Shale gas extraction: How the process works

Vast reserves of natural gas can be found trapped in densely packed rock such as shale. Here is how it is reached

1,500m-6,000m

Concrete casing

Shale rock

Bore

1

A vertical hole is drilled into the shale rock. The drill can run horizontally once it enters this layer of rock. Water supply for Cuadrilla in Lancashire will come from mains, from United Utilities

2

Bore is lined with concrete and an electric current is used to perforate holes into the casing and shale

Sand is used to

keep fissues open

3

High-pressure water, sand and various chemicals are pumped into the bore and perforated holes where it fractures the shale

4

Gas in the rock is forced into the bore and flows to the surface

1,500m-6,000m

Sand is used to

keep fissues open

Concrete casing

Shale rock

Bore

1

A vertical hole is drilled into the shale rock. The drill can run horizontally once it enters this layer of rock. Water supply for Cuadrilla in Lancashire will come from mains, from United Utilities

2

Bore is lined with concrete and an electric current is used to perforate holes into the casing and shale

3

High-pressure water, sand and various chemicals are pumped into the bore and perforated holes where it fractures the shale

4

Gas in the rock is forced into the bore and flows to the surface