Cel To use geothermal energy to heat 170,000 m2 of offices, the prefecture of Gironde and +- 300 dwellings in an area now being renovated and comprising120 000 m2 of offices and housing blocks which are to be heated by geothermal energy or, in the case of certain buildings, by means of existing heat pumps. Cretaceous-Jurassic reservoir formations are to be encountered between 850 and 1000 m comprising sands, sandstones, Cenomanian-Turonian Limestones and Jurassic dolomites (to be confirmed). A flow-rate of 100 to 150 m3/h of water at 45 C and a salinity of 0.6 g/l is expected. There are no plans to reinject the water (17 C) unless there is loss of pressure in the reservoir. The distribution network of 900 m is planned. The threshold below which the project becomes unprofitable has been fixed at +- 100 m3/h at 40 C. Geothermal output is estimated at 4,800 KW, which will give an annual saving of 1,600 TOE. The expected payback is 8 years.The operation is a technical and economic success with aquifer characteristics better than expected. Temperature, for example, is 8 C higher. The geothermal water comes from a bed of fresh water that presents a considerable potential under Bordeaux and suburbs. Many other drilling operations can be mounted for managing and further developing this important geothermal resource in the Northern Aquitaine Basin.The single production well was completed between October 1980 and February 1981 to a final depth of 1,150 m and the absence of Jurassic dolomites confirmed. The reservoir of the Upper Cretaceous is comprised of limestones and sandstones lying between 930 and 1,127 m and has been equipped with a screen-gravel pack completion (diameter 5" 1/2). Characteristics: net pay of aquifer - 67 m; transmissivity - 195 D.m. for the feeding zone at a distance from the well. Transmissivity is less (unassessable) near the walls of the well and particularly at the well completion level where very high losses occurred - 55 m of the total drawdown - (135 m at 125 m3/h). The high transmissivity of the reservoir was confirmed by an influence test with a second geothermal well at Bordeaux-Benauge, not far from Meriadeck. The artesian flow-rate is 30 m3/h rising to 125 - 150 m3/h when pump assisted with drawdown of 140 to 170 m. The temperature of 53 C at the surface and the salinity of 0.41 g/l mean that the water can be used directly for domestic hot water supplies and after cooling, as drinking water. At present there are no plans for a reinjection well. Drilling a well in a city has meant taking special precautions particularly the construction of a wall as a baffle to reduce on-site noise level by 20 db. The first stage (50%) of the surface work, with heating at a pump-assisted flow-rate of 70 m3/h was completed in November 1982.The main heat exchanger at the well-head extracts 40 deg.C from the geothermal water which is then treated and channelled into the city's drinking water supply. From the heat exchanger a closed loop distribution network of buried pipes carries 215 m3/h of heated water to substations to which customers are connected in parallel. A supply temperature of 50 deg.C is guaranteed and an estimated return temperature of 20 deg.C is expected.A telemetry system has been installed to monitor information on the main functions such as starting temperatures, operating faults, electrical switching operations, pressures etc.. Program(-y) ENG-ENALT 1C - Programme (EEC) of financial support for projects to exploit alternative energy sources, 1979-1984 Temat(-y) 2.2 - HEATING Zaproszenie do składania wniosków Data not available System finansowania DEM - Demonstration contracts Koordynator SBRU Wkład UE Brak danych Adres TERR. DE FRONT DE MEDOC 9 33006 Bordeaux Francja Zobacz na mapie Koszt całkowity Brak danych
