Abstract
Amphiphilic block polyelectrolytes are known for their remarkable thickening properties in water solution, originating from their ability to self-assemble into large micellar aggregates. This makes them promising flooding agent for chemical enhanced oil recovery (cEOR). However, to the best of our knowledge, they have not yet been directly investigated for this purpose. In this work, a survey of relevant properties for EOR (rheology, filterability and emulsification), and laboratory scale oil recovery experiments, were performed on water solutions of polystyrene-block-poly(methacrylic acid) amphiphilic block polyelectrolytes, and compared with a commercial partially hydrolyzed polyacrylamide (HPAM), to evaluate the real potential in EOR applications for the first time. It was found that the recovery of amphiphilic block copolymers in low salinity brine (0.2% concentration of NaCl) is remarkably higher than that of HPAM at comparable weight concentration and shear viscosity, despite a much lower molecular weight. Effect of salinity and emulsification properties of the studied polymers have also been preliminarily investigated. Our results suggest that the recovery mechanism of these polymers differs from the traditional mechanism of polymer flooding, possibly due to emulsification of the oil. In conclusion, the studied amphiphilic block polyelectrolytes show promise as chemical agents in low salinity polymer flooding.
Highlights
Despite the ongoing paradigm shift towards green and sustainable sources of energy and materials, humanity will still be dependent on fossil fuels for decades (Abas et al, 2015; Mohr et al, 2015; Raffa and Druetta, 2019)
Flopaam 3430 S, a commercial hydrolyzed polyacrylamide (HPAM) employed in polymer flooding, is a high molecular weight random copolymer of acrylamide and acrylic acid, synthesized by free radical polymerization
PS-b-PMAA amphiphilic block polyelectrolytes are compared to a commercial HPAM (Flopaam 3430 S) in terms of visco sifying properties, injectivity in filtration tests, emulsification ability and oil recovered in laboratory scale experiments, namely bidimensional flow cells and flood experiments in Bentheim sandstone cores
Summary
Despite the ongoing paradigm shift towards green and sustainable sources of energy and materials, humanity will still be dependent on fossil fuels for decades (Abas et al, 2015; Mohr et al, 2015; Raffa and Druetta, 2019). Previous work in LSP shows that this method can potentially perform better than high salinity polymer flooding, because of reduced retention, better long-term injectivity, and better rheological properties, when tested with HPAM in sandstone cores or sand packs (Kakati et al, 2020; Unsal et al, 2018) Combined with their theoretically higher shear resistance and tem perature stability, this makes amphiphilic block polyelectrolytes prom ising flooding agents. As a mean to explore the possibility of expanding the application of amphiphilic block polyelectrolytes for high salinity conditions, a modified version of the polymer, incorporating PEG-acrylate in the hy drophilic block, designed and prepared in previous work (Raffa et al, 2016b), has been compared to the other systems in terms of vis cosity in saline water and emulsification ability. The salt tolerance is improved as desired, this polymer performs poorly in filtration tests, it has not been further tested in core flood experiments
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