Experimental and numerical simulation studies of the zwitterionic polymers for enhanced oil recovery

Damir Karimov, Gulim Imekova, Zhexenbek Toktarbay, Nurxat Nuraje

2025

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DOI 10.1038/s41598-025-18351-w
Data confidence 70 medium
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Abstract

In this study, three zwitterionic copolymers, zPAM 1, zPAM 2, and zPAM 3, were synthesized by copolymerizing acrylamide with sulfobetaine-based monomers to investigate their suitability for polymer flooding in high salinity environment. These polymers were selected due to their strong hydration capability, high glass transition temperature and enhanced salinity and thermal tolerance compared to other polymers. The aim of this study was to enhance the thermal and salinity tolerance of polymers while improving their mobility control, with the ultimate goal of increasing oil displacement efficiency. The successful synthesis of the polymers was confirmed by FTIR spectroscopy, which identified characteristic zwitterionic functional group peaks, and 1 H NMR spectroscopy, which provided detailed insights into their chemical structures. Molecular weights were characterized using dynamic light scattering (DLS) and gel permeation chromatography (GPC). Scanning electron microscopy (SEM) revealed distinct morphologies, with zPAM 1 and zPAM 2 exhibiting highly ordered network structures that contributed to greater stability and structural integrity. Rheological analysis demonstrated shear-thinning behavior across all copolymers. Among the three copolymers, zPAM 1 exhibited the most favorable viscosity profile, maintaining stability across a broad range of salinity and temperature. Specifically, its viscosity increased by 30-40% as salinity rose from 100,000 to 200,000 ppm, while a temperature increases from 25 to 60 °C led to a reduction in viscosity of up to 60%. The favorable rheological properties of zPAM 1 translated into improved coreflooding performance. At an equal polymer concentration of 1000 ppm, zPAM 1 achieved a higher recovery factor of 56.5% compared to 52.3% for the commercial HPAM, along with higher postflush pressure drops.These findings suggest that the molecular structure of zwitterionic polymers influences their rheological behavior under high-salinity and high-temperature conditions, providing a useful basis for further development of polymer systems for enhanced oil recovery applications.