Nanohybrid Temperature-Responsive Hydrogels Based on Cellulose Derivatives for Enhanced Oil Recovery

The control of the mobility of fluids (such as hot water or steam) is an important issue in the thermal recovery of thick oil. In this research, a nanohybrid temperature-responsive gel (NS-HPMC) was constructed, which could improve the development of the thermal recovery effect in thick oil reservoirs based on the sol–gel transition that occurs during temperature changes. An NS-HPMC was prepared using a chemical grafting method, with hydroxypropyl methylcellulose (HPMC) being used as the main temperature-responsive agent and nanosilica (NS) being used as the reinforcing agent. The successful grafting of NS on the surface of the HPMC polymer was demonstrated by using infrared spectroscopy and X-ray photoelectron spectroscopy characterization. The gel transition temperature of NS-HPMC was observed to be 70.15 °C based on dynamic light scattering, differential scanning calorimetry, and rheological analysis. Compared with HPMC, NS-HPMC exhibited better temperature resistance (180 °C), salt resistance (50,000 mg/L NaCl or 5000 mg/L CaCl2), reversibility (≥5 cycles), and long-term thermal stability (with the starting degradation temperature being as high as 351 °C) according to rheological analysis and thermogravimetric analysis. With respect to the mobility control capability, the plugging rate of the NS-HPMC system was greater than 95% during three cycles of temperature increase and decrease. In addition, when the NS-HPMC was heated and transformed into a gel, it was able to effectively seal the hypertonic core and increase the enhanced recovery rate by 16.67%. In summary, the NS-HPMC system may exhibit a potential application for improving the performance of smart gel modulation for use in thick oil reservoirs.