An Overview of Asphaltene Precipitation and Methods to Prevent its Formation

Asphaltenes are heavy components in oil that do not dissolve in normal alkanes like normal heptane but can be soluble in aromatic compounds such as benzene and toluene. Usually changes in operating conditions such as temperature, pressure and fluid composition lead to asphaltene precipitation. Asphaltenes cause a lot of damage by depositing in porous media, wells, pipes and surface equipment. In order to prevent or postpone the formation of asphaltene precipitation in different conditions and places, it is very necessary and important to predict the onset point and the amount of precipitation. Temperature, pressure and flow rate are operating conditions that by changing each, the amount of precipitation can be reduced or intensified. The only solution in the industrial world to postpone asphaltene precipitation is to use chemicals and inhibitors, which is very important to know the mechanisms of deposition. In this review paper, the structure of asphaltene, deposition conditions, experiments of asphaltene precipitation, deposition mechanisms and inhibitors are discussed. The main purpose of this article is general acquaintance with asphaltene precipitation and the factors affecting deposition and applying knowledge to prevent the formation of asphaltene precipitation with the approach of using and applying inhibitors.