Cuadrilla Resumes Fracking: OGA (Update)
UK upstream regulator, the Oil & Gas Authority (OGA) confirmed December 13 that operations at Cuadrilla's Preston New Road site are continuing following a series of minor seismic events. (See update in final two paras, with Cuadrilla pausing ops again around 2pm after a further 0.9M small tremor)
Cuadrilla's hydraulic fracturing (fracking) on December 11 triggered the largest tremor, of 1.5 magnitude, since it resumed fracking in northwest England in mid-October, after a seven-year gap. OGA sets a 0.5 magnitude limit for caution, which it says is well below the level that can be felt at the surface. Any greater than that obliges the operator to suspend fracking for 18 hours.
OGA said that, during such pauses, it compares the location, magnitude and ground motion of these minor seismic events to the operator’s approved Hydraulic Fracture Plan (HFP). It said December 13 that it is satisfied that these events are "in line with the geological understanding set out in the HFP and that the risk of induced seismicity is being appropriately managed". It said that the 18-hour pause can be extended in future if it judges it to be necessary.
As at 11am GMT, no further quakes had been reported by the British Geological Survey since the 1.5M one at 11.21am on December 11. Cuadrilla's fracking in 2011 at a different site nearby induced quakes of 1.5M and 2.3M. (Banner of Preston New Road site, courtesy of Cuadrilla)
Update Dec.14 6pm - Cuadrilla said “a series of micro seismic events in Blackpool have been recorded on the BGS website today December 14; the largest recorded was 0.9ML at about 2pm; this occurred whilst we were hydraulically fracturing at the Preston New Road exploration site" adding that it has "paused ... for at least 18 hours after the event was recorded."
The BGS recorded that one micro-quake (0.0M) occurred 1.25pm Dec.13, plus eight others on Dec.14 between 1.06pm and 2.52pm ranging from minus0.6M to 0.1M, in addition to the 0.9M tremor at 1.41pm - so a total of ten tremors on Dec.13-14.