Calibrating wellbore spectrometers

A spectrometer for downhole applications can be calibrated without using radioactive sources. A spectrum of measured gamma ray counts can be received from a spectrometer in a calibration mode. A spectrum-to-window ratio can be used to determine a relationship between voltage level applied to a photo...

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Bibliographic Details
Main Author Galford, James E
Format Patent
LanguageEnglish
Published 26.10.2021
Subjects
DETECTING MASSES OR OBJECTS
EARTH DRILLING
EARTH DRILLING, e.g. DEEP DRILLING
FIXED CONSTRUCTIONS
GEOPHYSICS
GRAVITATIONAL MEASUREMENTS
MEASUREMENT OF NUCLEAR OR X-RADIATION
MEASURING
MINING
OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR ASLURRY OF MINERALS FROM WELLS
PHYSICS
TESTING
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Summary:A spectrometer for downhole applications can be calibrated without using radioactive sources. A spectrum of measured gamma ray counts can be received from a spectrometer in a calibration mode. A spectrum-to-window ratio can be used to determine a relationship between voltage level applied to a photoreceptor of the spectrometer and gain factors. A voltage level associated with a gain factor of one can be identified for use by the spectrometer in a non-calibration mode. The measured gamma ray counts and reference shapes for a plurality of radioactive elements can be used in a least squares fit process to determine an offset to apply to the spectrometer in the non-calibration mode.
Bibliography:Application Number: US201716754262