Chemical Concept

Formation of Crude Oil

Introduction

Crude oil, commonly known as petroleum is a liquid found in Earth’s crust and is made up of hydrocarbons, organic compounds and small amounts of metal.

Explanation

Dead animals and plants in the sea drop to bottom of sea bed and build up on the sea bed

There is a mud layer and dead animal layer on top of the sea bed. The mud layer gradually turns to rock

The mud layer turns into rock layer and dead animal and plant layer turns into crude oil

The remains of animals and plants in the sea were buried under sand and rocks where decomposition will occur. During  decomposition, certain chemicals such as phosphorus, nitrogen and oxygen will be removed by tiny bacteria. This leaves behind the remains that are mainly made up of carbon and hydrogen. At the bottom of the ocean there is insufficient oxygen for the remains to decompose entirely. Hence, what we are left with is the raw materials for the formation of petroleum.  In addition, over millions of years, the heat and pressure, without air, convert the remains to oil. In this process, gas is also produced.

At an oil rig, production wells cut through to oil layer in the sea bed and draws oil to the surface

Today, oil companies drill down deep into the sea bed through the impermeable rock to obtain crude oil through the process of fractional distillation.

References

How crude oil was formed. (n.d.). Retrieved March 22, from http://www.bbc.co.uk/bitesize/standard/chemistry/materialsfromoil/how_crude_oil_was_formed/revision/2/

Petroleum formation. (n.d.). Retrieved March 22, from http://www.petroleum.co.uk/formation

Making crude oil useful. (n.d.). Retrieved March 22, http://www.bbc.co.uk/schools/gcsebitesize/science/ocr_gateway_pre_2011/carbon_chem/4_crude_oil1.shtml