Phase Behavior Measurements and Modeling for N2/CO2/Extra Heavy Oil Mixtures at Elevated Temperatures

Abstract

Recently, a new technology, the so-called multithermal fluids huff and puff, to exploit extra heavy oil reservoirs has been applied successfully in several shallow heavy oil reservoirs in China. However, the use of this technology in deep extra heavy oil reservoirs is rare. Successful application of this technique in deep extra heavy oil reservoirs requires a good knowledge of the phase behavior and physical properties of multithermal fluids and extra heavy oil mixture. The major components of multithermal fluids mixtures are steam, N2, and CO2. In this work, targeting the application of multithermal fluids injection in heavy oil reservoirs, we conduct PVT experiments on the N2/CO2/heavy oil mixtures under deep reservoir conditions and develop equation of state models for representing these PVT data. Experimentally, it is found that CO2 solubility in extra heavy oil decreases with an increasing temperature at given pressure. Contrary to CO2, N2 solubility in extra heavy oil increases with an increasing te...