Experimental investigation of asphaltene adsorption in porous media due to solvent injection and effects on relative permeability

While reduction in rock permeability due to deposition of asphaltene fraction of crude oil imposes negative effects on oil production rate from producing formation, there is no clear understanding about adsorption of asphaltene and the resulting effects on rock-fluid properties such as relative permeability. This work reports the results obtained from a series of experimental investigations to address the adsorption of asphaltene in porous media and the consequent impacts on relative permeability and recovery of waterflooding. Experiments are implemented by means of a designed experimental rig for specific set of water salinity, asphaltene concentration, clay content and composition of injected fluids. Waterflooding is performed in sand-pack prior and after the dynamic adsorption step to measure relative permeability and evaluate the change in recovery factor of waterflooding. Adsorption level is measured from spectrophotometry analysis of injected asphaltene solution and collected samples using the developed material balance calculations for asphaltene. In addition, the extracted sand at the end of experiment is analyzed to clarify the distribution of adsorbed asphaltene along the sand-pack. Obtained results show that the salinity of water phase acts as a resistive force to adsorption. However, waterflooding experiments and the corresponding relative permeability curves show the possible improvement in displacement performance and recovery factor of watertlooding under effect of asphaltene adsorption at certain conditions. Longer breakthrough time, more favorable transient flow and reduced residual saturation during waterflooding indicate the positive effects of asphaltene on recovery factor. (C) 2017 Elsevier Ltd. All rights reserved.