Modelling of CO2 Injection

This paper presents results of secondary CO2 and CO2-rich gas injection experiments and simulations.<br>Displacements were performed in Berea cores under viscous dominated flow regime in order to evaluate<br>viscous effects at CO2 injection. The formation of three hydrocarbon phases under CO2 flood and its<br>effect on oil recovery have been already investigated in some core flood experiments. Few experimental<br>evaluations of CO2-rich phase injection effects have been performed at high pressure and above CO2<br>critical temperature. Immiscible CO2 injection was performed in high and low viscosity oil saturated<br>cores. Later gas breakthrough and higher oil production were observed at lower oil viscosity experiments.<br>The ultimate oil recoveries for low and high viscosity oils were very close at continuous CO2 injection. In<br>the floods with CO2-rich phase the achieved oil recovery could be correlated with CO2-rich phase<br>volume. Total oil recovery increases as the CO2-rich phase volume increases and miscible displacement<br>develops. Due to oil vaporisation and stripping by the moving CO2 tail-front significant amounts of oil<br>can be produced after the breakthrough of CO2. Representative simulation of CO2 injection requires<br>accurate modelling of viscous effects and formation of CO2-rich phase.