Using Heat as a Predictor of CO₂ Breakthrough in Highly Heterogeneous Reservoirs

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.