The minimum miscible pressure is one of the important parameters of CO2 injection in oil field. In order to determine the minimum miscible pressure between crude oil and CO2 in the tight reservoir of lucaogou formation, jimusar sag, Xinjiang, the laboratory slim tube test and interfacial tension test were carried out. The results show that the MMP measured by slim tube test in Xinjiang tight oil reservoir is 18.70 MPa, slightly higher than the MMP measured by the interfacial tension experiment, which is 18.44 MPa. The difference between the two is 1.4%, and both lower than the reservoir pressure of 43.00 MPa. Therefore, CO2 and crude oil can be miscible under the reservoir conditions. When the equilibrium pressure increases, the IFT decreased more as more CO2 dissolved in crude oil. When the system equilibrium pressure increased from 0.73 MPa to 28.46 MPa, the IFT value between crude oil and CO2 decreased from 22.62 mJ/m2 to 1.83 mJ/m2. When the equilibrium pressure was between 0.73 MPa to 13.33 MPa, the dissolution of CO2 in crude oil took the leading role. However, when the equilibrium pressure was between 15.84 MPa to 28.46 MPa, the extraction of light components in crude oil took the leading role, and the interaction mechanism between crude oil and CO2 changes from CO2 solubility to CO2 extraction of light components at the pressure of 13.67 MPa. Through the experimental study, the understanding of the MMP of the target reservoir and the microscopic interaction mechanism between crude oil and CO2 is deepened, which provided theoretical support for the formulation of CO2 injection development of the target reservoir.

In order to research on the impact of imbibition effects, mechanisms and the correlation factors of the tight oil cores, the experimental devices of tight core imbibiton were established. The experiments of oil-water imbibition of tight sandstone were carried out. The effects of temperature, pressure and surfactant on the oil-water imbibition in compacted core were studied. The curves of imbibition efficiency versus time, characteristic points of curve and the influential factor of imbibition were analyzed. The imbibition law and characteristics of tight sandstone core were obtained. The results showed that the effect of imbibition was mainly occurred on the surface layer of the tight oil core. The temperature had a large effect on the second stage of imbibition. The oilwater imbibiton efficiency of the single tight oil core is about 10%, which is about 25% under the formation conditions.