Part 1: Oil displacement by foam injection in Hele-Shaw cell with a pattern of impermeable regions

Abstract

Gas flooding is one of the most effective enhanced oil recovery (EOR) techniques. However, mobility control of the injected gas has always been an issue, especially for heterogeneous and fractured reservoirs. There is still a need to understand the phase interference (relative Permeability) and oil production from such heterogeneous and fractured systems. This study investigates the displacement of oil in a fractured system, conducted in a Hele-Shaw set up with a pattern of obstructions or impermeable regions. This 2D pattern is printed from an actual rock cross-section, obtained from high-resolution micro-computed tomography. Different displacement fluids were utilized, including water, gas, and foam in secondary and tertiary injection modes. Relative permeability curves were generated, which depict the interference between the phases flowing through the Hele-Shaw cell with tortuosity. The results showed that secondary foam injection is the most efficient technique as opposed to the other methods. Also, N2-foam achieves better recovery than air-foam, which is due to the solubility of N2 gas in the aqueous phase. This study provides more insight into foam flooding when high surfactant concentration is used. Under this condition, the effectiveness of foam injection compared to conventional water and gas injections is due to both emulsification and foam displacement effects.