Abstract: In an embodiment, a method includes receiving a first measurement of gamma rays via a detector during a first period of time, receiving a second measurement of gamma rays via the detector during a second period of time, removing the second measurement from the first measurement to produce an inelastic spectrum, determining a spectral slope from the inelastic spectrum, determining a scaling factor based on the spectral slope, determining a spectral shape associated with the detector, determining a detector-induced spectrum by applying the scaling factor to the spectral shape, and removing the detector-induced spectrum from the inelastic spectrum to produce a clean inelastic spectrum.

Abstract: A method for obtaining nuclear measurement data includes measuring a burst gate source intensity. The method also includes measuring at least one of burst gate neutron count rate or a capture gate neutron count rate at a neutron detector arranged proximate a gamma ray detector. The method further includes determining, based at least in part on the burst gate source intensity and at least one of the burst gate neutron count rate or the capture gate neutron count rate, a normalized neutron count rate. The method also includes determining at least one of an inelastic spectrum or a capture spectrum. The method includes determining based at least in part on the normalized neutron count rate, at least one of a corrected inelastic spectrum or a corrected capture spectrum.

Abstract: A downhole logging system includes a gamma ray source positioned within a logging tool. The system further includes a collimator associated with the gamma ray source, the collimator having an opening to direct a flow of radiation into the formation. The system also includes a radiation detector operable to detect backscatter radiation from the area. The system further includes a motor to rotate the collimator in either a continuous or stepping fashion for scanning a borehole and an actuator associated with the gamma ray source. The actuator moves the gamma ray source between a first position and a second position, the first position being misaligned with the opening and the second position being aligned with the opening.

Abstract: A method for identifying a defect within a cement layer of a multi string wellbore includes deploying a gamma scanner into the multistring wellbore, the gamma scanner including at least one source and at least one detector, the at least one source emitting radiation into the multistring wellbore and the at least one detector receiving backscatter radiation. The method also includes obtaining, from the gamma scanner, a count rate associated with at least one region of interest of the multistring wellbore. The method further includes identifying, based at least in part on data acquired from the gamma scanner, a background profile for the multistring wellbore. The method includes removing the background profile from the count rate. The method further includes identifying, within the at least one region of interest, a defect within the cement layer.

Abstract: A method for obtaining nuclear measurement data includes measuring a burst gate source intensity. The method also includes measuring at least one of burst gate neutron count rate or a capture gate neutron count rate at a neutron detector arranged proximate a gamma ray detector. The method further includes determining, based at least in part on the burst gate source intensity and at least one of the burst gate neutron count rate or the capture gate neutron count rate, a normalized neutron count rate. The method also includes determining at least one of an inelastic spectrum or a capture spectrum. The method includes determining based at least in part on the normalized neutron count rate, at least one of a corrected inelastic spectrum or a corrected capture spectrum.

Abstract: Systems and methods for measuring formation properties in downhole operations are provided. The systems and methods include generating, at a neutron source, neutrons that are emitted into a downhole formation (302), registering, at a detector, photons generated by chemical constituents of the downhole formation (304), measuring a response of the photons registered at the detector (306), transforming, with a computing system, the measured responses of the photons registered at the detector into thermal neutron capture probabilities (308), and transforming the thermal neutron capture probabilities into weight concentrations of the chemical constituents of the downhole formation (312).

Abstract: Systems and methods for measuring formation properties in down-hole operations are provided. The systems and methods include generating, at a neutron source, neutrons that are emitted into a downhole formation (302), registering, at a detector, photons generated by chemical constituents of the downhole formation (304), measuring a response of the photons registered at the detector (306), transforming, with a computing system, the measured responses of the photons registered at the detector into thermal neutron capture probabilities (308), and transforming the thermal neutron capture probabilities into weight concentrations of the chemical constituents of the downhole formation (312).

Abstract: In an embodiment, a method includes receiving a first measurement of gamma rays via a detector during a first period of time, receiving a second measurement of gamma rays via the detector during a second period of time, removing the second measurement from the first measurement to produce an inelastic spectrum, determining a spectral slope from the inelastic spectrum, determining a scaling factor based on the spectral slope, determining a spectral shape associated with the detector, determining a detector-induced spectrum by applying the scaling factor to the spectral shape, and removing the detector-induced spectrum from the inelastic spectrum to produce a clean inelastic spectrum.

Abstract: Methods and apparatus for estimating parameters of interest of a volume in an earth formation from a response spectrum representing radiation information obtained by a radiation detector in a borehole intersecting the volume responsive to nuclear phenomena in the volume, the response spectrum including spectral distortion resulting i) environmental conditions in the formation, or ii) deterioration of at least one component of the radiation detector. Methods include recovering an enhanced response spectrum estimating the true spectrum, comprising mitigating the spectral distortion by applying at least one contrast sharpening mask to the response spectrum. The at least one contrast sharpening mask may comprise at least a low pass smoothing mask subtracted from a unity mask which when applied to the response spectrum obtains high-frequency data and adds the high-frequency data to the response spectrum. The response spectrum may be a gamma ray spectrum.

Abstract: Estimating parameters of interest of a formation, including density, porosity, and fluid saturation. Methods relate to gamma ray energy spectra calibration for a radiation detector including generating a calibration radiation spectrum using measurements of radiation with the detector in a time interval wherein the radiation comprises predominantly gamma rays emitted by decay of radionuclides produced by neutron activation reactions resulting from neutron irradiation, the time interval following a prior time interval corresponding to thermal neutrons produced from the irradiation; making at least one other radiation measurement with the detector outside the time interval; and producing a calibrated radiation measurement from the at least one other radiation measurement using the calibration radiation spectrum. The measurements may be taken in the time interval by conveying the radiation detector in the borehole at high speed and using a background gate of the detector.

Abstract: Systems, methods, and devices for evaluating an earth formation intersected by a borehole. Apparatus may include at least one radiation detector configured to generate an analog electrical signal responsive to a plurality of radiation events, comprising absorption of incident ionizing radiation at a corresponding energy level, and an ionizing radiation spectrometer configured to convert each analog electrical signal from the at least one radiation detector into a plurality of digital signal pulses corresponding to the radiation events and resolve the plurality of digital signal pulses into radiation count information representative of the radiation events. Spectrometers include an input channel for each detector of the at least one radiation detector comprising an analog-to-digital converter (ADC) and configured to convert the analog electrical signal for each detector into the plurality of digital signal pulses; and at least one processor configured to generate the radiation count information.

Abstract: Methods and apparatus for estimating parameters of interest of a volume in an earth formation from a response spectrum representing radiation information obtained by a radiation detector in a borehole intersecting the volume responsive to nuclear phenomena in the volume, the response spectrum including spectral distortion resulting i) environmental conditions in the formation, or ii) deterioration of at least one component of the radiation detector. Methods include recovering an enhanced response spectrum estimating the true spectrum, comprising mitigating the spectral distortion by applying at least one contrast sharpening mask to the response spectrum. The at least one contrast sharpening mask may comprise at least a low pass smoothing mask subtracted from a unity mask which when applied to the response spectrum obtains high-frequency data and adds the high-frequency data to the response spectrum. The response spectrum may be a gamma ray spectrum.

Abstract: Estimating parameters of interest of a formation, including density, porosity, and fluid saturation. Methods relate to gamma ray energy spectra calibration for a radiation detector including generating a calibration radiation spectrum using measurements of radiation with the detector in a time interval wherein the radiation comprises predominantly gamma rays emitted by decay of radionuclides produced by neutron activation reactions resulting from neutron irradiation, the time interval following a prior time interval corresponding to thermal neutrons produced from the irradiation; making at least one other radiation measurement with the detector outside the time interval; and producing a calibrated radiation measurement from the at least one other radiation measurement using the calibration radiation spectrum. The measurements may be taken in the time interval by conveying the radiation detector in the borehole at high speed and using a background gate of the detector.

Abstract: Systems, methods, and devices for evaluating an earth formation intersected by a borehole. Apparatus may include at least one radiation detector configured to generate an analog electrical signal responsive to a plurality of radiation events, comprising absorption of incident ionizing radiation at a corresponding energy level, and an ionizing radiation spectrometer configured to convert each analog electrical signal from the at least one radiation detector into a plurality of digital signal pulses corresponding to the radiation events and resolve the plurality of digital signal pulses into radiation count information representative of the radiation events. Spectrometers include an input channel for each detector of the at least one radiation detector comprising an analog-to-digital converter (ADC) and configured to convert the analog electrical signal for each detector into the plurality of digital signal pulses; and at least one processor configured to generate the radiation count information.

Abstract: Methods, systems, and devices for evaluating an earth formation intersected by a borehole. Methods may include irradiating the earth formation using a radiation source to provoke radiation from the formation responsive to the irradiation; taking a radiation measurement and thereby generating radiation measurement information by producing light scintillations from a scintillation material responsive to the absorption by the scintillation material of the radiation from the formation and substantial intrinsic radiation of the scintillation material; and estimating a parameter of interest of the earth formation using the radiation measurement information.

Abstract: One general embodiment according to the present disclosure may be formation evaluation tool for detecting radiation in a borehole in a volume of an earth formation. The tool may include a detector including a monolithic scintillation element comprising a coherent assemblage of joined fibers, wherein the fibers are made of an optically transparent scintillation media. The fibers may be at least one of i) gamma ray responsive; and ii) neutron responsive. The coherent assemblage of fibers may be a continuous mass, may be heat-joined. The fibers may be solid. The scintillation media may comprise at least one of i) organic crystalline scintillation materials, ii) amorphous glass, and iii) nanostructured glass ceramics. The coherent assemblage of fibers may be asymmetric. The coherent assemblage of fibers may surround a further scintillation media having different scintillation characteristics than the scintillation media. The scintillation element may be azimuthally sensitive.

Abstract: An apparatus for estimating a property of an earth formation includes a pulsed neutron generator configured to emit a pulse of neutrons, a formation radiation detector configured to detect radiation emitted from the formation due to interactions with the pulse of neutrons, and a neutron generator radiation detector having a crystal structure and configured to detect a radiation particle emitted from the pulsed neutron generator and to provide a location within the neutron radiation detector at which the particle was detected. The crystal structure includes a plurality of detection cells, each detection cell having at least two electrically conducting columns with an applied potential difference such that electrons generated in the crystal structure by interaction with the radiation particle are collected by at least one of the electrically conducting columns to provide detection locations. A processor estimates the property using the detected formation radiation and the detection locations.

Abstract: An apparatus and method for detecting radiation in a borehole intersecting an earth formation. The apparatus may include a neutron sensitive scintillation media and at least one optically transparent neutron absorptive material optically coupled to the media, which may be positioned to prevent incident neutrons from reaching a neutron-shaded surface of the media, and to provide directional sensitivity. The neutron absorptive material may comprise a light guide optically coupled to the neutron sensitive scintillation media. The scintillation media may be disposed within the at least one optically transparent neutron absorptive material, which may be configured to prevent substantially all incident neutrons having an incident neutron energy below a selected energy threshold from reaching the media. The selected energy threshold may be approximately 0.2 eV. A neutron-reflecting material may be disposed within the scintillation media.

Abstract: An apparatus for estimating a property of an earth formation includes a pulsed neutron generator configured to emit a pulse of neutrons, a formation radiation detector configured to detect radiation emitted from the formation due to interactions with the pulse of neutrons, and a neutron generator radiation detector having a crystal structure and configured to detect a radiation particle emitted from the pulsed neutron generator and to provide a location within the neutron radiation detector at which the particle was detected. The crystal structure includes a plurality of detection cells, each detection cell having at least two electrically conducting columns with an applied potential difference such that electrons generated in the crystal structure by interaction with the radiation particle are collected by at least one of the electrically conducting columns to provide detection locations. A processor estimates the property using the detected formation radiation and the detection locations.

Abstract: Systems, methods and devices for evaluating an earth formation intersected by a borehole. The method includes using a first radiation responsive component to detect gamma rays having an energy below a threshold energy; using a second radiation responsive component configured to detect gamma rays that traverse the first radiation responsive component; generating a reduced-Compton gamma ray spectrum by generating an anticoincidence gamma ray spectrum indicative of the gamma rays detected by the first radiation responsive component and the gamma rays detected by the second radiation responsive component. The anticoincidence gamma ray spectrum represents those gamma rays of the gamma rays detected by the second radiation responsive component that are not detected in coincidence with the gamma rays detected by the first radiation responsive component.