Petroleum formation occurs over millions of years

Petroleum formation occurs over millions of years

Petroleum formation occurs by various hydrocarbons combining with certain minerals such as sulphur under extreme pressure. Modern day scientists have proven that most if not all petroleum fields were created by the remains of small animal and plant life being compressed on the sea bed by billions of tons of silt and sand several million years ago.

When small sea plants and animals die they will sink, they will then lie on the sea bed where they will decompose and mix with sand and silt. During the decomposition process tiny bacteria will clean the remains of certain chemicals such as phosphorus, nitrogen and oxygen.

This leaves the remains consisting of mainly carbon and hydrogen. At the bottom of the ocean there is insufficient oxygen for the corpse to decompose entirely. What we are left with is the raw materials for the formation of petroleum.

The partially decomposed remains will form a large, gelatinous mass, which will then slowly become covered by multiple layers of sand, silt and mud. This burying process takes millions of years, with layers piling up one atop another.

As the depth of the sediment build up increases the weight of the sand and silt pressing down on the mass will compress it into a layer which is much thinner than the original.

Finally, when the depth of the buried decomposing layer reaches somewhere around 10,000 feet the natural heat of the earth and the intense pressure will combine to act upon the mass. The end result, over time, is the formation of petroleum.

 With petroleum formation the actual temperature applied to the original organic mass is critical in determining the overall properties of the resulting petroleum. Typically lower temperatures during petroleum formation

will result in thicker, darker raw petroleum deposits, the most solid of which being a bitumen substance.

If the heat applied during the formation of petroleum process fluctuates too much then gas will be produced, often separating from the petroleum, sometimes remaining mixed with the raw oil. If temperatures are too high, in the somewhere over 450 degrees Fahrenheit then the original biomass will be destroyed and no gas or petroleum is formed.

As the mud and silt above the deposit become heavier and the forces placed upon the silt and mud begin to change the bottom layers of the compressing layer above the petroleum then it will turn into shale.

As the shale forms the oil will be forced out of its original area of formation. The raw petroleum then moves to a new rock formation, usually termed a reservoir rock, and lays trapped until it is accessed in some way.

As we can see, the formation of naturally occurring raw petroleum takes millions of years, certainly far longer than can be deemed renewable, yet mankind has managed to almost complete deplete the world supply in little more than a century.

source : http://www.petroleum.co.uk/formation/