Microfluidic chips used in bitumen gas analysis

Toronto, Canada- A research team at Toronto University has developed a process of analysing the behaviour of bitumen using microfluidic chips.

According to the group, the process could reduce the cost and time of analysing bitumen-gas interaction in heavy oil and bitumen reservoirs.

Dr David Sinton, who works in the Department of Mechanical and Industrial Engineering at Toronto University, has used the chips to examine the way highly pressurised CO2 behaves when injected into bitumen.

“To my knowledge, this is the first application of microfluidics in the study of gas-bitumen diffusion,” said Sinton.

Bitumen and heavy oil are difficult to extract from reservoirs because they are dense. There are several methods of extraction, one of which uses CO2-rich gas injections which helps liquify the bitumen for easier extraction.

This process can supplement the steam-injection method which requires heavy inputs of energy and water, and it presents opportunities for sequestration of CO2 in the reservoir.

However, before companies pump CO2 into reservoirs they need to first determine how the CO2 and oil will behave under specific pressures and in specific rock formations.

Conventional methods of analysis are conducted using around 5L of bitumen and in a process that can take days for a single test result.

Sinton and his colleagues used a small glass microchip to replicate a pore within a rock reservoir. The channels in the pore are 50 microns wide, or about half the diameter of a human hair.

The device is initially filled with CO2 at low pressure and a small sample of bitumen is injected into the centre of the chip. High pressure CO2 is then injected at both ends of the chip and the swelling of the oil is measured over time.

“This takes 10 minutes and uses a nanoliter plug of sample. If you can do a test in a few minutes and perform many tests in parallel, that’s a lot cheaper,” said Sinton. “The experimental setup is also quite simple compared to existing methods.”

Over the next few months, the researchers are planning to study different types of oil or combinations of diffusion gases at one time in one chip.

They also hope to expand the temperature and pressure ranges of tests to match the variety of conditions found in bitumen processing.