Scale-up of miscible flood processes

Abstract

The current project is a systematic research effort aimed at quantifying the interactions of physical mechanisms that control the scaling behavior of miscible floods. Displacement performance in a miscible flood is the result of a complex set of competing and interacting mechanisms. Phase behavior is of fundamental importance because the transfer of components from the oil to the injected fluid (as in most CO{sub 2} floods) or from the injected fluid to the oil (as in rich gas floods) can generate mixture compositions with displacement properties very different from those of pure CO{sub 2} and original oil. The goal of this project, is to make more accurate quantitative predictions of the impact of nonuniform flow, crossflow and phase behavior in flows in heterogeneous reservoir rocks. In past reports, we have discussed the instabilities arising from unfavorable mobility ratios that occur during injection of a solvent such as CO{sub 2}. In this report, two-dimensional (2D) and three-dimensional (3D) computations by a particle-tracking technique are compared for unstable displacements in homogeneous porous media, with and without gravity. In homogeneous porous media without gravity, 2D fingering patterns and the length of the transition zone are nearly the same as those obtained in 3Dmore » displacements. When gravity is added, however, calculated gravity tongues and fingering patterns can be very different when viscous and gravity forces are of comparable magnitude. We summarize results obtained by Ph.D. student Hamdi Tchelepi concerning 2D and 3D fingering in homogeneous media, and we compare displacements with and without gravity segregation. The computations show conclusively that there are some situations in which 2D simulations reproduce 3D behavior well and others for which they do not.« less