Tiny particles enlisted to tackle fracking's mysteries

Can magnetic nanoparticles injected deep underground with hydraulic fracturing liquids reveal detailed dimensions of shale rock fractures and track movements of gas molecules?

Can other particles -- that change form when they encounter oil -- be "interrogated" for clues about the amounts of oil in dense shale formations?

These are among the goals of the Advanced Energy Consortium (AEC), headquartered at the Bureau of Economic Geology at the University of Texas, Austin. It brings together university researchers and industry scientists seeking scientific breakthroughs that would remove some of the mystery in unconventional gas and oil development miles below ground. The 4-year-old venture has spent about $40 million so far.

Natural gas prices are still below most drillers' break-even points, analysts say. Wide disparities exist in best- and worst-case estimates of recoverable shale gas and oil resources. So the use of nanotechnology to boost efficiency and production has a substantial payoff potential, says consortium project manager Mohsen Ahmadian.

"Even though the industry has gotten good at fracturing, we don't know the exact extent of the fracture networks," Ahmadian said. That uncertainty can hamper a driller's search for the best fracturing techniques or cloud decisions about how much additional drilling and fracturing is necessary to exploit a shale formation.

So, in one part of the AEC agenda, the search is on for nano "contrast agents" that will penetrate the fractured shale rock and deliver a three-dimensional portrait of the fracking results. Nanoparticles are generally defined as being smaller than 0.1 micrometer in length (1 inch equals 25,400 micrometers).

"We want to have a more intelligent understanding of our resources," Ahmadian said. "If you have a previous understanding of how a particular reserve produces after a fracture, but you don't know how far you've penetrated, you continue fracking."

But with a contrast agent, "you could get a much higher-resolution image of the fracture network and you might say, 'This is telling me: Stop fracking, start production,'" he said. "The answer is not always drilling more wells. We want to give engineers better information so they can make better decisions."

The venture has enlisted as industry partners Schlumberger Ltd., BP America, BG Group PLC, Petrobras SA, Total SA and Royal Dutch Shell PLC. More than two dozen universities and close to 40 projects have been funded at this point, including research at the University of Texas, Rice University, Harvard University and the California Institute of Technology.


Some of the original partners -- Baker Hughes Inc., ConocoPhillips Co., Halliburton Energy Services Inc., Marathon Oil Corp. and Occidental Oil and Gas -- have left the consortium.

The consortium is recruiting new company members but is comfortable with the current pace of research and membership level, Ahmadian said. The majority of the companies that have left the consortium "didn't have sufficient bandwidth to remain actively engaged with the large number of funded projects," he said.

"It's a two-way process," he added: Mentors from the member companies work with the funded university researchers and help set directions for research. "The [university] nanotechnology experts help the members understand their technology," Ahmadian said. "We meet somewhere in between."

An MRI for shale plays

The search for contrast agents is not unlike the technology used in magnetic resonance imaging (MRI) exams to reveal a heart patient's blocked blood vessels, Ahmadian said. "In an MRI, typically, there is a contrast agent, which can be particles nano in size that can be energized using magnetic fields, providing a contrast between hard and soft tissues," he said.

"The human body is very analogous to a reservoir," Ahmadian added, citing the network of arteries and veins that connect diverse human tissues and the complex openings fractures create in varying shale rock geology. But the analogy has its limits, he and his colleagues acknowledge.

"The human body is very easy," adds Scott Tinker, director of the Bureau of Economic Geology at the Austin campus, who launched the consortium. "It's at surface pressure, surface temperature. You can cut it open and see where the things went. The earth has high pressure, high temperatures, nasty chemicals and you can't really get down there. It's a tough challenge. Within a decade or less, we might see some smart fracks, and certainly in the nearer term, things could be put into the fracking fluids to enhance remote sensing capabilities."

"The pharmaceutical industry has been able to produce materials safe enough to be injected into humans, that are degradable and so can be disposed of safely," Ahmadian said. "We want to use them in an analogous situation" in shale plays. "There is a lot of promise there."

Another research project involves novel "nanoreporter" compounds that release signaling molecules when they encounter oil, he said. These markers can be recovered after they travel through the reservoir and are brought to the surface, and their concentrations would give drillers an idea of how much oil remains in the reservoir.

An even more complex application involves proppant materials that operators force underground into the fractured spaces to keep them open so oil and gas can pass through. Researchers are working on adding nanobubbles to proppants that could respond to sound waves, recording changes in velocities and flows of oil or gas traveling toward the surface.

Ideally, to take the technology even further, there would be a communication channel between bubbles and the operators' monitors allowing the signals to be read in real time, he said. "That's a pretty big challenge to have enough power and communications to accomplish that. That is something we're trying to address."

30 patents in process

The project has produced more than 30 patents in various stages of development, Ahmadian said. The company members have equal access to this knowledge through royalty-free, nonexclusive licenses.

The consortium's university partners don't necessarily know which technologies are moving toward commercial application at the companies, he added. "The charter of the AEC is not to make commercial solutions. We are trying to develop a number of pre-commercial research concepts that we take to a certain level of development and pass on to the members," he said. "The members have the rights to all the patents, and if they choose to, they can commercialize them. We may not know how far they have gone."

Nanotechnology is already in use in more basic drilling applications: improving pipe coatings, for example. The more advanced applications on the consortium's list could be in the fields before the end of the decade, Ahmadian said. "I would venture that five years is a pretty conservative time frame.

"The nanoscale materials, used in day-to-day work in scientific labs, are produced in small scale," he said. "Once we develop a technology we feel is ready, we have to marry that to the chemical industry, to build these in large quantities for injection into reservoirs. Before we get there, we have to make sure the compounds we are developing can survive in the much harsher environment or reservoirs," he added. "And we have to make sure the outcome is environmentally safe."

The consortium has already had meaningful results, he said, although he cannot share details of the road map, which are proprietary to the member companies.

"We have a very complex set of research tasks that are being worked on in parallel fashion," Ahmadian said. "We are very optimistic. There are a lot of challenges. We are not unworried, but we are in the forefront of a brand-new science that is very exciting. Even if it is successful in recovering 1 percent of the resources remaining in place, we will have a significant economic impact."

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