Asphaltene stability in crude oil during carbon dioxide injection and its impact on oil recovery: A review, data analysis, and experimental study

Crude oils are usually associated with many compounds, some of which are favorable and others, which are not. One of the most unfavorable components of crude oil that pose severe operational problems and decreases oil production significantly are asphaltenes. These compounds are solids that are homogenized in the crude oil at room temperature but tend to separate from solution when agitated. They can deposit in the reservoir pores, wellbore, and transportation pipelines thus causing severe operational problems and oil recovery reduction. Even though researchers have been studying asphaltenes for more than 100 years, there is still an ambiguity concerning asphaltene structure and characteristics since asphaltenes have no unique structure. This research performed a comprehensive data analysis on both laboratory studies and field cases involving asphaltene in order to provide a generalized guideline on asphaltene properties asphaltene stability. The analysis was based on more than 200 references involving more than 4000 experiments and 19 field studies. Two statistical analysis tools were used, including histograms and boxplots. After determining the factor impacting asphaltene, this research conducted experiments to understand the impact of these factors on asphaltene stability in crude oil during carbon dioxide (CO2) injection in unconventional shale nanopores, since very limited research has been conducted in this area. The research investigated the impact of several factors including pressure, temperature, oil viscosity, pore size, porous media thickness, and heterogeneity on asphaltene precipitation, pore plugging, and oil recovery reduction. A Pareto Plot was also generated to determine the factor that had the strongest impact on asphaltene instability in the crude oil --Abstract, page iv