Measurements and Modeling of the Dissolution and Exsolution Kinetics of the Ethane/n-Heptane System

Abstract

Solvent-aided thermal recovery processes have been suggested and implemented to reduce the environmental impact of steam-based heavy oil and bitumen production. The injected solvents often undergo dissolution (exsolution) into (from) the oil phase throughout the heavy oil and bitumen recovery processes. New experimental data at elevated pressures and temperatures are essential to better understand the dissolution and dissolution kinetics of various solvents. To eliminate this gap, a new experimental setup was developed to study the kinetics of exsolution and dissolution of gases. The developed setup was used to study the exsolution of ethane from ethane-saturated heptane and the dissolution of ethane in heptane in a temperature range of 60 to 120 °C. An analytical model was adapted to model the experiments and estimate the diffusion coefficients of exsolution and dissolution of the ethane/heptane system. The results indicate that the exsolution of ethane from heptane is much faster compared to its dissolution. The molecular diffusion coefficients for exsolution and dissolution were found to be in the range of (2.02–5.44) × 10–6 and (1.76–11.80) × 10–8 m2/s, respectively. The measured experimental data were modeled using the Arrhenius-type kinetics. The results revealed lower activation energy for the exsolution of ethane from ethane-saturated heptane compared to its dissolution. The reported dissolution and exsolution data sets find applications in the design, simulation, and optimization of solvent-aided thermal recovery of bitumen/heavy oil and various chemical processes.