Visualizing oil displacement with foam in a microfluidic device with permeability contrast

Abstract

Foam mobility control and novel oil displacement mechanisms were observed in a microfluidic device representing a porous media system with layered permeability. Foam was pre-generated using a flow-focusing microfluidic device and injected into an oil-wet, oil-saturated 2-D PDMS microfluidic device. The device is designed with a central fracture flanked by high-permeability and low-permeability zones stratified in the direction of injection. A 1 : 1, 1% blend of alpha olefin sulfonate 14-16 (AOS) and lauryl betaine (LB) surfactants produced stable foam in the presence of paraffin oil. The oil saturation and pressure drop across the microfluidic device were measured as a function of time and the injected pore volume, indicating an increase in apparent viscosity for foam with an accompanying decrease in oil saturation. In contrast to the control experiments, foam was shown to more effectively mobilize trapped oil by increasing the flow resistance in the fracture and high-permeability zones and by diverting the surfactant solution into adjacent low-permeability zones. The foam was observed to separate into gas-rich and aqueous-rich phases depending on matrix permeability, suggesting that it is not appropriate to treat foam as a homogeneous dispersion of gas and liquid.

Waterflooding of Surfactant and Polymer Solutions in a Porous Media Micromodel

“…We also aim to control the pore structure of our system through photolithography techniques [16,26] and perform microparticle image velocimetry measurements [29] to map streamline profiles that can be compared to expected flow distributions as calculated by finite element analysis [79]. The approach we have used here can be used to evaluate other enhanced oil recovery systems, including other types of polymers or surfactants [80], nanoparticles [81,82], and foams [83,84]. Our platform can also be applied to other porous media situations that involve diffusion and transport in biomedical systems [40,85], carbon sequestration [86,87], and the additive manufacturing of complex fluid networks [41,88,89].…”

Oil/water displacement in microfluidic packed beds under weakly water-wetting conditions: competition between precursor film flow and piston-like displacement

“…However, many enhanced oil recovery and NAPL-remediation approaches involve the addition of chemical additives such as surfactants and polymers to the water that is injected into the system to displace the oil. Where the aim of a microfluidic experiment is to evaluate the performance of such additives, the addition of dye to the aqueous phase is not desirable as dyes can alter the interfacial properties of the test fluid; in such cases, the oil phase must be dyed instead (e.g., Conn et al 2014;Zhang et al 2011;Beaumont et al 2013;Gauteplass et al 2013;Nilsson et al 2013).…”

Design and analysis of different models of microfluidic devices evaluated in Enhanced Oil Recovery (EOR) assays

“…A dilute aqueous solution of partially hydrolyzed polyacrylamide is used as a pushing fluid in the injection wells to sweep oil in the reservoir into the production well [6]. Other approach to improve EOR is decreasing the mobility ratio (M): (1) Where k rD and μ D are relative permeability and viscosity of the displacing phase, respectively, and k rd and μ d represent the displaced phase [7]. Mobility ratios less than 1 indicate positive displacement.…”

“…Mobility ratios less than 1 indicate positive displacement. Foam has been used to lower mobility ratio as it diminishes mobility by reducing gas relative permeability k rD and by increasing the effective viscosity μ D [7,8].…”