New Mexico Geological Society Annual Spring Meeting — Abstracts

The Masson Radium Springs Farm is the largest geothermally-heated greenhouse in the United States with 30 acres (121,1406 m² or 12 hectares) of enclosed crop growing space. Three large diameter production wells supply up to 3,000 gpm (189 L/s) of 190 to 200 °F (87.8 to 93.3 °C) fluid to plate-and-frame heat exchangers that transfer heat to a massive closed-loop fresh water heating system of bare pipe heat and radiant floor heat. Three large diameter injection wells gravity feed cooled geothermal fluids piped from the surface plate-and-frame heat exchangers back to the natural geothermal flow regime. In 1986, the initial 4 acres (16,187 m² or 1.6 hectares) of greenhouse were supplied by two shallow productions wells completed in a highly-fractured and a shallow-angle, north-dipping Oligocene rhyolite dike. After heat exchange, the cooled fluids were returned to the fractured rhyolite via injection wells completed at distances between 300 and 800 ft (91.4 and 243.8 m) from the production wells. After several years, the production wells began to show cooling with thermal break- through from closely-located injection wells as the greenhouse grew in acreage and geothermal well production volume. In 2000, a large diameter production well was drilled across the fractured rhyolite and the confining Eocene andesitic volcanoclastic lahar unit of Palm Park Formation into the Permian Hueco Formation consisting of fractured limestone with solution permeability. The structural geometry provided a solution to the problem of thermal breakthrough as the Palm Park Formation provided a local barrier between hot upwelling fluid in the rhyolite and Hueco Formation. Upflow in the rhyolite is supplied by the Hueco Formation in the subsurface at an estimated distance of >3,500 ft (>2,750 m) north of the greenhouse. All geothermal production was transferred to the deep parent confined Hueco Formation reservoir and the injection was applied to the rhyolite to complete the short circuit of the natural flow path by tapping the deep reservoir for production. Drawdown provides hydraulic conductivity information for the deep confined carbonate reservoir. The production wells in the fractured limestone show an average transmissivity of 28,000 ft²/d. A nearby down-to-the-west Pleistocene fault forms a western boundary of the rhyolite and Hueco Limestone reservoirs and the fault proximity no doubt influences reservoir properties as a no-flow western boundary due to stratigraphic juxtaposition of aquitards (Palm Park Fm) and aquifers (rhyolite dike) and an enhancement of footwall fracture permeability. Recognition of the reservoir and flow components of geothermal hydrogeologic windows has important utility in reservoir characterization and management.