Abstract: A calibrator is positioned on a logging tool at an angular orientation with respect to the logging tool. The calibrator has a radioactive source of gamma radiation distributed inside the calibrator. A first detector count rate is determined based on a detector in the logging tool detecting gamma radiation. One or more of the calibrator and logging tool is rotated by a first number of degrees. A second detector count rate is determined based on the detector in the logging tool detecting gamma radiation. One or more of the calibrator and logging tool is rotated by second number of degrees. A third detector count rate is determined based on the detector in the logging tool detecting gamma radiation. The first, second, and third detector count rates are averaged to determine a calibration gain factor based on the average detector count rate and a known indication of gamma radiation emitted by the calibrator.

Abstract: A calibrator is positioned on a logging tool at an angular orientation with respect to the logging tool. The calibrator has a radioactive source of gamma radiation distributed inside the calibrator. A first detector count rate is determined based on a detector in the logging tool detecting gamma radiation. One or more of the calibrator and logging tool is rotated by a first number of degrees. A second detector count rate is determined based on the detector in the logging tool detecting gamma radiation. One or more of the calibrator and logging tool is rotated by second number of degrees. A third detector count rate is determined based on the detector in the logging tool detecting gamma radiation. The first, second, and third detector count rates are averaged to determine a calibration gain factor based on the average detector count rate and a known indication of gamma radiation emitted by the calibrator.

Abstract: In some embodiments, an apparatus and a system, as well as a method and an article, may operate to receive gamma ray measurements from a gamma ray detector; to generate a spectrum based on the gamma ray measurements, the spectrum including a plurality of channels and count rates for the plurality of channels, wherein a channel number of a channel corresponds to energy values of the received gamma rays; to fit a curve to a portion of the spectrum; to determine a location of the maximum of the first derivative of the curve; and to adjust a gain of the gamma ray detector based on the location of the maximum of the first derivative of the curve. Additional apparatus, systems, and methods are disclosed.

Abstract: A method for determining a material in an annulus between two objects disposed in a borehole includes positioning logging tools in the borehole, each of the logging tools being oriented at a different angle. The method also includes measuring a property of the material in the annulus using the logging tools and determining the material in the annulus based on the measured property.

Abstract: Various embodiments include apparatus and methods to conduct measurements on a formation using a dual purpose detector. The dual purpose detector can be disposed on a neutron tool in a borehole, where the dual purpose detector operatively detects neutrons and gamma rays in response to the formation being probed using a neutron source of the neutron tool. Porosity of the formation can be determined from data based on the neutrons and gamma rays detected by the dual purpose detector. Additional apparatus, systems, and methods are disclosed.

Abstract: Systems and methods are presented for communicating data representing formatted characteristics of a borehole from a downhole location to a surface location. A sensor array downhole produces a first data set from which a plurality of coefficients for use in a one-dimensional angular function are determined. The coefficients are transmitted to the surface to allow a second data set to be prepared representing the first data set. Other systems and methods are presented.

Abstract: A logging tool may include a stabilization source configured to emit gamma rays, a gamma ray detector configured to collect gamma rays from the stabilization source and a formation and an analysis module. The analysis module may be configured to determine a photopeak of the stabilization source in a gamma ray spectrum including counts of the gamma rays collected by the gamma ray detector and perform resolution calculations using the photopeak to determine a resolution of the gamma ray detector.

Abstract: A method for determining a material in an annulus between two objects disposed in a borehole includes positioning logging tools in the borehole, each of the logging tools being oriented at a different angle. The method also includes measuring a property of the material in the annulus using the logging tools and determining the material in the annulus based on the measured property.

Abstract: In some embodiments, an apparatus and a system, as well as a method and an article, may operate to receive gamma ray measurements from a gamma ray detector; to generate a spectrum based on the gamma ray measurements, the spectrum including a plurality of channels and count rates for the plurality of channels, wherein a channel number of a channel corresponds to energy values of the received gamma rays; to fit a curve to a portion of the spectrum; to determine a location of the maximum of the first derivative of the curve; and to adjust a gain of the gamma ray detector based on the location of the maximum of the first derivative of the curve. Additional apparatus, systems, and methods are disclosed.

Abstract: A logging tool may include a stabilization source configured to emit gamma rays, a gamma ray detector configured to collect gamma rays from the stabilization source and a formation and an analysis module. The analysis module may be configured to determine a photopeak of the stabilization source in a gamma ray spectrum including counts of the gamma rays collected by the gamma ray detector and perform resolution calculations using the photopeak to determine a resolution of the gamma ray detector.

Abstract: Systems and methods are presented for communicating data representing formatted characteristics of a borehole from a downhole location to a surface location. A sensor array downhole produces a first data set from which a plurality of coefficients for use in a one-dimensional angular function are determined. The coefficients are transmitted to the surface to allow a second data set to be prepared representing the first data set. Other systems and methods are presented.

Abstract: Various embodiments include apparatus and methods to conduct measurements on a formation using a dual purpose detector. The dual purpose detector can be disposed on a neutron tool in a borehole, where the dual purpose detector operatively detects neutrons and gamma rays in response to the formation being probed using a neutron source of the neutron tool. Porosity of the formation can be determined from data based on the neutrons and gamma rays detected by the dual purpose detector. Additional apparatus, systems, and methods are disclosed.

Abstract: In some embodiments, apparatus and systems, as well as methods, may operate to acquire borehole standoff data (321), segregate the standoff data into a plurality of azimuthal bins (363), derive a plurality of diameters from the standoff data in the bins, determine an average borehole diameter from the plurality of diameters (367), calculate a standard deviation from the average borehole diameter (375), and compute a caliper measurement (383), a major elliptical axis length, and a minor elliptical axis length based on the average borehole diameter and the standard deviation (387).

Abstract: Apparatus and methods for operating the apparatus provide a modular unit of hardware to make measurements in a well. The modular unit may include a housing arranged for placement in a drill-string element, where the housing includes a sensor and is structured such that the housing is transferable to another drill-string element without a calibration during or after the transfer. The drill-string elements associated with the transfer may be of different sizes.

Abstract: In some embodiments, apparatus and systems, as well as methods, may operate to irradiate a portion of a geological formation with neutrons in a neutron burst generated by a switchable electronic source, to measure (with one or more detectors) a flux of gamma rays to provide a measured flux, at least a portion of the gamma rays being generated by the neutrons, and to determine one or more of a neutron porosity, a density, and/or a photoelectric factor of the geological formation based on the measured flux. Other apparatus, systems, and methods are disclosed.

Abstract: Formation density measurements in the presence of invasion of drilling fluids. At least some of the illustrative embodiments are methods including: irradiating a formation with gammas from a source of gammas, wherein drilling fluid has invaded the formation, and wherein Pe of the drilling fluid that has invaded the formation is greater than Pe of the formation; determining a first value indicative of a parameter of the formation; determining a second value indicative of a parameter of the formation; determining a third value, the third value determined based on gammas in an energy range different than used in determining the first value; and calculating, using the first, second, and third values, information such as a standoff, a formation porosity, a formation density prior to invasion by the drilling fluid, and radial depth of invasion of the drilling fluid into the formation.

Abstract: Formation density measurements in the presence of invasion of drilling fluids. At least some of the illustrative embodiments are methods including: irradiating a formation with gammas from a source of gammas, wherein drilling fluid has invaded the formation, and wherein Pe of the drilling fluid that has invaded the formation is greater than Pe of the formation; determining a first value indicative of a parameter of the formation; determining a second value indicative of a parameter of the formation; determining a third value, the third value determined based on gammas in an energy range different than used in determining the first value; and calculating, using the first, second, and third values, information such as a standoff, a formation porosity, a formation density prior to invasion by the drilling fluid, and radial depth of invasion of the drilling fluid into the formation.

Abstract: Apparatus, methods for forming the apparatus, and methods for operating the apparatus provide a value for a formation property or a borehole property from measurements obtained in a well. The value may be generated from determining a weighted average of the value for the formation property or the borehole property using both values corresponding to different azimuths and weights corresponding to different azimuths.

Abstract: Apparatus, methods for forming the apparatus, and methods for operating the apparatus provide a modular unit of hardware to make measurements in a well. The modular unit may include a housing arranged for placement in a drill-string element, where the housing includes a sensor and is structured such that the housing is transferable to another drill-string element without a calibration of the sensor during or after the transfer. The drill-string elements associated with the transfer may be of different sizes.

Abstract: A downhole gamma ray density measurement system is described. The gamma ray density measurement system includes a pressure housing and a gamma ray source within the pressure housing. One or more detectors within the pressure housing detect gamma radiation. One or more low-attenuation inserts may be located in the pressure housing near the gamma ray source and/or one or more of the detectors. One or more high-attenuation inserts may be located in the pressure housing near the gamma ray source and/or one or more of the detectors.