Asphaltene-modified surfaces

Table II. Thin Film Spreading Agents Make Asphaltene-Modified Surfaces More Strongly Water-Wet...

Contact angle measurements for a water droplet on an asphaltene modified borosilicate surface confirmed that low concentrations of TFSA molecules change the wettability of the surface from fractionally-wet to water-wet. Table II shows the results of the contact angle measurements all reported results are the average of 10 separate measurements, none of which varied from the mean by more than 5° As the concentration of the TFSA... 

Hartley, P.G. and Scales, P.J., Electrostatic properties of polyelectrolyte modified surfaces studied by direct force measurement, Langmuir, 14. 6948, 1998. Rodrigues, E.A., Monteiro, P.J.M., and Sposito, G., Surface charge density of silica suspended in water-acetone mixtures, J. Colloid Interf. Sci.. 211, 408, 1999. Abraham, T. et al.. Asphaltene-silica interactions in aqueous solutions Direct force measurements combined with electrokinetic studies, Ind. Eng. Chem. Res., 41, 2170, 2002. 

The slow settling and consolidation after the suspension, reaching about 30% solids, have been attributed to the presence of unrecovered bitumen (Figure 9) (5) or to the presence of fine clays and amorphous materials, which either may hold amounts of water disproportionate to their concentration or may form an ordered floe structure at 30 wt% solids (4). One explanation emphasizes the possible role of soluble organic surfactants that modify the clay surfaces, the effect of strongly bound organic material on the minerals, asphaltenic components from... 

Surfactant adsorption on the reservoir surface is another important factor to be considered when using foams in EOR processes is discussed in [258]. Adsorption experiments with surfactants of different structures were performed on cores of a number of materials (quartz, sandstones, kaolin, calcite and others), both clean and modified (impregnated) with hydrocarbons of various structure ( light oil, high-viscosity oil, asphaltenes). Minimum adsorption, as well as maximum oil recovery based was observed when using amphoteric surfactants as well as surfactant mixtures, e.g. diphenyl ether disulfonate - a-olefin sulfonate (DPES-AOS). 

As a sequence it follows that adsorption of petroleum macromolecules asphaltenes, resins and paraffines modifies inner pore surface and sequently influences to permeability k. Porous media is classified to next classes (Table 1). 

When the chemical and physical properties of the polymer and asphalt are not matched to each other, a polymer rich phase could develop near the surface of the asphalt when stored at 160-170 °C for a few days without agitation as reported by Brule et al. with SBS modified asphalts [16]. The asphalt composition in the polymer rich phase is vastly different from the original asphalt One of their results with Asphalt E modified with 5 % SBS polymer is shown in Fig. 12-4. The aromatic and saturate components preferentially partition to the polymer phase, thus concentrating the asphaltenes and polar resin fractions in the asphalt phase. The majority of asphaltenes are retained in the asphalt phase, resulting in an increase in the asphaltenes/aromatic ratio. This potentially leads to reduced swelHng of asphaltenes, which would have negative effects on low temperature flexi-bihty of asphalt. 

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