Alternative energy sources are being investigated and developed in the UK. Whilst considered to be controversial by some, exploitation of shale gas is an attractive option for providing energy from natural gas which is trapped inside rock formations. “Fracking” or hydraulic fracturing is the process of creating fractures in these strata to release the natural gas trapped inside.
In the UK it is believed hydraulic fracturing first took place in the late-1970s; and in the United States it was practised as early as 1947. It is estimated that over 2.5 million fracture treatments have now taken place and over 50% of onshore natural-gas production comes from hydraulically fractured wells. Off shore hydraulic fracturing has been performed many thousands of times in the North Sea. It is still widely practised in the US (which is close to self-sufficiency in gas as a result) and Canada.
Prior to the fracking process, considerable research is carried out to analyse technical data including rock properties and wellbore mechanics in order to ensure the process is feasible. During the fracking process large volumes of fracturing fluid are injected into the rock formation at high pressure and this creates a maze of millimetre-sized cracks at depths of several thousand metres.
The fracturing process is initiated at the start of a well’s life. The process is repeated several times lasting up to 2 hours, and can take place over several weeks, during which time readings are continually assessed. Once fracturing is completed a well can produce gas for years without the need for further treatments.
In September the European Commission published three new studies on shale gas. ESI co-authored one of these studies: ‘Potential Risks for the Environment and Human Health Arising from Hydrocarbons Operations Involving Hydraulic Fracturing in Europe’. ESI worked with AEA Technology as part of a multi-disciplinary team, particularly providing specialist hydrogeological expertise and experience in environmental risk assessment and management.