Question

Read the sections titled "Oil basics," "What fuels are made from crude oil?," and "What is a refinery?" Then, answer the questions. How and when oil was formed? (Site 1)

Answer 1

All of the oil and gas we use today began as microscopic plants and animals living in the ocean millions of years ago. As these microscopic plants and animals lived, they absorbed energy from the sun, which was stored as carbon molecules in their bodies. When they died, they sank to the bottom of the sea. Over millions of years, layer after layer of sediment and other plants and bacteria were formed.

As they became buried ever deeper, heat and pressure began to rise. The amount of pressure and the degree of heat, along with the type of biomass, determined if the material became oil or natural gas. More heat produced lighter oil. Even higher heat or biomass made predominantly of plant material produced natural gas.

After oil and natural gas were formed, they tended to migrate through tiny pores in the surrounding rock. Some oil and natural gas migrated all the way to the surface and escaped. Other oil and natural gas deposits migrated until they were caught under impermeable layers of rock or clay where they were trapped. These trapped deposits are where we find oil and natural gas today.

Answer 2

Crude oil is made of several components- called hydrocarbons-  mixed together and can be chemically separated.  These components are, majorly, fuels. Examples of these fuels are; diesel, petrol, kerosene, liquefied petroleum gas and heavy oils such as bitumen (used on tarmac roads).

An oil refinery is basically a big plant that utilizes the chemistry of fractional distillation to separate the oil components. This involves boiling the crude oil at different temperatures to evaporate the different components that have different boiling points. Each component is later condensed and recovered separately.

Crude oil is a natural resource that is formed over millions of years from organic matter especially planktons. When the organic matter dies and settles at the bottom of oceans, they are overlaid by layers and layers of sediment. This, over time, subjects the organic matter to high pressure and temperatures  and they metamorphose into crude oil.