The effects of SO4 2- and Mg2+ on the adsorption/displacement of stearic acid (SA), N,N-dimethyldodecylamine (NN-DMDA) and asphaltene, as oil soluble additives, onto or from calcite, quartz, and clay minerals are addressed in this paper. Thermal gravimetric analysis, isothermal water vapor adsorption, and contact angle methods are used to determine the extent of surface modification and evaluate the hydrophilicity/hydrophobicity of the modified powders and minerals, respectively. The experimental results of the modified mineral surfaces are analyzed using a suggested wettability index based on water vapor adsorption isotherm and contact angle. It is interesting to observe that SO4 2- and Mg2+ ions enhance hydrophilicity characteristic of the modified calcite surface while SO4 2- ions have insignificant effect on adsorption of the tested polar components on the silicate minerals. Mg2+ ions enhance the hydrophilicity of quartz and kaolinite surfaces modified by N,N-dimethyldodecylamine. On the other hand Mg2+ ions increase the hydrophobicity of silicate minerals when asphaltene is the surface modifying component. This may be due to bridging of the hydrated Mg2+ ions with asphaltene. The suggested bridging mechanism is also consistent in the case of alteration of calcite surface with asphaltene, however to lesser extent due to the more affinity toward calcite surfaces.

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The paper pertains to the analysis of the chemical interaction between sea water ions, asphaltene colloids and silicate /calcite mineral as a substrate during water/low salinity water flooding. The work tackles modeling of salinity dependent relative permeability and capillary pressure functions from contact angle to estimate oil recovery during water/low salinity water. The paper has two main parts. In the first part, static contact angle is calculated based on disjoining pressure and compared to the experimental values, reported in the literature. In the second part, the model is used to demonstrate that water film is more stable in presence of low salinity water compared to distilled water and sea water, for carbonate and silicate minerals. Increasing temperature enhances the stability of the water film around the substrate for both types of minerals. This could be future interpreted as an indication for extra oil recovery applying low salinity water injection at elevated temperature. It is interesting to observe from the model that, increasing the Mg 2+ ion concentration enhances the hydrophilicity characteristics for calcite mineral modified by asphaltene while for silicate surface modified by asphaltene, SO 4 2-ion enhances the hydrophobicity behaviour.

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Interaction of CO 2 with mineral surfaces is of increasing importance to the activities related to CO 2 sequestration and enhanced oil recovery. Adsorption/interaction of CO 2 with mineral powder surfaces is addressed using microcalorimetric method coupled with gas chromatograph as a detector. Calcite powder surface is modified with stearic acid (SA) and asphaltene, while the silicate mineral powder surfaces (quartz and kaolinite) are modified with N,N-dimethyldodecylamine (NN-DMDA) and asphaltene. Unmodified calcite in presence of humidity has shown to have the highest capacity for CO 2 adsorption among the tested minerals, where a reaction may occur at the calcite surface. The adsorption capacity of calcite is reduced upon modification with SA and asphaltene. Similar observation is also shown with the modified silicate minerals with asphaltene. In contrast, for the modified silicate with NN-DMDA, the adsorption capacity of CO 2 increased, which may be explained by the interaction of CO 2 with the amine group of NN-DMDA.