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| Titel |
New approaches in the indirect quantification of thermal rock properties in sedimentary basins: the well-log perspective |
| VerfasserIn |
Sven Fuchs, Niels Balling, Andrea Förster |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250124961
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| Publikation (Nr.) |
 EGU/EGU2016-4476.pdf |
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| Zusammenfassung |
| Numerical temperature models generated for geodynamic studies as well as for geothermal
energy solutions heavily depend on rock thermal properties. Best practice for the
determination of those parameters is the measurement of rock samples in the laboratory.
Given the necessity to enlarge databases of subsurface rock parameters beyond drill core
measurements an approach for the indirect determination of these parameters is developed,
for rocks as well a for geological formations. We present new and universally applicable
prediction equations for thermal conductivity, thermal diffusivity and specific heat capacity in
sedimentary rocks derived from data provided by standard geophysical well logs. The
approach is based on a data set of synthetic sedimentary rocks (clastic rocks, carbonates and
evaporates) composed of mineral assemblages with variable contents of 15 major
rock-forming minerals and porosities varying between 0 and 30%. Petrophysical
properties are assigned to both the rock-forming minerals and the pore-filling fluids.
Using multivariate statistics, relationships then were explored between each thermal
property and well-logged petrophysical parameters (density, sonic interval transit time,
hydrogen index, volume fraction of shale and photoelectric absorption index) on a
regression sub set of data (70% of data) (Fuchs et al., 2015). Prediction quality
was quantified on the remaining test sub set (30% of data). The combination of
three to five well-log parameters results in predictions on the order of <15% for
thermal conductivity and thermal diffusivity, and of <10% for specific heat capacity.
Comparison of predicted and benchmark laboratory thermal conductivity from
deep boreholes of the Norwegian-Danish Basin, the North German Basin, and the
Molasse Basin results in 3 to 5% larger uncertainties with regard to the test data
set. With regard to temperature models, the use of calculated TC borehole profiles
approximate measured temperature logs with an error of <3∘C along a 4 km deep
profile. A benchmark comparison for thermal diffusivity and specific heat capacity is
pending.
Fuchs, Sven; Balling, Niels; Förster, Andrea (2015): Calculation of thermal conductivity, thermal
diffusivity and specific heat capacity of sedimentary rocks using petrophysical well logs, Geophysical
Journal International 203, 1977-2000, doi: 10.1093/gji/ggv403 |
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