## 3 Results  
A sandstone core was tested to have a porosity of 24.5% and water permeability of 116 mD. Core temperature was controlled between 0 \({}^{\circ}\)C and 5 \({}^{\circ}\)C, and data are recorded for each degree Celsius interval. CO\({}_{2}\) was injected through the core at different flow rates between 20 mL/min and 60 mL/min, but here a dataset of a flow rate of 40 mL/min is presented only to ascertain the formation of hydrates in dynamic conditions. Data associated with other flow rates will be used in future research. The confining pressure was set at twice the injection pressure. Data analysis is summarized as follows:  
According to [PERSON] and [PERSON] [20], at the seafloor temperature of 0 \({}^{\circ}\)C, the minimum pressure required for CO\({}_{2}\) to form hydrate is about 1.0 MPa (145 psi). The temperature inside the core holder was lowered to 0 \({}^{\circ}\)C by the cooler during fluid injection. Following water injection, CO\({}_{2}\) was introduced to the core holder at various pressure settings of the backpressure regulator at the outlet. The longest injection time is 32 h.  
Figure 2 presents observed pressures during CO\({}_{2}\) injection at 0 \({}^{\circ}\)C. The backpressure was initially set to 350 psi. The CO\({}_{2}\) injection rate was set at 40 mL/minute, which should generate a Darcy velocity of 0.0333 cm/s in the core. Although the pressure values in this figure drift slightly at first, the data points show almost no difference between the inlet and outlet pressures, which implies that the injected fluid experienced little restriction in the core, indicating that no significant quantity of hydrates was formed in the core to affect fluid flow. Running like this for nearly 130 min, the backpressure was set to 365 psi, keeping the same flow rate (40 mL/min). A noticeable rise in inlet pressure is found after injecting for about 140 min. The trend continues to go up, keeping the outlet pressure almost constant. This increased injection pressure indicates the formation of a significant quantity of hydrates at 365 psi. The next test was carried out at a core temperature of 1 \({}^{\circ}\)C. As noted by [PERSON] and [PERSON] [20], at 1 \({}^{\circ}\)C, the minimum pressure required for CO\({}_{2}\) to form hydrate in static condition is about 1.25 MPa (180 psia). Figure 3 shows the pressure profiles observed during CO\({}_{2}\) injection at 1 \({}^{\circ}\)C at the same flow rate (40 mL/min). The initial near-identical inlet and outlet pressures imply little to no hydrate formation in the core. However, when the backpressure regulator was changed to 395 psi, the plot demonstrated a significant rise in inlet pressure when the outlet pressure was fixed at 395 psi, indicating hydrate formation within the core. A similar experimental procedure has been maintained for regulating the temperature at 2 \({}^{\circ}\)C, where the minimum pressure in static conditions is expected to be 1.50 MPa (220 psia) [20]. The generated Figure 4 with this dataset shows very little pressure difference across the core initially, indicating no hydrate formation. But as time went by, the backpressure was elevated to 450 psi, which was 430 psi earlier; noticeable spikes in inlet pressure were observed even though the outlet pressure remained constant. This agrees with the interpretations of the previous tests that hydrate formation is taking place inside the core. Figure 3: Observed pressures during CO\({}_{2}\) injection at 1 \({}^{\circ}\)C.  
Figure 2: Observed pressures during CO\({}_{2}\) injection at 0 \({}^{\circ}\)C.  
At temperature 3 \({}^{\circ}\)C, the minimum pressure required for CO\({}_{2}\) to form hydrate in static conditions is about 1.87 MPa (275 psia) [20]. Figure 5 illustrates the pressure data during CO\({}_{2}\) injection. Initially, the backpressures were set from 475 up to 530 psi. The small pressure difference between the inlet and outlet suggests that no significant hydrate formation occurred.