Gas reinjection is the reinjection of
natural gas
Natural gas (also fossil gas, methane gas, and gas) is a naturally occurring compound of gaseous hydrocarbons, primarily methane (95%), small amounts of higher alkanes, and traces of carbon dioxide and nitrogen, hydrogen sulfide and helium ...
into an underground
reservoir
A reservoir (; ) is an enlarged lake behind a dam, usually built to water storage, store fresh water, often doubling for hydroelectric power generation.
Reservoirs are created by controlling a watercourse that drains an existing body of wa ...
, typically one already containing both natural gas and
crude oil
Petroleum, also known as crude oil or simply oil, is a naturally occurring, yellowish-black liquid chemical mixture found in geological formations, consisting mainly of hydrocarbons. The term ''petroleum'' refers both to naturally occurring u ...
, in order to increase the pressure within the reservoir and thus induce the flow of crude oil or else sequester gas that cannot be exported. This is not to be confused with
gas lift, where gas is injected into the
annulus of the well rather than the reservoir. After the crude has been pumped out, the natural gas is once again recovered. Since many of the wells found around the world contain heavy crude, this process increases their production. The basic difference between
light crude and
heavy crude is its viscosity and pumpability—the lighter the crude the easier it is to pump. Recovery of
hydrocarbon
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and Hydrophobe, hydrophobic; their odor is usually fain ...
s in a well is generally limited to 50% (heavy crudes) and 75–80% (light crudes).
Recycling
Recycling is the process of converting waste materials into new materials and objects. This concept often includes the recovery of energy from waste materials. The recyclability of a material depends on its ability to reacquire the propert ...
of natural gas or other inert gases causes the pressure to rise in the well, thus causing more gas molecules to dissolve in the oil lowering its viscosity and thereby increasing the well's output. Air is not suitable for
repressuring wells because it tends to cause deterioration of the oil, thus carbon dioxide or natural gas is used to repressure the well. The term 'gas-reinjection' is also sometimes referred to as repressuring—the term being used only to imply that the pressure inside the well is being increased to aid recovery.
Injection or reinjection of carbon dioxide also takes place in order to reduce the emission of CO
2 into the atmosphere, a form of
carbon sequestration
Carbon sequestration is the process of storing carbon in a carbon pool. It plays a crucial role in Climate change mitigation, limiting climate change by reducing the amount of Carbon dioxide in Earth's atmosphere, carbon dioxide in the atmosphe ...
. This has been proposed as a method to
combat climate change, allowing mass storage of CO
2 over a geological timescale. Reinjection of carbon dioxide in the Norwegian Sleipner gas field saves the operators 1 million Norwegian Kroners per day in national carbon taxes.
External links
GAS RE-INJECTION. Total experience Elisabeth PROUST, 2006
How Does Gas Injection Work?// RIGZONE
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{{Petroleum industry
Petroleum production