1.5 PV of gas was injected at the flow rate of 0.005 mL/min, corresponding to gas flooding 1. Then, the gas flow rate was increased to 0.01 mL/min, and the sample was scanned after 1.5 PV gas flloding (gas flooding 2). Finally, the gas flow rate was increased to 0.02 mL/min, and the images were obtained after 4 PV (gas flooding 3) and 15 PV gas flooding (gas flooding 4).
The brine was injected at the flow rate of 0.01 mL/min, and the first water flooding image was obtained at 0.01 MPa of pore pressure. Then the pore pressure was gradually increased to 0.7 MPa, 1 MPa, corresponding to water flooding 2 and water flooding 3 respectively.
