Abstract: Study of using CO₂ stimulation process in Wei-5 thin-layer heavy oil reservoir with medium-low permeability and complicated small fault block is conducted. By numerical simulation technique, sensitivity factors of CO₂ stimulation are analyzed. The result shows that the major factors afcting CO₂ stimulation performance include cyclic CO₂ injection volume,CO₂ injection rate and bottom hole pressure, while the soaked period has restricted effect. Based on increased oil production and improved oil production per unit volume of CO₂ injection as evaluated basis, the calculated result indicates that under high CO₂ injection volume,high CO2 injection rate and reasonably controlled bottom hole pressure, optimal cyclic numbers can be determined and better CO₂ stimulation performance can be obtained. This study can be as a guide for development of those similar to this type of heavy oil reservoir.

Key words: Jiangsu oilfield, heavy oil, CO₂, numerical simulation, recovery percent