Sushanta Mitra and PhD student Naga Siva Gunda show off their new Reservoir on a Chip microfluidics device.

Edmonton—It is estimated that 25 per cent of Alberta’s heavy oil reserves are inaccessible, trapped inside tightly packed minerals called carbonates. Globally, about 60 per cent of the world’s heavy oil is held in such formations.

But now, a University of Alberta mechanical engineering professor has gained new insights into how oil stuck in carbonates behaves. Sushanta Mitra has developed technology to map pores in the dense minerals and create a micro-scale replica of it.

Called Reservoir-on-a-Chip (ROC), the new device enables researchers to see, for the first time, how oil is transported through the tiny pores, at a scale too small for the human eye to see.

Until now, researchers have forced water through large core samples of the minerals to “wash” the oil from its pores, in traditional core flooding, said Mitra. Using nanotechnology, Mitra and his research team have etched exact replicas of mineral pores into transparent slides made of silica and quartz so they can see how the oil is flushed from the rock.

“For the first time ever, we can do reservoir flooding experiments on a chip,” said Mitra. “The physical process occurs inside the pores and we said ‘Why don’t we shrink the entire reservoir down to a chip to see how this process takes place?’ This is the first time that a pore network has been etched on silicone and quartz.”

In experiments, the research team fills the ROC microfluidic device with oil, then uses water to displace the oil and then measures the percentage of the oil that was removed from the pores. Using different mixtures and different chip characteristics will produce different results, said Mitra—and that is just what his team intends to examine.

“We can now go in and change the fluids or the surfaces. We can change the surface of the pores so they are hydrophobic or hydrophilic, and we can flood the reservoir with an oil in water emulsion to see how things change.

“It’s the first time anyone has done this—it’s a completely new paradigm.” These findings are now published as a feature article in Lab on a Chip, a high-impact journal from the Royal Society of Chemistry.