Fe<sub>3</sub>O<sub>4</sub> Nanoparticles as Surfactant Carriers for Enhanced Oil Recovery and Scale Prevention
Maria Luiza de O. Pereira, Kelly C. B. Maia, Walner Costa Silva, Arthur Coimbra Leite, Agatha Densy dos Santos Francisco, Thiago L. Vasconcelos, Regina Sandra Veiga Nascimento, Daniel Grasseschi
Abstract
The growing demand for petroleum products and the natural decline of well’s pressure during oil production turned the oil industry’s focus onto the development and improvement of enhanced oil recovery (EOR) techniques. Nanotechnology and nanomaterials may increase oil recovery rates through nanofluid flooding applications. In this scenario, a nanofluid containing Fe3O4 nanoparticles (NPs) with the ability to carry surfactants such as cetyltrimethylammonium bromide (CTAB) was synthesized; a synergistic effect was observed when used for wettability modification of calcite fragments, reaching 80% of contact angle reduction. Raman and XPS analysis revealed that Fe3O4 NPs were able to selectively remove smaller and more disordered asphaltene molecules that present a less planar aromatic core, as indicated by the D/G Raman peaks intensity ratio and consequently weaker adsorption on the calcite surface. The presence of CTAB improved nanoparticle mobility in limestone porous medium during flooding experiments and its stability in saline solutions with high concentrations of divalent cations, while the presence of nanoparticles improved the wettability modification. Furthermore, the nanofluid can slow down CaCO3 scale formation, contributing to the flow assurance during the nanoflooding process. These combined effects improve nanofluid efficiency in tertiary oil recovery as observed during the flooding tests in an unconsolidated porous medium, giving a recovery factor up to 60%.