Justin Rubinstein said that measures to reduce earthquakes caused by saltwater injection wells in Harper and Sumner counties have succeeded – sort of – but with a twist and unanswered questions.
Rubinstein is a seismologist and deputy chief of the Induced Seismicity Project at the U.S. Geological Survey in Menlo Park, Calif. He spoke Saturday morning at the Kansas Cosmosphere, updating the audience on the causes of the recent earthquakes and the research into the success in controlling them.
He said scientists predict that the number of larger earthquakes will be down a bit this year from their peak in 2015.
The first point he made is that there is no longer any question that the recent earthquakes in Kansas and Oklahoma are caused by high-volume saltwater injection wells used to dispose of wastewater produced by some oil and gas drilling operations.
It’s not the hydraulic fracturing needed to finish a well but the disposal of saltwater – pumped out of the well along with the oil and gas during regular well operations – that causes earthquakes.
And an earthquake doesn’t happen in most places that oil is produced, he said. It happens only in a limited number of oil and gas plays, including the Mississippian Lime formation beneath northern Oklahoma and southern Kansas.
He said that in the past two years, academic, government and industry scientists have come together on the science of what caused the upsurge of earthquakes.
“The science is settled,” Rubinstein said. “Injection causes earthquakes. Nobody is disputing that.”
As a scientist, he was careful Saturday not to make any policy suggestions, but he did lay out what has happened since the Kansas Corporation Commission restricted high-volume water injection in five areas of Harper and Sumner counties a year ago.
The state studied the map and saw distinct clusters of earthquakes in five “areas of seismic concern” in Harper and Sumner counties. The KCC mandated that in those areas, high-volume wells – which pump at least 5,000 barrels of water per day into the ground – must reduce the amount they pump. Wells that pump less than that amount were unaffected.
A year later, experts are still studying the results, Rubinstein said.
The total number of earthquakes appears to be trending down after peaking in 2015, particularly since the start of 2016. He said the USGS expects the number to fall in 2016.
But there was a surprise: While the number of earthquakes has fallen inside the five “areas of seismic concern,” it has risen outside them elsewhere in Harper and Sumner counties.
That raises a lot of questions, such as what’s driving that, what’s causing the earthquakes still happening in the areas of seismic concern, how much of the reduction comes from the pumping restriction and how much from reduced drilling, and how widespread should restrictions on high-volume pumping be.
Rubinstein said the staff at the KCC is working on a proposal to restrict high-volume injection wells over a much broader area, covering parts of four counties. This must be approved by the KCC to be enacted.
The good news, Rubinstein said, is that it does seem that regulations have some control over the earthquakes, but obviously more study and fine-tuning are required. Governments and industry are working together on this.
But, he said, although there has been some progress in controlling these earthquakes, Kansas should now be considered an active earthquake site.
“I would say we’ve been fortunate to really not have a large earthquake,” he said. “You’re seeing a few magnitude 5’s, but not a whole lot.
“There is a possibility that there could be larger earthquakes.”
Building standards in Kansas, Oklahoma and Texas aren’t as strong as they are in traditional earthquake-prone areas such as California.
“I strongly encourage everyone to have an earthquake kit,” he said. “I have one at my house, and, if you live in earthquake country, it’s something you should have to be ready for a significant earthquake.”