Objective
Use of geothermal energy for space heating in a north suburb of Madrid. The detritic formations to be tapped lie between 1500-2000 m depth. Reservoir characteristics are : 250 m thickness-40 d. m transmissivity -250 m3/h pump assisted flowrate. The high water salinity implies to reinject geothermal brine after cooling. Production well will be vertical and reinjection well deviated from the same platform to ensure adequate spacing. Geoheat will be exploited by means of titanium exchanger for space heating and sanitary hot water before being used for agricultural purpose (greenhouses), in order to achieve a full use of the available geothermal capacity.
The production well is successful and has reached productive sandy reservoir. The geothermal fluid lacks H2S and the gas/water ratio is 2% in volume. CO2 content limited to 2,5% and estimated bubble point of 1 bar appears very favourable.
These results and geological cross section suggest to drill the second well deeper (220 m) to have a higher temperature (80 deg. C) in the reservoir.
An injection test has been done on core taken during drilling in order to estimate the permeability, the behaviour of clays, the type of chemical stabilizers to avoid plugging problems and to prepare the design of the filtering surface installations.
The production well has been drilled between July and September 1990 to a total depth of 2000 m. The reservoir crossed between 1580 and 2000 m is made of alternating levels of green compacted clays and medium fine grained sands of Tertiary formations.
Reservoir characteristics are :
- productive thickness : 100 m
- porosity : 15-19%
- transmissivity : 45 D.m
- temperature : 75-76 deg. C
- salinity : 20-25 g/l
- static level : 150 m/ground level
A pumping test carried out with a submerged pump indicate a possible exploitation at 200 m3/h with a 200 m drawdown.
Due to the salinity of the geothermal water and to maintain a sufficient exploitation pressure, it is necessary to drill an injection well. The calculated spacing between the two wells will be about 1000 m to prevent a decreasing temperature while exploiting during 30 years.
Assuming an injection temperature of 35 deg. C, the "doublet" will provide 97% of enery need for sanitary hot water production (2955 TOE)
Topic(s)
Call for proposal
Data not availableFunding Scheme
DEM - Demonstration contractsCoordinator
28015 Madrid
Spain