Simulation of Curve Characteristics of Well Inflow Performance Relationship of Low Permeable Oil Field

The functional relation of flowing coefficient with flowing pressure was described as a parabolic function,and a new type of inflow performance relationship which contained 3 undetermined coefficients was setup. According to test results of three or more than three points of flowing pressure and corresponding liquid output,the regression equations that contained the 3 undetermined coefficients were setup by the least squares method rule,and the undetermined coefficients were solved by the optimization method. The new type of IPR includes both the classical ones that are used at present and a particular type of one that is of inflection point. The relationship equation that is used to distinguish whether or not the inflow performance relationship is of inflection point was established,and the formula of calculating the reasonably flowing pressure at which the liquid output can get the maximal value is setup. When the new IPR is used to direct the design of suction parameters of rod pumping wells,the oil wells can run at the reasonably flowing pressure and the maximal liquid output,which is of important significance to raising economic effects of low permeability oil field.