Fracking suspension remains following Sylvan Lake-area earthquake
|calgaryherald.com 18 May 2019 at 07:56|
More than two months after an earthquake near Sylvan Lake, a ban on so-called fracking remains in place as authorities seek to determine if the tremors were caused by oilfield drilling.
On March 4, near where Vesta Energy had been conducting hydraulic fracturing, a process that involves pumping liquids into geological formations to free oil and gas deposits.
In locales in that region deemed low risk for seismic, the company has been given a green light to resume limited operations, as long as it provides a hazard-assessment plan, said Alberta Energy Regulator (AER) spokeswoman Natalie Brodych.
“All other fracturing sites remain suspended,” she added in an email.
Vesta, she said, has yet to provide a risk assessment and mitigation plan that would permit it to resume operations in the low-risk zones, Brodych said.
“Vesta is only permitted to perform surface construction, not resume operations, at their suspended sites,” she said.
In the meantime, the AER and Alberta Geological Survey (AGS) are still conducting a review of the March 4 incident to determine if it was caused by fracking.
“We have to compare passive seismic data, which is regular land movement, to the earthquake that happened,” said Brodych.
The AER couldn’t say how long the suspension would last or when its review of the earthquake would be completed.
Vesta Energy would only say it is continuing to work with the AER on the matter.
The incident triggered the AER’s traffic light-like protocol, which demands a driller cease activities in that area and report seismic events within 5 kilometres of its wells, once a tremor reaches a magnitude of 4.
The AER has previously linked oilpatch activity to earthquakes, noting those associated occurrences have increased since 2013, particularly in the Fox Creek area 260 kilometres northwest of Edmonton.
There, in January 2016, a tremor measured at 4.8 magnitude shook the area and was linked to fracking.
“We need to continue to study the links between hydraulic fracturing operations, geology and geomechanics, and their effects on induced seismicity,” Kristine Haug, AGS geological engineer, said on an AER website.
No injuries or notable damage to structures or the environment have resulted from any of the tremors, says the AER.
But that seismic activity had led the AER to declare orders imposing special regulatory requirements on drilling in five different zones in the province.
“These are orders tailored to subsurface conditions and there are many variances in those conditions,” said Brodych.