| Abstract |
The Bouillante geothermal field is developed around the Bouillante Bay along the western coast of Basse-Terre Island, Guadeloupe, F.W.I. The total installed capacity is 15 MWe. The steam field includes two producers (wells BO-5, BO-6), one injector (well BO-2) and two observation wells (BO-4, BO-7). A detailed monitoring of the reservoir has been done since 2002. The main recorded parameters are: production and reinjection flow rates, dynamic wellhead pressures and static wellhead pressures. In addition, a geochemical monitoring of the fluids extracted from the reservoir is carried out regularly. P and T profiles have been done several times since 1998. No production-induced chemical change has been observed in Cl content, NCG content and other major elements after 15 years of exploitation. The temperature profiles show no temperature decline through time. This suggests that the nowadays exploited area is probably part of a larger reservoir with a rather uniform fluid chemical composition. The pressure drawdown within the reservoir has been limited to about 5 bars. It appears to be closely related to the total mass of extracted fluid as shown by the lumped modeling of pressure decline using LUMPFIT. The best history matching is obtained by considering an open, double-tank reservoir with natural recharge. Prediction model of reservoir pressure decline in response to fluid extraction is now used as a routine tool by the plant staff. Benefits of brine reinjection in reservoir pressure support and enhancing energy extraction have not been assessed yet. In order to prevent silica scaling, the minimum reinjection temperature in well BO-2 has been set at 163°C corresponding to an ASSI Index of 0,9. This also reduces the risk of cold-front breakthrough and cooling of production wells which are rather close to the injection well BO-2, due to local topographic and environmental constraints. |