Geochemical Monitoring of the Thermal Manifestations Located Near the Bouillante Geothermal Power Plant, in Guadeloupe (FWI)

The Bouillante high-temperature geothermal field, 250-260 °C, is developed around the Bouillante Bay along the western coast of Basse-Terre Island, in Guadeloupe (French West Indies, FWI). Since 2005, the new geothermal power plant has an installed capacity of 15.5 MWe gross, which represents about 6-7% of the annual electricity needs in the Island.Among the research efforts carried out by the BRGM group and partially funded by ADEME (French Environment and Energy Management Agency), different geophysical and geochemical monitoring methods of the geothermal exploitation have been started, tested and developed1in order to optimize and secure electricity production and to control its impact on the immediate environment of the power plant. This is especially important because the power plant is located inside the Bouillante town. Among these methods, this paperpresents the main results and conclusions obtained for the geochemical monitoring of the terrestrial thermal manifestations located near the geothermal power plant. This study shows that, except for the “Tuyau” hot water,located inside the main production area and for which the steam contribution increases and salinity decreases when the power plant is in production (decreasing reservoir pressure), no significant geochemical change depending on the geothermal exploitation is observed in the fluids of the other terrestrial thermal manifestations. Consequently, the quality of the thermal waters of the Bouillante area can be considered as not damaged by the geothermal exploitation.