Calibration of spectral gamma-ray logs to deltaic sedimentary facies from the Cretaceous Atane Formation, Nuussuaq Basin, West Greenland
Gamma-ray logs are widely used as a lithology indicator in wells as part of standard petrophysical interpretations. In cored wells, gamma-ray logs should always be calibrated to the lithology in order to correct the petrophysical model. Gamma radiation is emitted from three elements, K, Th and U (po...
| Published in: | Geological Survey of Denmark and Greenland (GEUS) Bulletin |
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| Main Authors: | , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Geological Survey of Denmark and Greenland (GEUS)
2013
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| Subjects: | |
| Online Access: | https://geusbulletin.org/index.php/geusb/article/view/4726 https://doi.org/10.34194/geusb.v28.4726 |
| Summary: | Gamma-ray logs are widely used as a lithology indicator in wells as part of standard petrophysical interpretations. In cored wells, gamma-ray logs should always be calibrated to the lithology in order to correct the petrophysical model. Gamma radiation is emitted from three elements, K, Th and U (potassium, thorium and uranium) which occur in minerals such as feldspar, mica, glauconite, clay minerals, zircon, titanite and apatite as well as in organic complexes. Organic-rich mudstones usually have high gamma-radiation values and quartz-rich sandstones low values. In many places, upward-coarsening successions are recognisable from the gamma log. The gamma log records the sum of radiation from K, Th and U, and their relative contributions are measured in a spectral gamma-ray log. The present case study focuses on spectral gamma-ray characterisation of the deltaic Atane Formation which shows well-developed, upward-coarsening delta-front deposits in outcrops (Fig. 1C). |
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