Lawrence Berkeley National Laboratory

Injecting supercritical CO2 into the subsurface changes the temperature, pressure, and geochemistry of the storage reservoir. Understanding these perturbations within the reservoir may be used to monitor the CO2 plume during a carbon capture and sequestration (CCS) project. Here we analyze results from 1-D, 2-D, and 3-D numerical modeling studies to investigate how the thermal signature of the CO2-water system evolves during CCS. These models show that the thermodynamic processes of the CO2-water system results in a characteristic thermal profile within a homogeneous storage reservoir during a CO2 injection. This thermal signature is characterized by warming front of up to 4 °C, which is caused by CO2 dissolution and migrates contemporaneously with free-phase CO2 migration. When reservoir properties are highly heterogeneous, this thermal front travels well ahead of free-phase CO2, thus implying that thermal monitoring may be an effective predictor of CO2 breakthrough.