How Oil Is Formed
Oil is commonly formed in rock or in sealed pockets under the seabed and it is from the Latin for ‘rock oil’ that the word ‘Petroleum’ is derived, though this umbrella term also covers natural gas as well as oil.
What we commonly refer to simply as ‘oil’ is properly known as mineral oil or crude oil and is formed from plant and animal matter that has broken down and been subjected to extremes of temperature and pressure over millions of years.
The resulting mix of hydrocarbons is a very valuable resource.
Not all crude oil is the same and its characteristics and chemical composition depend entirely on the type of matter that it is derived from and the environmental conditions it has been subjected to during its formation. As a result of these differing characteristics and chemical compositions, some crude oil is more desirable than others. In all cases the base material needs to be refined to separate out the various constituents, which vary from light compounds that can be further refined into fuels, to heavy compounds such as bitumen and resins, which of course have their own uses.
Crude oil production levels and reserves are still measured in barrels although this should be viewed these days as a quantitative assessment rather than an illustration of how it is actually stored – this dates from early large-scale usage of oil in the 19th century where it was stored in wooden barrels of a standard size of 42 US gallons, equal to 159 litres.
Recent reports from OPEC (Organisation of the Petroleum Exporting Countries) place current confirmed crude oil reserves at around 1.2 billion barrels) and billions of dollars are invested every year in locating and exploiting new sources of crude oil. OPEC claims that at the current rate of production there are around 80 years of oil production remaining. OPEC member countries are responsible for around three quarters of the worlds confirmed oil reserves.