Fractal modeling of capillary pressure curves for The Geysers rocks

Capillary pressure curves of The Geysers rocks have unique features because of their microfractures. The frequently used Brooks–Corey (1964) model does not match these capillary pressure curves. It would be useful to represent these curves mathematically, to provide a model for use in reservoir performance calculations. A general model developed from fractal modeling of a porous medium was applied and found to match the capillary pressure curves of The Geysers rocks satisfactorily. Capillary pressures were measured using a mercury intrusion technique. The values of fractal dimension, which is a representation of rock heterogeneity, were inferred from the match of the general capillary pressure model to the experimental data. The results demonstrate that the heterogeneity of The Geysers rocks can be determined quantitatively using the values of fractal dimension.