Determination and model prediction of solubilities of CO2 in heavy oil under high pressure

In this work, the heavy oil from some oilfield in East China was investigated. The binary vapor-liquid equilibrium data of CO2 in heavy oil was determined at 363.15, 368.15, and 373.15 K in the pressure range of 2— 22 MPa by a static high pressure apparatus. The heavy oil can be regarded as one pure compound and the critical parameters of the heavy oil were calculated with group contribution method. Then the regression analysis of binary interactive parameters of supercritical carbon dioxide and heavy oil system with Peng-Robinson equation of state (P-R EOS) and the modified Patel-Teja equation of state (P-T EOS) was used to estimate the vapor-liquid equilibrium data under the same condition. It was found that the modified P-T EOS can predict the solubility data better than the P-R EOS. Thus the modified P-T EOS was more suitable for description of gas-liquid equilibrium of CO2 in heavy oil at high temperature and pressure.