Correlation between rational formation pressure and water cut

Formation pressure is one of the important marks to determine the state of formation energy, and thus the rational formation pressure needs to be determined. On the basis of the fundamental principle of petroleum engineering and relative permeability, the relational expression showing the correlation between the nondimensional fluid productivity index and productivity index and the water cut are deduced. Then, according to the normalization processing of relative permeability curves from reservoirs and applying the principle of injection-production ratio, the paper presents the relationship between the rational pressure and water cut as well as injection-production under different oil production rate, and gives the practical application to oilfields. The result of study indicates that the rational formation pressure maintenance will decrease dramatically when the nondimensional fluid productivity index or productivity index takes the minimum value. This method has some scientific guidance and practical value for the analysis of the waterflood technology and production rate of low-to-moderate water development phase.