Creative porosity

‘Nano Balls’ Prop Shale Fractures

Andrew Barron
Andrew Barron

Nanotechnology is the field of science defined by the nanometer, which is the equivalent of one-billionth of a meter and appears poised to make a significant impact in the oil and gas industry, demonstrating that minuscule particles are suited for big jobs.

It’s currently playing a role in the contentious hydraulic fracturing segment of the industry, among other applications.

One of the latest examples is the new fracking proppant stemming from nanotechnology research at Rice University’s Smalley Institute for Nanoscale Science and Technology (SINST) in Houston. These new agents will help to optimize production from unconventional oil and gas wells.

Ordinary proppants, typically made up of sand grains or ceramics, are dispersed into the formation along with the injected fluids. Their purpose is to keep the fractures open when the fluid injection ceases. As the pressure drops, the rock ordinarily will collapse without the support of substantive proppants.

“We were out to make proppants that are lighter and stronger than previous materials,” said Andrew Barron, Welch Chair of chemistry and professor of materials science at Rice. Barron spearheaded the research effort, which was initially funded by the Advanced Energy Consortium (AEC) at the Bureau of Economic Geology at University of Texas at Austin. The AEC funds scientific research in the nanorealm.

Nano-proppants OxBall and OxFrac are light, high-strength ceramic proppants, which evolved out of the nanotechnology research at the SINST. They are being produced at a Texas-based company founded by Barron.

“OxBall is heavier and slightly larger, and OxFrac is lighter and smaller,” Barron said. “They’re essentially the same type of thing but have different applications. For example, OxBall is more suited for west Texas type oil and OxFrac for shale gas like the Barnett.

“The material can be tailored especially for particular mineral types, in terms of whether you’re in west Texas, Oklahoma or wherever,” he noted. “It can be designed to be optimum for different reservoir types.”

OxBall currently is being used to enhance production from the deeper Haynesville and Eagle Ford plays.

The big advantage in these lighter, more uniform proppants is that they’re all the same size, so the hydraulic fracturing process requires less water, chemicals and additives.

A Practical Explanation

Here’s a simple take on how it works:

Picture a bucket filled with ping-pong balls. Spaces exist where the surfaces don’t touch. The balls are all uniform size, so they pack uniformly and create “porosity” providing significant space for all and gas to flow.

In contrast, if the proppant being used has particles of varying shapes and sizes, such as the grains in commonly used, relatively inexpensive sand, they pack tighter, and the rate at which oil and gas come out of the well is slower.

“The flow rate with same-size proppant particles can be as much as 100 percent higher than using traditional ones,” Barron emphasized.

Another consideration is downhole injection.

Where fluid is pumped down the borehole with varying-sized proppant particulates, their tendency to aggregate will limit how far down they can be pumped.

Barron noted the company puts together a number of different materials to make the ceramic proppants. One is waste material from China, Russia, Ukraine and U.S. power stations (coal-powered power stations). They use this as a base and use various different minerals – nano-crystalline minerals – to create the proppant.

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Emphasis: Downhole Geology