A panel of experts from GFRAC Technologies, Keele University and the British Geological Survey were commissioned by DECC to examine the possible relationship between hydraulic fracturing or “fracking” operations carried out by Cuadrilla Resources Limited near Blackpool and a number of earthquakes which occurred in the local area in April and May 2011. The report which was published on 17 April 2012 confirms that the earthquake activity was caused by the fracking operations and recommends a cautious approach to future operations. See the full text of the report here (26 page pdf).
DECC is seeking views on the report and has launched a consultation period which will end on 25 May 2012. Operations at the site in Lancashire have been suspended pending the response to the consultation.
Preese Hall
On 1 April and 27 May 2011, two earthquakes with magnitudes 2.3 ML and 1.5 ML were detected in the Blackpool area. This seismic activity was immediately suspected to be linked to hydraulic fracture injections at the Preese Hall well and this was later confirmed by a study carried out by the operator, Cuadrilla. Cuadrilla concluded that the activity was caused by fluid injection into an adjacent fault zone during fracking, but that the chance of further tremors occurring was low. The panel of independent experts queried Cuadrilla’s assertion that the risk of future tremors occurring in the area was low and made certain recommendations regarding future operations in the local area and elsewhere in the UK.
Recommendations
The independent experts made the following recommendations to DECC to mitigate the risk of future earthquakes in the area:
1) smaller pre-injection and monitoring stage before the main injection;
2) microseismic monitoring of fracturing occurring during operations;
3) future operations in the area should be subject to a monitoring system (providing locations and magnitudes without delay); and
4) operations should be halted and remedial action instituted, if events of magnitude 0.5 ML or above are detected.
In addition, the report set out recommendations for seismic hazard assessment prior to commencing operations elsewhere in the UK, as follows:
1) baseline seismic monitoring to establish background seismicity in the area;
2) characterisation of any possible active faults in the region; and
3) ground motion prediction modelling to assess the potential impact of any induced earthquakes.
US stance
Safety issues around production and exploration of shale gas are also being explored in the United States. On 4 May 2012, the Obama administration issued a proposed set of regulations governing fracking operations on public land that will require disclosure of the chemicals used in the process.
The Obama administration is supportive of fracking operations generally and scientists in the US have not found any direct correlation between fracking operations and increased seismic activity. The experts appointed by DECC concluded that the geological position is significantly different in the US and that, accordingly, no useful comparison can be made with the UK.