CO₂ Flooding

When injected into a geological formation, a portion of the supercritical CO₂ may be dissolved in any fluids, such as water or oil, that are present in the formation, while another portion will be available to react with rock minerals. When CO₂ dissolves in oil, it acts as a solvent, reducing oil viscosity and increasing the oil's mobility (see diagram).

The sequestration of CO₂ in a supercritical form is beneficial because:

• The supercritical state maximizes the number of CO₂ molecules that can be injected into a given volume.
• If injected into an oil reservoir, supercritical CO₂ can increase oil production, which in turn can be used to pay for the capture and transportation of the CO₂ from the original source.
• Usually reservoir temperature and pressure conditions require that injected CO₂ be in a supercritical state.