Abstract: Oil reserve in the low-permeability reservoirs acounts for a large percentage of the known but intact reserves. In-depth study of the pore structure characteristics of such reservoirs can shed guidance on the study of fluid flow mechanism and on de-velopment planning for these reservoirs. On the basis of analyses of the qualitative character and quatitative parameters of capil-
lary pressure curves from selected samples, it is found that the capillary pressure curve from low-permeability reservoir can be discribed with a hyperbola. Using measured capillary pressure data, the capillary pressure curves are presented with a set of hyperbola. With this method, accurate mathematical calculation of some important parameters of capillary pressure curves for such reservoirs is made poosible.

Key words: low-permeability reservoir, pore structure, capillary pressure curve, hyperbola