New Methodology for the Modeling of Compositional Grading within the Gas-oil Transition Zone in Petroleum Reservoirs

摘要

A general theory and a method are developed to model compositional grading and fluid saturation change within the gas-oil transition zone using a non-isothermal model for compositional grading that accounts for the modifying effect of capillary pressure on phase equilibrium (gas and oil pressures are not the same at a point). At each depth, compositional grading calculations will result in the prediction of capillary pressure, and then concept of Leverett's J-function will be used to calculate phase saturation.