In this paper, the mutual interactions between a crude oil and CO2 under different pressures and their effects on the crude oil-CO2 interfacial tension (IFT) and the CO2 enhanced oil recovery (EOR) are experimentally studied. Firstly, a series of crude oil-CO2 saturation tests is conducted under different equilibrium pressures in a visual high-pressure saturation cell to determine the onset pressure of the asphaltene precipitation for the crude oil-CO2 system. Secondly, the axisymmetric drop shape analysis (ADSA) technique for the pendant drop case is applied to measure the equilibrium IFT between the crude oil and CO2 as a function of the equilibrium pressure at T = 27 degrees C. The major component of the ADSA system is a see-through windowed high-pressure cell, which makes it possible to visualize the interfacial interactions between the crude oil and CO2 under the practical reservoir conditions. It is found that the measured crude oil-CO2 equilibrium IFT is reduced almost linearly with the equilibrium pressure, as long as it is lower than a threshold pressure. It is observed that if the equilibrium pressure is high enough, the light components in the original crude oil are quickly extracted from the oil drop to CO2 phase at the beginning. This physical phenomenon is referred to as the initial strong light-components extraction. The onset pressure of the initial strong light-components extraction is found to be higher than that of the asphaltene precipitation for the crude oil-CO2 system determined in the saturation tests. Thirdly, a series of CO2 coreflood tests is performed to study the effect of the mutual interactions between the crude oil and CO2 under different CO2 injection pressures on the CO2 EOR. The detailed CO2 coreflood test results show that the CO2 EOR is increased sharply with the CO2 injection pressure only if it is in an intermediate range. (c) 2008 Elsevier B.V. All rights reserved.