Aratai Arangam: How do we get oil and gas out of the ground?

Oil and gas can get trapped in pockets underground such as where the rocks are folded into an umbrella shape.

Oil and gas can move through the porous rocks (rocks with gaps between the grains). The oil and gas move upwards from the source rock where they were formed. When they met a layer of cap rock (a rock with no spaces between the grains) the oil and gas are trapped.

A well is drilled so that the crude oil and other liquids travel up the bore hole. When it comes to the surface the crude oil has to be moved closer to where it is needed.

Finding oil and gas trapped deep underground and drilling a well are very complicated and expensive. It costs millions of pound to drill a well and only a few are successful. The liquids found underground can be a complicated mixture of water, crude oil and gas. The crude oil and gas need to be separated before they can be transported safely.

Which rocks are porous and could make good reservoir rock?

Plan an investigation to find out which rocks are most porous.

Can you find out how the people who search for oil discover oil traps deep beneath the land and sea bed?

How are oil and gas transported?

Oil and gas are often found far away or under the sea.
They have to be transported to an oil refinery.
This is often through a pipeline or in a tanker.

The crude oil is often found in remote places such as deserts, jungle or the Arctic. Transport of the crude oil to the refinery is sometimes very complicated. The oil refinery turns crude oil into useful products and materials. These are transported all over Britain or abroad. The products can travel through pipelines, by road, rail or by boats around the coast or along rivers and canals.

How is crude oil turned into finished products?

Crude oil is often a dark, sticky liquid that cannot be used without changing it. The first part of refining crude oil is to heat it until it boils. The boiling liquid is separated into different liquids and gases in a distillation column. These liquids are used to make petrol, paraffin, diesel fuel etc.

Crude oil is a mixture of different chemical called hydrocarbons. The boiling oil turns into a mixture of gases in the column. The gases flow up the column which is hottest at the bottom and cooler at the top. The gases cool down as they go up the column until they condense (turn back into liquid again). The separated liquids and gases, after cleaning and further processing, are used to make many products.

Liquids from refining oil still have to be changed to make them more useful. Sometimes it's to make them clean enough to be used. Sometimes it's to turn some of the unwanted liquids into things people want to buy.

The heavier liquids are in less demand from customers so are turned into lighter products that are in demand. One of the processes is called catalytic cracking. It breaks down some of the heavy liquids from the distillation column.

The heavy liquids are changed into simple and more useful liquids and gases. Cracking is just one of many chemical changes in an oil refinery.

Which of the products from oil refining are used in the largest quantities?
What is the point of cracking heavy liquids into lighter liquids and gases?

What things are made from oil and gas?

In an oil refinery and in a chemical works, crude oil and gas are turned into hundreds of useful products.

How do these products get to the customer?

Thousands of people are employed to make sure all these useful products get to the millions of people in Britain and overseas who wat to buy them everyday.

Many thousands of people are employed in Britain's oil and gas industry. Many of these work to get petrol and diesel fuel to where it is wanted - Britain's 10,000 filling stations - for motorists, lorrydrivers, taxis and buses.