Identification of Fluid Dynamics in Forced Gravity Drainage Using Dimensionless Groups

Abstract

A number of forced gravity drainage experiments have been conducted using a wide range of the physical and operational parameters, wherein the type, length, and permeability of the porous medium as well as oil viscosity and injection rate were varied. Results indicate that an increase in the Bond number has a positive effect on oil recovery whereas the capillary number has an opposite effect. These trends were observed over a two-order of magnitude change in the value of the dimensionless groups. Furthermore, it was found that use of each number alone is insufficient to obtain a satisfactory correlation with recovery. A combined dimensionless group is proposed, which combines the effect of all the three forces. Recoveries from all the experiments conducted in this study show a very good correlation with the proposed group. The exponent of the Bond number in the proposed group is larger than the capillary number suggesting a larger importance for the former. We then show that the same group provides a good correlation for recovery from additional experiments conducted in this study (in the presence of connate water) with that of another set of experiments in the literature.

Effect of Buoyancy on Pore-Scale Characteristics of Two-Phase Flow in Porous Media

“…4 for packed beds of glass beads with the diameters 100 µm, 200 µm and 400 µm. With an increase in capillary number, the initial gas saturation decreases, as has been reported by many researchers (Morrow & Songkran, 1982;Chatzis et al 1983;Morrow et al 1988;Rostami et al 2010). At a capillary number of 9.30 × 10 −6 with 200-µm diameter glass beads, the initial gas saturation varies widely due to fingering of the interface (Fig.…”

“…Bo and Ca represent the ratio of buoyancy force and of viscous sheer stress to the capillary force, respectively. Instead of Equation 1, the Dombrowski-Brownell number, which is the ratio of the pore scale hydrostatic pressure drop to the capillary pressure (Rostami et al 2010), is defined as…”

“…With an increase in Bond number, the initial gas saturation increases. With higher diameter glass beads, the higher critical gravity drainage velocity results in the higher displacement efficiency associated with the reduction in capillary force (Rostami et al 2010). The displacement front of drainage is stable for all experimental runs shown in Fig.…”

“…On the other hand, in the case of oil production by gas-assisted gravity drainage (GAGD) processes, crestal gas injection uses wells in higher structural positions close to the top of the reservoir. GAGD has been considered to be a very attractive oil recovery process because of its higher efficiency (Hagoort 1980;de Mello et al 2009;Rostami et al 2010). When gas is injected vertically downward into the formations, the higher sweep efficiency could be achieved with the aid of stabilization of a displacement front by buoyancy.…”

Effect of Heterogeneity of Porous Media on Gas Permeation and Entrapment

“…The initial gas saturation at the start of the water inflow is also affected by various factors including the characteristics of porous medium, the viscosity ratio, buoyancy, and capillary forces of the flowing fluids [24]- [27]. At the natural sandstone cores, the initial gas saturation depends on pore size distribution and the heterogeneity caused by the sedimentary layers [23].…”