein at least one of the sensors is attached to the housing spaced approximately equidistant from the other two sensors in an azimuthal plane of the housing, and wherein each of the sensors is spaced apart from the other sensors in a longitudinal direction of the housing. Further activity includes determining at least three gradient field values from the total magnetic field strength measured by the three sensors, and determining an approximate range from a first well in which the sensors are disposed, to a casing of a second well, using the at least three gradient field values. Additional apparatus, systems, and methods are disclosed.

Abstract: An example logging tool includes a tool body characterized by a longitudinal axis and an antenna coupled to the tool body. The logging tool further includes a ferrite element coupled to the tool body proximate at least a portion of the antenna and in a non-parallel orientation with respect to a normal of a plane defined by the antenna.

Abstract: Disclosed embodiments include well ranging apparatus, systems, and methods which operate to receive normal and tangential components of electromagnetic field strength measurements within a first well as a set of field strength components from at least one sensor, wherein the at least one sensor is used to take multiple azimuthal field strength measurements at a single depth. Further activities include determining an approximate range from the at least one sensor to a second well that serves as a source of an electromagnetic field, via direct transmission or backscatter transmission, when a ranging direction associated with a housing upon which the at least one sensor is mounted is unknown. Additional apparatus, systems, and methods are disclosed.

Abstract: Disclosed embodiments include well ranging apparatus, systems, and methods which operate to receive normal components of electromagnetic field strength azimuthal measurements within a first well at different tool azimuth angles in the first well. Further activities include determining an approximate range from the sensors to a second well that serves as a source of an electromagnetic field, via direct transmission or backscatter transmission, using the normal components of the electromagnetic field strength azimuthal measurements. In some embodiments, the approximate range can be determined without introducing sensor azimuthal separation into range calculations. Additional apparatus, systems, and methods are disclosed.

Abstract: Disclosed embodiments include apparatus, systems, and methods which operate to include monitoring an electromagnetic signal and/or gamma ray spectra count values to determine interception of a first well created by a drill string, with a well casing surrounding a second well. Interception can be determined when a reception antenna is used to receive the electromagnetic signal, by examining values associated with the magnitude of the signal. Interception can also be determined when a ratio of the gamma ray spectra count values have exceeded a first predetermined threshold, or when capture gamma energy indicated by the gamma ray spectra count values exceeds a second predetermined threshold. Additional apparatus, systems, and methods are disclosed.

Abstract: Disclosed embodiments include well ranging apparatus, systems, and methods which operate to measure electromagnetic field strength components associated with an electromagnetic field originating at a first well, via direct transmission or backscatter transmission, using at least one ranging electromagnetic field strength sensor attached to a housing, to provide ranging measurements. Further activities may include obtaining distorting field strength measurements using one or more reference electromagnetic field strength sensors, which may form or be attached in a closed loop path around the housing; and determining an approximate range between the first well and a second well in which the ranging electromagnetic field strength sensors are disposed, based on the ranging measurements and the distorting field strength measurements. Additional apparatus, systems, and methods are disclosed.