ANALYSIS OF JOULE−THOMSON EFFECT OF CARBON DIOXIDE LEAKAGE THROUGH VERTICAL LEAKY PATHWAYS

The major objective of this work is to investigate the Joule-Thomson effect (J-T effect) of CO2 leakage through vertical porous pathways. A one-dimensional depressurization process model is established, in which the Span-Wagner equation is employed to describe the thermophysical properties of CO2. The effects of heat exchange between CO2 and the surroundings, pressure drop, and the permeability of leaky pathways on the J-T effect are presented for different leakage scenarios. The results indicate that a large temperature drop is present along the leaky pathway due to the drastical variation of the thermophysical properties of CO2. Based on the hierarchical leakage scenarios, the J-T effect always leads to the CO2 temperature profile approaching the CO2 saturation line, whereas the heat exchange between CO2 and the surroundings induces the CO2 temperature profile inclining to the geothermal temperature distribution. A remarkable temperature drop is observed due to the larger pressure drop, although the increase in the permeability of the leaky pathway mitigates the influence of heat transfer on the J-T effect. For the direct leakage scenario, a sharp temperature drop of CO2 appears in the near-surface segment. The inlet depth of the leaky pathway primarily determines the pressure drop, the temperature drop, and the flow rate of CO2 leakage. For different scenarios of CO2 leakage, an in-depth data analysis of the CO2 depressurization process will provide insight into the monitoring and evaluation of CO2 leakage.