Rapid Microfluidics-Based Measurement of CO2 Diffusivity in Bitumen

In this paper, we demonstrate the first application of microfluidics to study diffusive transport in extra heavy oils, such as bitumen. A cross-channel glass microfluidic chip was used to measure the CO 2 diffusion in Athabasca bitumen. The device was initially filled with CO 2 at low pressure (<1.0 bar). A plug of bitumen was injected into the central (50 μm wide and 20 μm deep) channel and, subsequently, exposed to high-pressure CO 2 on both ends. One-dimensional oil swelling in response to CO 2 diffusion was imaged over time. A simple mathematical approach was applied to calculate the diffusion coefficient based on the oil-swelling data. Measurement results are reported here at a range of pressures (1–5 MPa) and room temperature (21 °C). The measured diffusion coefficients in this range are on the order of 10 –10 m 2 /s, in good agreement with the relevant published data using conventional methods. In sharp contrast to conventional methods that require hours or days and ∼0.5 L of sample, the method presented here requires ∼10 min and a 1 nL plug of sample.