With the introduction of new risk controls last week, the British government has cleared the way for hydraulic fracturing (fracking) to resume in the country where the shale gas reserve could be 4.2 Tcf, according to one estimate.
Last year the government halted exploratory fracking at a site in northwestern England due to small tremors thought to be associated with the fracking. Cuadrilla Resources Ltd. was drilling on its field near Blackpool, in Lancashire, England . The company has claimed that there may be 200 Tcf of gas in place in the Bowland Basin.
"The analysis carried out by Cuadrilla's advisers, and confirmed by our independent panel of experts, has however concluded that the most likely cause of the tremors is the movement of the frack fluid into and along a fault which was already under stress," said Energy and Climate Change Secretary Edward Davey. "The additional pressure of the fluid allowed the fault to move, releasing the energy stored in the fault and resulting in the perceived tremors at the surface."
To move exploration and fracking forward, Britain has instituted controls to mitigate the risk of seismic activity that require a fracking plan to be submitted to the Department of Energy and Climate Change (DECC) showing how seismic risks will be addressed; seismic monitoring to be carried out before, during and after fracking; and a new system to categorize seismic activity and direct appropriate responses that include a trigger mechanism to stop fracking operations in certain conditions.
The fracking plan should be progressive, starting with the injection of small volumes of fluid and analyzing the resulting data carefully before the full stage, Davey said. "Each stage of the frack will be carefully designed to use just enough fluid to create a fracture sufficient to enable gas to flow, he said. "A flowback period will be required immediately after each stage to rebalance the pressures. Real-time recording of earthquakes during and for 24 hours after each stage of the frack will be analyzed to look for abnormal induced events amidst the normal background seismicity."
Britain has also created the Office of Unconventional Gas and Oil, led by the DECC and will also be tackling the issue of shale gas development and its possible impact on greenhouse gas emissions and climate change, Davey said. "We are still in the very early stages of shale gas exploration in the UK and it is likely to develop slowly," he said.
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