Carbon Dioxide & Enhanced Oil Recovery

The main methods needed to store CO2 in old oil and gas fields have already been extensively used for Enhanced Oil Recovery (EOR).

This process involves pumping CO2 into an oil reservoir, increasing the reservoir pressure and allowing CO2 to dissolve into the oil and so reducing its viscosity and increasing its volume. All of these effects allow oil to flow out more easily and this method is used extensively in older oil fields where the original reservoir pressure has been lost as a result of oil production.

CO2 is pumped into the reservoir through an ‘injection well’ forcing oil towards a ‘production well’ where it is pumped to the surface. In most commercial onshore oil fields the CO2 is extracted at the surface and is then re-injected back into the reservoir. However, it is quite possible to not recover the CO2 and leave it stored within the oil reservoir. Injection can be designed to maximise CO2 storage, rather than oil production.