My Science School

Drilling rigs are used to drill into the ground to reach oil. The rigs have a flat base called a platform. A tower holds up the drilling equipment. The drill is a steel pipe which has a point at the end. This is called a ‘drill bit’.

Oil-rigs can be built in the sea.

When oil is found under the seabed, an oil-rig is built over the oil-field. Different rigs are used depending on how deep the water is. Oil-rigs with legs are used in water less than 400 m deep. Floating rigs are used in water up to 1,000 m deep. They are tied to blocks on the seabed to stop them drifting away. In even deeper water, rig ships are used, which are kept in place by anchors.

The drill bit cuts down through the rock.

As the drill bit bores deeper into the ground, more lengths of pipe are added at the top. The drill bit is covered with diamond dust. Diamonds are very hard and strong, so they help the drill to grind through the rock.

Drills reach oil deep under the ground.

In many oil-fields, the oil is pressed and squashed deep inside the rock. When a hole is drilled into the rock, the pressure pushes the oil upwards and out. The pressure can last for days or years, but eventually the flow of oil drops. Then, pumps are needed to bring more oil to the surface.