Numerical Simulation On The Effect Of Evolution Of Thief Zones On The Remaining Oil Distribution

Thief zones are those laterally continuous stratigraphic units of relatively high permeability, which come into being in the reservoir after long-term water-flooding. The existence of thief zones will lead to inefficient water circulation, which seriously influences the fluid flowing law in porous media, the remaining oil distribution and the oil field development effect. Therefore, the study of the effect of evolution of thief zones on the remaining oil distribution, has become imperative for the exploitation of high water cut oilfield to improve oil recovery.For the reason that the effect of formation parameters vatiation on the fluid flowing law in porous media and the remaining oil distribution is not taken into consideration in the commercial numerical simulation software, based on the network modeling of formation parameters variation, a coupled mathematical model is established when combining the black oil model and the formation parameters variation model. Then a corresponding Fortran90 program is developed to establish the numerical simution method of formation parameters variation.According to the characteristics of multilayer in an China offshore heavy oil reservoir, based on the numerical simulation method of formation parameters variation, the development and evolution law of thief zones in different rhythm reservoir is studied under the circumstance of different location, permeability ratio, oil viscosity, water-cut stage and fluid production intensity. What’s more, the effect of thief zones on the remaining oil distribution in different rhythm reservoir is discussed under the situation of considering the thief zones or not, different permeability and fluid production intensity. Then the effect of thief zones on the remaining oil distribution is summarized as follows. The thief zones are developed gradually in the dominant flowing region in reservoir after long-term water flooding, which results in inefficient water circulation and the enrichment of remaining oil.