Abstract: A downhole tool is provided that includes radiation shielding using a material that is lighter, stronger, less expensive, and/or more commercially available than tungsten radiation shielding. Such a down-hole tool may include an electronic radiation generator that emits photons to through a source window located on an outer surface of the downhole tool. A detector may detect at least some of the photons through a detector window. Radiation shielding of the downhole tool may attenuate photons that travel from the electronic radiation generator toward the detector without passing through the detector window. The radiation shielding may include a material that has a density less than 10.5 g/cc and an element of atomic number greater than 40.

Abstract: Systems, methods, and devices are provided for radiation detector windows that have an improved shape or density and/or provide collimation of radiation that passes through. Thus, a radiation-based logging tool may include a source that emits radiation and a detector that detects, through a detector window, a first portion of the radiation scattered off of a geological formation. The detector window may include a dome having a first surface and a second surface and a support structure that provides support for the dome. The detector window may include a window insert that shields the detector from a second portion of the radiation.

Abstract: The present disclosure describes a downhole tool including an electrically operated radiation generator that selectively output radiation to a surrounding environment based at least in part on supply of electrical power; and a control system that determines likelihood of exposing living beings in the surrounding environment to output radiation by determining whether one or more check conditions is met; determine that each of the one or more check conditions is met before instructing the electrically operated radiation generator to output radiation; and instruct the electrically operated radiation generator to cease output of radiation when at least one of the one or more check conditions is no longer met.

Abstract: A method for determining formation hydrogen index includes using as input to a computer measurements of numbers of burst gamma rays (gamma rays detected during operation of a pulsed neutron source) and numbers of thermal neutron capture gamma rays made at two different axial spacings from the pulsed neutron source. A ratio of the numbers of burst gamma rays and a ratio of the numbers of thermal neutron capture gamma rays is determined. A corrected ratio of the numbers of thermal neutron capture gamma rays using the ratio of numbers of burst gamma rays is determined. The formation hydrogen index is determined from the corrected ratio.

Abstract: A method for evaluating wellbore conduit condition includes using measurements of at least one of (i) inelastic gamma rays made during emission a burst of neutrons into the conduit from within the conduit at at least one spaced apart location from a position of the emission and (ii) epithermal neutrons or capture gamma rays therefrom detected at at least two spaced apart locations from the position of the emission within a selected time after the emission. The at least one of the measurements of inelastic gamma rays and epithermal neutron or capture gamma ray counts are characterized to estimate an amount of loss of iron in the conduit.

Abstract: A system for a downhole tool includes an X-ray generator that outputs X-ray radiation into a surrounding sub-surface formation using electrical power received from a power supply and a detector device adjacent the X-ray generator. The detector device includes a first detector with a first radiation sensitivity that outputs a first measurement signal based on interaction between a first portion of the X-ray radiation and the first detector. The detector device also includes a second detector with a second radiation sensitivity adjacent the first detector, where the second detector outputs a second measurement signal based on interaction between a second portion of the X-ray radiation and the second detector.

Abstract: A system includes a data processing system including a processor operatively coupled to a memory. The processor is configured to receive a first dataset indicative of spectral information regarding photons received from a first detector of a formation density tool. The processor is configured to receive a second dataset indicative of a total count rate of photons from a second detector of the formation density tool. The processor is configured to determine physical characteristics of a geological formation based on the spectral information and the total count rate. The processor is configured to display the physical characteristics of the geological formation in a display.

Abstract: The techniques and device provided herein relate to regulating a source generator in an X-ray based equipment. In particular, an X-ray system is provided that comprises an X-ray generator and a reference detector system that regulates the output of the X-ray generator. The reference detector system comprises a direct channel that allows at least a portion of the photons to directly reach the detector crystal and a plurality of fluorescent channels, such that photon flux entering the reference detector from the fluorescent channels is negligibly impacted by variations of beam spots, shapes and/or positions.

Abstract: A system for a downhole tool includes an X-ray generator that outputs X-ray radiation into a surrounding sub-surface formation using electrical power received from a power supply and a detector device adjacent the X-ray generator. The detector device includes a first detector with a first radiation sensitivity that outputs a first measurement signal based on interaction between a first portion of the X-ray radiation and the first detector. The detector device also includes a second detector with a second radiation sensitivity adjacent the first detector, where the second detector outputs a second measurement signal based on interaction between a second portion of the X-ray radiation and the second detector.

Abstract: A system includes a data processing system including a processor operatively coupled to a memory. The processor is configured to receive a first dataset indicative of spectral information regarding photons received from a first detector of a formation density tool. The processor is configured to receive a second dataset indicative of a total count rate of photons from a second detector of the formation density tool. The processor is configured to determine physical characteristics of a geological formation based on the spectral information and the total count rate. The processor is configured to display the physical characteristics of the geological formation in a display.

Abstract: A system is disclosed for downhole logging. The system comprises a photon source configured to generate photons at different endpoint energies; at least one radiation detector configured to detect photons after interactions with a wellbore, a geological formation surrounding the wellbore, or both; an energy detection system configured to determine an endpoint energy of the photon source; and a processing system configured to determine properties of a wellbore, a geological formation, or both, based on photons detected at the at least one radiation detector and the endpoint energy determined by the energy detection system.

Abstract: The techniques and device provided herein relate to regulating a source generator in an X-ray based equipment. In particular, an X-ray system is provided that comprises an X-ray generator and a reference detector system that regulates the output of the X-ray generator. The reference detector system comprises a direct channel that allows at least a portion of the photons to directly reach the detector crystal and a plurality of fluorescent channels, such that photon flux entering the reference detector from the fluorescent channels is negligibly impacted by variations of beam spots, shapes and/or positions.

Abstract: The present disclosure describes a downhole tool including an electrically operated radiation generator that selectively output radiation to a surrounding environment based at least in part on supply of electrical power; and a control system that determines likelihood of exposing living beings in the surrounding environment to output radiation by determining whether one or more check conditions is met; determine that each of the one or more check conditions is met before instructing the electrically operated radiation generator to output radiation; and instruct the electrically operated radiation generator to cease output of radiation when at least one of the one or more check conditions is no longer met.

Abstract: A method for well logging includes emitting a plurality of bursts of high energy neutrons into a wellbore and formations surrounding the wellbore. During and for a selected duration after at least one of the plurality of bursts, gamma rays are detected at at least one location spaced apart from the emitting and characterizing an energy of the detected gamma rays. After the last burst, gamma rays are detected and energy spectrum and rates of detection with respect to time thereof are determined. The foregoing is repeated for a selected number of times. After the selected number of times background gamma rays are measured. At least one of the numbers of detected gamma rays during a selected time interval and an energy spectrum of the detected gamma rays during the selected time interval is used to determine selected formation properties.

Abstract: A method for evaluating wellbore conduit condition includes using measurements of at least one of (i) inelastic gamma rays made during emission a burst of neutrons into the conduit from within the conduit at at least one spaced apart location from a position of the emission and (ii) epithermal neutrons or capture gamma rays therefrom detected at at least two spaced apart locations from the position of the emission within a selected time after the emission. The at least one of the measurements of inelastic gamma rays and epithermal neutron or capture gamma ray counts are characterized to estimate an amount of loss of iron in the conduit.

Abstract: A method for evaluating wellbore conduit condition includes using measurements of at least one of (i) inelastic gamma rays made during emission a burst of neutrons into the conduit from within the conduit at at least one spaced apart location from a position of the emission and (ii) epithermal neutrons or capture gamma rays therefrom detected at at least two spaced apart locations from the position of the emission within a selected time after the emission. The at least one of the measurements of inelastic gamma rays and epithermal neutron or capture gamma ray counts are characterized to estimate an amount of loss of iron in the conduit.

Abstract: A tool having a neutron source, a gamma ray detector, and a photomultiplier tube is provided. The gamma ray detector and the photomultiplier tube are at least partially surrounded by a layer of boron. The tool is used to make measurements, and the number of prompt gamma rays emitted by the boron is determined from the measurements. The number of neutrons detected may be inferred using the determined number of prompt gamma rays. The tool may also have a layer of neutron absorbing material different from boron or a layer of heavy metal at least partially surrounding the boron. The tool may be a logging tool used to delineate a porous formation and to determine its porosity. The tool may have a plurality of gamma ray detector/photomultiplier tube pairs and those pairs may be used to determine a formation hydrogen index and/or a borehole hydrogen index.

Abstract: A method for determining thermal neutron decay constant for a formation includes counting radiation events corresponding to numbers of thermal neutrons with respect to time (decay spectrum) after irradiating the formation with neutrons. At least one moment of a first order of the decay spectrum or a single exponential curve to fit the decay spectrum is determined. A first apparent decay constant from the at least one moment or the single exponential curve. A second apparent decay constant is determined either by repeating the calculating a moment or exponential curve for different time segments of the decay spectrum or by using radiation events detected by at least a second radiation detector at a different spacing from a position of the irradiating than the at least a first radiation detector to determine a second apparent decay constant. A wellbore corrected thermal neutron decay constant is determined from the first and second apparent decay constants.

Abstract: A method for well logging includes emitting a plurality of bursts of high energy neutrons into a wellbore and formations surrounding the wellbore. During and for a selected duration after at least one of the plurality of bursts, gamma rays are detected at at least one location spaced apart from the emitting and characterizing an energy of the detected gamma rays. After the last burst, gamma rays are detected and energy spectrum and rates of detection with respect to time thereof are determined. The foregoing is repeated for a selected number of times. After the selected number of times background gamma rays are measured. At least one of the numbers of detected gamma rays during a selected time interval and an energy spectrum of the detected gamma rays during the selected time interval is used to determine selected formation properties.

Abstract: A method for evaluating wellbore conduit condition includes using measurements of at least one of (i) inelastic gamma rays made during emission a burst of neutrons into the conduit from within the conduit at at least one spaced apart location from a position of the emission and (ii) epithermal neutrons or capture gamma rays therefrom detected at at least two spaced apart locations from the position of the emission within a selected time after the emission. The at least one of the measurements of inelastic gamma rays and epithermal neutron or capture gamma ray counts are characterized to estimate an amount of loss of iron in the conduit.