Effect of aluminium oxide nanoparticles on oilfield polyacrylamide: Rheology, interfacial tension, wettability and oil displacement studies

Polymers play an important role for oil recovery in reservoirs through the mechanism of improving mobility ratio and disproportionate permeability reduction. However, the efficiency of oilfield acrylamide polymer in reservoirs is limited because of saline brines and temperature conditions. Recently, due to their unique properties, nanoparticles (NP's) are incorporated as additives to improve rheological properties of oilfield polyacrylamide. Nonetheless, previous studies have focussed solely on SiO₂ nanoparticles. Herein, the use of metallic aluminium oxide nanoparticle was explored, exploited and evaluated. The morphology of the formulated polymeric nanofluids was determined using Fourier transform infrared (FTIR) spectroscopy. The performance of aluminium oxide (Al₂O₃) NP on the rheological properties of HPAM in the presence of different electrolyte concentrations representative of field brine and temperature conditions was investigated. Moreover, interfacial tension (IFT) behaviour of the polymeric nanofluid at the oil/water interface was studied used Kruss tensiometer while wettability studies was carried out using goniometer. Comparative analysis was made between the shearing, IFT, and wettability behaviour of Al₂O₃ polymeric nanofluid, silica (SiO₂) polymeric nanofluid, and base polymer without nanomaterial. Experimental result shows that inducing oilfield polyacrylamide with nanoparticles caused an enhancement of the rheological properties, and inhibited degradation of polymer molecules in the presence of hardness brine and temperature. At 2000 ppm HPAM solution (27 mol. % hydrolysis degree) and 0.1 wt% NP concentration, Al₂O₃ polymeric nanofluid exhibited better steady shear performance under the different electrolyte concentration and temperature conditions studied. Besides, IFT result shows the Al₂O₃ polymeric nanofluid lowers the IFT of the oil/water interface and alters the wettability of sandstone cores from oil-wet to water-wet condition. Finally, heavy oil displacement test in sandstone cores showed that oil recoveries of Al₂O₃ polymeric nanofluid had 10.6% incremental oil recovery over conventional HPAM. This study is beneficial for extending the frontiers of knowledge in nanomaterials application for EOR.