November 10, 2009
Notice: This article is dedicated to 500th fan of Geothermania on Facebook – Ms. Maria Leitnerova.
From the west to the east, from Sweden to France – hot dry rocks are not just some stones somewhere on the beach, hot due to sunlight, but as we wrote before, Hot Dry Rock (HDR) is also the synonym for geothermal energy utilization – thanks to EGS and establishing engineered closed geothermal water loop.
Let‘s look closer at the most famous „hot rocks“ in Europe, which mean for HDR research and development the milestones:
- Rosemanowes Quarry in Britain,
- European HDR Project Soultz in France,
- Le Mayet in France,
- Fjällbacka in Sweden,
- Falkenberg in Germany,
- Bad Urach in Germany.
Before the summer, our team organized geothermal trip thorough Europe. One among the stops was Soultz-sous-Forets (European HDR Project Soultz) in France. This one is well known as the „Mecca“ of geothermal research, so our personal expectations were naturally very high. On the other hand, we must state that we found not satisfactory level of HDR development there. We were quite disappointed due to „non-engineered“ approach to stimulation of the heat exchanger. It is left to the natural conditions typical for that area. In Soultz, there are no real HDR geothermal systems, only classical hydro-thermal facilities.
Now some general facts to HDR project in Soultz. There are two drilling platforms there: GPK1 and GPK2/3/4. The first one was accomplished between 1987 – 1997 and the wells are 3590 and 3876 meters deep. In 1998 the second platform started to be drilled. To this time, there is one injection well (GPK3) and two production ones (GPK2 and GPK4) – all with the depth of five kilometers (finished in 2008). The natural fractured rocks had been discovered in depth of 3900 m, with the temperature exceeding 165 Celsius degrees. Now, in5 km depth, the temperature reachs 200 Celsius degrees.
This is one of the first geothermal test projects in Europe ever. All began in 1977 and ran for next 15 years. This one was second focused on studying the techniques for engineering the reservoir. The main question was whether the HDR technology can be made to work at all. Thanks to 15 years of studies in Britain, Rosemanowes Quarry proved it works. In addition it provided a lot of useful information about deep crystalline rock masses.
The initial phase‘s aim was to drill four 300 m deep wells. Then, two 2 km deep boreholes followed. After 6 years of operation and poor performance of reservoir, the spiraling boreholes were drilled to depth of 2,5 km. They established closed water loop through the reservoir with relatively low losses (20 percent). Afterwards, from 1986 to 1988 the long-term circulation test were made. The final phase (1988 – 1992) was focused mainly on small scale viscous stimulations.
The R&D project in Cornwall was financed by UK government under UK HDR Programme. It was administrated mainly by Camborne School of Mines at Rosemanowes Quarry in Cornwall. In addition, also British Geological Survey, Sunderland Polytechnic, Taylor Woodrow Construction Limited and RTZ Consultants Limited attended.
Le Mayet de Montagne
The next from the HDR experimental projects is located not far from Vichy in France. It composed of two almost vertical wells with depths of 780 m and 840 m. The main aims were the studies of long-term water circulation as well as the studies of high flow rate (20 – 30 liters per second) stimulation of selected intervals conventional hydraulic fracturing (hydrofrac) stimulation, which means the flow about 73 liters per second. In addition, also the microseismic activities and their impact had been monitored. Other part of research was the installation of array of tilt-meters that monitored the surface deformation caused by fluid injection. The project was in operational phase from 1978 to 1989.
… to be continued (part 2 on Friday).Author : geothermania