October 3, 2019

More questions than answers on how to reuse produced water

Kendra Chamberlain

A warning sign near a fracking well in the Greater Chaco area.

While fresh water supplies in the state are slowly dwindling, oil and gas activity generates millions of gallons of produced water each year. The state is currently deciding how best to regulate the use of treated produced water, while researchers, oil and gas producers and other companies are trying to find new uses for the wastewater.

Produced water is a byproduct of the oil and gas extraction activities currently going on in two energy-generating sections of the state, the Permian Basin in the southeastern portion of the state, and the San Juan basin in the Four Corners area. The wastewater comes into contact with hydrocarbons and drilling constituents, and is generally considered contaminated.

As the state gears up to hold a series of public meetings on recycling produced water throughout October, there are some serious question marks over the feasibility of using treated produced water in applications outside the oil and gas industry.

Tackling the water-energy nexus

Hydraulic fracking is a water-intensive process and the main generator of produced water, though oil extraction also uses water. A single horizontal well can use an average of 12 million gallons of water during the multi-stage fracking process, turning that water into produced water in the process. New Mexico Environment Department (NMED) estimates 42 million gallons of produced water was generated in the state’s portion of the Permian Basin in 2018 alone.

Earlier this year, state lawmakers passed the Produced Water Act, which establishes jurisdictional and legal clarity over produced water use in New Mexico. The law encourages oil and gas producers to reuse produced water when possible, rather than rely on fresh water sources for oil and gas extraction.

The bill passed the House without a dissenting vote and passed the Senate on a 32-6 vote.

The legislation was a first step in the right direction for the state, according to Jeri Sullivan Graham, a research professor at UNM’s Center for Water and the Environment. She previously worked as a science advisor for brackish and produced water issues at Los Alamos National Laboratory (LANL).

“New Mexico is probably one of the most important places where this gets done because of our lack of abundant fresh water resources,” Sullivan Graham told NM Political Report.

Reusing wastewater in extraction processes like fracking is just one component to the state’s emerging strategy for managing freshwater resources amid an oil and gas sector boom. Last month, NMED signed a memorandum of understanding with New Mexico State University (NMSU) to develop new technologies for treating produced water so that it could possibly be used for agriculture irrigation or even drinking water.

“New Mexico’s innovation in this area is and will continue to be the envy of other states,” Gov. Michelle Lujan Grisham said at the time. “Turning this waste product into a commodity is good for preserving fresh water resources, good for compact requirements with other states, good for conservation purposes, good for local and county governments; it’s good for small and large producers, it’s good for agriculture. It’s good for New Mexico, and it represents an exciting leap forward.”

Potentials for produced water

Produced water can be reused in oil and gas activities with very little if any treatment, which makes this use case a no-brainer for the state to encourage, Sullivan Graham said.

“Reusing produced water in oil and gas: That is the best use for this water, flat out. There is no question that is the best place for this water to be used,” she said. “They won’t be able to get away from using fresh water all together, they have to use some fresh water in their operations, but the more produced water they can reuse, the better.”

But the feasibility of treating produced water for use in areas outside the oil and gas sector is less certain. For one thing, the wastewater generated in New Mexico tends to be very salty and desalinating water is more cost-intensive than just removing the other contaminants in the water.

“Treating produced water, particularly in the Permian Basin, is extremely expensive because of the amount of salt in it,” Graham Sullivan said. “Treating salination — that’s where the bulk of the energy cost comes from. People get scared the most from the organic chemicals and the drilling constituents. To be honest, when you have water that is 200,000 mg/l of salt, and 1 mg/l other stuff, the energy it takes to desalinate that is quite a bit.”

Using produced water for agriculture isn’t unheard of, but there isn’t a one-size-fits-all approach to treating and reusing wastewater. Sullivan Graham pointed to other states, such as California, which has been treating its produced water and blending it with freshwater for use in agricultural irrigation for years.

“That’s a great example of how it can be done well,” she said, but added that California’s produced water doesn’t have nearly as much salt in it as New Mexico.

“The cleaner [produced] water is low-hanging fruit,” she said. “It’s not got a lot of salt in it, so the treatment is much simpler and cheaper.”

For Sullivan Graham, desalination is the biggest obstacle to using produced water in applications outside the oil and gas sector in New Mexico.

“It doesn’t make sense to do it on a [large] scale for something like agriculture. You’d have to spend a ton of money and be really desperate,” she said. “I don’t think we’re quite that desperate yet. Water conservation and treating municipal water for reuse is much easier when you’re not removing a bunch of salt.”

Exploring desalination technologies

The state plans to lean on the research and expertise at NMSU in water desalination and water treatment to inform its policies for produced water reuse. NMED and NMSU launched the Produced Water Research Consortium on Tuesday in Las Cruces, following the MoU signed in September.

The consortium will help the state “fill scientific and technical knowledge gaps necessary to establish regulations and policies for the treatment of produced water,” NMED said in a statement. It will include industry stakeholders, NGOs and researchers from other universities in the state, and will be funded in part through oil and gas membership to the consortium. NGL Energy Partners is the first industry member to join the consortium. The company pledged $1 million in funding on Tuesday at the event in Las Cruces.

“The goal of the produced water consortium is to advance the science and technology of produced water treatment and reuse, to assist the regulatory agencies in New Mexico to make science-based regulations and policies,” Dr. Pei Xu, the PESCO Endowed Professor and Ward Family Endowed Interdisciplinary Chair in Civil Engineering at NMSU, told NM Political Report. “This is a pressing issue in New Mexico. We want to reuse the water to augment our regional water supplies because we’ve been in drought for so many years.”

Pei and NMSU are also part of a team that was selected just last week by the U.S. Department of Energy to lead a water desalination hub. The DOE hub casts wider net for exploring desalination and water treatment technologies than the state consortium, but produced water has been identified as one area for research, along with inland desalination, municipal water treatment, and other areas. 

“Because produced water is a key area for the desalination hub, NMSU researchers will also contribute to the produced water research, such as the characterization of produced water quality and development of treatment technologies,” Pei said.