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| Titel |
Thermal Conductivity Determination in the North German Basin: New Approaches - New Results. |
| VerfasserIn |
S. Fuchs, A. Forster |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250065013
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| Zusammenfassung |
| Thermal properties of rocks are first-order controls on the thermal structure of sedimentary
basins. Reliable basin models therefore need to be based on credible in situ thermal
conductivity values. Until today, no cost-efficient method for in-situ borehole measurements
of thermal conductivity exists, and drill core samples on which thermal conductivity could be
measured are rare and often limited to special exploration targets.
We report new results from thermal-conductivity measurements performed on drill core
samples from five Mesozoic formations of the North German Basin. A total of 650 samples
from nine boreholes were measured in the laboratory under ambient conditions using the TCS
method (Fuchs et al., 2012a, in prep.). In order to fill the data gaps for the remainder of the
Mesozoic and Cenozoic geological section a well-log based approach was developed
and applied (Fuchs et al., 2012b, in prep.) The thermal conductivities resulting
from this approach then were compared to those resulting from other published
well-log based approaches. The applicability and performance of all these approaches
was evaluated on two borehole locations by comparison with measured laboratory
values.
Bulk thermal conductivity, corrected for in situ temperature, ranges between 2.7
and 3.7 Wm-1K-1 (sandstone), 1.6 and 3.2 Wm-1K-1 (siltstone), 1.4 and 2.8
Wm-1K-1 (claystone), 2.2 and 2.6 Wm-1K-1 (limestone) and 1.7 and 3.1 Wm-1K-1
(dolomite), respectively. Highest average sandstone values were observed in the Jurassic
Aalenian (3.3 ± 0.7 Wm-1K-1) and in the Triassic Postera sandstone (3.3 ± 0.6
Wm-1K-1) and the lowest in the Triassic Stuttgart Formation (2.0 ± 0.1 Wm-1K-1),
respectively.
The new well-log based approach applied to data sets from two borehole locations results
in a linear prediction equation that is based on volume fraction of shale, neutron porosity and
sonic travel time as descriptors. The approach applied to the Stuttgart Formation at
Ketzin (the location of the CO2SINK project), made up of muddy sandstone, marl,
siltstone and claystone, shows the predicted thermal conductivity to be in error by 0.19
Wm-1K-1 (RMS-error). In general, the new equation provides a better fit (error
reduction: 33-65%) to measured values as previously published prediction equations. |
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