Exploitation of heavy oil by supercritical CO2: Effect analysis of supercritical CO2 on H2O at superheated state in integral joint tubing and annuli.

Abstract: The injection of supercritical CO₂ coupled with superheated steam (SHS) for heavy oil recovery can improve development efficiency. In order to help oil fields to improve the efficiency of CO₂ and SHS utilization we must predict the thermophysical properties at well bottom. Based on the mass, energy, and momentum conservation equations, a non‐isothermal pipe‐flow model is established considering heat exchange between the integral joint tubing (IJT) and annuli. Coupled with the transient thermal conduction model in stratum and the S‐R‐K real gas model, a comprehensive model is established for the mixture flow in concentric dual‐tubing wells (CDTW). The model is solved by a numerical method and an iteration technique. The results show that: (a) the accuracy of the temperature profile calculation has been greatly improved compared with the previous model; (b) the heat‐carrying capacity per unit mass of the mixture and heating efficiency decrease with increasing supercritical CO₂ content; (c) when a temperature difference exists between the IJT and annuli, a rapid flow of thermal energy exists inside the CDTW, which causes a significant temperature change near the wellbore, but the influence of temperature change on pressure profiles is negligible. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]