Nitrogen injection into oil reservoirs mainly has the following functions:

1. Maintain reservoir pressure

The pressure of the oil and gas reservoir is maintained at or above its dew point pressure or bubble point pressure, or at the current pressure level, so that the oil and gas laminar flow can flow smoothly.

2. Gravity drain and immiscible flooding

Based on the low density of nitrogen, it can be injected into the top of the structure or allowed to migrate to the top of the structure to enhance the downward displacement of reservoir fluids or the effect of gravity and stable miscible slug, and improve the production of reservoir fluids.

3. Miscible phase drive

Multiple contact miscibility of nitrogen is used to displace oil and gas in oil and gas reservoirs.

4. Drive the carbon dioxide slug

A miscible slug formed by using nitrogen as a displacement fluid to move carbon dioxide and other solvents in oil and gas reservoirs.

5. Attic oil extraction

High pressure nitrogen can displace trapped oil from the attic layer at the top of the structure into the production well.

6. Gas cap displacement

Nitrogen injection in the best part of the reservoir can maintain or increase the reservoir pressure and simultaneously displace and produce the gas cap.

7. Pipe purge

Before the maintenance of flammable and explosive gas and liquid transportation pipeline, the residual gas and liquid in the pipeline shall be purged. According to the actual situation of the pipeline, purge the pipeline with a certain pressure and flow of nitrogen.

8. Gas seal of fuel storage tank

The residual air on the top of fuel tank is one of the main causes of fire and explosion of fuel tank. Filling the top of the tank with nitrogen is the fundamental way to solve this problem, which is also used in other liquid storage tanks.