Istituto di Geoscienze e Georisorse     
D'Amore F., Rivera J., Giusti D., Rossi R. Preliminary geochemical and thermodynamic assessment of the geothermal resources, Sulphur Springs Area, St. Lucia, W.I. In: Applied Geochemistry, vol. 5 (5-6) pp. 587 - 604. Elsevier, 1990.
A high-temperature geothermal resource has been located on the island of St Lucia (W.I.), which was tapped by means of a well drilled in 1988 to a total depth of 1410 m, in the Sulphur Springs area. The well encountered mainly dacitic agglomerates and lava flows and a permeable zone below ≈1340 m, with a maximum temperature of ≈290C. Well productivity decreased from an initial value close to 62 t/h to about 33 t/h under well-head pressures of 1.5 MPa (15 bar a) after 255 h of production. Initial reservoir static pressure was 7.5 MPa (75 bar a). A decline in reservoir pressure of about 15% was observed at the end of the production test. During the first two days of exploitation the well initially produced a two-phase fluid with high steam fraction, which then developed into superheated steam with a high content of non-condensable gas exceeding 100 1/kg at standard conditions and a computed P(CO2) of 1 MPa (10 bar). The average steam fraction at reservoir conditions, computed from gas composition after 120 h of production is 0.3. High HCl concentrations of about 300 ppm are present in the condensate steam indicating the presence of a high concentrated boiling brine to the point of halite saturation. All data support the hypthesis of a hydrothermal hot-water system prior to drilling, that underwent a very rapid drawdown with production.
URL: http://https://www.journals.elsevier.com/applied-geochemistry/
Subject geochemical thermometers
isotopic composition
waters: analytical data
geochemical prospecting

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