Determination of Flow Connectivity and Heat Exchange Surface in Fractured Media Using Multicomponent Tracer Test

Multicomponent tracer tests were conducted to understand advective and diffusive transport processes in fractured permeable media, and to determine the heat exchange surface and spatial connectivity of fracture network. The experiments were operated in a near-field setting with crushed granite specimens collected from the Songliao Basin, China. Conservative tracer pairs with different hydraulic diffusivities (fluorobenzoic, chloride and benzoic acids), sorptive tracer (lithium ion) and thermally degrading phenolic compound were used. The tracer concentration signals were observed and analyzed by conventional dual-media model and multi-rate diffusion model to estimate the connectivity parameters of fluid flow including advective porosity, permeability and dispersivity. Meanwhile the sorptive tracer and thermally degrading tracer were used to determine heat exchange surface parameters. The application of multicomponent tracers can improve the understanding of both fluid and heat transport processes in fractured media.

Key words: Multicomponent tracer test; fractured media; fluid connectivity; heat exchange surface.