Equivalent block transmissivity in an irregular 2D polygonal grid for one-phase flow: A sensitivity analysis

Upscaling is needed to transform the representation of non-additive space-dependent variables, such as permeability, from the fine grid of geostatistical simulations (to simulate small-scale spatial variability) to the coarser, generally irregular grids for hydrodynamic transport codes. A new renormalisation method is proposed, based on the geometric properties of a Voronï grid. It is compared to other classic methods by a sensitivity analysis (grid, range and sill of the variogram, random realisation of a simulation); the criterion is the flux of a tracer at the outlet. The effect of the upscaling technique on the results appears to be of second order compared to the spatial discretisation, the choice of variogram, and the realisation.