1. Current status of the high enthalpy conventional geothermal fields in Europe and the potential perspectives for their exploitation in terms of EGS A. Manzella CNR – IGG, Pisa, Italy Hervé Traineau CFG-Services, Orléans, France Olafur Flovenz ISOR, Grensásvegur, Iceland

2. The electrical energy production from geothermal power plants in Europe comes almost entirely from Iceland, Italy, Russia (Kamtchatka and Kuril islands), France (Guadeloupe, French West Indies), Portugal (Azores) and Turkey. Italy Iceland Turkey Portugal (Azores) Russia (Kamtchatka and Kuril islands) France (Guadeloupe, French West Indies)

3. France n Volcanic island (Guadaloupe, French West Indies) n Brines with 60% seawater, 40% meteoric waters n Temperature of 250-260°C intersected by wells at 300-1000 m depth n 4MW in Bouillante 1 on 1995-1996, 11MW on 2004, for a total of 15 MW with 2 power plants n Exploration recognized a large extension of the reservoir. Third unit in the pre-fesibility phase n Two other islands (Martinique and La Réunion) in exploration

4. Iceland n Volcanic scenario, active rifting. Large active volcanic zone running SW-NE n Various heat sources (dikes or magma chamber) and fluids: seawater, meteoric water with/without volcanic gases n Water-dominated, > 300°C at 2.5 km depth n Natural recharge and reinjection

5. Iceland n Bjarnarflag on 1969, then Krafla, Nesjavellir and Svartsengi n 2 new power plants in 2006 and 2007 for 220 MWe in Hengill area n 7 new production field: 3 in N- Iceland, 1 central, 3 in the S 120 MW

6. Iceland Min. casing depth Target depth In addition there are plans to develop Unconventional Geothermal Systems. The main idea is to drill deep enough into the intrusion complexes of the volcanic systems to get supercritical fluids and exploit the enormous energy stored in the depth interval 3-5 km within the volcanic systems. The Iceland Deep Drilling Project is a part of these plans (see www.iddp.is). www.iddp.is)

7. Italy 2 exploited areas (Larderello-Travale/Radicondoli and Mt. Amiata) in one region (Latera decommisioned) 2 exploited areas (Larderello-Travale/Radicondoli and Mt. Amiata) in one region (Latera decommisioned) A shallow reservoir in carbonatic, a deeper reservoir in metamorphic units A shallow reservoir in carbonatic, a deeper reservoir in metamorphic units Steam dominated in Larderello-T/R, water dominated in Mt. Amiata (extinct volcano) Steam dominated in Larderello-T/R, water dominated in Mt. Amiata (extinct volcano) 20 MPa and 300-350°C at 3 km 20 MPa and 300-350°C at 3 km

8. Italy Larderello-T/R in 400 km2, 202 wells, 27 units, 702 MW installed capacity, reinjection Larderello-T/R in 400 km2, 202 wells, 27 units, 702 MW installed capacity, reinjection Mt. Amiata 5 units, 88 MW, reinjection Mt. Amiata 5 units, 88 MW, reinjection 1° experiment worldwide 1904, 1° production in 1913, increase of production (apart 2nd WW period) 1° experiment worldwide 1904, 1° production in 1913, increase of production (apart 2nd WW period) Reinjection and deep exploration in the ’70, when field started to deplate. New rapid increase of production Reinjection and deep exploration in the ’70, when field started to deplate. New rapid increase of production Increase of 100 MW foreseen in 5 years Increase of 100 MW foreseen in 5 years

9. Portugal Azores volcanic islands, São Miguel Azores volcanic islands, São Miguel 2 Power plants, 16 MW 2 Power plants, 16 MW 1 new power plant for 10 MW 1 new power plant for 10 MW Exploratin on-going in Terceira island, project for 12 MW by 2008 (50% energy of island) Exploratin on-going in Terceira island, project for 12 MW by 2008 (50% energy of island)

10. Russia 1 – suitable for heat pumps; 2 – promising for “direct” utilization; 3 – regions of active volcanism, power generation at binary plants / high capacity GeoPP Areas of active volcanism, Kamchatka and Kuril Islands Areas of active volcanism, Kamchatka and Kuril Islands 2 reservoirs, vapour and water dominated fields, 250-310°C 2 reservoirs, vapour and water dominated fields, 250-310°C

11. In Kamchatka 3 power plants, 73 MW installed capacity. 106 MW under development In Kamchatka 3 power plants, 73 MW installed capacity. 106 MW under development In Kuril Island 6 MW installed capacity, foreseen increase of 14MW In Kuril Island 6 MW installed capacity, foreseen increase of 14MW Russia

12. Turkey Kizildere geothermal field, active tectonic setting Kizildere geothermal field, active tectonic setting Shallow reservoir in limestones and marble (195-205 °C at 600- 800 m) and deep reservoir in gneiss (240 °C at 1.5 km) Shallow reservoir in limestones and marble (195-205 °C at 600- 800 m) and deep reservoir in gneiss (240 °C at 1.5 km) liquid CO 2 and dry ice production factory liquid CO 2 and dry ice production factory

13. Turkey Discovered in 1968, productive since 1984, 20.4 MW of installed capacity, 12-15 MW running capacity Discovered in 1968, productive since 1984, 20.4 MW of installed capacity, 12-15 MW running capacity Reinjection test with positive results. Reinjection wuld solve the decline of production and the pollution due to waste water Reinjection test with positive results. Reinjection wuld solve the decline of production and the pollution due to waste water

14. EUROPE

15. EUROPE

16. EGS techniques and how they could improve high enthalpy geothermal fields Different ways have been tested or are imagined for enhancing and broadening geothermal energy reserves which can be classified into Unconventional Geothermal Resources, i.e. mainly Enhanced Geothermal Systems (EGS) and Supercritical Reservoirs: stimulating reservoirs in Hot Dry Rock systems, stimulating reservoirs in Hot Dry Rock systems, enlarging the extent of productive geothermal fields by enhancing/stimulating permeability in the vicinity of naturally permeable rocks, enlarging the extent of productive geothermal fields by enhancing/stimulating permeability in the vicinity of naturally permeable rocks, enhancing the viability of current and potential hydrothermal areas by stimulation technology and improving thermodynamic cycles, enhancing the viability of current and potential hydrothermal areas by stimulation technology and improving thermodynamic cycles, defining new targets and new tools for reaching supercritical fluid systems, especially high-temperature downhole tools and instruments, defining new targets and new tools for reaching supercritical fluid systems, especially high-temperature downhole tools and instruments, improving drilling and reservoir assessment technology, improving drilling and reservoir assessment technology, improving exploration methods for deep geothermal resources. improving exploration methods for deep geothermal resources.

17. Well stimulation methods to improve permeability of poor-producer wells are the most common among the technologies derived from EGS and applied to conventional fields. They were successfully applied in Italy, Guadeloupe and could be profitably applied in other fields, wherever the permeability appears reduced and for broadening the reservoirs. This would correspond to a potential increase of exploitation and hence of power production, and at the same time the sustainability of resources would be guaranteed. Tracer tests are now becoming a tool for detection of reservoir volume and prevent strong interference between wells, in particular during reinjection. They have been applied in Turkey, Iceland and may provide useful information in all the exploited fields. Efficient scale inhibitors to prevent scaling in wells and surface pipes are becoming very important for the maintenance of exploitation. High enthalpy fields are the obvious base for the exploitation of supercritical fluids, which can be found in these fields at drillable depths. High enthalpy steam produced by these fluids would generate a much higher electric power than conventional geothermal wells.

18. Improved geophysical imaging tools to determine the extent of faulted reservoirs as well as integrated reservoir modelling have been developed during the EGS experiments. Their application to conventional system may provide a new insight in geothermal structures that are, by definition, very complex. Time lapse geophysical measurements have proved to be particularly effective in exploring and monitoring the dynamic of EGS, but their application is not common in conventional fields. The improvement of technology and reduction of costs are making them particularly attractive in any kind of geothermal system. The combination of different data through integrated modelling are helping in defining both static and dynamic geothermal features and should be applied in all fields to reduce the mining risks and improve the control of the system.

19. However, the importance of high enthalpy fields is not only restricted to themselves, but to the entire geothermal scenario. These fields should be considered as ideal laboratories for experimenting new ideas for geothermal exploitation, since the more accessible depth of interesting temperatures would decrease the cost of the experiment, being the drilling usually the most expensive part of geothermal exploitation. Moreover, long-exploited fields such as in Italy and Iceland, where a huge amount of data is already available, may serve as demonstration plants for a variety of tests in order to improve the reservoir assessment technology and the exploration methods.