Successful Discovery Drilling in Roseau Valley, Commonwealth of Dominica

A study completed by the French geological survey, Bureau de Recherches Géologiques et Minières (BRGM), in 1984 suggested the existence of a large geothermal reservoir in the Wotten Waven and Laudat areas of the Roseau Valley (BRGM, 1984). Many surface manifestations are apparent, including hot and warm springs, solfatara, and fumaroles, which produce sodium-chloride water, and exhibit strong 18O isotopic shifts and geothermometer temperatures exceeding 230°C. The possible extent of the system over an area of approximately 8 km2 was delineated by complimentary resistivity and gravity surveys.

In 2012, the Geothermal Program Management Unit (GPMU) of the Commonwealth of Dominica successfully completed exploration drilling in the Roseau Valley Geothermal Field. Three slim holes were drilled to depths ranging from 1200 m to 1613 m. All of the wells completed in 2012 were productive, with the strongest exhibiting flow rates up to 29 kg/s at a wellhead pressure of 17.5 barg. Measured temperatures, as high as 246°C and in agreement with earlier BRGM exploration, are accompanied by neutral pH, low salinity fluids. ELC Electroconsult S.p.A (ELC) evaluated the results of the well tests and provided a preliminary volumetric reservoir assessment, using a Monte Carlo approach, estimating indicated and inferred potentials of 60 MW and 90 MW, with probabilities of 90% and 60%, respectively. Aside from providing technical assistance from 2009 to 2013, ELC also selected the well sites for WW-1, WW-2, and WW-3. Development of the Roseau Valley geothermal resource is continuing in 2014 with the drilling of full-size production and injection wells, and feasibility studies for the construction of a 10-15 MW power plant.

View Full Document