Microfluidics-based measurement of solubility and diffusion coefficient of propane in bitumen

Solubility and diffusivity are essential to the design, implementation, and ultimate success of solvent extraction processes. In this paper, we demonstrate a microfluidic approach to determine both the solubility and diffusivity of propane in the Athabasca bitumen at a range of reservoir-relevant pressures and temperatures (P=6.0-14.7 bar and T=20-50 degrees C). The glass-silicon microfluidic chip contains a PVT microchannel with full temperature and pressure control, connected to both solvent and bitumen supply. The cross-sectional area of the bitumen supply channel was only 2.5% that of the cell, approximating a closed PVT system. One-dimensional oil swelling as a result of solvent diffusion was imaged by fluorescence microscopy and the solvent solubility and diffusion coefficient were then determined through image analysis and established mathematical models. The results achieved are in an agreement with the available published data obtained by conventional methods (i.e., in a range of 2.5-5.1 kg/m(3) for solubility and 10-(10) - 10(-8) m(2)/s for diffusion coefficient for the range of conditions tested). This microfluidic approach offers advantages over the conventional methods including fast quantification, small volume requirement, and ease of operation at high temperatures and pressures. With a 1 nL fluid sample, the microfluidic method presented here requires less than 1 h, which is 150-fold faster than similar to 7 days required for a typical pressure decay test in a 500 mL PVT cell with bitumen.