| Title | Reservoir Cooling After 25 Years of Heat Production in the Lund Geothermal Heat Pump Project |
|---|---|
| Authors | Leif Bjelm and Per-Gunnar Alm |
| Year | 2010 |
| Conference | World Geothermal Congress |
| Keywords | Reservoir cooling, long term thermal development, direct use, logging, reflection seismic interpretation |
| Abstract | After 25 years of heat extraction and reinjection of cold water to the reservoir the expected cooling is now at hand. About 550 l/s is extracted from 4 wells and subsequently reinjected into 5 wells. Yearly about 250 GWh of heat energy is produced to the district heating net. The distance between the production and injection areas is about 2 km. The reservoir is an unconsolidated sandstone of Cretaceous age. It is a confined reservoir with a thickness of several hundred meters. The deposit is part of a complex delta formation sitting close to a major tectonic feature, which was active while sedimentation was going on. The last few years repeated temperature and flowmeter logging has been carried out in the wells in order to evaluate the distribution of cold water within the reservoir. The cold water migration seems to follow certain layers within the delta deposit. A high-resolution reflection seismic campaign has recently been carried out and it is now possible to compare the layering revealed by seismic data and thermal layering determined by borehole logging. Also the thermo-hydraulic development after 25 years of use of the reservoir is discussed. |