Buy your London Pass at the Heathrow Express Ticket Office at Terminals 3 & 5 and London Paddington. For prices please ask our friendly staff at our Terminal 3 or 5 Ticket Offices or contact our Customers Relations Team on +44 (0) 345 600 1515.
When the hydraulic pressure is removed from the well, small grains of hydraulic fracturing proppants (either sand or aluminium oxide) hold the fractures open. Hydraulic fracturing began as an experiment in 1947, and the first commercially successful application followed in 1950.
- the process explained in 15 seconds. 13 December 2012 Last updated at 10:06 GMT. The government has given the go-ahead for a firm to resume the controversial technique known as fracking to exploit gas in Lancashire. The firm, Cuadrilla, was stopped from fracking after two small earthquakes. The process involves drilling down and creating tiny explosions to shatter and crack hard shale rocks to release the gas inside. Judith Moritz explains.