Steam-on-a-chip for oil recovery: the role of alkaline additives in steam assisted gravity drainage†
We present a lab-on-a-chip approach to informing thermal oil recovery processes. Bitumen – a major global resource – is an extremely viscous oil which is extracted by injecting steam underground in a process known as Steam Assisted Gravity Drainage (SAGD). Here, a microfluidic network saturated with bitumen provides a physical model of the SAGD reservoir; steam is injected into the chip, and the oil recovery dynamics are visualized and quantified in real-time. The unique advantage of this approach is the pore-scale quantification of fluid phase dynamics under relevant reservoir conditions and pore sizes. High resolution is achieved by leveraging the inherent fluorescence of the native bitumen. The approach is applied to quantify the efficacy of an alkaline steam additive. With the additive, the mean characteristic size of oil-in-water emulsions formed during SAGD is reduced from 150 μm to 6 μm, and the corresponding recovery effectiveness is improved by ∼50%. These results demonstrate that pore-scale process quantification enabled by lab-on-a-chip methods can improve the efficacy, and the associated carbon footprint, of energy intensive thermal oil recovery processes.