The economic and reasonable well pattern density is the key point to enhance the reservoir conformance factor and ultimate recovery factor, and the oilfield development adjustment is also based on it. In view of the problem that the result of well pattern density made by Cher card Geoff formula cannot be suitable for the actual situation of production, we formulate the economic well pattern density from the theory and practical method so as to clarify and definite the connotation and extension of current common well pattern density, and define the conception of economic well pattern density. Based on the improvement of Cher card Geoff formula, we found the empirical formula, that calculates the economic limit well pattern density, can be suitable for various different kinds of oil blocks and reservoir in Sinopec. According to the statistical data of practical reserves abundance and fluidity in different type reservoir, we combine the state with the rectified Cher card Geoff formula, and use this formula to calculate the economic limit well pattern density of different type reservoir in five primary oil blocks, which include the high permeability reservoir, low permeability reservoir, and heavy oil reservoir. The result of calculation shows that we can drill the infilling well in the number of 20 515 and 19 466 in eastern main oil block and different types reservoir, when the price of oil can maintain at 80 $/bar.