Shale gas is mainly methane that is trapped in shale, which is very fine-grained sedimentary rock.
The gas is tightly 'locked' in between the very small particles in the shale.
It flows naturally into boreholes that are drilled into the shale, but to get more of the gas out, artificial fractures can be created within the shale using high pressure water. This is called hydraulic fracturing (see illustration).
What's fracking and is it dangerous? |
BBC Bang Goes the Theory
Geology and shale gas
Testing the rocks
Groundwater and our environment
Contact Prof. Mike Stephenson for further information or enquiries about BGS shale gas consultancy services