Stability and Rheological Properties of the Hydroxypropyl Methyl Cellulose-Based Graft Copolymer/Halocynthia roretzi Drasche-Based Cellulose Nanocrystal/Sodium Dodecyl Sulfate Dispersion for Enhanced Heavy Oil Recovery

Abstract

As a "green" displacing agent, nanocellulose is enriched, nontoxic, biodegradable, and environmentally friendly; therefore, the development and potential application of nanocellulose in oilfield chemistry have attracted widespread attention in recent years. In this study, a thermothickening copolymer synthesized in our laboratory called hydroxypropyl methyl cellulose-based graft (PHAD) copolymer was chosen to mix with Halocynthia roretzi Drasche-based cellulose nanocrystals (TCNCs), and anionic surfactant sodium dodecyl sulfate (SDS) was added to improve the stability of the displacing agent. After the optimal SDS concentration was confirmed, PHAD/TCNCs/ SDS dispersions containing 0.05−0.15 wt % TCNCs can be stable for a long time. Hence, the rheological performance of dispersions containing 0.05−0.15 wt % TCNCs was investigated systematically, and the results revealed that the PHAD/TCNCs/SDS dispersions had outstanding thermothickening ability, salt resistance, shear resistance, and viscoelastic property in a simulated oil reservoir circumstance, and the interaction mechanism among PHAD, TCNCs, and SDS was analyzed. Finally, a core flooding test was conducted, and the obtained data showed that the oil recovery of dispersion was 21.5%, which is higher than the control dispersion without TCNCs, confirming that the PHAD/TCNCs/SDS dispersions have significant practical application prospects.