Abstract: To demonstrate the feasibility of CO₂ flooding development of the heavy reservoirs in Well Ji7 of Changji oilfield in the Junggar Basin, experiments on injecting CO₂ into crude oil and slim-tube displacement were carried out to investigate the solubility of CO₂ in heavy oil. The experiment results proved that:(1) When injecting CO₂ at 50mol/mol at present 16.41MPa underground pressure, the viscosity of the crude oil was reduced by 42.3%-66.7%, the density was reduced from 0.9011g/cm³ to 0.8428 g/cm³, the volume factor was increased by 20%, the expansion factor was increased to 1.13-1.24, the gas-to-oil ratio increased by 6.3-8 times, and the saturation pressure increased by 140%-306%. (2) The oil recovery increased with injection pressure, and gas breakthrough was delayed. When the injection pressure was 45MPa, the oil recovery was 46.68%, and non-miscible displacement worked. (3) CO₂ effectively reduced the viscosity and made the crude oil expand in the study area. All these results above show that CO₂ flooding technology is effective for the development of deep heavy oil reservoirs in the study area.

Key words: Changji oilfield, heavy oil, CO₂ flooding, slim-tube displacement experiment