Mineral sequestration is among several promising methods of CO2 reduction. It involves incorporation of CO2 into a solid phase via precipitation of carbonate minerals. A prerequisite to carbonate precipitation is the availability of aqueous metal cations and a network of porous media for fluid flow and water-rock interactions. The Hellisheidi-Threngsli lava field in SW Iceland comprises ideal conditions for studying the feasibility of permanent CO2 storage as minerals in basaltic rocks. In this paper we report on a tracer test conducted between two wells at the Hellisheidi-Threngsli site to characterize the physical properties of the main aquifers. The results suggest that most of the water flow between the wells is through an homogenous thick layer with high tortuosity along flow paths and a high reactive surface area for water-rock interactions.