Polymers have been successfully deployed in the Oil&Gas Industry for various field applications, including waterflood mobility control, flow divergence, and well conformance control. Polymers are among the most widely used chemical EOR methods. Polymer intermolecular interaction and resulting permeability alterations are not fully understood. In this study, we present a novel approach for dynamic visualization of polymer molecular interaction and transport behavior using porous media replication in a microfluidic device, including fluorescent tagging of polymers and single-molecule microscopy. We then use pore-scale simulations to reproduce the experimental observations. The microfluidic chip, conceptually referred to as "Reservoir-on-A-Chip", serves as a two-dimensional proxy, which facilitates assessing the flow mechanisms occurring at pore-scale. A microfluidic model was developed to observe polymer flow behavior and transport mechanisms through porous media. The designed microfluidic chip honors the pore-size distribution of oil-bearing conventional reservoir rocks, with pore-Throats ranging from 2 to 10 μm. We built the micromodel out of polydimethylsiloxane (PDMS) through soft-lithography. The traditional use of tracers to track polymers has a limitation because of the tendency of polymer molecules to segregate. Polymer induced pore-clogging, alongside with the reverse mechanism, namely pore-unclogging, have been dynamically captured, for the first time. On the basis of the experimental observation, pore-scale simulations were performed to model the phenomenon. We investigated the flow of the polymer molecules and agglomerates residing in the polymer solution and the clogging-unclogging mechanisms. The simulations emphasize consistent flow conductance increase with time, in the flow channels that underwent unclogging. Both experimental and simulation results bring evidence of polymer retention and attainable flow conductance restoration to the initial pre-polymer flooding values. We show the first direct dynamic observations of a tagged polymer molecules at dynamic conditions. The conducted single-phase flow experiments enabled direct observation of polymer molecules flow behavior within the hosting phase. Additionally, the retention mechanisms manifested during flow and their impact on apparent permeability are analyzed. The study presents a novel approach for labeling and visualizing polymer molecules and their flow behavior in porous media. We successfully used advanced microscopy techniques, to present dynamic visualization of polymer pore-clogging and unclogging mechanisms, for the first time. Using microfluidic techniques and singlemolecule microscopy, we provide new insights at the molecular level, and flow behavior at the pore-scale, which helps to optimize polymer selection for field implementation.
|Original language||English (US)|
|Title of host publication||IOR 2021|
|Publisher||European Association of Geoscientists & Engineers|
|State||Published - 2021|