The European HDR Programme: Main Targets and Results of the Deepening of the Well GPK2 to 5000m

Abstract

In 1997 a circulation test was carried out at the European HDR Project in Soultz-sous-ForÍts which showed that it was possible to circulate at around 25 l/s between two deep wells in the depth range of 3000-3500 m and a separation of about 450 m. The test lasted for about 4 months and produced excellent results but it was observed that although the heat produced was sufficient for space heating (140-150?C, 10 MWth), the temperature was not sufficiently high for electricity generation at an economic rate. Both the funding agencies and the industrial consortium felt that heat production by HDR at around 200?C was more attractive for electricity generation and therefore it was decided to extend an existing deep well GPK2 to a depth of around 5000 m to access the required temperature. Scientific investigation was carried out to characterise the rock mass at great depth and assess if they would be as favourable as found for the successful circulation test at 3000-3500 m in 1997. The targets and the preliminary scientific data obtained during and after the deepening of GPK2 are also described.