Using Heat as a Predictor of CO 2 Breakthrough in Highly Heterogeneous Reservoirs

Injecting supercritical CO 2 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 CO 2 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 CO 2 ‐water system evolves during CCS. These models show that the thermodynamic processes of the CO 2 ‐water system results in a characteristic thermal profile within a homogeneous storage reservoir during a CO 2 injection. This thermal signature is characterized by warming front of up to 4 °C, which is caused by CO 2 dissolution and migrates contemporaneously with free‐phase CO 2 migration. When reservoir properties are highly heterogeneous, this thermal front travels well ahead of free‐phase CO 2 , thus implying that thermal monitoring may be an effective predictor of CO 2 breakthrough.