A New Mathematical Model for Force Gravity Drainage in Fractured Porous Media

Abstract

In force gas/oil gravity drainage process in fractured porous media, gas is flowing in both matrix and fractures leading to produce a finite gas pressure gradient. Consequently, viscous force plays an important role for displacing matrix oil toward fractures in addition to gravity force that is required to be modeled appropriately. A new analytical model for estimation of steady state oil saturation distribution with assumption of fixed gas pressure gradient throughout the matrix is presented. Moreover, based on some results of this analytical model a different numerical formulation is developed to predict the performance of oil production process. Comparison of the results obtained from this numerical model with the results of a conventional simulator demonstrates that the newly developed model can be applied with satisfactory accuracy. Numerical simulations show that the viscous displacement in fractured porous media can reduce the capillary threshold height, and thus it suggests the force gravity drainage as a favorable production mechanism when the matrix length is close to the threshold height.

Free fall and controlled gravity drainage processes in fractured porous media: Laboratory and modelling investigation

“…Gravity drainage is an effective mechanism in these situations for producing the remaining oil. [13][14][15] Several experimental studies for different types of gravity drainage processes were conducted in unconsolidated models. [16][17][18][19] However, accurate determination of the parameters requires mathematical modelling of this process.…”

“…[16][17][18][19] However, accurate determination of the parameters requires mathematical modelling of this process. There are some mathematical models in the literature, [5,10,15,20] though most previously proposed models have many simplifying assumptions, because of the complexities associated with the gravity drainage process and non-linearity of the governing equations. Complexity of fluid flow in this type of reservoir is mostly attributed to the fluid flow in two completely different media (matrix and fracture).…”