PTNG tools measures gamma ray emissions from naturally occurring radioactive isotopes to determine formation lithology. The PTNG detector uses sodium iodide (Nal), a scintillation crystal, and a photomultiplier tube to measure gamma ray radiation. Gamma rays strike the Nal crystal causing photons to be emitted. The photons strike the photomultiplier tube and are amplified to give a current pulse large enough to measure. The pulses are counted to determine the energy received. The photon pulse is directly proportional to the energy level of the gamma ray. Pay zones made up of sandstones, limestones, and dolostones exhibit low radiation. The PTNG tool can be run in any type of borehole.
Applications:
- Indicate potential hydrocarbon-bearing zones
- Estimate shale volumes
- Detect ore deposits
- Correlate formations in different wells
- Correlate depths on logs run in the same well
- Delineate bed boundaries
- Detect water migration
Miscellaneous
- Combinable with other logging tools
- Can be run in open and cased holes
