An Experimental Study on Strength of Inhibitors Stabilizing Asphaltene Flocculates Using a Viscometric Method

One of the most important issues in EOR is asphaltene deposition. Asphaltene is partly dissolved in oil, partly in steric-colloidal form and partly in micellar form depending on the composition of crude oil. Adding dispersing agents to oil, which are functionally similar to natural resin, prevents the aggregation of asphaltenes in crude oil. Inhibition strength is a capability of the inhibitor to delay formation of asphaltene flocculates, which depends on the interaction between the inhibitor and asphaltene particles. In this study, the onset of asphaltene precipitation was evaluated using a viscometric method in the presence of three types of inhibitors. In order to determine stabilization (dispersion) strength, the context of “effective adsorption point” of inhibitor is introduced by the use of the shear effects of asphaltene aggregates. The results showed that the inhibitor was adsorbed on asphaltene micelles and the stabilization strength increased with increasing inhibitor concentration. The comparison between colloidal instability index (CII) and the stabilization strength of the inhibitor indicated that the inhibition and stabilization strengths of the studied inhibitors were much higher than the natural resins.