Verfahren und Vorrichtung zum Aufspüren und Errechnen von radioaktiven Stoffen auf einem Rohr in einem Bohrloch.

摘要

A logging tool for detecting and quantifying radioactive material deposited on a tubing disposed in a borehole, comprising: a) a logging sonde adapted to be lowered in the tubing, and comprising means for detecting and counting gamma rays emitted by the radioactive material at different depths in the borehole; b) means for determining, from the measured gamma rays, a measured radioactivity level; and c) means for calculating, from the measured radioactivity level, the radioactive level which would be detected outside and in the vicinity of the tubing, by applying to the measured radioactivity level a first tubing thickness attenuation factor. In a preferred embodiment, means are provided to correct for the natural background radioactivity level, by subtracting a reference natural radioactivity level, itself corrected for tubing thickness by applying a second tubing thickness attenuation factor.