*2.1. Materials*

Removal of brine and gases from crude oil samples. The crude oil used in the experiment came from China's Shengli Oilfield. The viscosity of the crude oil was tested by a rheometer (Model MCR 302, Anton Paar, Austria). The relationship between viscosity and temperature is shown in Figure 1. The flue gas used in the experiment was a 1:4 mixture of CO2 and N2, which was similar to actual flue gas produced by steam generators in oil fields. The purity of CO2 and N2 were both 99.9 mol%, provided by China Tianyuan Company. Two types of silica sands were used to fill the sandbags: 80 mesh and 120 mesh, respectively. The water used in the laboratory to generate steam was distilled water. The parameters of the sand bag used in the oil displacement experiment are shown in Table 1. The physical properties of the sand bag were the same, which was consistent with actual field conditions.

**Figure 1.** The relationship between the viscosity and temperature of the heavy oil used in the experiment.


**Table 1.** Parameters of the sandpack used in the flooding experiment.
