Spectral Gamma Tool

Parameters Logged:

Potassium (1)

Scintillation Crystal NaI(TI) 38mm x 305mm (1.5 x 12 in.)

K (percent ⁴⁰K) ±2%

Uranium (2)

Scintillation Crystal NaI(TI) 38mm x 305mm (1.5 x 12 in.)

U parts per million ±10ppm

Thorium (3)

Scintillation Crystal NaI(TI) 38mm x 305mm (1.5 x 12 in.)
 

T parts per million ±10ppm

The Spectral Gamma tool offers three-channel analysis of the gross gamma ray spectrum as it relates to potassium, uranium, and thorium content. An internal energy source of less than 1 micro-curries of Cs137 is used to excite the crystal and to stabilise the electronics prior to logging.  The spectral window is recorded via a 256 channel spectrum board so that the different energy levels from the formation can be analysed.

Applications:

The Spectral Gamma Tool has applications in a number of mineral exploration and environmental areas.

In uranium exploration the advantage of KUT logging is that (aside from disequilibrium problems) the occurrence of potassium, uranium and thorium are geologically distinct. This is of particular advantage in cases of low grade uranium deposits where KUT logging allows the determination of a true uranium deposit to be distinguished from a thorium deposit.

The spectral gamma tool has applications in other areas of mineral exploration, particularly where uranium leaching may mask true lithology where traditional gross (as opposed to spectral) gamma logging tools are used in its determination.

Spectral gamma data can also be used for more detailed lithological analysis.

The tool can be used in fluid or air filled holes and through PVC casing. Responses through steel casing will be reduced. The tool is run uncentralised.

The most common applications are:

• Uranium exploration
• Detailed lithological mapping (particularly in regard to shale content)
• Sedimentology
• Correlate structural and stratigraphic features
• Environmental – contamination studies

Example Log Image: