What is Lifting Gas ?

Gas Elevator is a method to increase the natural reach of an oil well by reducing the weight of liquid in the column by means of high pressure gas injection. The weight of oil in the column well, with the resistance caused by the viscous crude oil flow through the system well, the natural pressure of the reservoir must be exceeded to provide flow. Gas injection near the bottom of the column and reduces the density of the oil, and the total weight of liquid within the column well. Gas lift plants are generally more compact and require less energy than other methods of increasing flow rates, and are a popular solution for offshore drilling projects.

Most oil reserves are under adequate natural pressure to provide an economic rate of flow at the time of the first exploited. As oil is removed from the tank, however, the pressure decreases and the flow rate slows or stops completely. Since this usually occurs before the bulk of the oil has been removed from the tank, the rest of the oil can be utilized by reducing the downward pressure of the column and reservoir. This can be done by pumping the oil directly through the column, replacing the missing oil in the tank with water or other liquids, or by reducing the weight of the liquid in the column.

The gas is injected into the column and either through the well of the well or directly through the production tube. If the gas is injected through the well coating, the gas inlet valve is usually placed in a spindle, a kind of niche built on the side of the production tube. This allows the oil to flow through the pipe without being obstructed by the gas injection equipment, and is generally favored in low volume wells. In larger wells, the gas lifting system can be lowered into the production tube directly without significantly affecting the oil flow.

In the case of most land-based wells, other streamlining methods are simpler and cheaper than gas lifting. It is mainly used on offshore drilling rigs, where space is a premium and the compact nature of the injection mechanisms is an advantage. It is also used in petroleum fields that produce a high volume of natural gas. The gas can be passed through a washing plant to purify and dry the gas on site, where it can be injected immediately into oil wells with marginal production. Once the gas is injected into a well, the majority is recovered to the surface and can be compressed and re-injected without a large amount of waste.