Objective
The supply of geothermal heat to the district heating network to be set-up in Mons, using the existing St Ghislain geothermal well (74 C; artesian flow-rate - 95 m3/h; pump assisted flow - 200 m3/h) and a planned second well in Ghlin.
The project is also intended to:
- prove the extension of the Visean productive reservoir in the Mons - St Ghislain area;
- to allow a 400 m3/h flow-rate in Ghlin: this will provide a central heating station by means of heat exchangers and heat pump.
No injection well is required due to the low salt content.
Expected savings related to the new geothermal well are 3,700 TOE/yr: payback (excluding financial costs) is 8 years. The connection between St Ghislain and Ghlin geothermal network will give annual saving of 4,800 TOE.
From a hydro-geological point of view the project is successful, despite the absence of any use for the geothermal water. Reservoir continuity has been proved, while the presumed size of the Visean Karst tends to indicate that ten or more similar wells could be realized in this area, with no adverse impact on the hydrodynamics of the aquifer, which displays exceptional potential (100 m3/h normal artesian flow-rate). With salinity of less than 2 g/l no injection well is required.
Drilling at Ghlin was completed to a depth of 1,579 m in June and July 1981. The initial drilling was vertical until a permeable limestone formation was reached at 1580 m where total losses occurred. The jamming of a tool (loss of 250 m of drilling stems) meant a side-tracking at 1,298 m. The Visean karst was traversed between 1,452 and 1573 m where total losses were incurred. A 7" 5/8 liner was installed between 1,175 and 1,516 m with a 6" 3/4 open hole left from 1,516 to 1,579 m. The test carried out with air lift gave the following result:
stabilised air-lift flow rate : 160 m3/h
temperature : 70 C
salinity : below 1.5 g/l artesian pressure - 5 bars
roughly stabilised artesian flow-rate : approximately 100 m3/h
maximum pump-assisted flow-rate : between 250 m3/h and 300 m3/h.
Long-term trials with pressure build-up, between April and June 1983 showed that the artesian flow-rate declines over time in correlation to a limit effect for the highly permeable karst zone.
Transmissivity, as measured from the pressure build-up curve is 35 D.m. for the reservoir.
Programme(s)
Topic(s)
Call for proposal
Data not availableFunding Scheme
DEM - Demonstration contractsCoordinator
QUAREGNON
Belgium