The Application of Halogenated Alkanes as Vapor-Phase Tracers: A Field Test in The Southeast Geysers

Abstract

A new class of vapor phase tracers, the halogenated alkanes, was field tested in the Low Pressure Area of the Southeast Geysers geothermal field. Two tracers, R-12 and R-13 were injected into NCPA Well C-11. Tracer was found in 38 of the 49 production wells monitored during the 51 day test. Tracer breakthrough was very rapid, with 13 of the 16 wells monitored on the first day after injection showing breakthrough. Peak transit times occurred within 1 to 11 days Comparison wit stable isotope data for this area demonstrated that the vapor phase tracers and the build injection fluid followed similar paths. Although both tracers proved useful in tracing injection flow paths, R-12 displayed significant decay during the test. R-13, in contrast, showed little or no decay. The decay rate of R-12 appears to have been reduced by a factor of three to four on day 20 of the test. This change may be related to movement of the tracer plume outside of the oxidized zone surrounding the injection well.