Stratigraphy, Temperature Profiles, and Flow Test Data from the PLTG-1 and PLTG-2 Coreholes, Platanares Geothermal System, Honduras

摘要

Stratigraphy, temperature profiles, and flow test data from the PLTG-1 and PLTG-2 coreholes in Platanares, Honduras, have been used to determine production characteristics from a 160 deg C fluid zone at 625 to 640 m depth and to estimate depth to the source geothermal reservoir. The two coreholes penetrate thin Quaternary deposits and several hundred meters of Miocene volcanics and Cretaceous to Eocene sedimentary rocks. Extrapolation of the deep thermal gradient of 139 deg C/km in PLTG-2 (depth 401 m) indicates the source reservoir of 220 to 240 deg C fluid occurs at 1.2 to 1.5 km depth. Flow tests of PLTG-1 from the 625 to 640 m zone show that 160 sup 0 C geothermal fluids similar in composition to ''end-member'' hot springs originate from fractured meta-conglomerates of the Valle de Angeles Group. Pressure transient analysis indicates this flow zone taps a localized reservoir having a volume on the order of 0.065 km sup 3 . Maximum thermal power of PLTG-1 is roughly 3 MW/sub t/. Scaling of aragonite results from flashing of the dilute, high pH, high HCO sub 3 fluid. Use of the shallow, 160 deg C resource will require binary cycle power plants and, possibly, downhole pumps to successfully extract heat from the fluids for electrical applications. (ERA citation 12:045282)