As an efficient way to reduce CO2 in the atmosphere and to extract more hydrocarbons from reservoir, CO2 flooding is important to reduce environmental and ecological damage by traditional energy. Study on performance of CO2 in the reservoir and its impact on formation fluids is necessary to oil recovery and to further carbon capture and storage (CCS). In practical, CO2 is injected into reservoir at low temperature, and both field tests and predictions show that temperature of CO2 would be lower than that of reservoir while it reaches the target formation, especially for high injection rate. Therefore, further estimation should be conducted to predict how reservoir temperature and properties of fluids are changed during cold CO2 flooding. In this paper, a mathematical model for non-isothermal immiscible CO2 flooding is firstly established, then full thermo-hydraulic coupling of the model is simulated on COMSOL by introducing several temperature-dependent and pressure-dependent physical properties of CO2, oil and rock. The basic reservoir parameters of the model are obtained from one block of Daqing Oilfield, China. Furtherly, effect of CO2 injection temperature, of CO2 injection rate and of injector shut-in on reservoir performance is studied. Results show that injection of colder CO2 causes rapid reduction in reservoir temperature near the injector at the earlier stage. Effect of temperature change is timely shown on physical properties of fluids for full thermo-hydraulic coupling. Oil production rate, oil recovery and production gas-oil ratio all increase as injection temperature increases. Based on a practical situation, this study gives an insight into reservoir performance during cold CO2 flooding with a numerical method, and it can provide some support for study on temperature change in the reservoir.

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