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DETERMINATION OF TEMPERATURE AND FORMATION THERMAL CHARACTERISTICS OF GEOTHERMAL RESERVOIR IN DENMARK.

Objetivo

INCREASE OF KNOWLEDGE OF LOCAL GEOTHERMAL RESSOURCES AND RESERVES.THIS KNOWLEDGE IS OF INTEREST FOR THE EVALUATION OF LOW ENTHALPY GEOTHERMAL ENERGY UTILIZATION FROM SEDIMENTARY BASINS.
The subsurface thermal regime in Denmark has been studied. New high precision, high density measurements of temperature in deep boreholes under equilibrium conditions have been carried out to great depth (1000 to 3000 m). New measurments of rock thermal properties on cores from deep boreholes and new values of heat flow density measured at shallow depth (less than 500 m) have been obtained. Special emphasis has been given to thestudy of temperature gradient variability across sedimentary sequences including reservoir units and adjacent formations. Temperature gradients are found to vary over lithological units (formations and members) by a factor of 4 within the range of 15 to 60 mK/m. Vaiations are associated with differences in lithology and thus interpreted as induced by differences in thermal conductivity. Some claystone units were found to show marked thermal conductivity anisotropy with low vertical component conductivity. These units have high thermal gradients. Positive temperature anomalies are generally found beneath lithologies of low thermal conductivity.

The subsurface thermal regime is found to be dominated by transfer of heat by conduction. Only locally have temperature gradient variations interpreted as due to convective transfer of heat been observed. Heat flow density at shallow depth is low, probably mainly due to transient effects including a palaeoclimatically induced reduction. Locally, effects of near surface ground water movements were observed. Information on temperatures of geothermal reservoirs onshore Denmark has been obtained. Results have been processed in the form of a database containing reservoir depth and temperature at sites of deep boreholes and generalized isothermal maps have been produced for each main reservoir unit. Geothermal reservoirs are found in most parts of the Danish Basin at a depth between 800 m and 3000 m and at temperatures between 25 C and 100 C. Main emphasis is given to the mapping of temperature structure f or reservoirs within the approximate depth range of 1000 m to 2500 m and where porosity, permeability and transmissivity may be sufficiently high for energy extraction. At this depth range reservoir temperatures are between 30 C and 90 C. At the geothermal plant at Thisted (northern Jutland) production is from the Gassum reservoir (Upper Triassic to Lower Jurassic) at a depth of approximately 1250 m with temperature of approximately 45 C.
ACCURATE VALUES OF RESERVOIR TEMPERATURE,FORMATION THERMAL PROPERTIES AND HEAT TRANSFER MECHANISMS FOR SELECTED GEOTHERMAL AREAS AND LOCALITIES IN DENMARK WILL BE DETERMINED.

Tema(s)

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Régimen de financiación

CSC - Cost-sharing contracts

Coordinador

UNIVERSITY OF AARHUS
Aportación de la UE
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Dirección
1,Nordre Ringgade 1-3
8000 AARHUS C
Dinamarca

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Coste total
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