CO2 Flooding
When injected into a geological formation, a portion of the supercritical CO
2 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 CO
2 dissolves in oil, it
acts as a solvent, reducing oil viscosity and increasing the oil's mobility (see diagram).
The sequestration of CO
2 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.