SF6 - a New Nonradioactive Geothermal Tracer

Abstract

SF6 is a nonradioactive inert gas, readily available, not naturally present geothermal system, and can be detected at very low levels using an Electron Capture Detector (ECD) gas chromatograph suggesting that it has potential as a geothermal tracer. Two systems were designed and used successfully to inject gm into geothermal wells at Wairakei. Separate injections were made into the steam and water reservoirs at Wairakei. Tracer injected into the hot water zone, primarily remained in that fluid. The velocities of the peak concentration were 3 - 6 for the steam and 9 - 12 for the water zones. The velocities of the "initial" return were 16 - 21 in both the steam and water zone experiments. The total return in the monitored wells was 34.9 for the steam wells and for the water wells. Preliminary comparisons are made with Rhodamine and Fluorescein.