Up to now much of the work on permeability heterogeneity has focussed on viscous flow ignoring the effect on capillary pressure. Small scale permeability variations, however, may lead to capillary trapping of a considerable amount of oil within for instance the crossbeds of channel sands.

Fractional Brownian motion (fractal) permeability fields have been generated to obtain heterogeneous permeability fields with a varying degree of smoothness. It appears that these are ideal fields to investigate the relation between capillary trapping and local variability. The fractal fields have been used as input in a probabilistic simulator in which capillary forces have been implemented.

From the simulations presented it has been concluded that effect of the capillary and viscous forces on the saturation distribution is related to the Hurst coefficient.

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