It seems you can’t turn around without another study involving earthquakes and oil and gas drilling or wastewater injection wells.
While residents around Enid this week got a shaking from two 4.2 magnitude earthquakes, a new research study found that the risk is man-made quakes is greatly reduced, or increased due to the distance from well sites. This latest study recommends a distance further than the recommendation of earlier research.
The ReFINE (Researching Fracking) consortium recommended this week the risk plunges if high-pressure fluid injection used to crack underground rocks is 895 meters or 2,953 feet from faults in the Earth’s crust.
The recommendation is based on microseismic data from 109 fracking operations carried out in the U.S. But the study was led by Durham and Newcastle Universities in the United Kingdom. It focused on reduction of risks of reactivating geological faults by fluid injection in boreholes.
Researchers found a one percent chance that fractures from Fracking activity could extend horizontally beyond 895 meters or more than 2,900 feet in shale rocks.
The research is published in the journal Geomechanics and Geophysics for Geo-Energy and Geo-Resources.
While the USGS, the Oklahoma Geological Survey and regulators at the Oklahoma Corporation Commission have studied the geological influence of fracking and wastewater injection wells, the UK researchers were influenced by 2011 tremors in Blackpool, UK.
The tremors were caused when injected fluid in the fracking process reached a previously unknown geological fault at the Presse Hall facking site. If it sounds familiar to what happened at the Pawnee earthquake that measured 5.8 magnitude in 2016, it is. There, an unknown fault was apparently affected by wastewater injection wells.
Research lead author Miles Wilson, a PhD student in Durham University’s Department of Earth Sciences, said: “Induced earthquakes can sometimes occur if fracking fluids reach geological faults. Induced earthquakes can be a problem and, if they are large enough, could damage buildings and put the public’s safety at risk.
“Furthermore, because some faults allow fluids to flow along them, there are also concerns that if injected fluids reach a geological fault there is an increased risk they could travel upwards and potentially contaminate shallow groundwater resources such as drinking water.
“Our research shows that this risk is greatly reduced if injection points in fracking boreholes are situated at least 895m (2,953 feet) away from geological faults.”
The latest findings go further than a 2017 ReFINE study which recommended a maximum distance of 433m (1,438 ft) between horizontal boreholes and geological faults. That research was based upon numerical modelling in which a number of factors, including fluid injection volume and rate, and fracture orientation and depth, were kept constant.