Synthesis and application of polyacrylamide grafted GO and MWCNT nanocomposites for enhanced oil recovery: a coreflooding study

Most of the oil reserves have remained unrecovered during primary and secondary recovery scenarios which raise the need for novel and more useful recovery methods to produce the unrecovered oil and increase the recovery factor as an Enhanced oil recovery method. As the most common oil recovery method, the performance of the water injection can be further enhanced by adding polymers to water by the mobility control mechanism. Nanoparticle and nanohybrid flooding are one of those novel methods which can recover oil using wettability alteration and IFT reduction mechanisms. In this study, we synthesized polyacrylamide-based nanohybrids such as graphene oxide (GO)/PAM and carbon nanotube (CNT)/PAM combine the advantages of both nanoparticle and polymer flooding using a novel and simple method. The effect of different mechanisms involved such as wettability alteration, IFT reduction, and mobility control were studied separately in form of contact angle, IFT, and viscosity measurements and in combination with each other in the form of coreflooding tests were studied. The stability of the synthesized nanohybrids against temperature and salinity was investigated using TGA and bulk tests. The effectiveness of these novel nanohybrids was never investigated to this extent. Our investigation showed that GO/PAM nanohybrids had better performance in IFT reduction and mobility control and CNT/PAM in wettability alteration. During coreflooding tests, the GO/PAM showed the highest light and heavy oil recoveries with recovering 63.8% and 28.57%, respectively, in comparison to CNT/PAM with recovery factors of 60.95% and 25.71%. Both of the nanohybrids showed great performance in oil recovery due to wettability alteration and IFT reduction but the GO/PAM showed the best performance because of its higher viscosity which made the mobility control of the injected fluid much better.