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.
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:
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:
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 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. The neutron-reflecting material may comprise a light guide optically coupled to the neutron sensitive scintillation media.
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.