Use of Nitrogen in Oil Extraction

Under normal circumstances, only 15% of the oil can be extracted from an oil well. This low efficiency is caused by the pressure produced by the oil well. To increase the efficiency of the extraction, oil companies deploy a number of methods such as gas lift and stimulation but these methods have a very negative impact on the environment and only improve the efficiency by not more than 50%.

Nitrogen is a natural gas that is perfect for re-pressurizing oil wells because of its inert gas properties. Moreover, being an inert gas, Nitrogen does not have any corrosive effect on the drilling equipment and is suitable for use in acidic as well as the saline environment. Nitrogen also helps in displacing oxygen in the drilling rigs and thus reduces the chances of oxidation.

Nitrogen generators help in increased pressure in the oil well during the extraction process to improve the efficiency. They can be used in depleted oil wells as well to extract hard-to-recover oil and increase the efficiency of oil extraction in depleted reservoirs by more than 180%.

Functioning of Nitrogen Generators

Nitrogen generators don't create Nitrogen but actually separate it from other elements. They use various methods to segregate nitrogen from the rest of the gases.

There are two methods that are used to separate gaseous in the air which are, Pressure Swing Adsorption and Nitrogen generator membrane system.

Adsorption Based Generators

These kinds of generators work by using compressed air to generate a continuous stream of nitrogen gas. The high pressured air is passed through carbon molecular sieve in the first cylinder which absorbs the oxygen molecules, and the remaining nitrogen gas is passed to the second cylinder while the first cylinder vents out the contaminants, mainly oxygen.

This method is mostly deployed for enhanced oil recovery, extraction, and underbalanced drilling operations.

Membrane-Based Generators 

A Nitrogen generator membrane system works by filtering air and passes it through advanced membrane fibers. The hollow fibers function as reverse filters. Oxygen moves easily throughout the fiber walls, but nitrogen gets caught inside the fibers and passes to the end of the fiber tubes. As a result, compressed gaseous nitrogen is generated.

The purity of Nitrogen can be altered by using various membrane sizes and increasing or decreasing the air pressure.

Compared to membrane-based generators, adsorptive nitrogen generators have a higher purity and low energy consumption. But adsorptive nitrogen generators need much larger space on the site and require more maintenance.