Spectral Gamma Ray Tools

Overview Library

Potassium, thorium, and uranium: gamma ray insights into composition

Spectral gamma ray tools provide insight into the mineral composition of formations. The total gamma ray spectra measured is resolved into the three most common components of naturally occurring radiation in sands and shales—potassium, thorium, and uranium (K, Th, and U, respectively). These data are used to distinguish important features of the clay or sand around the wellbore. The clay type can be determined, and sand can be identified as radioactive. The deposition of radioactive salts behind the casing by the movement of water can also be identified.

NGS natural gamma ray spectrometry tool

The NGS natural gamma ray spectrometry tool uses five-window spectroscopy to resolve the total gamma ray spectra into K, Th, and U curves. The standard gamma ray and the gamma ray minus the uranium component are also presented. The computed gamma ray or Th curve can be used to evaluate the clay content where radioactive minerals are present.

Hostile Environment Natural Gamma Ray Sonde

The increased sensitivity of the Hostile Environment Natural Gamma Ray Sonde (HNGS) set of detectors improves the tool's statistical response to the formation gamma rays to produce a better spectral analysis than that of previous tools. The improvement in measurement also results from the use of two detectors instead of one. The HNGS can log at a faster speed than other tools that measure the formation natural gamma ray emissions. Its temperature rating of 500 degF [260 degC] makes it suitable for operations in hot borehole environments.

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