Numerical Study of Immiscible Foam Propagation in Porous Media in the Presence of Oil Using an Implicit-Texture Foam Model

Abstract

Gas injection is one of the established methods in enhanced oil recovery. Nevertheless, poor sweep efficiency and viscous instabilities result in early gas breakthrough. Lowering injected gas mobility through foaming is a potential solution to solve the forenamed challenges. Although foaming of the injected gas has been proposed in various stages of oil production, comparatively few studies are carried out about foam injection modeling in the presence of oil. In this study, we aimed to numerically investigate the immiscible foam propagation in a thick, heterogeneous, water-flooded sandstone reservoir with a primary goal to control the surge of the produced gas–oil ratio (GOR) and also the possible incremental oil production by foam. To this end, the implicit-texture local-equilibrium foam model was used to address that how a stable foam front could affect fluid saturation and their mobility in the presence of waterflood residual oil. We treated the reservoir model by considering a pair of horizontal injection/production well through the upper and lower parts of the reservoir to mimic the foam-assisted gravity drainage scheme. Foam generation was considered through alternating (SAG) and simultaneous injection of gas and surfactant solution, and its performance was compared with continuous gas injection and water alternating gas injection. Results showed that gas-phase mobility was reduced in the presence of foam, leading to delaying of gas breakthrough and thereby improvement of gas sweep efficiency. The latter caused a significant reduction in produced gas–oil ratio, enhanced the control of the front movement, and resulted in better oil sweeping. In comparison to the SAG method, occurrence of fingering phenomena in foam co-injection was less likely. In addition, foam front in co-injection method exhibited relatively slower movement compared to the SAG method. Also, with ignoring the prescribed pressure constraint in injection well, the stability and uniformity of the generated foam front decreased, leading to more occurrences of fingering and thus reduction in oil recovery.

Foam-Assisted Capillary Trapping in Saline Aquifers—An Initial–Residual Saturation Analysis

“…In general, foam can be generated with two main injection strategies, namely ex situ and in situ foam generation. Ex situ involves generating foam outside the porous medium before the process of injection, while in situ involves either co-injecting liquid and gas in a porous medium or by surfactant alternating gas (SAG) injection strategy [34,35]. It is worth mentioning here that the SAG injection strategy avoids some of the drawbacks of the co-injection method, such as minimizing the contact between water and gas in surface facilities that may lead to corrosion in some cases and avoiding the total blockage of porous media that may happen under the co-injection foam strategy [36].…”

Application of a Developed Numerical Model for Surfactant Flushing Combined with Intermittent Air Injection at Field Scale

“…A few studies have used numerical modeling to investigate the mechanism of enhanced remediation associated with various physical and chemical processes involved in surfactant flushing combined with air injection [10,11]. Similarly, with the aim of enhancing oil recovery, numerical simulations have been conducted to investigate the effectiveness of SAG injection for increasing displacement efficiency; these studies have considered surfactant foam transport in terms of the gas mobility reduction and relative permeability changes associated with a reduction of interfacial tension [12][13][14][15][16][17][18][19]. However, most of these works considered only some, and not all, of the processes that improve remediation when surfactant flushing is combined with air injection.…”