Abstract Numerous industrial problems are related to the deposition of asphaltene in oil and gas reservoirs. Recently, different researchers used asphaltene inhibition using different types of nanoparticles. In this study, a new nanocomposite named carbon nitride nanosheet/magnesium oxide nanocomposites (MgO/CN) were used for asphaltene inhibition in carbonate porous media, and a comparison was made with magnesium oxide nanoparticles (MgO). After performing characterization tests, a series of ultraviolet-visible spectrometer (UV-Vis), CO2/oil interfacial tension, and atomic force microscopy (AFM) tests were performed at real reservoir carbonate conditions to see asphaltene adsorption on MgO/CN and MgO. Finally, as MgO/CN had better results for asphaltene adsorption in the mentioned tests, a series of natural depletion tests observing asphaltene deposition in porous media were designed using MgO/CN. The Langmuir isotherm was fitted better than Freundlich for maximum asphaltene adsorption on MgO/CN and MgO. Moreover, comparing MgO MgO/CN demonstrates superior asphaltene adsorption capacity in CO2/oil interfacial tension testing, especially at 5200, 4900, and 4600 psi, which were chosen to conduct natural depletion tests. Roughness data from AFM tests was in line with adsorption tests. Average roughness, peak to valley roughness, and root mean square roughness for carbonate sheets dropped from (46.70±1.38 nm, 335.71±2.64 nm, and 57.21±1.98 nm) to (15.36±1.25 nm, 131.5±2.62 nm, 19.24±1.2 nm), and (5.42±0.25 nm, 23.37±1.62 nm, and 17.52±0.86 nm) using MgO/CN and MgO, respectively. Finally, MgO/CN decreases asphaltene deposition and improves permeability/porosity reduction in carbonate formation..
