Determining Lower Limit of Physical Property in Low-porosity and Low-permeability Sandstone Reservoirs:An Example from the 3~(rd) Layer in P_1s~2 of Zizhou Gasfield

The third layer in P1s2 of Zizhou Gasfield is a typical low-porosity and low-permeability sandstone reservoir.Its porosity is between 0.10%~10.50%,averaging at 4.77% ;and its permeability is(0.01~87.8)×10-3μm2,averaging at 1.52×10-3μm2,respectively.Taking the sandstone reservoir for instance,aiming at its porous structure,making an intensive core study on the relationship of porosity,permeability oil-saturation and relative permeability,the lower limit of physical property may be determined by a minimum throat radius method and an integrated method of porosity,water saturation and relative-permeability curve.