Thinking Differently About Wastewater Management

A trend in centralized wastewater treatment points the way to future improvements in water usage, with lessons to be learned for other industries.

Jeff Easton has seen the future of wastewater treatment for the shale oil and gas industry. Easton, a process engineer at Salt Lake City-based industrial water management consultancy WesTech Engineering, is earning his Ph.D. in oil industry water use at the University of Utah. He says the industry is poised for a major shift in the way it handles wastewater. And it seems clear that lessons learned in shale could prove worthwhile for other manufacturing industries as well when it comes to better managing industrial wastewater.

Hydraulic fracturing (commonly referred to as fracking) pumps water, sand and chemicals deep underground to release trapped natural gas and oil. The process can use up to 9.6 million gallons of water per well, according to the U.S Geological Survey. Most of what’s used to frack a well is fresh, clean water with chemicals and sand added. But once a well has been fracked and is producing, water released with the oil and gas also flows to the surface. On average, water production exceeds hydrocarbon production by about 7 percent, says Gordon Mackenzie, director for water management at oilfield service company Baker Hughes.

And therein lies an opportunity. “Once your wells are producing, you’ve got produced water that you have to deal with anyway,” Easton notes. “So if you had the infrastructure built up for a development area, you could not only deal with the flowback issues when you're initially fracking the field, but also be able to treat the produced water that comes off of it.”

Besides diverting water from other uses—which adds to image problems for the oil and gas industry—using fresh water for fracking also affects the industry’s bottom line.

In most wells, wastewater, which contains a mix of chemicals, petroleum, salts and other contaminants, is either stored on site in open ponds or trucked to another location, where it might be pumped back underground for disposal.

On-site storage, trucking and deep injection all have their problems and costs. For example, large numbers of trucks carrying contaminated water out of oil fields could present regulatory and safety issues as well as cost, as do open-air storage ponds. And use of fresh water for fracking wells continues to carry its own rising costs as groundwater is depleted and rivers are regulated out of use.

Even more fundamental, Easton says, is that these are temporary measures, designed for expediency rather than sustainability. “Right now, it's just convenient to do whatever minimal amounts you can at the wellhead,” he says.

What’s needed is a long-term, sustainable strategy for wastewater treatment. “The need for it will only be increasing as the availability of freshwater sources reduces as the environmental regulation increases,” Easton says. And then will come the tipping point. “At some point, the value of water will be significant enough and the economic impact due to regulation will be significant enough that it will make a lot more sense to deal with that water, to treat it.”

The future of wastewater treatment
Crucial to any treatment of wastewater is monitoring the water condition, and automation has an important role to play here, says Marc Mason, business development manager at Emerson Process Management. “Remote monitoring of these parameters saves considerable labor time and costs vs. manual grab samples.”

Along with saving time and money, remote monitoring also provides better data, says Todd Langford, water solutions leader for unconventional oil and gas at GE Power. “Real-time analytical data is becoming more and more important,” he says. “For example, when a water sample is sent to a lab for analysis, that sample will change from the time it is sent out to the time it is analyzed.”

Automation can further enhance the accuracy of water analysis by keeping tabs on the sensors collecting the data, Mason adds. “The most important aspect of automation is the availability of real-time diagnostics on sensor condition. Sensors can be replaced or calibrated when needed before readings are impacted.”

As far as Easton is concerned, the best wastewater treatment solution is a central processing plant that makes maximum advantage of economies of scale and automation. The ideal system, he says, draws in the wastewater from surrounding wells to be processed in one place. There, wastewater is piped in and treated water is piped out, as in a municipal wastewater treatment plant.

Just such a system is in place at Shell Oil’s Pinedale Anticline Project Area (PAPA) in Wyoming, which reclaims more than half of all the water it uses. The facility is one of a handful of oilfields taking this new approach to wastewater treatment. At PAPA, some 400 wells send their wastewater to a central location, where it undergoes a variety of processes to render it reusable. Treatment takes two main paths: The water can either be treated for release back into the environment—at which point it exceeds drinking water standards—or it can be further treated for use in fracking another well.

Sizing up options
There’s no one size fits all for water treatment, Easton says. It all depends on the characteristics of the water going into the system, and the intended use for the water coming out. “In any kind of treatment, if you know what your inlet qualities are and you know what output qualities you’re trying to achieve, then the role of the process engineer is just to devise how do I get from point A to point B,” he explains.

At PAPA, for example, water goes through separate processes for de-oiling, biological and organics removal, filtration of suspended particles, softening and more. In broad terms, Easton breaks water treatment down into four major categories, though these are by no means all-inclusive:

  • Primary three-phase separation draws out natural gas, liquid oil and gel, and solid contaminants such as sand.
  • Secondary separation comes next to remove—in the case of water from fracking—polymers used in the fracking process, as well as additional oils and solids remaining from the first treatment process. At this stage, bacterial growth could be checked with bactericide.
  • Next, metal in the water may be removed through precipitation, the process of solidifying the metals for easy extraction. At this stage, salt may also be removed using reverse osmosis.
  • Finally, a sludge management process is needed to remove the remaining water from the solids left over from the other processes.

“There’s never, ever one piece of equipment that does everything,” Easton says. “There are many, many, many ways of doing each process step.” That’s why, he adds, it’s important to take a process engineering approach to the whole picture. “Because you have to combine process steps together; you have to select the types of equipment that you want to use based on how you propose to get from A to B.”

Along with the specific technologies needed to remove different contaminants, another major consideration is the question of flow equalization. “That’s a process decision,” Easton says. “Do you have large flows during certain hours of the day? Do you have one continuous flow? What are the conditions coming in? You definitely have to take that into account.”

Automation provides the key to efficient, cost-effective water treatment, no matter how large the operation. Take, for example, a case where three centralized water treatment plants together serve a 100-square-mile oil field. “The approach, certainly from an automation/instrumentation standpoint, would be remote telemetry,” Easton explains. “So now, instead of having to have an operator at every plant, I can have an operator that can roam.”

A wireless laptop in this scenario would keep the operator up to date on the conditions at each water treatment plant, keeping an eye on consumables such as treatment chemicals, for example. In the not-too-distant past, Easton says, each plant would have required its own staff for monitoring and control. Advances in automation have changed all that. “Now, the level of automation and instrumentation allows you to operate with much, much less man power.”

Add reduced costs enabled by automation to the benefits of central wastewater treatment. Together with the benefits that come with reduced water usage, easier compliance with regulations and reduced health risks, treatment would seem to be a no-brainer for an industry that produces a lot of wastewater. Unfortunately, economics don’t always enable best practices.

Next steps
Beginning in 2014, the price of oil dropped precipitously, from $100 a barrel to less than half that amount, driven downward by an abundance of oil on the market. Since then, more than two-thirds of wells have been decommissioned and hundreds of thousands of oil workers laid off. In this economic climate, investments in the industry, including in the area of wastewater treatment, have slowed considerably.

“That’s not to say that the industry isn’t prepping for an improvement,” Easton says. “But until that oil price starts to go back up, there probably won’t be a whole lot happening.”

The good news is that the processes and the tools and the technology are already available to further expand the use of centralized wastewater treatment in the industry, Easton says. When investment does come, it will take the form of pipelines and other infrastructure, and not much, if any, R&D. “This stuff is inevitably going to come around,” he says. “My pitch is to prepare for it now. It’s not that big of an apple to eat if you start on it early.”

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