Multi-function natural gamma ray logging system

Patent · Tue Apr 29 04:00:00 EDT 1986

OSTI ID:5601939

Arnold, D M; Smith, Jr, H D

A method is described for natural gamma ray spectral logging of a well borehole to determine the relative elemental abundancies of uranium, potassium, and thorium gamma rays in earth formations by comparison with standard gamma ray calibration spectra of uranium, potassium, and thorium taken in standard boreholes having standard geometrical and constituent properties. The method consists of: (a) obtaining with a borehole measurement system an unknown gamma ray energy spectrum in a measurement borehole having non-standard borehole conditions, the unknown gamma ray spectrum comprising gamma ray intensities measured in at least four energy bands corresponding to a first energy band containing the 2.61 MeV thorium decay peak, a second energy band containing the 1.76 MeV uranium decay peak, a third energy band containing the 1.46 MeV potassium decay peak, and one or more additional energy bands for monitoring the shape of the unknown gamma ray spectrum as a function of elemental concentrations and borehole conditions, (b) deriving an elemental sensitivity matrix from borehole condition information supplied by a source other than the detector, and (c) combining the sensitivity matrix and the gamma ray intensity information in the at least four energy bands to derive elemental abundancies of potassium, uranium, and thorium.

• Assignee: Halliburton Co., Duncan, OK
• Patent Number(s): US 4585939
• OSTI ID: 5601939
• Country of Publication: United States
• Language: English

Related Subjects

050200* -- Nuclear Fuels-- Exploration-- (-1987)
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
440400 -- Well Logging Instrumentation
47 OTHER INSTRUMENTATION
ACTINIDES
ALKALI METALS
BOREHOLES
CALIBRATION
CAVITIES
DECAY
ELEMENTS
ENERGY RANGE
EQUIPMENT
GAMMA LOGGING
GAMMA SPECTRA
GEOLOGIC DEPOSITS
METALS
MEV RANGE
MEV RANGE 01-10
MINERAL RESOURCES
NATURAL RADIOACTIVITY
POTASSIUM
QUANTITY RATIO
RADIOACTIVITY
RADIOACTIVITY LOGGING
RESOURCES
SENSITIVITY ANALYSIS
SPECTRA
THORIUM
URANIUM
URANIUM DEPOSITS
WELL LOGGING
WELL LOGGING EQUIPMENT