Natural Gas from Oil Wells- Chemical Composition
As we have seen, natural gas is found in solution with the crude oil as associated gas, also being present in the reservoir rock pores as free gas.
The chemical composition of the natural gas from oil wells varies with the location of the oil reservoirs, for example gas from a North Sea Oil Platform and that from a Saudi Arabian oil reservoir will have different chemical compositions; therefore, for the purpose of this article we shall give the major components of natural gas from oil wells in general.
The main constituents of natural gas from oil wells are as follows:
1. Hydrocarbon Main Components
There are two main components:
Methane is a colorless, odorless, flammable gas and is the main component (75%) of natural gas.
Ethane is a liquefied, colorless odorless, flammable gas and is around 15% in natural gas.
2. Hydrocarbon Secondary Components
There are five secondary components:
Propane can be liquid or gas and is odorless, colorless and flammable.
Butane is highly flammable, colorless and odorless being easily liquefied.
Hexane is a colorless, very odorous gas and can be toxic, inhalation should therefore be avoided.
Pentane is the most volatile of the hydrocarbon with the same properties as butane.
3. Other Non-Hydrocarbon Components
There are a number of other components:
Carbon Dioxide is a chemical compound, odorless in small quantities, but highly toxic causing dizziness and asphyxiation, it is also non-flammable.
Hydrogen Sulfide is a poisonous, colorless, flammable gas with the obnoxious smell of rotten eggs, inhalation should be avoided.
Helium is a chemical element and is an odorless, tasteless, inert and non-toxic gas.
Nitrogen is a chemical element and is a colorless, odorless, tasteless inert gas.
When the natural gas from oil wells is processed; only the methane (CH4) and a few traces of the other components remain in the gas.
The remaining components that make up around 10% of the natural gas are further processed, being used for a variety of purposes in industry.