Microfluidic and Micro-core Methods for Enhanced Oil Recovery and Carbon Storage Applications

Injection of CO2 into the subsurface, for both storage and oil recovery, is an emerging strategy to mitigate atmospheric CO2 emissions and associated climate change. In this thesis microfluidic and micro-core methods were developed to inform combined CO2-storage and oil recovery operations and determine relevant fluid properties. Pore scale studies of nanoparticle stabilized CO2-in-water foam and its application in oil recovery to show significant improvement in oil recovery rate with different oils from around the world (light, medium, and heavy). The CO2 nanoparticle-stabilized CO2 foams generate a three-fold increase in oil recovery (an additional 15% of initial oil in place) as compared to an otherwise similar CO2 gas flood. Nanoparticle-stabilized CO2 foam flooding also results in significantly smaller oil-in-water emulsion sizes. All three oils show substantial additional oil recovery and a positive reservoir homogenization effect. A supporting microfluidic approach is developed to quantify the minimum miscibility pressure (MMP) - a critical parameter for combined CO2 storage and enhanced oil recovery. The method leverages the inherent fluorescence of crude oils, is faster than conventional technologies, and provides quantitative, operator-independent measurements. In terms of speed, a pressure scan for a single minimum miscibility pressure measurement required less than 30 min, in stark contrast to days or weeks with existing rising bubble and slimtube methods. In practice, subsurface geology also interacts with injected CO2. Commonly carbonate dissolution results in pore structure, porosity, and permeability changes. These changes are measured by x-ray microtomography (micro-CT), liquid permeability measurements, and chemical analysis. Chemical composition of the produced liquid analyzed by inductively coupled plasma-atomic emission spectrometer (ICP-AES) shows concentrations of magnesium and calcium. This work leverages established advantages of microfluidics in the new context of core-sample analysis, providing a simple core sealing method, small sample size, small volumes of injection fluids, fast characterization times, and pore scale resolution. Lastly, a microfluidic approach is developed to analyze the complex, multiphase fluid interactions in CO2 enhanced oil recovery at relevant reservoir temperature and pressure. Fluorescence imaging is applied to visualize and measure the effect of CO2 pressure on contact angles changes at the pore scale.Ph.D