Effect of scale and corrosion inhibitors on well productivity in reservoirs containing asphaltenes

During oil production from several wells in Arabian Gulf area, significant productivity decline was noticed. One of the reasons behind the productivity decline might be asphaltene precipitation. Production data of the particular wells were collected and analyzed. It was found that many of these wells were injected with scale and corrosion inhibitors in downhole and surface equipment. Thus, it was desired to investigate the potential of formation damage due to asphaltene in the presence of scale and corrosion inhibitors as field chemicals. The effect of asphaltenes on the wettability, surface, and interfacial tensions were measured in the presence of scale and corrosion inhibitors. It was observed that the scale inhibitor did not indicate any alteration of the wettability, while the presence of corrosion inhibitor indicates high potential for wettability change into oil-wet conditions especially in the presence of asphaltenic oil. Similar results were obtained from the measurements of surface and interfacial tensions, in which corrosion inhibitors showed a significant decrease in surface and interfacial tensions. To assess the potential of asphaltene precipitation in the presence of both inhibitors and to study the effect of asphaltenes on the oil productivity, flooding experiments were carried,out and oil/water relative permeability was determined. The results of flooding displacements showed that the presence of scale inhibitors indicates no effect on the oil/water relative permeability even in the presence,of asphaltenes, while a significant decrease in oil relative permeability associated with an increase of residual oil saturation was observed in the presence of corrosion inhibitors. Mixture of scale and corrosion inhibitors showed no effect on relative permeability curves. (c) 2005 Elsevier B.V. All rights reserved.