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Comparison of magnetic and gamma ray logging for correlations in chronology and lithology: example from the Aquitanian Basin (France)
- Source :
- Geophysical Journal International. 137:839-846
- Publication Year :
- 1999
- Publisher :
- Oxford University Press (OUP), 1999.
-
Abstract
- SUMMARY Precise time and facies correlations between drilled holes are fundamental for a better understanding of the geological evolution of sedimentary basins. A downhole magnetic measurement device called the geological high-sensitivity magnetic tool (GHMT) has been run within two wells drilled by Gaz de France in the Landes oil-field (southwest France) as part of a gas storage exploration program. The method of interpretation of downhole magnetic measurements yielded a magnetostratigraphy within each well, allowing absolute dating and time correlations between the wells. Magnetic susceptibility and natural gamma ray intensity are useful parameters for establishing high-resolution lithological correlations at a basin scale. We present a correlation parameter established from a simultaneous analysis of the susceptibility and the gamma ray logs within each well. The correlation parameter appears to provide a new tool for delineating lithological elements when local lithological changes are too subtle to show clear well-to-well correlations either from susceptibility logs or from gamma ray logs. This new approach is interpreted as a sensitive way to detect relative variations between the detrital and clay content of the penetrated sediment.
Details
- ISSN :
- 1365246X and 0956540X
- Volume :
- 137
- Database :
- OpenAIRE
- Journal :
- Geophysical Journal International
- Accession number :
- edsair.doi...........2e550a00f3ed91bd8f27e83d49f118bb