 |
| Titel |
Thermophysical properties of potential geothermal reservoir rocks: an outcrop analogue study of the sedimentary series of the Buda Mts., Hungary |
| VerfasserIn |
A. E. Götz, Á. Török, M. Tóth, V. Hlavička, I. Sass |
| Konferenz |
EGU General Assembly 2012
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250060612
|
|
|
|
|
|
| Zusammenfassung |
| The detailed knowledge of sedimentary features from microscopic to regional scales is
regarded as crucial in reservoir characterization and prediction of deep geothermal systems.
Generally, in the early stages of reservoir exploration, characterization of the reservoir is
accomplished by evaluation of drilling data and seismic surveys. However, for reservoir
prognosis, the main geothermal parameters such as permeability, thermal conductivity, and
reservoir heat flow have to be quantified with respect to a 3D structural model. Outcrop
analogue studies serve to predict such subsurface thermophysical properties, and based on
detailed facies analysis, the geothermal exploration concept becomes more precise and
descriptive.
Our data from the Meso- and Cenozoic sedimentary series of Budapest include
carbonates and clastic sediments of Triassic, Eocene, and Oligo-Miocene age as well as
Pleistocene travertine, exposed on the western side of the river Danube. Field and laboratory
analyses reveal distinct horizons of different geothermal potential and thus, enable us to
identify and interpret corresponding exploration target horizons in geothermal prone depths
of the Pannonian Basin.
Upper Triassic limestones (Main Dolomite, Budaörs Dolomite, Mátyáshegy Limestone)
show values of thermal conductivity in the range of 2,0 to 3,5 W/(m-
K). Matrix
permeabilities measured with a gas mini-permeameter span in the range of 10-12 to 10-14
m2. Additionally, these limestones are highly fractured and show a different degree of
karstification increasing the fluid migration. Thus, hydrothermal exploration of such
limestone reservoirs in geothermal prone depths of about 5 km known from the Zala and
Danube basins of W Hungary is seen very promising.
Miocene bioclastic limestones (e.g, Tinnye Limestone) reveal lower values of thermal
conductivity in the range of 1,0 to 1,5 W/(m-
K). On the other hand, they are characterized by
much higher permeabilities (10-11 to 10-12 m2). Depending on their occurrence
in the deep subsurface, they might be considered as reservoir rocks. Marls and
travertines show values of thermal conductivity in the range of 2,0 to 2,5 W/(m-
K).
Matrix permeabilities of marls are low (10-15 to 10-16 m2), whereas travertines
are characterized by the highest permeabilities up to 10-11 m2. Both, marls and
travertines are not considered as deep geothermal reservoir rocks: marls due to
their low permeabilities, and travertines due to their occurrence mostly in surface
outcrops.
Clastic sediments of Palaeo- and Neogene age are grouped into low permeable and low
heat conducting clays (e.g., Kiscell Clay), and high permeable, high heat conducting
sandstones (e.g., Hárshegy Sandstone). Thus, hydrothermal exploration of high permeable
sandstone reservoirs in geothermal prone depths known from different basins in Hungary
(e.g., Central Great Plain) is also seen very promising.
Based on these preliminary results, further outcrop analogue studies will serve as a
powerful tool to predict such subsurface properties and thus, finally lead to a better
understanding of deep geothermal reservoirs in the Pannonian Basin. |
|
|
|
|
|
|