Study of asphaltene precipitation during CO2 injection for Malaysian light oil reservoirs

This work focuses on asphaltene precipitation problem during dynamic displacement by CO₂. Although CO₂ injection is one of the most important methods currently being used in enhanced oil recovery but it may change the properties of the crude oil and increase the possibility of asphaltene precipitation occurrence. The presence of asphaltene in form of precipitated, flocculated or deposited particles may alter reservoir characteristics in such a way that recovery reduction is evitable. The main concern is the effect of the asphaltene on the formation characteristics. The damage that asphaltene can cause to formation is sever, since reservoir formation is not accessible and applicable remedial methods are expensive even well shut down might be necessary. More than that sometimes the damage is irreversible. Therefore this research attempts to gain a better understanding about asphaltene precipitation induced by CO₂ injection. For this purpose a Malaysian light oil crude sample was selected since light oils are more prone to have asphaltene precipitation problem. Precipitation quantity, interaction between asphaltene and formation, in the presence of CO₂ under different injection pressures is investigated in this research. Obtained results revile that at asphaltene precipitation increases as pore volume of injected gas increases. More than that, it was observed that asphaltene precipitation decreases when injection pressure increases.