Numerical Modeling of the gas-oil gravity drainage process in stratified and fractured porous media

The saturation profiles in homogeneous and nonhomogeneous layered porous media have been analyzed, and the oil recovery rates as well as the ultimate recovery have been calculated. A two-phase flow model is set up and solved numerically to produce the oil saturation profile and estimate the rate of oil recovery in layered porous medium under the gas-oil gravity drainage process. The model was further extended to model very high permeability layers stacked in between two dense layers to simulate horizontally fractured media. This numerical scheme reveals the importance of capillary pressure in the vicinity of the different layers for the calculation of the saturation profile. Oil entrapment in the matrix on top of the more permeable layers is responsible for the low oil recovery efficiency from fractured reservoirs under gravity drainage. Several different tests, including the use of a single high-permeability layer a single low-permeability layer and a low on top of a high and high on top of a low permeable stratum, are performed using the proposed technique, qualitatively.