Abstract: Borehole logging methods for estimating a parameter of interest using nuclear radiation. Methods include estimating a water saturation of the formation from gamma radiation from at least the formation detected in the borehole using a radiation detector, the gamma radiation responsive to a pulsed neutron source and resulting from at least one of: (i) decay of nitrogen-16 formed by activation of oxygen-16, and ii) inelastic scattering of neutrons from oxygen. This may include using at least one processor to: obtain a gamma ray count measurement, representing gamma rays from one of (i) the decay of nitrogen-16 (ii) and the inelastic scattering, and estimate the water saturation using the gamma ray count measurement and a model comprising a relationship between measured gamma ray counts and modeled gamma ray counts from each of a fully water saturated formation and a minimally water saturated formation.

Abstract: The present disclosure relates to borehole logging methods and apparatuses for estimating formation properties using nuclear radiation, particularly an apparatus and method for estimating amounts of silicon and/or oxygen in the formation. The method may include using nuclear radiation information from at least one nuclear radiation detector to estimate at least one parameter of interest. The method may include separating a gross nuclear radiation count into separate nuclear radiation components. The method may also include reducing an error in the estimated formation properties due to speed variations of a nuclear radiation source that activates the silicon and oxygen in the formation. The apparatus may include at least one nuclear radiation detector. The apparatuses may include an information processing device to perform the methods.

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: Methods, systems, devices, and products for estimating at least one parameter of interest of a volume of interest of an earth formation using nuclear radiation based measurements. Logging tools include a limited aperture collimated radiation beam source, detectors, and at least one processor configured to take measurements. The source is configured to emit a beam of radiation radially from the logging tool into an elongated volume of interest outside the wellbore such that the beam penetrates a plurality of zones of the volume of interest. Each zone represents a range of radial depths corresponding to a respective infrastructure component associated with the wellbore, such as nested tubulars. Each detector has a unique angle of detection and is configured to generate measurement information in response to spatially coherent backscattered gamma rays. Each detector is associated with scattering events at one of the plurality of zones.

Abstract: Borehole logging methods for estimating a parameter of interest using nuclear radiation. Methods include estimating a water saturation of the formation from gamma radiation from at least the formation detected in the borehole using a radiation detector, the gamma radiation responsive to a pulsed neutron source and resulting from at least one of: (i) decay of nitrogen-16 formed by activation of oxygen-16, and ii) inelastic scattering of neutrons from oxygen. This may include using at least one processor to: obtain a gamma ray count measurement, representing gamma rays from one of: (i) the decay of nitrogen-16 (ii) and the inelastic scattering, and estimate the water saturation using the gamma ray count measurement and a model comprising a relationship between measured gamma ray counts and modeled gamma ray counts from each of a fully water saturated formation and a minimally water saturated formation.

Abstract: Borehole logging methods for estimating a parameter of interest using nuclear radiation. Methods include estimating a water saturation of the formation from gamma radiation from at least the formation detected in the borehole using a radiation detector, the gamma radiation responsive to a pulsed neutron source and resulting from at least one of: (i) decay of nitrogen-16 formed by activation of oxygen-16, and ii) inelastic scattering of neutrons from oxygen. This may include using at least one processor to: obtain a gamma ray count measurement, representing gamma rays from one of: (i) the decay of nitrogen-16 (ii) and the inelastic scattering, and estimate the water saturation using the gamma ray count measurement and a model comprising a relationship between measured gamma ray counts and modeled gamma ray counts from each of a fully water saturated formation and a minimally water saturated formation.

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: Methods, systems, devices, and products for estimating at least one parameter of interest of a volume of interest of an earth formation using nuclear radiation based measurements. Logging tools include a limited aperture collimated radiation beam source, detectors, and at least one processor configured to take measurements. The source is configured to emit a beam of radiation radially from the logging tool into an elongated volume of interest outside the wellbore such that the beam penetrates a plurality of zones of the volume of interest. Each zone represents a range of radial depths corresponding to a respective infrastructure component associated with the wellbore, such as nested tubulars. Each detector has a unique angle of detection and is configured to generate measurement information in response to spatially coherent backscattered gamma rays. Each detector is associated with scattering events at one of the plurality of zones.

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: An apparatus and method for estimating at least one parameter of interest of an earth formation including an estimation of the parameter of interest using a time-dependent ratio of information obtained from at least one neutron detector through the exposure of the earth formation to a radiation source, particularly a pulsed nuclear source. The apparatus includes a processor and storage subsystem with a program that, when executed, implements the method. Also, an apparatus and method for estimating at least one parameter of interest of an earth formation including an estimation of the parameter of interest using a first component and a second component of an information set obtained using a single radiation detector.

Abstract: Methods, systems, devices, and products for estimating a parameter of interest of a volume of an earth formation. Methods may include correcting a measurement relating to the parameter of interest by a downhole tool using at least one correction model determined from a plurality of predefined models. The at least one correction model may be determined based on an estimated borehole standoff of the tool from the borehole wall that is associated with the measurement. Correcting the measurement may include determining a correction factor using the correction model and applying the correction factor to the measurement. Each of the plurality of predefined models may be associated with each of a plurality of standoff bins, wherein each of the plurality of standoff bins is defined as a mutually exclusive interval of distance values from the downhole tool to the borehole wall.

Abstract: A method of identifying barite in a subterranean annulus that surrounds a wellbore, where the method includes detecting gamma rays in the wellbore that are generated from the annulus, obtaining a count rate of the detected gamma rays, comparing the count rate with reference data, and determining the presence of barite in the wellbore based on the comparison. The count rate can be a ratio of counts of detected gamma rays obtained from spaced apart receivers on a downhole tool, or a ratio of detected inelastic and capture gamma rays. The reference data is obtained by using a simulation algorithm.

Abstract: A method of identifying barite in a subterranean annulus that surrounds a wellbore, where the method includes detecting gamma rays in the wellbore that are generated from the annulus, obtaining a count rate of the detected gamma rays, comparing the count rate with reference data, and determining the presence of barite in the wellbore based on the comparison. The count rate can be a ratio of counts of detected gamma rays obtained from spaced apart receivers on a downhole tool, or a ratio of detected inelastic and capture gamma rays. The reference data is obtained by using a simulation algorithm.

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: An apparatus for estimating a property of an earth formation and a borehole fluid includes a carrier configured to be disposed in a borehole, and a pulsed neutron measurement assembly including a pulsed neutron source configured to emit neutrons into the borehole and the earth formation, and a gamma ray detector. The apparatus also includes a fluid density measurement assembly including the gamma ray detector and a gamma ray source configured to irradiate a borehole fluid with gamma rays. The gamma ray detector is positioned relative to the gamma ray source to detect both of: gamma rays resulting from neutron interactions and gamma rays emitted from the borehole fluid in response to irradiation from the gamma ray source. The apparatus further includes a processor configured to differentiate a pulsed neutron gamma ray spectrum associated with the interactions from a density gamma ray spectrum.

Abstract: An apparatus for estimating a property of an earth formation and a borehole fluid includes a carrier configured to be disposed in a borehole, and a pulsed neutron measurement assembly including a pulsed neutron source configured to emit neutrons into the borehole and the earth formation, and a gamma ray detector. The apparatus also includes a fluid density measurement assembly including the gamma ray detector and a gamma ray source configured to irradiate a borehole fluid with gamma rays. The gamma ray detector is positioned relative to the gamma ray source to detect both of: gamma rays resulting from neutron interactions and gamma rays emitted from the borehole fluid in response to irradiation from the gamma ray source. The apparatus further includes a processor configured to differentiate a pulsed neutron gamma ray spectrum associated with the interactions from a density gamma ray spectrum.

Abstract: Borehole logging methods for estimating a parameter of interest using nuclear radiation. Methods include estimating a water saturation of the formation from gamma radiation from at least the formation detected in the borehole using a radiation detector, the gamma radiation responsive to a pulsed neutron source and resulting from at least one of: (i) decay of nitrogen-16 formed by activation of oxygen-16, and ii) inelastic scattering of neutrons from oxygen. This may include using at least one processor to: obtain a gamma ray count measurement, representing gamma rays from one of (i) the decay of nitrogen-16 (ii) and the inelastic scattering, and estimate the water saturation using the gamma ray count measurement and a model comprising a relationship between measured gamma ray counts and modeled gamma ray counts from each of a fully water saturated formation and a minimally water saturated formation.

Abstract: Methods, systems, devices, and products for estimating at least one parameter of interest of a volume of an earth formation, including density, porosity, and fluid saturation of the volume. Methods may include normalizing radiation information relating to radiation emissions from a spatially distributed nuclear source and indicative of a property of the earth volume using a correction factor determined using an estimated lithology of the volume. The nuclear source may be in the volume. Radiation emissions may be generated by neutron irradiation of at least one nuclide in the volume. The correction factor may be determined using any of nuclear density of the at least one nuclide; an estimated concentration of the at least one nuclide in the volume; or a parameter relating to concentration of the nuclide in the volume. The emissions may include gamma rays.

Abstract: Borehole logging methods and apparatuses for estimating formation properties using nuclear radiation, particularly an apparatus and method for estimating amounts of silicon and/or oxygen in the formation. Methods include estimating a formation property using an oxygen estimate and at least a formation lithology. The method may include using nuclear radiation information from at least one nuclear radiation detector generate the oxygen estimate. The apparatus may include at least one nuclear radiation detector. The apparatuses may include an information processing device to perform the methods.

Abstract: An apparatus for estimating porosities of a formation includes: a borehole conveyable pulsed neutron generator to emit a pulse of high energy neutrons; a short spaced neutron detector to provide a count rate as a function of time; a long spaced neutron detector to provide a count rate as a function of time; a timing gate to synchronize a timing of neutrons detected by the detectors with respect to the neutron pulse; and a processor. The processor is configured to determine epithermal count rates and thermal count rates for the detectors based on timing of detection of neutrons with respect to the neutron pulse and calculate a first ratio of short to long spaced detector epithermal count rates and a second ratio of short to long spaced detector thermal count rates. The processor estimates an epithermal porosity using the first ratio and a thermal porosity using the second ratio.