A recent report from the nonprofit Heartland Institute brought encouraging news to oil and gas producers in the Sooner state, as researchers shared new findings that demonstrate that seismic activity in Oklahoma does not bear a direct correlation to increases in oil and gas activity. Given that seismicity has actually fallen over a three-year term, while oil and gas production has risen over the same years, the two factors would almost seem to be inversely proportional. But the researchers stopped short of drawing that conclusion, instead asserting that greater awareness of seismicity and better practices in disposal of produced water are likely the reasons for a drop in earthquake activity.
The May 17 report, which is headlined “As Oklahoma Oil Production Climbs, Seismic Activity Falls,” bears this subheading: “Earthquakes have decreased 83 percent between 2015 and 2018.” To see the report in its entirety, go here.
Author Tim Benson observed that a spate of earthquakes some years ago “led to public confusion as to whether hydraulic fracturing, commonly called ‘frac’ing,’ was the direct cause of these earthquakes. Some Oklahoma state lawmakers even called for an outright moratorium on fracking in Oklahoma in 2015. The problem did not stem from frac’ing activity, but from the wastewater disposal wells, and this problem seems to have been mitigated by the actions of state regulators and the oil industry.”
Benson stated that it is not drilling itself that was causing tremors. Wastewater disposal involves much higher injection pressures and volumes of fluid than does frac’ing, because the aim of drillers is to keep those fluids in well reservoirs. The practice, by law, is overseen by local or regional Environmental Protection Agency (EPA) officers.
For observers to conclude that frac’ing is the cause of these earthquakes, simply because frac wastewater is occasionally injected into deep reservoirs—this is comparable to saying that turning on the ignition of a car causes traffic accidents, he wrote.
The article continued:
“In a major study, the EPA concluded most injection wells do not cause earthquakes and ‘very few’ earthquakes produced by those that do can be felt by humans. Another study, published in Science in 2014, found only four of the roughly 4,500 injection wells in Oklahoma had most likely induced seismic activity, while an Oklahoma Geological Survey analysis released in October 2017 found that only 282 of 23,000 measurable earthquakes in Oklahoma from 2011 to 2016 occurred within two kilometers of a frac’d well within a week of the well’s stimulation.”
Meanwhile, as the USGS notes on its “Myths and Misconceptions” webpage, frac’ing is not the primary cause of induced (human-caused) earthquakes. The page directly states, “Frac’ing is NOT causing most of the induced earthquakes.”
The Heartland Institute article went on to cite a database administered by researchers at the United Kingdom’s University of Durham and University of Newcastle upon Tyne. Analysis of this database, “the largest and most up-to-date database of earthquake sequences purported to have been induced or triggered by human activity worldwide since the 1800s,” leads to the conclusion that frac’ing has been conclusively linked to only 6 percent of all human-caused earthquakes, 46 earthquakes overall. Considering there are at least 1.1 million active frac’ing wells in the United States, this number is miniscule. In Oklahoma, only three earthquakes have been conclusively linked to frac’ing.