Experimental Study of the Asphaltene Aggregates Size Due to CO2 Gas Injection under Static Conditions

One of the major and complex problems which confront oil industry is the asphaltene precipitation that could cause numerous problems in manufacturing process, operation and transmission pipelines and etc. Importance of this debate gets clearer when we regard the formation of asphaltene deposition as one of the most negative consequences of Enhanced Oil Recovery methods - specially carbon dioxide gas injection- and it is inevitable to use these methods due to inability the natural drain of oil reservoir. The present investigation focuses on effect of CO2 gas injection on asphaltene precipitation in two Iranian oil reservoir samples, and examines the the effect of operating pressure and CO2 concentration on asphaltene precipitation. We first measure the asphaltene precipitation content of two different samples of Iranian oil reservoirs under conditions of carbon dioxide gas injection, and then in order to obtain information about the size of deposited aggregates, structural analysis is performed using Scanning Electron Microscope (SEM). Gas injection increases the amount of asphaltene precipitation. Of course decreasing trend of sediment is observed down the bubble. By increasing the amount of the injected gas, the average size of particles increases. The maximum particle size of the deposited asphaltene is observed at bubble point pressure for both fluids used this study.