The Department of Energy & Climate Change has released a report on the seismic events which occurred in the Bowland Basin in Lancashire, in May and July 2011, based on a review of the reports submitted by Cuadrilla resources.
Cuadrilla Resources had been conducting test fracking in the region to test the potential volumes of shale gas and inadvertently caused two earthquakes, of Magnitudes 2.3 and 1.5 in April and May 2011.
The report agrees with Cuadrilla in that two test drillings at the company’s Preese Hall site led to the earthquakes but Cuadrilla maintain that it is very unlikely any further seismic events will be caused by drilling and the review supports this claim. The earthquakes were caused by an adjacent fault in the earth, which had not been identified.
The review also pointed out that it is unlikely that future fracking will cause an earthquake of more that magnitude 3. "There's no record of a quake at this size doing any structural damage," said Prof Styles. "But they would be strongly felt, and there is a possibility of superficial damage.
The report recommends the following measures to mitigate the risk of any damaging seismic activity from future shale gas operations in the Bowland Basin:
- The fracking procedure should include a smaller pre-injection and monitoring stage.
- Set-up an effective monitoring system to provide near real-time locations and magnitudes of any seismic events.
- Set-up a a ‘traffic light’ control regime, similar to that recommended by Cuadrilla’s consultants. A red light at activity levels of magnitude of 0.5 or above means fracking should be stopped and remedial action taken (this is lower than the magnitude 1.7 proposed by Cuadrilla’s report).
Responding to the expert review recommendations, Cuadrilla’s Chief Executive Mark Miller said, “We are pleased that the experts have come to a clear conclusion that it is safe to allow us to resume hydraulic fracturing, following the procedures outlined in the review."
"We have already started to implement a number of the experts’ recommendations in the pursuit of best practice and look forward to the final decision by DECC ministers concerning the resumption of hydraulic fracturing following the six week period for public comment commencing on 17 April.”
Written by Peter Farrell
Read the article online at: https://www.oilfieldtechnology.com/exploration/17042012/cuadrilla-resources-fracking-campaign-safe/