Objectif The use of geothermal water to supply two sites in the Freiburg area:- Weingarten, to supply a district heating network of 3,900 dwellings;- Bremgarten, to supply heat to an army barracksThese two operations will supply 33,000 MWh and 20,000 MWh respectively, contributing to an annual energy saving of 5,800 TOE. In addition, the substitution of heavy fuel oil will reduce the annual emission of pollutants by 20 T of SO2 and 9 T of NO2.After three shallow, exploratory wells have been drilled at Weingarten, a deep well (700 m) will be drilled down to the Muschelkalk yielding a flow-rate of 110 m3/h at 40 C. installation of a heat pump will make it possible to recover the maximum amount of geothermal energy. At Bremgarten once vibro-seismic studies have been completed an exploratory well will be drilled down to the Upper Muschelkalk (2,500, 65 C and 70 m3/h). Whether or not reinjection wells are drilled will depend on the salinity of the geothermal fluids.The project is unsuccessful although the high temperature at the bottom of the hole (99 C) removes the need for a heat pump. Geophysical investigation by vibroseismics showed the absence of Rhenian directions. The fault system is influenced by a salt dome (NW/SE). Temperature measurements prove a thermal gradient of 5,4 C/100 m higher than forecast.The second target "oberer Muschelkalk" was not explored as a result of necessary changes in the casing programme due to drilling problems, and deeper than expected.After drilling of two exploratory wells at Weingarten, the 150 m well in January 1980 and the 290 m well in May 1980, vibro-seismic investigations were carried out in February and March of the same year. For fear of possible side-effects, on a nearby thermal Spa the Freiburg authorities refused to grant drilling permission for the 700 m production well.Vibro-seismic investigations were carried out in Bremgarten between January and February 1980. A production well was drilled to 2,400 m between January and July 1982, fitted with a 7" casing from 1,796 m to the 2,281 m mark (directional drilling) and left as a 6" 1/4 open hole from 2,281 m to 2,372 m. Oolitic limestone with clay and Bajocian dolomite between 2,281 m and 2,372 m. A reservoir exists between 2,360 m and 2,372 m, but of little potential (less than 2 m3/h for a drawdown of 600 m - a pressure acidification treatment failed to improve the flow-rate). The bottom hole temperature of 99 C was higher than forecast . Formations were generally +- 200 m deeper than predicted, due to the thick accumulation of salt at the Tertiary horizon (500 m to 1,800 m). The well is situated one Kilometer north of the salt dome: this was directed by seismic prospecting prior to commencement of drilling. The thick clay bed between 1,827 and 2,281 m with its 10% gas content resulted in the loss of 150 m of drillrods: this necessitated deviation to the present depth. The existing well will fail to strike the primary target reservoir - the Muschelkalk limestone - in view of the current technical conditions and of the superjacent Keuper clay which can be expected to present drilling problems. In January 1983 the well was deepened by 200 m to a final depth of 2,421 m. Samples of the core confirmed the lithological composition of the upper reservoir. Last tests confirmed the aquifer characteristics previously collected. Programme(s) ENG-ENALT 1C - Programme (EEC) of financial support for projects to exploit alternative energy sources, 1979-1984 Thème(s) 2.2 - HEATING Appel à propositions Data not available Régime de financement DEM - Demonstration contracts Coordinateur WALTER GEWERKSHAFT Contribution de l’UE Aucune donnée Adresse AM HANDELSHOF 1 POSTFACH 570 4300 Essen Allemagne Voir sur la carte Coût total Aucune donnée
