A new approach to brine spill remediation could help landowners pull damaging salts directly from the soil.
Aaron Daigh, an assistant professor of soil physics at North Dakota State University, presented a method for on-site treatment aimed at removing salts from the earth through a chemical process, rather than physical displacement, during the second and final day of the fourth annual North Dakota Reclamation Conference Tuesday in Dickinson.
Daigh said salts will naturally move upwards in soil until local moisture evaporates and the salt crystallizes, leaving a kind of inhospitable “cemented zone” of crust behind.
In order to prevent that zone from being formed, Daigh said he and his fellow researchers focused on bringing salts out of the soil’s surface without disturbing the dirt itself.
He contrasted that to other other approaches to the extraction of salts in which “people try pushing them down, people try excavating them out.”
“We spent a half a year or more digging around in all sorts of bizarre literature trying to figure out how salts crystallize,” Daigh said, adding that the hunt included crystal-related information as diverse as the formation process of kidney stones in the human body.
Eventually, the team found a crystallization inhibitor that disrupts the process until the salts reach the surface of the soil and “grow like trees.”
Daigh showed conference attendants a time-lapse video of the blooming crystallization of leeched salts, the structures of which he said formed as rapidly as in 48 hours and were easy to clean off the surface of the ground.
The researchers tested different concentrations and application methods of the crystallization inhibitor on different sample soil types, Daigh said, and measured the salt extracted from each test item.
After seven days, researchers “harvested” the crystals and measured an extraction of 30-60 percent of all salts from the soil zones where water was flowing.
Daigh said field research on the method will be conducted this summer in both the eastern part of the state and in Bottineau County-area brine pits left behind from older oil explorations.
In the meantime, Daigh encouraged the audience to be creative in their approaches to reclamation, even at the risk of asking “silly” questions.
“We had no expectations that we’d ever be able to get salts to grow out of the ground and be able to just wipe them off without any mechanical disturbance to the soil at all,” he said. “To us it was an absurd question, but as scientists we tend to embrace those questions -- especially if you sometimes come across something that actually works.”
Eric Brevik, chair of the Dickinson State University Department of Natural Sciences and a professor of geology and soils, said after the conference’s conclusion that the salt extraction technique presented by Daigh “has the potential to be huge.”
“That’s been a major challenge for remediation for a long time -- that’s really big,” Brevik said of the finding.
‘Reclamation always follows up’
Despite the disruption to the regional oil economy, the conference’s second day was still well-attended.
Brevik said he “wasn’t completely sure what to expect” of this year’s event given the state of the industry, but said the two-day series had a good turnout and strong presentations. Currently, Brevik and the faculty of his department are attempting to build a graduate certificate in reclamation at DSU which would fall under their auspices.
Brevik said the field of reclamation is not very affected by low oil costs, at least in the short term.
“Reclamation always follows up,” he said. “It’s the response to problems, and that doesn’t change because the price of oil declines. … There’s been enough done already that there’ll be a lot of reclamation work for a long time.”
Brevik said there’s currently a heavy focus on pipeline-related reclamation, which he predicted would continue to be “a big thing in the near term” while oil infrastructure is built.
These reclamation projects around oil transportation lines will also occasionally run alongside the pressing work of attending to leaks and spills, he said.
As more recent Bakken wells begin to play out in the coming years and decades, Brevik continued, reclamation efforts will increasingly turn to taking down wellsites and pads and the roads that previously serviced them.
While the exact type and quantity of the work may change over time, Brevik said the need for reclamation will remain consistent.
“We could be putting kids through college right now, training to go into various aspects of this field, that could retire after 40 years of work to see more left to do,” he said.