  A model of randomly distributed overlapping spheres of different radii is
represented to describe a heterogeneous porous medium. Two-particle correlation
function of the relative position of pores of different radii in the medium
space was calculated and detailed analysis was carried out. The model allows to
characterize the disordered porous medium with the number of nearest neighbors,
the area of all mouths that connect pore with the neighboring pores. These
paramaters depend on the pore size and porosity and --- in addition to the
specific surface area, porosity, and percolation threshold and the distribution
function of pore size.
