Nanofluids based on hydrolyzed polyacrylamide and aminated graphene oxide for enhanced oil recovery in different reservoir conditions

Abstract Partially hydrolyzed polyacrylamide (HPAM) aqueous fluids in reservoirs produces a significant increase in the produced oil volume. However, the viscosity of these fluids is highly influenced by the temperature and salinity of the medium which is crucial in some reservoir conditions for the oil recovery. Thus, addition of nanomaterials in HPAM solutions to prepare nanofluids has been shown to be a promising alternative to increase viscosity and improve the performance in enhanced oil recovery. In this work, graphene oxide (GO) was prepared using modified Hummers method through the oxidation/exfoliation of expanded graphite while the aminated graphene oxide (GOA-EDA) was prepared using ethylenediamine in an ultrasonic bath. Spectroscopic techniques, elementary and thermogravimetric analyses confirmed the chemical composition of the produced nanomaterials. Images obtained by transmission electron microscope also confirmed the interfacial interactions between GO / GOA-EDA and HPAM. Rheological measurements were performed to determine the nanofluids viscosity as a function of concentration at high temperature (70 °C) under different salinity conditions. The results indicate that the viscosity increases promoted initially by the nanofluids prepared with GOA-EDA were smaller than those obtained by the nanofluids prepared with GO. In particular, the greatest increases in viscosity values occurs in the medium with the highest ionic strength ( η i % μ = 0.6 > η i % μ = 0.3 > η i % μ = 0.1 ). However, after 90 aging days, nanofluids prepared with GOA-EDA showed better performances reaching gains of up to 146% in viscositiy when compared to the HPAM reference fluids indicating that nanofluids prepared with GOA-EDA are more promising for application in enhanced oil recover.