Iron oxide (Fe3O4) and nickel oxide (NiO) nanoparticles were employed to control the aggregation of asphaltenes in reservoir model oils along the production streamline from the far-field region to near-wellbore area to wellbore conditions. Fe3O4 and NiO nanoparticles with an average particle size of 30 and 78 nm, respectively, were synthesized via a simple precipitation method and characterized by X-ray diffraction, Brunauer, Emmett, and Teller (BET), Fourier transform infrared spectroscopy, and field emission scanning electron microscopy imaging techniques. Asphaltenes were extracted from an Iranian heavy oil sample, and their structure and functional groups were characterized. The asphaltenes were dissolved in toluene at a concentration of 400 mg/L, designated as reservoir model oil. The average size of the asphaltene nanoaggregates in the model oil, as determined by dynamic light scattering (DLS), is 18 nm, representative of the size of asphaltene aggregates in reservoir oils. The nanoparticles were added to the model oil at an optimum ratio of 0.09 m(2) BET surface area/g of the asphaltenes, and the samples were shaken at 70 rpm to approach equilibrium. In order to simulate the effects of pressure depletion on aggregation of asphaltenes at far-field conditions, n-heptane was added at different volume ratios to the thus-obtained equilibrium model oil followed by shaking to approach a new equilibrium, designated as far-field tests. The equilibrium samples obtained from the far-field tests were exposed to shear stress in a flow assurance apparatus to simulate the effects of shear rate on aggregation/fragmentation of asphaltenes at near-wellbore/wellbore conditions, classified as near-wellbore tests. The CouetteTaylor flow assurance apparatus consists of two concentric cylinders, and the fluid in the annular space is subjected to shear stress by rotation of the internal cylinder. In order to determine the size distribution of the asphaltene aggregates at the far-filed and near-wellbore conditions, the samples were exposed to a magnetic field or centrifugation, and the supernatant liquids were subjected to dynamic light scattering analysis. It is found from the far-field tests that the asphaltenes onset point, i.e., the average aggregate size of 500 nm, is obtained at 21, 29, and 45 vol % of n-C7 in the absence of the nanoparticles, in the presence of NiO and in the presence of Fe3O4, respectively. The higher activity of the Fe3O4 nanoparticles for the control of the asphaltene aggregation is attributed to the number and strength of the interactions of the asphaltenes functional groups with the surface sites of the nanoparticles. Furthermore, the near-wellbore test results show that the shear stress leads to aggregation where the size of the asphaltene nanoaggregates is smaller than around 50 nm. Fragmentation of the asphaltene aggregates is the result of shear stress for samples with aggregates sizes of higher than about 50 nm. This may be ascribed to the effects of the shear stress on the development of electrostatic fields (aggregation) as well as fragmentation (break up) of the asphaltene aggregates in the model oils.