A novel green nanocomposite suppresses asphaltene precipitation: Multiscale analysis from AFM to core flooding in carbonates

Asphaltene deposition in oil and gas reservoirs presents numerous operational challenges. Recent studies have explored the application of various nanoparticle-based solutions to mitigate asphaltene precipitation. In this study, a novel ZnO/SiO ₂ /xanthan/eucalyptus nanocomposite of solid materials (NCs) was investigated for asphaltene inhibition in carbonate porous media. The asphaltene adsorption potential of NCs was evaluated through a series of experiments, including ultraviolet-visible (UV-Vis) spectroscopy, CO₂/oil interfacial tension measurements, and atomic force microscopy (AFM), under realistic carbonate-reservoir conditions following material characterization. Given its superior asphaltene adsorption performance in preliminary tests, NCs was selected for subsequent natural depletion studies to monitor asphaltene deposition in porous media. Adsorption isotherm analysis revealed that the Langmuir model provided a better fit than the Freundlich model for NCs, indicating monolayer adsorption behavior. Furthermore, interfacial tension assessments demonstrated that NCs exhibited enhanced asphaltene adsorption capacity, particularly at pressures of 3700, 3500, and 3300 psi conditions, under which natural depletion experiments were conducted. AFM and adsorption tests yielded consistent surface roughness trends. Upon treatment with NCs, the average roughness ( Rₐ ), peak-to-valley roughness ( Rₜ ), and root-mean-square roughness ( R _q ) of carbonate substrates decreased significantly. Specifically, Rₐ declined from 56.70 ± 1.42 nm to 11.42 ± 0.25 nm, while Rₜ decreased from 335.71 ± 2.64 nm to 13.23 ± 1.74 nm when subjected to NCs exposure. Similarly, R _q was reduced from 67.21 ± 1.39 nm to 12.52 ± 0.56 when subjected to NCs exposure. The application of NCs was found to mitigate permeability and porosity reduction in carbonate formations while effectively minimizing asphaltene deposition.