Improved Oil Recovery by Carbon Dioxide Flooding

摘要

The injection of CO2 can enhance oil recovery as well as help in mitigating the problem of increased CO2 concentrations in the atmosphere by storing large quantities of CO2 for a long period of time. At most reservoir conditions CO2 is a supercritical fluid with high solvency power to extract hydrocarbon components and displace oil miscibly. ECLIPSE compositional simulator was used in this study to reproduce CO2 displacement processes. In the Reservoir Simulation Model, certain parameters that are pivotal to the overall output of the process were held constant while others whose contributions are to be investigated were varied in the different runs for a 25 year period and Oil recoveries with respect to the different parameters were evaluated. An incremental recovery was observed for the 25 year period as the reservoir dip moves from 0° to 40° resulting in a 25% additional recovery. Heterogeneity index has inverse relationship with recovery from CO2 processes. CO2 evaporates the condensable portion of the fluid giving CO2 flooding an edge over methane injection. Higher mobility ratios favour more oil recovery. This research shows the additional recovery being expected by the use of CO2 Enhanced Oil Recovery (EOR). In conclusion CO2 EOR performance is influenced by reservoir heterogeneity, reservoir dip, mobility ratio of the CO2 to oil, injection rate, volume of CO2 available and reservoir fluid type. The reservoir dip favours recovery significantly as the reduced viscosity of the oil is further propelled downward to the completed zone.