1. n. [Enhanced Oil Recovery]
A process whereby nitrogen gas is injected into an oil reservoir to increase the oil recovery factor. Below the minimum miscibility pressure (MMP), this is an immiscible process in which recovery is increased by oil swelling, viscosity reduction and limited crude-oil vaporization. Above the MMP, nitrogen injection is a miscible vaporizing drive. Miscibility of nitrogen can be achieved only with light oils that are at high pressures; therefore, the miscible method is suitable only in deep reservoirs.