Mitigation of asphaltenes precipitation phenomenon via chemical inhibitors

Abstract

The main aim of this study is to mitigate asphaltenes precipitation phenomenon using chemical inhibitors under reservoir conditions. Different conventional screening test methods such as UV-Vis and solids detection system (SDS) equipped with a low-intensity near infrared (NIR) light and a high-pressure microscope (HPM) were used to assess the effectiveness of asphaltenes inhibitors on a stock tank oil (STO) and downhole samples (DHS). These tests have been employed as part of a rigorous investigation to understand (evaluate) the performance of chemical inhibitors in mitigating asphaltene precipitation and deposition. The extracted asphaltenes were characterized by higher aromaticity due to relatively low hydrogen/carbon molar ratios, hence, the higher tendency of asphaltenes aggregation and subsequent precipitation upon changes in thermodynamic factors. Moreover, the evaluation tests of the commercial asphaltenes inhibitors showed efficient asphaltenes dispersion performance when tested by using different conventional methods. Finally, the high-pressure microscope tests conducted on the DHS at reservoir temperature showed that the most efficient inhibitors reduced the aggregated asphaltenes average particles size by 58%. This is attributed to the presence of the high aromatic content, and polar acidic and/or alcoholic functionalities in the molecular structures of those inhibitors, which is vital for the dispersion of the asphaltenes and the prevention of the formation of large asphaltenes aggregates through π-π interactions and van der Waals forces.