Nanofluidos à base de poliacrilamida e óxido de grafeno aminado: aplicação em recuperação avançada de petróleo

Abstract

Enhanced oil recovery (EOR) is an oil and gas industry strategy capable of recovering up to 60% of the oil after the application of primary and secondary processes, and is crucial to avoid the abandonment of mature fields. In the chemical EOR method, the application of partially hydrolyzed polyacrylamide (HPAM) aims to increase the water viscosity and improve the displacement of the remaining oil in the well. However, under severe conditions of high temperature and salinity, HPAM is degraded and its efficiency is compromised. Graphene oxide (GO) functionalized with aminated polymers emerges as a promising solution to improve the rheological properties of HPAM. In addition, microwave (MW) synthesis offers a sustainable alternative because it does not require the use of toxic coupling agents. In this work, the amination of GO with polyethyleneimine (PEI) was performed by MW radiation, and by traditional methods, aiming to obtain GO-PEI as a way to improve the rheological properties of HPAM. Several characterization techniques were used to evaluate the surface modification of GO, including: FTIR, Raman, TG/DTG and elemental analysis, and it was possible to confirm that the modification of GO occurred successfully by the observation of amide bonds in FTIR spectra, in addition to a greater thermal stability of the aminated GO in TG/DTG. In addition, the structural and morphological modification of the aminated carbon nanomaterials (NMCA) was evaluated by TEM and SAED images, and it was possible to confirm the surface modification of GO by observing structural changes in the nanosheets. To evaluate the stability of the dispersions, the results of Zeta Potential and DLS allowed the selection of three colloidal systems in saline solution with μ = 0.3 for the production of nanofluids and, thus, rheology tests were performed under high salinity conditions and at high temperatures. The obtained fluids presented pseudoplastic behavior and an increase of 27% in viscosity was obtained for NF-GO-PEI-1-MM-075 in 30 s-1 and for NF-GO-PEI-1-70-050 of 11% in 7.34 s-1 at 70 °C compared to HPAM. A viscosity study with temperature also allowed a 42% increase in viscosity for NF-GO-PEI-1-MW-075 compared to HPAM at 70 °C. Therefore, it is concluded that it was possible to obtain the amination of GO with PEI successfully, in addition to preparing nanofluids that presented improvement in rheological properties under relevant well conditions, making them promising in EOR.