Tabletop Device to Trace Fracking Fluids

Tabletop Device to Trace Fracking Fluids
Rice University chemist Andrew Barron and graduate student Brittany Oliva-Chatelain investigate the prototype of a device that allows for rapid testing of nanotracers for the evaluation of wells subject to hydraulic fracturing. (Photo courtesy of Jeff Fitlow/Rice University)

For drilling contractors, knowing exactly where hydraulic fracturing fluids travel is becoming as important as how much production the fluid will stimulate. A tabletop device developed at Rice University promises to predict how effectively a nanoparticle tracer will travel through a well, helping oil and gas producers to gauge the effectiveness of fracking efforts. 

“We developed nanoparticle tracing technology at the university,” says Rice chemist Andrew Barron, who created the device along with Rice alumnus Samuel Maguire-Boyle and other university colleagues. “However, to a nanoparticle, all fracking fluids are not created equal. The major difference in fluids from one drilling site to another is the type of proppant — sand or ceramic — used to keep hydraulic fractures open. Various laws of physics, including simple friction, cause nanoparticles to adhere to the surface of a proppant or slow it down.” 

The device uses a solid core that simulates a hydraulic fracture and most importantly the proppant pack. The operator combines silver nanoparticles with a sample of the contractor’s own hydraulic fracturing fluid, then injects it into the device. The concentration of nanoparticles in the outgoing solution, viewed by a spectroscope, determines how quickly the particles will travel between the actual insertion well and the production well. 

“Contractors may be pumping fracturing fluid into several wells, but they often have very little idea of how the insertion well is connected to the production side,” Barron says. “Using this device, they can determine how the nanoparticle tracers are likely to move through the fracking fluid. By collecting the particles at the production well and logging how long it took the tracer particles to get there, they’ll know a lot more about how the wells are connected.” 

Studying how nanoparticles interact with fracturing fluids will also allow drilling contractors to collect more information using a smaller volume of tracers. 

“If you know how the nanoparticles travel, you can prevent the tracers from clumping, or adhering to the proppants,” Barron says. 

Knowing where fracturing fluids travel underground is also important from a legal standpoint as both government agencies and the general public turn a watchful eye to potential contamination of aquifers surrounding gas and oil operations.

“You can customize the nanotracers so that each one has a magnetic signature, for example, that provides its own corporate identity,” Barron says. “If any government agency believes that an injection well operator has violated a local aquifer, the nanotracer should show up in the water sample. That’s a lot better than relying on a jury to decide who is responsible for the presence of methane in someone’s water supply, when that methane could have been produced by anything from the decomposition of biological material from the Jurassic era to a more recent rubbish heap.” 

Barron notes that states such as Texas are considering legislation that would require contractors to employ individualized nanotracers in fracking operations. 

Contractors interested in Barron’s tabletop device can make their own using instructions found in a paper appearing online in the February 2014 issue of Environmental Science: Processes & Impacts.

“All of the instructions are available for free in the supplementary materials attached to the article,” Barron says.



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