Abstract

After thermal processes, steam injection is the most common enhanced oil recovery (EOR) methods in heavy oil reservoirs. It is common in heavy and semi heavy oil reservoirs to inject gas in conjugate with surfactant solutions to enhance the effect of gas on reservoir fluid which is called surfactant alternating gas (SAG) injection. The interest in immiscible and miscible SAG process has been grown recently. In this work, an experimental study of immiscible heated SAG injection in a sand pack was performed.This new method is a combination of SAG and thermal process and can be used in heavy and semi-heavy reservoirs. The experiments were performed with sand pack under certain temperature, pressure, constant rate and 1.2 pore volume (PV) injected. Result shows that method effectively improves oil recovery in comparison with SAG injection and other method [gas flooding, water flooding and water alternating gas (WAG)]. Conducting these experiments indicate that using heated surfactant and heated nitrogen instead of unheated surfactant solution and nitrogen and other method can lead to interfacial tension reduction, oil swelling and viscosity reduction. Thereafter, immiscible heated SAG injection can be used as an effective and feasible EOR method in heavy and semi-heavy oil reservoirs.

Key words: Surfactant alternating gas (SAG), sand pack, heated SAG, foam.