Investigation on C02 Induced Asphaltene Precipitation Using Baronia Oil Samples

Asphaltene precipitation is one of the serious problems during the secondary and tertiary
oil recovery in light oil reservoirs using C02 injection. Baronia RV2 light oil sample has
been chosen to study the possibility of asphaltene precipitation during the contact of C02
with oil. When C02 is in contact with light oil, there is a tendency for asphaltene
precipitation which might lead to serious production and reservoir problems such as
permeability reduction, porosity alteration, and plugging of wellbore and possibility of
blocking the whole production system.
The present research is to investigate the asphaltene precipitation phenomenon and to
analyze the mechanism of asphaltene deposition during the C02 injection process. A
laboratory study for crude oil characterization has been carried out to determine the
properties of reservoir fluid. A routine and special PVT analysis using a high pressure
and temperature visual cell has been carried out to examine the phase behavior of
asphaltene and C02• Oil expansion test under C02 injection and micro- slim tube test
have been carried out to investigate the swelling factor and minimum miscibility pressure
and to identify the effect of different concentration of C02 on asphaltene precipitation.
Static and dynamic asphaltene studies have been carried out to determine the asphaltene
precipitation at different C02 concentrations and different pressures. Asphaltene
precipitation was found during the static asphaltene test when the C02 concentration was
changed under reservoir pressure and temperature. The results show that the amount of
precipitated asphaltene increased with increasing the concentration of injected C02 .
However; in the dynamic test asphaltene precipitation fluctuated when both pressure and
C02 concentration were changed simultaneously. Results from dynamic asphaltene test
were analyzed using statistical analysis method to predict the asphaltene precipitation
under the effect of both pressure and C02 concentration. Multiple regression analysis and
analysis of variance (ANOVA) were used to get the multiple linear regression model of
asphaltene precipitation for Baronia RY2. The model was tested by using different
concentration of C02 at selected pressures to predict the asphaltene precipitation at any
pressure and C02 concentration. Comparison was made between the measured and
predicted asphaltene precipitation.