The Effect of Inhibitors on Asphaltene Precipitation in Crude Oil Using the Viscometric Method

Abstract

One of the main problems in production of oil reservoirs is the formation of asphaltene precipitation. Blockage in porous medium, wells, and facilities has a detrimental effect on the production of asphaltenic oil. Generally, asphaltenes are heaviest and most polar fractions that can be found in crude oil. These compositions have a complex molecular structure that is a series of non-hydrocarbon molecules and they are soluble in benzene and insoluble in normal alkanes and solvents with low molecular mass. Based on recent experiments, it is supposed that these compositions can be partially solved in oils at a colloidal state. The nature and behavior of asphaltene in crude oils is complex, so changes in temperature, pressure, and composition of crude oils during production can result in precipitation of asphaltene components. These parameters affect the chemical equilibrium in reservoirs and result in precipitation. A possible way to prevent asphaltene precipitation is by adding an asphaltene stabilizer, i.e., inhibitor. Asphaltene inhibitors act in a way similar to resins, peptizing the asphaltenes and keeping them in solution. The inhibitor efficiency largely depends on its chemical and structural characteristics. However, the inhibitor ability to stabilize asphaltenes depends also on the solvent or dispersion medium. The main objective of this research is to investigate the effect of three different inhibitors on asphaltene deposition using a viscometric method.