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Germany
Thermal and hydraulic
rock properties
of
paleozoic, mesozoic and tertiary rocks
A major
obstacle in geothermal energy development lies in the high
risk of failure due to the unknown thermal and hydraulic
properties of the target rocks at depth. To overcome the
insufficient knowledge of rock properties at depth, a
project funded by the German Federal Environment Ministry
has been initiated to compile a statistically significant
database of thermal and hydraulic properties of subsurface
rocks in Germany. Geophysica was ordered for workings in
the field of log analysis and thermal property prediction
by the Institute of Applied Geophysics and Geothermal
Energy of Aachen University, the principal investigator of
the project.
We
selected samples and data sets from core and data archives
of the State Geological Surveys and from industrial
exploration wells (hydrocarbons, coal and lignite). In the
first stage of the project we provided a statistically
representative database of thermal and hydraulic
properties for the lithostratigaphical units in the
western part of the Molasse Basin in Southern Germany and
the adjacent Triassic and Jurassic landscapes north of the
Molasse (Swabian Alp). During the second stage of the
project we attended the subsurface rocks of the western
part of North Rhine Westphalia (Niederrheinische Bucht,
Ruhrgebiet, Rheinisches Schiefergebirge).
Data
from direct measurements on core samples were combined
with the interpretation of geophysical borehole
measurements and complementary mineralogical analyses to
derive statistical moments of the desired properties for
selected main rock types. Additionally, we considered
spacial facies changes and the effects due to variations
of temperature and pressure increase with depth. In the
beginning of our studies we selected and sampled relevant
rock series from the target areas. In parallel different
analytical methods were enhanced to support the project
tasks. These techniques were related to the rapid and
cost-efficient derivation of permeabilities from nuclear
magnetic resonance (NMR) measurements and to the
quantification of uncertainty with respect to rock
properties and state variables in geothermal reservoirs,
respectively. Our results improved the database of
geothermal relevant information and facilitate the
commercial and area-wide exploration of geothermal energy
in Germany.
Regions of interest,
covering a wide spectrum of paleozoic, mesozoic and
tertiary rocks.
Definition of
petrophysical relationships to relate thermal conductivity
to rock composition and rock porosity.
Cross-hole correlation
of thermal conductivity profiles for sediments of the
middle Jurassic drilled in south Germany. Thermal
conductivity profils were generated from wireline log data.
Final
Report 1 (Westmolasse and Schwäbische Alp)
Final
Report 2 (Ostmolasse and Niederrheinische Bucht)
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