Design of polymer nanofluids (PNFs) for enhanced oil recovery (EOR) and carbon sequestration
Global energy consumption has been rising progressively over the past decade. Despite recent advances in the usage and development of renewable energy, oil continues to be the dominant energy source throughout the world. However, the rate of increase in energy demands has not been matched with discovery of new hydrocarbon reserves. Additionally, most oil and gas reservoirs have reached a state of maturity in terms of recoverable oil through existing techniques. Considering these energy and economic issues, it is imperative to focus on developing new cheap, energy-efficient and sustainable methodologies aimed at improving oil production from existing reservoirs. To achieve this goal, we are interested in developing PNFs with stimuli-responsive behavior to manipulate flow and interfacial properties that underlie the limited oil recovery from porous media. In another complementary objective, we plan to develop PNFs with tunable properties that can act as robust CO2 capture and CO2-based enhanced oil recovery agents.
The choice of polymer and nanoparticle plays a central role in determining the properties of the injecting nanofluids. We will focus on materials that have the potential to address individual attributes necessary for enhanced oil recoveries. These include PNF stability at harsh reservoir conditions, low adsorption on rock surfaces, excellent wettability alteration, programmable emulsification and demulsification and a favourable injectant mobility inside the porous medium. More fundamentally, we expect to get a concise understanding of the way different interactions like Van der waals forces, steric repulsions, electrostatic and hydrophobic interactions impact the equilibrium phase behavior for a complex PNF-water-oil systems.
The second part of the project will be dedicated towards preparing PNF-CO2-foams. Injection of these foams in oil and gas reservoirs has been considered as a viable strategy to sequester CO2 into geological formations with simultaneous enhancement in displaced oil. CO2 injection with water alone is prone to premature breakthrough, viscous fingering, and poor sequestration. To address these, and to obtain the desired mobility control, we will investigate the rheological behavior of the synthesized PNFs. Along with the CO2 capture capacity, we will also investigate the role played by PNFs in stabilizing the foams. Specifically, it is expected that destabilizing forces such as Ostwald ripening and coalescence can be more effectively arrested in particle-stabilized foams. To improve the adsorption of PNFs to CO2, we will add surfactants which can form polymer-surfactant complexes to modify the wettability of the particles. We note that these complexes can also reduce the size of CO2 bubbles and enhance stability of the foams by reducing CO2-water interfacial tension (IFT) and increasing the interfacial shear.
In summary, the outcomes of the project will not only significantly advance the current state of PNF based carbon capture and EOR techniques but also provide fundamental insights into the role played by polymer-NP composites in modulating interfacial properties. The perspectives gained from the work can be translated into developing functionalized sustainable materials, reduced energy consumption and waste generation.