An oilfield-waste treatment facility will separate solids from drilling mud, then inject the remaining liquid waste into a saltwater-disposal well — a first in North Dakota.

A Texas-based company has received the go-ahead to build an oilfield waste treatment facility in North Dakota that will separate solids from drilling mud, then inject the remaining liquid waste into a saltwater-disposal well — a first in North Dakota. 

The North Dakota Industrial Commission (NDIC) approved the treatment plant proposal submitted by Trisun Energy Services LLC in Houston. The facility, which will be located about 7 miles south of Killdeer in western North Dakota, will be capable of processing 4,000 barrels of waste a day, says Alison Ritter, public information officer for the North Dakota Department of Mineral Resources. 

“This disposal process for drilling mud will be the first of its kind in North Dakota, but more than likely not the last,” Ritter says, noting that since April 2012, drilling-and-exploration companies no longer can store drilling mud in on-site reserve pits. As such, exploration companies currently must truck post-separation liquid waste to other municipal or privately owned treatment centers in North Dakota or out of state, which is expensive, or take it to special waste landfills, she says. 

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“This venture is significant because it provides another means of oilfield waste disposal in our state,” Ritter adds. “As the industry grows, we want to be able to accommodate that growth.” 

North Dakota officials banned yearlong storage of drilling mud in on-site reserve pits because when winter sets in, the waste freezes, which stymies pit-reclamation efforts. It also creates a potential environmental hazard in spring, when melting snow and heavy rains could cause reserve pits to overflow, Ritter says. 

“The backlog of unreclaimed pits became too large,” she says. “The state wanted companies to dispose of drilling mud in a more timely manner.” 

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The treatment center will use a shaker to separate solids that cannot be ground up. The ungrindable solids will be transported to landfills, while the remaining material — liquids and fine solids — will be transferred to mixing/milling tanks. After adding water to create a slurry, the mixture will be transferred to an agitated transfer tank, where more water is added to adjust the viscosity to the proper level. 

From there, the waste is injected into an existing adjacent saltwater-disposal well. The waste is injected into the so-called Dakota Formation, a sandstone formation about a mile underground. According to minutes of an NDIC meeting, injection of liquid oilfield waste is already an accepted practice in Louisiana and Alaska’s North Slope oil region. 

The NDIC is requiring additional bonding for the project because of the potential for environmental liability. In addition, Ritter says the well where the waste will be injected under pressure will be subject to more intense monitoring and more stringent requirements than if it were just accepting saltwater. 

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“This disposal technique is new area for our state, but we’re taking extra environmental steps to ensure it’s environmentally safe,” she explains. “This particular well will be subjected to even more requirements than a saltwater-disposal well because of the nature of the fluids. The operator will be required to do daily pressure tests and keep a daily log, and the well and log will be inspected monthly to ensure compliance.” 

The cost of the facility and the date it’s expected to start operating is not known. Trisun officials could not be reached for comment.

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