Hydrodynamic thickness of petroleum oil adsorbed layers in the pores of reservoir rocks

• Published in: Journal of colloid and interface science 2006-06, Vol.298 (1), p.13-19
• Main Authors: Alkafeef, Saad F., Algharaib, Meshal K., Alajmi, Abdullah F.
• Format: Article
• Language: English
• Subjects: Asphaltene; Chemistry; Colloidal state and disperse state; Disjoining pressure; Electrokinetic measurements; Exact sciences and technology; General and physical chemistry; Hydrodynamic thickness; Permeability; Porous materials; Porous medium; Streaming current; Streaming potential; Zeta potential
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2005.12.038

The hydrodynamic thickness δ of adsorbed petroleum (crude) oil layers into the pores of sandstone rocks, through which the liquid flows, has been studied by Poiseuille's flow law and the evolution of (electrical) streaming current. The adsorption of petroleum oil is accompanied by a numerical reduction in the (negative) surface potential of the pore walls, eventually stabilizing at a small positive potential, attributed to the oil macromolecules themselves. After increasing to around 30% of the pore radius, the adsorbed layer thickness δ stopped growing either with time or with concentrations of asphaltene in the flowing liquid. The adsorption thickness is confirmed with the blockage value of the rock pores' area determined by the combination of streaming current and streaming potential measurements. This behavior is attributed to the effect on the disjoining pressure across the adsorbed layer, as described by Derjaguin and Churaev, of which the polymolecular adsorption films lose their stability long before their thickness has approached the radius of the rock pore. After increasing to around 30% of the pore radius, the adsorbed layers thickness δ stopped growing either with time or with concentrations of asphaltene in the flowing liquid.