Abstract: Oil from tight reservoirs has grown to dominate the liquid petroleum production in the U.S., which greatly benefits the petroleum industry. The industry, however, faces challenges in improving oil recovery from these reservoirs and reducing its carbon footprint. CO2 injection for enhanced oil recovery (EOR) and CO2 sequestration helps address these challenges. However, its practice is hindered by a lack of predictive tools for the storage and transport of oil and CO2 in these reservoirs. Fundamentally, since tight reservoirs’ porosity is dominated by pores smaller than 10-100nm, confinement and chemistry of pore walls can affect the storage and transport of oil-CO2 in these reservoirs, and physical processes underpin their effects occur at the molecular scale. Here, I will introduce our work on the molecular thermodynamics and hydrodynamics of CO2 EOR and sequestration in tight reservoirs. I will first examine CO2-mediated oil transport in nanopores, focusing on the dual role of interfacial CO2 in modulating oil flow. Next, I will examine critical steps in the Huff-n-Puff scheme of EOR and CO2 sequestration at the single nanopore scale, focusing on the transport and storage of CO2 in nanopores, the recovery of oil from pores, and their coupling. These works highlight the critical role of adsorption in oil recovery and CO2 storage in tight reservoirs. Dimensionless parameters governing the importance of adsorption are identified, and the scaling law of oil recovery in the presence of adsorption is revealed. Finally, I will present diffusioosmosis of oil-CO2 mixture driven by CO2 gradient and discuss its importance relative to the pressure driven flow in tight oil reservoirs.
Biography: Dr. Rui Qiao received his B.S. degree from Huazhong University of Science and Technology and an M.S. degree from Tsinghua University. He obtained his Ph.D. and postdoctoral training at the University of Illinois at Urbana-Champaign. He was a faculty at Clemson University before joining Virginia Tech in 2014. His research centers on clarifying the essential physics of interfacial and transport phenomena underlying engineering technologies to shape and accelerate their development.