Abstract:Physical parameters were directly related to fracturing effect of the ultra low permeability reservoir. Based on the investigation and analysis of more than one thousand production wells that the formation pressure were similar in Changqing oilfield, the conclusion was that porosity was the most sensitive factor to fracturing effect, the next was permeability、reservoir effective thickness, and the most insensitive factor was oil saturation. In the actual reservoir , the variation scope of porosity and permeability was small, but the reservoir effective thickness was big, so the quantitative relation of reservoir thickness、permeability、porosity and oil saturation should be comprehensively considered in the actual fracturing process of well and layer selection. And the quantitative relation can be determined by grey correlation method. the actual fracturing construction of seven wells in a block of Changqing oilfield show that grey correlation evaluation method can better meet the actual oil field fracturing on the basis of the reservoir physical properties on fracturing effect.