New Insights and Mechanisms for Chemical Enhanced Oil Recovery using Polymers

Matthew Balhoff, Director, Center for Subsurface Energy and the Environment and
Professor, Hildebrand Department of Petroleum and Geosystems Engineering 
Tuesday, April 12, 2022, 12 pm -1 pm Central
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Water-based polymers areoften used to improve oil recovery beyond a waterflood by improving the mobility ratio and increasing sweep efficiency. However, polymer floods are not expected to affect residual (trapped) oil saturation. In this work, it is shown hat polymers, particularly those that are viscoelastic, can reduce residual oilsaturation.

Bentheimer an d Berea sandstone cores were saturated with either high (120cp) or low (< 10 cp) viscosity oil and then waterflooded to residual oil saturation. These floods were followed by injection of a water-based polymer, hydrolyzed polyacrylamide (HPAM), that was non-Newtonian and viscoelastic. Significant reduction in residual oil saturation was observed for all core floods when the polymer had significant elasticity, which contradicts conventional wisdom of the efficiacy of polymer flooding (improved sweep but not recovery of capillary trapped oil). Experiments in glass microfluidic channels and micromodels show unique flow behavior, including oscillation of oil droplets, at pores.Computational fluid dynamics modeling is used to explain the pheneomena by calculating the forces acting on a trapped oil droplet by a viscoelastic fluid. Finally, field scale simulations are performed for a real pilot study using a chemical floodingmreservoir simulator. It is shown that viscoelastic polymer results in significantly larger recovery than even polymer floods that are notviscoelastic.


Dr. Balhoff is the Director of the Center for Subsurface Energy and the Environment (CSEE) at UT-Austin and a Professor in the Hildebrand Department of Petroleum and Geosystems Engineering and. He co-leads the
Industrial Affiliate Program on Chemical Enhanced Oil Recovery. Dr. Balhoff received his BS (2000) and PhD (2005) in chemical engineering from Louisiana State University. He became an SPE Distinguished member in 2017 and is a
winner of the 2017 SPE Southwestern North America Regional Reservoir  Description and Dynamics Award, 2014 SPE International Young Member Service Award, and 2012 SPE International Teaching Fellow Award.Dr. Balhoff has 85 peer-reviewed publications and 39 conference papers in the areas of enhanced oil recovery, carbon storage, unconventional resource production, and fundmental processes of flow and transport through porous media.