Miscible Gas Flooding

This method uses a fluid that is miscible with the oil. Such a fluid has a zero interfacial tension with the oil and can in principal flush out all of the oil remaining in place.

In practice a gas is used since gases have high mobilities and can easily enter all the pores in the rock providing the gas is miscible in the oil.

Three types of gas are commonly used:

CO2

N2

Hydrocarbon gases.