(185x) Observation of Oil-Film Formation in Gas-Assisted Gravity Drainage (GAGD) Using a Microfluidic Device

Gas-assisted gravity drainage (GAGD) is one approach currently in use to collect residual oil during the tertiary production stage. In this process, three fluids (e.g., air, water, and oil) flow through the porous rock of the reservoir which forces the oil phase downwards toward the collection vessel. One challenge with GAGD is the formation of oil films at the oil/water/air interface which traps residual oil. Traditional methods to observe this phenomenon are limited in their ability to directly visualize and measure oil film formation. To address this limitation, a microfluidic device was fabricated to mimic micron-scale channels found in the sediment to observe oil-film formation. A sacrificial mold made of polydimethylsiloxane (PDMS) was replicated from a silicon master wafer imprinting a mock pore network. The PDMS mold was used to generate a microfluidic device made from Norland Optical Adhesive 81 (NOA81), an alternative material for device fabrication that is compatible with organic solvents. The NOA81 replica was permanently bound to a glass slide to allow for direction visualization of oil-films using light microscopy. To characterize the oil-film layers, experiments have been undertaken by adding Sudan 1 and FITC to the water and oil (e.g., decane or soltrol) solutions which were observed using a colored camera. Following the determination for the clearest method of oil-film formation observation, experiments have been run to visualize the three-phase fluid flow and extract data such as the width and length of oil-film thickness at several different intersections within the pore network. Finally, this study will provide new insight into the role that fluid velocity plays on oil-film thickness through experimental analysis. The success of this device allows better understanding of conditions in a reservoir to optimize the enhanced oil recovery process.