Canadian Journal of Chemical Engineering, Vol.97, No.7, 2028-2038, 2019
Experimental investigation of dynamic asphaltene adsorption on calcite packs: The impact of single and mixed-salt brine films
In this study, the dynamic adsorption of asphaltene on a calcite surface is investigated. This study investigates the effect of mixed-salt brines on asphaltene adsorption. The results of this work can facilitate the understanding of the complex wettability behaviour of carbonate reservoirs. All experiments were performed in porous media, which were sand-packs filled with calcite powder, to study the influence of the type and concentration of salt on adsorption. The experiments were conducted with asphaltene concentration of 500 mg/L for brines of NaCl, Na2SO4, and a mixture of the two at various ionic strengths. In addition, two tests were performed with an asphaltene concentration of 2000 mg/L to observe the effect of increasing the asphaltene concentration on the adsorption. Moreover, the impact of brine film on asphaltene adsorption was investigated by conducting an additional experiment without brine saturation. The results show that by increasing the ionic strength, asphaltene adsorption increased at first owing to the reduction of electrostatic forces, then it reached its maximum, and it finally decreased as a result of the rise in the hydration force. The results show that in the presence of Na2SO4 brine, the asphaltene adsorption is more than that of the NaCl brine. For the mixed-salt brine, as the ionic strength was increased, the asphaltene adsorption decreased at first and then it became constant. Furthermore, quadrupling the initial asphaltene concentration increased the adsorption up to 3.4 times. Additionally, the presence of brine film reduced the asphaltene adsorption by similar to 80 %.