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Final Conference - Vilnius, Lithuania
Final Conference - Vilnius, Lithuania
12-15 February 2008 Le Méridien Villon
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Subsurface thermal inference from simultaneous inversion of thermal information from many wells: Improving the geothermal field predictions
One of the major risks in geothermal energy exploration is related to defining the areas of high heat flow. Due to the frequently poor quality of borehole thermal information this may be the case even in areas with a relatively high density of wells,  
The use of exploration wells in geothermal studies is often made difficult by the poor quality of borehole temperature observations, which cannot be corrected for the influence of the drilling process, and the absence of proper thermal conductivity measurements. However, in many areas the density of wells is high enough that useful information can still be extracted. Here we present a flexible inverse formalism that allows analysing thermal parameters such as surface heat flux and basement heat production rate from exploration wells and to assess the uncertainty of subsurface thermal inference for use, for example, in terrestrial heat flow studies and geothermal energy planning.
Our quantitative model is based on three-dimensional heat conduction in a horizontally stratified subsurface. The solution is obtained using a two-dimensional Fourier cosine representation. The borehole data are modelled using the Markov Chain Monte Carlo method. This method is very flexible and provides histograms of the parameters of interest, including, for example, the surface heat flow or the temperature at the depth of planned geothermal reservoir.
The West Lithuanian thermal anomaly displays a surface heat flow greater than 100 mW/m2 in a background East European Platform (EEP) heat flow of 50-60 mW/m2. This makes it one of the most profound heat flow anomalies of the EEP. It is located in an area of mainly early Palaeozoic platform sediments of thickness ~2 km overlying crystalline basement of Palaeoproterozoic age in western Lithuania and the Baltic Sea. The data available comprise borehole temperatures, basement heat production rates and estimates of thermal conductivity. The results show that the thermal anomaly can be explained by the thermal blanketing effect by sediments overlying a basement with an excessive heat production rate.
Id: 32
Place: Le Méridien Villon
Vilnius, Lithuania
Starting date:
13-Feb-2008   10:45
Duration: 20'
Contribution type: poster
Primary Authors: NIELSEN, Søren (The University of Aarhus)
Co-Authors: SLIAUPA, Saulius (Institute of Geology and Geography & Vilnius University)
STEPHENSON, Randell (Faculty of Earth and Life Sciences, VU University Amsterdam)
MOTUZA, Gediminas (Vilnius University)
ČIURAITė, Kristina (Vilnius University)
Presenters: STEPHENSON, Randell
Material: poster Poster
Included in track: Poster Session - Investigation of Unconventional Geothermal Resources and EGS

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