Effects of asphaltene structure and polythiophene-coated magnetite nanoparticles on surface topography and wettability alteration of silica surface

Abstract

Natural chemical structures in asphaltene cause it to form a colloidal aggregate that can affect crude oil properties, alter the wettability of reservoir rock surface, and reduce oil recovery. The objective of this research work is to investigate variations in surface properties of silica surface such as topography and wettability during asphaltene precipitation in the presence of magnetite (Fe3O4) nanoparticles (NPs). The magnetite nanoparticles (MNP) are coated with polythiophene to make them more stable and enhance their adsorption capacity. The structure of three asphaltenes used in this research work is determined using nuclear magnetic resonance (NMR), elemental analysis, and Fourier-transform infrared spectroscopy (FTIR) to obtain more details about asphaltene adsorption on the surface of the polythiophene-coated magnetite nanoparticles (MNP@PT). The results show that heteroatoms (e.g., O, N, and S) and aromatic rings as functional groups can affect asphaltene agglomeration and adsorption process onto silica surface. Atomic force microscopy (AFM) is used to obtain adequate topography information. Roughness parameters show that a heterogeneous surface is formed after asphaltene precipitation on the homogeneous silica surface. Contact angle measurement technique and modified Wenzel model are used to investigate the effect of MNP@PT on wettability alteration. The change in contact angle for pure silica upon asphaltene precipitation is lower in the presence of MNP@PT. The silica surface is extremely oil-wet after asphaltene precipitation, but it becomes preferentially oil-wet in the presence of MNP@PT. We showed that MNP@PT are an excellent absorbent to reduce asphaltene precipitation/deposition. The outcome of this research work can increase the current understanding of molecular interactions between asphaltene and solid surfaces in the presence of MNP@PT to reduce impact of asphaltene precipitation on wetness characteristics of the silica surface during oil production.