1. Geothermal Development in the Caribbean and EGS Perspectives ENGINE Launching Conference – Orléans, Feb. 12 th to 15 th, 2006 H. Traineau, B. Herbrich, E. Lasne, D. Tournaye CFG Services, 3 av. Cl. Guillemin 45064-Orléans cedex 2 – France A. Genter, B. Sanjuan BRGM, 3 av. Cl. Guillemin, 45060-Orléans cedex 2 - France Geothermal Development in the Volcanic Caribbean Islands and EGS Perspectives

2. Geothermal Development in the Caribbean and EGS Perspectives ENGINE Launching Conference – Orléans, Feb. 12 th to 15 th, 2006 Map of the Caribbean volcanic islands ( red color ) and their active or recent volcanoes. Subduction of the Atlantic Plate below the Caribbean Plate

3. Geothermal Development in the Caribbean and EGS Perspectives ENGINE Launching Conference – Orléans, Feb. 12 th to 15 th, 2006 Energy in the Caribbean -More than 90% of electricity comes from fossils fuels; -Low contribution of Renewable energy sources : -Electricity needs increase by 4-5% every year. - Biomass - Hydro - Solar - Wind - Geothermal

4. Geothermal Development in the Caribbean and EGS Perspectives ENGINE Launching Conference – Orléans, Feb. 12 th to 15 th, 2006 Volcanic Islands SurveyPre- feasibility Deep drillings Installed capacity (MWe) Expected Potential (MWe) Saba yes St Eustatius yes St Kitts yes Nevis yes 10 - 50 Montserrat yes Guadeloupe yes 1530 - 50 Dominica yes 50 -100 Martinique yes Ste Lucia yes 10 - 50 St Vincent yes Grenada yes

5. Geothermal Development in the Caribbean and EGS Perspectives ENGINE Launching Conference – Orléans, Feb. 12 th to 15 th, 2006 Geothermal resources might contribute to power generation in some islands instead of fossil fuels Bouillante, the case history in Caribbean Dominica, the most promising geothermal potential

6. Geothermal Development in the Caribbean and EGS Perspectives ENGINE Launching Conference – Orléans, Feb. 12 th to 15 th, 2006 The Bouillante geothermal field, Guadeloupe Urban area Steep topography area Sea proximity

7. Geothermal Development in the Caribbean and EGS Perspectives ENGINE Launching Conference – Orléans, Feb. 12 th to 15 th, 2006 The story of the Bouillante geothermal exploitation

8. Geothermal Development in the Caribbean and EGS Perspectives ENGINE Launching Conference – Orléans, Feb. 12 th to 15 th, 2006 - Several recent eruptive centers (<1 MA) around the Bouillante Bay, with the possible occurrence of shallow magmatic intrusion under cooling; - Several main normal faults which promote permeability and fluid circulations at depth and represent potential fractured reservoirs; - Only a part of the reservoir is now exploited through BO-4 vertical production well, BO-5 and BO-6 deviated and inclined production wells which intersect the Cocagne Fault. The Bouillante geothermal field

9. Geothermal Development in the Caribbean and EGS Perspectives ENGINE Launching Conference – Orléans, Feb. 12 th to 15 th, 2006 Simplified model of fluid circulations in the Bouillante geothermal reservoir Simplified cross-section along a West-East profile within the Bouillante geothermal field showing the assumed model of fluid circulation with seawater and rainfall recharge, mixing (60% seawater + 40% rainfall) and heating to 250-270°C.

10. Geothermal Development in the Caribbean and EGS Perspectives ENGINE Launching Conference – Orléans, Feb. 12 th to 15 th, 2006 Selected temperature profiles in the Bouillante wells. 240°C at shallow level (well BO-2) Reservoir temperature around 250°C

11. Geothermal Development in the Caribbean and EGS Perspectives ENGINE Launching Conference – Orléans, Feb. 12 th to 15 th, 2006 Cross-section along a NW-SE profile showing well trajectories, location and quality of permeable zones in relation with faults deduced from surface geology. - Only the Cocagne Fault appears to be highly permeable. - Plateau Fault shows low permeability. - Descoudes Fault has no permeability possibly due to carbonates scaling

12. Geothermal Development in the Caribbean and EGS Perspectives ENGINE Launching Conference – Orléans, Feb. 12 th to 15 th, 2006 High temperature conditions at shallow depth (< 1000 m deep) but strong anisotropy in permeability related to fracture network and possibly to scaling (carbonates, silica). Main characteristics of the 7 deep wells drilled at Bouillante WellYearTrajectoryTotal length (m) Bottom hole T (°C) Result BO-11969vertical850(225) No HP production BO-21970vertical350245-250Producer BO-31970vertical850(245) No HP production BO-41974-77vertical2 500250Low producer (Stimulation needed) BO-52001deviated1 197250Good producer BO-62001deviated1 248250Good producer BO-72001deviated1 400240 No HP production

13. Geothermal Development in the Caribbean and EGS Perspectives ENGINE Launching Conference – Orléans, Feb. 12 th to 15 th, 2006 High temperature conditions at shallow depth (< 1000 m deep) but strong anisotropy in permeability related to fracture network and possibly to scaling (carbonates, silica). Main characteristic of the 7 deep wells drilled at Bouillante WellYearTrajectoryTotal length (m) Bottom hole T (°C) Result BO-11969vertical850(225) No HP production BO-21970vertical350245-250Producer BO-31970vertical850(245) No HP production BO-41974-77vertical2 500250Low producer (Stimulation needed) BO-52001deviated1 197250Good producer BO-62001deviated1 248250Good producer BO-72001deviated1 400240 No HP production Extension of EGS methods might be addressed first to accurate location of faults within the high temperature, fracture-permeable reservoir.

14. Geothermal Development in the Caribbean and EGS Perspectives ENGINE Launching Conference – Orléans, Feb. 12 th to 15 th, 2006 Stimulation of the low productive well BO-4 A limited, low cost experiment with cold seawater injected into the well BO-4 has been conducted from August 10 - 27, 1998 to enhance the secondary permeability through thermal cracking. Productivity increases by 50% and fluid discharge is more stable.

15. Geothermal Development in the Caribbean and EGS Perspectives ENGINE Launching Conference – Orléans, Feb. 12 th to 15 th, 2006 Stimulation of the low productive well BO-4 A limited, low cost experiment with cold seawater injected into the well in steps has been conducted from August 10 - 27, 1998 to enhance the secondary permeability through thermal cracking. Productivity increases by 50% and fluid discharge is more stable. Extension of EGS methods could be very useful to improve permeability of low producers.

16. Geothermal Development in the Caribbean and EGS Perspectives ENGINE Launching Conference – Orléans, Feb. 12 th to 15 th, 2006 The location of the plant within the city induced strong environmental constraints (no noise, no steam plume, …). Aerial view of the geothermal plant located within the city Bouillante 1 Unit (4,5 MWe) Bouillante 2 Unit (11 MWe)

17. Geothermal Development in the Caribbean and EGS Perspectives ENGINE Launching Conference – Orléans, Feb. 12 th to 15 th, 2006 Steep topography and urban area reduce land availability for well pads, pipe routes, etc…, and consequently may hinder best locations for production and reinjection zones. Aerial view of the well pad and the pipe route.

18. Geothermal Development in the Caribbean and EGS Perspectives ENGINE Launching Conference – Orléans, Feb. 12 th to 15 th, 2006 Sea proximity also reduces surface availability for well siting and might require to reduce distances between production and reinjection zones. Bouillante

19. Geothermal Development in the Caribbean and EGS Perspectives ENGINE Launching Conference – Orléans, Feb. 12 th to 15 th, 2006 Sea proximity also reduces surface availability for well siting and might require to reduce distances between production and reinjection zones. Extension of EGS methods could be very useful to improve and secure reservoir monitoring and exploitation (tracer tests, …) Bouillante

20. Geothermal Development in the Caribbean and EGS Perspectives ENGINE Launching Conference – Orléans, Feb. 12 th to 15 th, 2006 Dominica Island Two promising high enthalpy geothermal fields with abundant surface manifestations, related to very recent volcanic activity. Wotten Waven Soufriere Valley of Desolation

21. Geothermal Development in the Caribbean and EGS Perspectives ENGINE Launching Conference – Orléans, Feb. 12 th to 15 th, 2006 Dominica Island Development of geothermal resources in Dominica and reservoir exploitation will face similar problems as experienced in Guadeloupe (remote location, steep topography, national park, …) Valley of Desolation Micotrin lava dome Wotten Waven

22. Geothermal Development in the Caribbean and EGS Perspectives ENGINE Launching Conference – Orléans, Feb. 12 th to 15 th, 2006 Conceptual model of the Wotten Waven geothermal reservoir(s) with inferred location of deep chloride reservoirs and fluid flow pattern.

23. Geothermal Development in the Caribbean and EGS Perspectives ENGINE Launching Conference – Orléans, Feb. 12 th to 15 th, 2006 Permeability within the basement is provided by fault networks. Faults will be the main targets for well siting. Rose diagram of fractures recorded on the field

24. Geothermal Development in the Caribbean and EGS Perspectives ENGINE Launching Conference – Orléans, Feb. 12 th to 15 th, 2006 Volcanic islands in the Caribbean have proved or expected high enthalpy geothermal resources which could be used for electricity production. Due to their location, Bouillante and other fields (will) have to face problems related to : - Permeability anisotropy within the geothermal reservoir; wells have to intersect main faults in order to be good producers; - Steep topography and limited land availability for well pad, pipe routes,…; - Environmental constraints due to urban areas or national park; - Remote location (extra costs for survey, drilling, logging, stimulation and work over operations, plant maintenance,…); -Limited size of the exploitation and limited financial capacity of geothermal operators; CONCLUSIONS

25. Geothermal Development in the Caribbean and EGS Perspectives ENGINE Launching Conference – Orléans, Feb. 12 th to 15 th, 2006 Some problems could be addressed by EGS methods to promote development of their geothermal resources : - Accurate location of fault network; - Permeability improvement through well stimulation; - Reservoir monitoring (tracer tests, logging); - Management of close production and reinjection zone; - …. EGS PERSPECTIVES