Active ions’ impact in the enhanced oil recovery process: a microfluidic-based approach

More than 50% of the crude oil is trapped inside the pores of the rock after the primary and the secondary oil recovery stage, various methods have been currently used for enhanced oil recovery (EOR) to recover the trapped oil. Brine injection, as the most commonly used approach in EOR, was heavily influenced by the concentration of active ions like Ca²⁺, Mg²⁺, and SO₄²⁻. In this study, two kinds of polydimethylsiloxane (PDMS)-based microfluidic devices were designed and fabricated to mimic the porous structure in order to study the active ion’s impact in the brine flooding process. Since the PDMS is transparent in the visible range, the fluid flow inside the fabricated porous structure can be observed directly during the brine flooding process. The effect of active ions including Ca²⁺, Mg²⁺, and SO₄²⁻ in the brine flooding process was studied in detail with the microfluidic devices. The proposed method could have wide application potential in the screening of flooding reagents in the oil industry.