Scale up of flow in porous media

The authors study the scale up problem for flow in porous media. The general nature of this problem is outlined, leading to a discussion of assumptions on random fields appropriate for the description of geological heterogeneities. The main point of this paper is to use direct numerical simulation to evaluate the ensemble averages describing fluid dispersion, for flow in porous media. The relation between ensemble dispersion and single realization dispersion is discussed in the case of linear transport, and the role of plume or channel width is also explored. Finally, they consider nonlinear transport, and contrast dispersive to hyperbolic renormalization of the flow equations. For the geological and fluid parameters considered here, the hyperbolic renormalization is trivial, indicating that dispersive renormalization is appropriate in these cases. Further study of the ideas explored in this paper will be required for a proper understanding of their role in a more complete theory which the authors hope will follow.