The heterogeneity of porosity and permeability of reservoirs are closely related to the architectures of depositional systems

and can be studied by scale.(1)On the scale of depositional system

different depositional systems are different in porosity and permeability.Porosity and permeability of different genetic facies in the same depositional system may have great differences.This depends mainly on the paleo current energy and environment in which the genetic facies were formed.(2)On the scale of genetic facies

porosity and permeability of the same fluid flow unit and between different fluid flow units are on the whole different.This is related to lithology of reservoirs constituting the fluid flow units.The superimposition of nonhomogenous diagenesis could decrease greatly the porosity and permeability of fluid flow units.(3)On the scale of core

porous media show anisotropic characteristics.