Water reuse could be key for future of hydraulic fracturing

Enough water will come from the ground as a byproduct of oil production from unconventional reservoirs during the coming decades to theoretically counter the need to use fresh water for hydraulic fracturing operations in many of the nation’s large oil-producing areas. But while other industries, such as agriculture, might want to recycle some of that water for their own needs, water quality issues and the potential costs involved mean it could be best to keep the water in the oil patch.

That is the takeaway from two new studies led by researchers at The University of Texas at Austin.

“We need to first maximize reuse of produced water for hydraulic fracturing,” said Bridget Scanlon, lead author on both of the studies and a senior research scientist with the UT Bureau of Economic Geology. “That’s really the message here.”

The first study was published in Environmental Science and Technology on Feb. 16. It quantifies for the first time how much water is produced with oil and natural gas operations compared with how much is needed for hydraulic fracturing. The authors also projected water demand for hydraulic fracturing needs and produced water over the life of the oil and gas plays, which span decades. A play is a group of oil or natural gas fields controlled by the same geology.

The second study was published in Science of the Total Environment on Feb. 3. It assesses the potential for using the water produced with oil and natural gas in other sectors, such as agriculture. It included researchers from New Mexico State University, The University of Texas at El Paso and Penn State University. It shows that current volumes of produced water are relatively small compared with irrigation water demands and will not solve water scarcity issues.

Dealing with water issues has become increasingly challenging with oil and natural gas development in unconventional shale reservoirs. Operators need significant amounts of water to hydraulically fracture shales to produce oil and natural gas, which can be an issue in areas where water is scarce. And large quantities of water are brought up from the reservoirs as a byproduct of production, posing a whole new set of issues for how to manage the produced water, particularly as science has shown that pumping it back into the deep subsurface is linked to seismic activity in some regions.

The studies can help inform significant public policy debates about water management related to oil and natural gas production in Texas, Oklahoma, New Mexico and other parts of the country, Scanlon said.

“The water volumes that are quoted vary widely. That’s why we did this study,” she said. “This really provides a quantitative analysis of hydraulic fracturing water demand and produced water volumes.”

The research looked at eight major plays across the U.S., including the Permian (Midland and Delaware), Bakken, Barnett, Eagle Ford, Fayetteville, Haynesville, Marcellus and Niobrara plays.

The scientists used historical data from 2009 to 2017 for all plays, and projections were developed for the life of the oil plays based on the technically recoverable oil using current technology. Oil plays produced much more water than natural gas plays, with the Permian Basin producing about 50 times as much water as the Marcellus in 2017. As far as recycling potential for hydraulic fracturing, the research shows that in many cases there’s plenty of water that could be put to good use. For instance, in the Delaware Basin, which is part of the larger Permian Basin in Texas, scientists found that projected produced water volumes will be almost four times as great as the amount of water required for hydraulic fracturing.

Managing this produced water will pose a significant challenge in the Delaware, which accounts for about 50% of the country’s projected oil production. Although the water could theoretically be used by other sectors, such as agriculture in arid West Texas, scientists said water quality issues and the cost to treat the briny water could be hurdles. In addition, if the water is highly treated to remove all the solids, large volumes of salt would be generated. The salt from the produced water in the Delaware Basin in 2017 alone could fill up to 3,000 Olympic swimming pools.

“The ability to beneficially reuse produced waters in arid and semi-arid regions, which can be water stressed, is not the panacea that we were hoping,” said co-author Mark Engle, a professor at The University of Texas at El Paso. “There is definitely potential to do some good, but it will require cautious and smart approaches and policies.”

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Researchers generate terahertz laser with laughing gas

Within the electromagnetic middle ground between microwaves and visible light lies terahertz radiation, and the promise of “T-ray vision.”

Terahertz waves have frequencies higher than microwaves and lower than infrared and visible light. Where optical light is blocked by most materials, terahertz waves can pass straight through, similar to microwaves. If they were fashioned into lasers, terahertz waves might enable “T-ray vision,” with the ability to see through clothing, book covers, and other thin materials. Such technology could produce crisp, higher-resolution images than microwaves, and be far safer than X-rays.

The reason we don’t see T-ray machines in, for instance, airport security lines and medical imaging facilities is that producing terahertz radiation requires very large, bulky setups or devices that produce terahertz radiation at a single frequency — not very useful, given that a wide range of frequencies is required to penetrate various materials.

Now researchers from MIT, Harvard University, and the U.S. Army have built a compact device, the size of a shoebox, that produces a terahertz laser whose frequency they can tune over a wide range. The device is built from commercial, off-the-shelf parts and is designed to generate terahertz waves by spinning up the energy of molecules in nitrous oxide, or, as it’s more commonly known, laughing gas.

Steven Johnson, professor of mathematics at MIT, says that in addition to T-ray vision, terahertz waves can be used as a form of wireless communication, carrying information at a higher bandwidth than radar, for instance, and doing so across distances that scientists can now tune using the group’s device.

“By tuning the terahertz frequency, you can choose how far the waves can travel through air before they are absorbed, from meters to kilometers, which gives precise control over who can ‘hear’ your terahertz communications or ‘see’ your terahertz radar,” Johnson says. “Much like changing the dial on your radio, the ability to easily tune a terahertz source is crucial to opening up new applications in wireless communications, radar, and spectroscopy.”

Johnson and his colleagues have published their results in the journal Science. Co-authors include MIT postdoc Fan Wang, along with Paul Chevalier, Arman Armizhan, Marco Piccardo, and Federico Capasso of Harvard University, and Henry Everitt of the U.S. Army Combat Capabilities Development Command Aviation and Missile Center.

Molecular breathing room

Since the 1970s, scientists have experimented with generating terahertz waves using molecular gas lasers — setups in which a high-powered infrared laser is shot into a large tube filled with gas (typically methyl fluoride) whose molecules react by vibrating and eventually rotating. The rotating molecules can jump from one energy level to the next, the difference of which is emitted as a sort of leftover energy, in the form of a photon in the terahertz range. As more photons build up in the cavity, they produce a terahertz laser.

Improving the design of these gas lasers has been hampered by unreliable theoretical models, the researchers say. In small cavities at high gas pressures, the models predicted that, beyond a certain pressure, the molecules would be too “cramped” to spin and emit terahertz waves. Partly for this reason, terahertz gas lasers typically used meters-long cavities and large infrared lasers.

However, in the 1980s, Everitt found that he was able to produce terahertz waves in his laboratory using a gas laser that was much smaller than traditional devices, at pressures far higher than the models said was possible. This discrepancy was never fully explained, and work on terahertz gas lasers fell by the wayside in favor of other approaches.

A few years ago, Everitt mentioned this theoretical mystery to Johnson when the two were collaborating on other work as part of MIT’s Institute for Soldier Nanotechnologies. Together with Everitt, Johnson and Wang took up the challenge, and ultimately formulated a new mathematical theory to describe the behavior of a gas in a molecular gas laser cavity. The theory also successfully explained how terahertz waves could be emitted, even from very small, high-pressure cavities.

Johnson says that while gas molecules can vibrate at multiple frequencies and rotational rates in response to an infrared pump, previous theories discounted many of these vibrational states and assumed instead that a handful of vibrations were what ultimately mattered in producing a terahertz wave. If a cavity were too small, previous theories suggested that molecules vibrating in response to an incoming infrared laser would collide more often with each other, releasing their energy rather than building it up further to spin and produce terahertz.

Instead, the new model tracked thousands of relevant vibrational and rotational states among millions of groups of molecules within a single cavity, using new computational tricks to make such a large problem tractable on a laptop computer. It then analyzed how those molecules would react to incoming infrared light, depending on their position and direction within the cavity.

“We found that when you include all these other vibrational states that people had been throwing out, they give you a buffer,” Johnson says. “In simpler models, the molecules are rotating, but when they bang into other molecules they lose everything. Once you include all these other states, that doesn’t happen anymore. These collisions can transfer energy to other vibrational states, and sort of give you more breathing room to keep rotating and keep making terahertz waves.”

Laughing, dialed up

Once the team found that their new model accurately predicted what Everitt observed decades ago, they collaborated with Capasso’s group at Harvard to design a new type of compact terahertz generator by combining the model with new gases and a new type of infrared laser.

For the infrared source, the researchers used a quantum cascade laser, or QCL — a more recent type of laser that is compact and also tunable.

“You can turn a dial, and it changes the frequency of the input laser, and the hope was that we could use that to change the frequency of the terahertz coming out,” Johnson says.

The researchers teamed up with Capasso, a pioneer in the development of QCLs, who provided a laser that produced a range of power that their theory predicted would work with a cavity the size of a pen (about 1/1,000 the size of a conventional cavity). The researchers then looked for a gas to spin up.

The team searched through libraries of gases to identify those that were known to rotate in a certain way in response to infrared light, eventually landing on nitrous oxide, or laughing gas, as an ideal and accessible candidate for their experiment.

They ordered laboratory-grade nitrous oxide, which they pumped into a pen-sized cavity. When they sent infrared light from the QCL into the cavity, they found they could produce a terahertz laser. As they tuned the QCL, the frequency of terahertz waves also shifted, across a wide range.

“These demonstrations confirm the universal concept of a terahertz molecular laser source which can be broadly tunable across its entire rotational states when pumped by a continuously tunable QCL,” Wang says.

Since these initial experiments, the researchers have extended their mathematical model to include a variety of other gas molecules, such as carbon monoxide and ammonia, providing scientists with a menu of different terahertz generation options with different frequencies and tuning ranges, paired with a QCL matched to each gas. The group’s theoretical tools also enable scientists to tailor the cavity design to different applications. They are now pushing toward more focused beams and higher powers, with commercial development on the horizon.

Johnson says scientists can refer to the group’s mathematical model to design new, compact and tunable terahertz lasers, using other gases and experimental parameters.

“These gas lasers were for a long time seen as old technology, and people assumed these were huge, low-power, nontunable things, so they looked to other terahertz sources,” Johnson says. “Now we’re saying they can be small, tunable, and much more efficient. You could fit this in your backpack, or in your vehicle for wireless communication or high-resolution imaging. Because you don’t want a cyclotron in your car.”

This research was supported in part by the U.S. Army Research Office and the National Science Foundation.

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IEEE Spectrum

How an Australian State Fought Back Against Grid-Sparked Wildfires

Nine years before Paradise, California burned to the ground, a similar tragedy unfolded in Australia. On a searing, windy day in 2009 that came to be known as “Black Saturday,” hundreds of fires erupted in the state of Victoria. One of the worst razed the bucolic mountain town of Marysville, northeast of Melbourne. And just as sparks from a Pacific Gas & Electric (PG&E) power line launched the Camp Fire that destroyed Paradise, Marysville’s undoing began with high-voltage current.

In all, the Black Saturday fires killed 173 people and caused an estimated AUS $4 billion ($2.75 billion) in damage. Fires started by power lines caused 159 of the deaths.

California’s wildfires have “brought it all back,” says Tony Marxsen, an electrical engineering professor at Monash University in Australia. His parents honeymooned in Marysville. “It was a lovely little town nestled up in the hills. To see it destroyed was just wrenching,” he recalls.

Marxsen says faded memories increased Marysville’s death toll. “It had been 26 years since Australia’s last major suite of deadly fires,” he says. “People had come to believe that they could defend their house against a firestorm. Some stayed, and they all died.”

While they go by different names, California’s wildfires and Victoria’s bushfires are driven by the same combination of electrical networks and extreme weather, stoked by climate change. How Victoria responded after the Black Saturday fires—work that continues today—differs significantly from what is happening in California today, especially in PG&E’s territory.

IEEE Spectrum

FedEx Ground Uses Virtual Reality to Train and Retain Package Handlers

Package handlers who work on FedEx Ground loading docks load and unload 8.5 million packages a day. The volume and the physical nature of the work make it a tough job—tougher than many new hires realize until they do it. Some quit almost immediately, according to Denise Abbott, FedEx Ground’s vice president of human resources.

So, when FedEx Corp.’s truck package delivery division evaluated how best to incorporate virtual reality into employee training, teaching newly hired package handlers what to expect on the job and how to stay safe doing it quickly rose to the top of the list.

“It allows us to bring an immersive learning technology into the classroom so people can practice before they step foot on a dock,” said Jefferson Welch, human resource director for FedEx Ground University, the division’s training arm. He and Abbott talked about the company’s foray into VR-based training during a presentation at the recent HR Technology Conference in Las Vegas.

3D Printing Industry

Re-engineering large format 3D printing in the BigRep STUDIO G2

In May 2019, leading large format 3D printer manufacturer BigRep broke new ground with the launch of the STUDIO G2. A successor to the original BigRep STUDIO system, the G2 is one of the first fully-enclosed 3D printers from the company, offering the same tried and true principles of its predecessors in a controlled environment, […]

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Author: Beau Jackson


Military drills for robots

Army researchers tested ground robots performing military-style exercises, much like Soldier counterparts, at a robotics testing site in Pennsylvania recently as part of a 10-year research project designed to push the research boundaries in robotics and autonomy.

RoMan, short for Robotic Manipulator, is a tracked robot that is easily recognized by its robotic arms and hands — necessary appendages to remove heavy objects and other road debris from military vehicles’ paths.What’s harder to detect is the amount of effort that went into programming the robot to manipulate complex environments.

The exercise was one of several recent integration events involving a decade of research led by scientists and engineers at the U.S. Army Combat Capabilities Development Command’s Army Research Laboratory who teamed with counterparts from the NASA/Jet Propulsion Laboratory, University of Washington, University of Pennsylvania, Carnegie Mellon University and General Dynamics Land Systems.

As part of ARL’s Robotics Collaborative Technology Alliance, the work focused on state-of-the-art basic and applied research related to ground robotics technologies with an overarching goal of developing autonomy in support of manned-unmanned teaming. Research within the RCTA program serves as foundational research in support of future combat ground vehicles.

The recent robot exercise was the culmination of research to develop a robot that reasons about unknown objects and their physical properties, and decides how to best interact with different objects to achieve a specific task.

“Given a task like ‘clear a path’, the robot needs to identify potentially relevant objects, figure out how objects can be grasped by determing where and with what hand shape, and decide what type of interaction to use, whether that’s lifting, moving, pushing or pulling to achieve its task,” said CCDC ARL’s Dr. Chad Kessens, Robotic Manipulation researcher.

During the recent exercise, RoMan successfully completed such as multi-object debris clearing, dragging a heavy object (e.g., tree limb), and opening a container to remove a bag.

Kessens said Soldier teammates are able to give verbal commands to the robot using natural human language in a scenario.

“Planning and learning and their integration cut across all these problems. The ability of the robot to improve its performance over time and to adapt to new scenarios by building models on-the-fly while incorporating the power of model-based reasoning will be important to achieving the kinds of unstructured tasks we want to be able to do without putting Soldiers in harm’s way,” Kessens said.

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Materials provided by U.S. Army Research Laboratory. Note: Content may be edited for style and length.

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Kinetik Aims to Be the Most Agile Skateboard-Style Vehicle in the World

The vast majority of ground vehicles utilize wheels for a reason: they’re extremely efficient over flat ground. One of the best examples of that principle is the humble bicycle. The average person can travel on a bicycle many times further — and faster — than they could while running or walking. Skateboards aren’t quite as efficient, but they do have the benefit of being lightweight and portable. Josh Geating and his team are trying to improve on typical electric skateboards to build the “most agile, rideable flatground wheeled vehicle in the world.”

A key word in that quote is “agile.” That means speed in a straight line isn’t the primary goal of this project. Instead, Geating’s team is try to build a skateboard-style vehicle that can maneuver better than any other. Power and speed are certainly a factor, but the ability to turn on a dime is just as important. To make it happen, they’ve designed three prototypes so far. All of them are using massive 80mm brushless DC motors that are controlled by an Arduino Due board through VESCs (Vedder Electronic Speed Controllers). Those motor controllers have additional features when compared to a conventional ESC, including regenerative braking.

The first of the prototypes was designed with omniwheels in order to facilitate extremely tight turns. Unfortunately, those wheels are normally intended for slow speed robots and were quickly torn to shreds by the power from the large motors. The following two designs utilized swerve drives and hard wheels, which allow each wheel to be turned and powered independently. The first of those had three wheels, but ended up being unwieldy. The second of those had four wheels and fared better, but still didn’t perform at the level they’re hoping for.

The Kinetik project is, however, still underway. Be sure to follow along with their build logs as they continue to push towards their goal.

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Author: Cameron Coward