Prevention and Control of Corrosion-Induced Asphaltene Deposition

Abstract

Although multiple problems occur simultaneously in oil production, the solution strategy is typically presented by addressing one problem at a time. The objective of this work is to provide insight into the detrimental effect of iron ions, which are produced as a result of corrosion, on the asphaltene precipitation and deposition tendency during oil production. Furthermore, we aim to provide means to control these adverse effects by using chelating agents. In a series of experiments, a model oil system, which was prepared by dissolving asphaltenes in toluene, was put in contact with aqueous solutions of iron ions to study the effect of these species on the stability of asphaltenes using the indirect method. Also, a new experimental setup, consisting of a multi-section Teflon column packed with carbon steel spheres was built to quantify the deposition of asphaltenes under different operating conditions. This device was used to study the effect of the aqueous iron solutions on the asphaltene deposition tendency. It was found that the solubility of iron species is relatively high in the oil phase, compared to other cations, and that unlike other metals iron has a significant destabilizing effect on the asphaltene system. Furthermore, the multiphase systems that were analyzed in the column that is packed with carbon steel spheres, showed increasing deposition as the concentration of iron in the aqueous phase increased. A chelating agent was tried to reduce the adverse effect of iron and successful results were obtained. A systematic study was conducted to analyze the effect of different variables on the iron-induced asphaltene precipitation. Charge of metal ions, pH, and emulsified water do not seem to affect the asphaltene precipitation tendency as much as the iron concentration. In this work we account for the corrosion of pipelines and asphaltene deposition and the interrelation between them. According to the evidence that we have found, the corrosion of pipelines might be an aggravating cause for asphaltene deposition in wellbore and surface facilities. By addressing the corrosion problem, asphaltene deposition might actually subside.