Abstract
In this article, by using geochemical methods, the effect of CO2 injection effect on the asphaltene precipitation and changing of other oil components was investigated. This study was performed in one of the eastern Persian Gulf oil fields with an API of 30.5. For this subject, gas injection was executed with a slim-tube instrument and minimum miscibility pressure was also measured. An asphaltene precipitation test and liquid column chromatography test were conducted on the oil samples retrieved from the slim-tube instrument. This study indicates that CO2 influences the oil reservoir properties so intensively that all oil components were changed by the injection.