This thesis presents a reservoir-on-a-chip study of waterflooding, acoustic streaming and ultrasonic streaming as enhanced oil recovery mechanism. Microfluidic devices with different porosities are fabricated using photolithography or close-packed microbeads to sever as reservoir-on-a-chip micromodels. Optical video fluorescence microscopy is used to track the invasion of a water phase through the oil saturated porous micromodel.
In waterflooding study, the degree of water saturation is compared to water containing two different types of chemical modifiers, sodium dodecyl sulfate (SDS) and polyvinylpyrrolidone (PVP), with water in the absence of a surfactant used as a control. Image analysis of our video data yield saturation curves and calculate fractal dimension, which we use to identify how morphology changes the way as invading water phase moves through the porous media. An inverse analysis based on the implicit pressure explicit saturation (IMPES) simulation technique uses mobility ratio as an adjustable parameter to fit our experimental saturation curves. The results from our inverse analysis combined with our image analysis show that this platform can be used to evaluate the effectiveness of surfactants or polymers as additives for enhancing the transport of water through an oil-saturated porous medium.
In acoustic streaming study, we also use microparticle image velocimetry to characterize acoustic streaming-induced pumping as a function of frequency and amplitude. A scaling model applied to the velocity distribution is used to construct a state diagram that connects acoustic pressure to filed frequency and amplitude. Based on the measurements of water phase displace oil saturated porous micromodel, we calculate the Black number as a function of frequency to show our system exhibits a narrow band dynamic response consistent with a system operating near resonance. Our observations are compared to a general model for Blake number as a function of frequency, porosity and voltage amplitude that was derived from a force balance model of micromodel undergoing force oscillation.
In ultrasonic streaming study, we use particle tracking method to characterize diffusion coefficient and ultrasonic streaming induced as a function of frequency, voltage amplitude and porosity. Brownian dynamics model with ultrasonic streaming force and Hindered diffusion are used to simulation particle diffusion under two parallel wall microfluidic device when ultrasonic wave applies to the system. Based on these measurements, we observe that ultrasonic streaming phenomena appear significantly when amplitude voltage increase or porosity decrease. Besides, porous structure affect resonance frequency for the device.
The results from this thesis are broadly applicable to systems beyond enhanced oil recovery, including separations, bio-analytical instrument, additive manufacturing, mixing and flow control
