In oil and water phases

fluid percolation obeys Darcy's law.According to this

the formula for calculating producing pressure differences of the interwell fluid units could be established.The fluid units could be classified according to the pore radius

permeability and petrophysical property of a reservoir.The fluid units in Shuanghe Oilfields could be divided in to 4 different types.Calculated results suggest that the theoretical pressure differences of different flow units in Shuanghe Oiffields fitted well to the measured pressure differences.