GEOTHERMAL WELL AND LOW TEMPERATURE DISTRICT HEATING IN CASTELJALOUX (FRANCE)

Objetivo

To use geothermal energy to heat public facilities and buildings in a small town (population 5000) 100 km south east of Bordeaux. The primary target is a 45-50 deg groundwater reservoir located in Jurassio limestone at a depth of 1230 m. A flowrate of 70 to 100 m3 per hour of water with very low salinity (3-5 g/l) is expected. Consequently, no reinjection well will be needed. The water will be distributed to the individual consumers via a two-channel PVC network before discharge into a small river. All new buildings constructed will be designed for fully geothermal heating. The water could also be used at a spa resort.
Start of drilling : 26 March 1990.
After installation of the well-head casing down to 13 m, the well was drilled down to 161 m (through Tertiary clay and sandstone) and 13 3/8" casing was
fitted. Between 375 and 450 m, a thick silicious gravel formation (aquifer) was struck.
9 5/8" casing was installed down to 940 m (Dolomite limestone).
Drilling between 940 and 1237 struck no further water. No casing was installed at this depth.
End of drilling : 11 May 1990.
Results of long-term pumping
- static level : 44 m underground;
- dynamic level after 266 hours' pumping at 36 m3/hour : 77.26 m underground;
- specific flowrate : 1082 m3/m
- transmissivity : 8.9 x 0,0001 m2/g;
- clear water temperature : 42.5 deg. C
Preliminary analysis of the water (by the Bordeaux laboratory)
Water containing calcium sulphate and bicarbonate and sodium chloride and with a high iron content.
Conclusions :
Before considering applications for the geothermal well, a simulation will have to be conducted to check whether the thermal and economic studies are confirmed by the results in practice.
A. SUBSURFACE INVESTIGATION : Based on the geological data about the surface and subsurface obtained from reference wells in the region (AEP sources or drilling, oil and gas wells and geotechnical probes), a prediction of the geological cross sections will be made to assess the depth to which the well must be drilled.
- Forecasts of the nature of the reservoir, operating conditions and of the composition of the water. B. DRILLING PROGRAMME : After completion of the platform, the deep well is predicted to have the following characteristics :
- from 0 to 10 metres : drilling of the well head and cementing of 500 mm casing;
- 10-150 metres : vertical drilling with bentonite mud, 13 3/8" casing and cementing;
- 150-1020 metres : rotary drilling with bentonite mud, 9 5/8" casing and cementing;
- 1020-1230 metres : directional drilling with polymer mud and vertical drilling with a diameter of 8 1/2".
After drilling : wire logging, flowmeter survey, thermometry, tests and analyses.
C. SURFACE INVESTIGATIONS : Based on these predictions of the quantity and quality of the water, an inventory of potential users will be compiled, ways of operating the wells will be studied and additional uses will be considered for the water, wether hot or after cooling.

Programa(s)

ENG-ENDEMO C - Programme (EEC) of demonstration projects and industrial pilot projects (EEC) in the energy field, 1985-1989

Tema(s)

4.1 - HEATING

Convocatoria de propuestas

Data not available

Régimen de financiación

DEM - Demonstration contracts

Coordinador

MAIRIE DE CASTELJALOUX

Aportación de la UE

Sin datos

Dirección

47700 CASTELJALOUX
Francia

Coste total