Soil CO2 Flux Surveys: A Review of the Technique in Geothermal Exploration

Abstract

Portable equipment capable of surveying CO2 flux from volcanoes and in geothermal prospect has only been commercially available since the late 1990’s. Since that time, much research has been applied to development of the technique for the purpose of volcanic monitoring. The use of the technique for commercial geothermal exploration is even more recent, but is gaining momentum. The technique has advantages of being relatively low cost, and providing immediate results so that the survey coverage can be adapted in real time. The technique offers a range of information relevant to resource evaluation, including mapping of permeable structures, resolving system boundaries, estimation of NCG content, estimation of heat flow, and refinement of conceptual models. The technique can also be used to establish an environmental baseline for CO2 emissions prior to development. This paper provides a review of publically available CO2 flux surveys conducted in settings where geothermal power projects are planned or already exist.