Tracers and buoyancy driven dispersion in permeable rock

Abstract:

In this presentation, a series of new experiments and supporting theoretical models will be presented to illustrate some of the controls on the dispersal of tracers spreading through both homogeneous and heterogeneous porous media as governed by a buoyancy driven flow. Such flows may arise when water is injected into reservoirs, to displace oil, or during the injection of CO2 into deep saline aquifers as part of a geosequestration scheme. Tracers, which can be used to help identify the flow pattern and flow speed, can exhibit unusual trajectories within a porous layer when controlled by buoyancy driven flow, and may be hostage to the mixing effects of buoyancy driven shear dispersion. The effects of capillarity on such dispersion will also be discussed. A series of idealised models of the flow will be presented to illustrate some of the key phenomena through a combination of analogue bead pack experiments and theoretical calculations of the associated flow processes.