A potential method
NDSU project studies using wicking materials to remediate brine-contaminated soils
Accidental releases of brine or produced water, a byproduct of oil and gas production, has increased over the past years.
Brine spills negatively affect the soil and vegetation, impairing their ability to produce crops and forage, according to North Dakota State University officials in Fargo.
NDSU is conducting research on a potential method to remove salts from the topsoil while keeping the soil in place.
A study has been done to determine the ability of using highly absorbent “wicking” materials to draw water and dissolved salts from the soil as permanent salt removal.
Tom DeSutter, professor/program leader of the NDSU Department of Soil Science, a presenter at a brine spill discussion held May 1 at the North Central Research Extension Center, south of Minot, said they have been trying to take some different approaches to how to reclaim soils.
Consisting of water from a geologic formation, injection water, oil and salts, brine has a high salt concentration. According to NDSU information, brine can have up to 10 times the salinity of ocean water.
The high salt concentrations in brine come from salt deposits in oil-producing formations, as seen in the Bakken and Three Forks formations in western North Dakota. The overall salinity and concentrations of sodium though can vary widely by location and depth of extraction, NDSU officials say.
Brine spill mitigation using the ex situ method of excavation and removal (dig and haul) has been the predominant practice used in the Williston Basin because it is a quick and effective way to remove the contaminant, NDSU officials say.
DeSutter said a student at NDSU has worked on how to bring salts out of the soil as opposed to moving it down through the soil.
“We’ve used a number of wicking materials to saturate the soil and allow the salts to move up into the wicks and then remove the wicks from the soil,” DeSutter said. He said this was done in a greenhouse at NDSU using straw and other wicking materials. He said three of the four wicking materials were able to take up about 80% of the salt in their experiment. The experiment was conducted over a period of several weeks.
“Water always wants to go back up into the atmosphere. We thought as opposed to fighting it and a lot of it is pushed down, actually to bring it back up,” he said.
“We are still in the development stages of identifying a commercial mix to use,” DeSutter added.
He said the plans are to try out the research on some actual spills.