Hydrologyand Hydrothermal Alteration, Reporoa Well (1), Reporoa, New Zealand

Abstract

The Opaheke-Reporoa thermal system has surface activity that consists of hot, neutral alkali chloride-bicarbonate pools; minor sinter, mudpools; steaming ground and hot water seepage. Regional resistivity measurements and fluid chemistry surveys suggest that the Reporoa system is a lateral outflow of hot water from the Waiotapu Geothermal System to the north-east. A deep exploratory drillhole, encountered a sequence of lacustrine sediments, volcanic, tuffaceous and ignimbritic rocks. The well was discharged in October 1966, but was shut down after 5 hours during which time wellhead pressure fell from to Downhole temperatures in were measured after 47 days of heating and showed a significanttemperature inversion between and which is interpreted to be caused by hot water at about depth flowing above a coolerwater influx.