THOR
Schlumberger%Thorium
Thorium concentration from spectral gamma ray. Thorium is immobile and clay-associated, making the Th/K ratio one of the best log-based clay-typing tools and a robust detrital and heavy-mineral indicator.
- Property
- Thorium Concentration
- Concentration
- Quantity
- dimensionless
- % · GEuc · ppm · mEuc · cEuc · MEuc · nEuc · pEuc · kEuc · ppk · fEuc · µEuc · dEuc · EEuc · TEuc · Euc
- Typical range
- ~0.6–12.7 PPM
- parts per million (ppm)
Logging tool
No logging tool is associated with this curve.
Service company
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How it's measured
From the thorium emission window (2.62 MeV, thallium-208 in the thorium series) of the spectral gamma tool, reported in ppm.
How it's used
Clay mineral identification via the Th/K crossplot, provenance and heavy-mineral (zircon, monazite) detection, and — being uranium-free — a stable shale indicator.
Common gotchas
Heavy detrital minerals can spike thorium without indicating clay. Like all spectral channels it is statistically noisy and logging-speed-sensitive.
In LAS files
Recorded as THOR (or TH) in ppm, alongside POTA and URAN from spectral gamma logs.
Also seen with THOR in real logs
Curves that appear alongside THOR in the same wells across the public corpus.