Modeling of two-phase flow processes in strongly heterogeneous porous media using multi-rate mass transfer approaches

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Modelling of displacement of one fluid by another immiscible one and mass transfer between the phases is important for many geotechnical applications. An example is the injection of supercritical carbon dioxide into brine. To include the influence of heterogeneous structure that is not resolved by the numerical grid into modelling concepts is a challenge, in particular if parameter contrasts are high. In this proposal we want to derive up scaled model concepts for two-phase flow on large length scales, where we focus on the transition zone between displacing and displaced fluid (the mixing zone) during a displacement problem. The mixing zone is the critical zone, for example, for mass transfer of a dissolved component between the two phases. Based on the models that quantify the mixing zone we want in a second step to analyze the relation between mixing zone volume and interfacial area between the fluids.To derive such model concepts we want to apply multi-rate mass transfer modelling approaches that have been developed to describe solute transport in flow fields with mobile and stagnant flow zones in complexly structured and highly heterogeneous porous media. These approaches have been very successful for linear problems. We want to extend them to the non-linear problem two-phase flow problem.