Deposition and removal studies of asphaltene from the glass surface

Asphaltene deposition in crude oil reservoirs and transportation lines affects the oil recovery and incurs additional operational costs. The current study discusses the removal of asphaltene from inorganic silica surfaces using hydrodynamic forces. The deposition of asphaltene was carried out on clean glass slides (proxy material for silica) from heptane-asphaltene dispersions via aging. For the removal of asphaltene, a parallel plate channel is fabricated with a pocket to place aged substrates under varying shear rates. The apparatus enables studying the surface morphology changes on a glass slide due to controlled flow conditions through physical contact techniques like atomic force microscopy (AFM). AFM characterizes the extent of both deposition and removal of asphaltene from the surface. The results show that large aggregates of asphaltene are removed from the surface with an increase in flow rates. The extent of removal of asphaltene from the substrate as a function of shear rate is determined. The study also discusses the possible mechanism of asphaltene removal from the surface using the hydrodynamic force calculations. The colloidal interactions calculated from hydrodynamic forces are reported to be Fadh/(d/2) = 1.29 mN/m. The presence of asphaltene tends to alter surface wettability. Interestingly, the contact angle measurements carried out on the asphaltene-deposited glass slides and after removal of asphaltene from the surface showed a negligible change, indicating incomplete removal of asphaltene from the surface.