The ratio (3) of high permeability over low permeability is the inflection point, if the ratio is less than 3, oil recovery of medium-low layers will increase a lot.

• 高渗层渗透率与中低渗透层位渗透率比值3是采出程度与渗透率比值关系曲线的拐点，渗透率比值小于3，中低渗透层采出程度大幅度增加。