OPPORTUNITY STUDY OF TRANSFORMATION OF THE OIL FIELDS TO THE GEOTHERMAL FIELDS IN WEST LITHUANIA
(Šliaupa S., Puronas V., Zalaudiene G., Šliaupiene R.)
The main part of the costs of the geothermal stations comprises the drilling and installation of the deep wells. West Lithuania is characterized by anomalously high heat flow. There is a number of the oil fields that reached the tail phase of exploitation. The depth and construction of wells are suitable for exploitation of the geothermal heat. The application of those wells can reduce considerably the costs of the geothermal stations for the district heating. 13 oil fields were analysed.
Only four oil fields (Girkaliai, Genciai, Kretinga, Plunge) are located close to the towns, the potential customers. The data base of the temperature measurements in the oil field wells was compiled. The reservoir properties of the Middle Cambrian, Lower Devonian and Middle-Upper Devonian aquifers were analysed in detailed. The chemical composition of the formation water varies considerably across the area that is important for prediction of the chemical reactions during the exploitation of the thermal water. The study was supported by geothermal chemical modeling. The inventory of the construction of the wells was performed. In most cases the common well completion scheme is applied in west Lithuania. Based on temperature and reservoir data the geothermal heat potential was estimated for the three major aquifers in all oil fields. The largest potential is related to the Lower Devonian aquifer that is in the range of 9-68 MW. The potential of the Middle-Upper Devonian aquifer range in order of 6-28 MW. The deepest Middle Cambrtain reservoir can supply 1-16 MW of heat. The Genciai, Kretinga, and Girkaliai oil fields have the highest priority for the development of the geothermal heat supply stations in west Lithuania.
Fig.3. Geothermal capacity of Sventoji-Upninkai (Middle-Upper Devonian) reservoir of oil fields, MWth