Fluid phase equilibria in asymmetric model systems. Part I: CO2+ diphenylmethane

Asymmetric reservoir fluids with high gas-to-oil ratios and heavy oils could present complex phase behaviors at reservoir or production conditions, as observed in Brazilian Pre-Salt reservoirs. To better understand the phase behaviors of these types of reservoir fluids with high carbon dioxide and methane contents, we initiated a study in our laboratory on the fluid phase equilibria of systems containing supercritical CO2 and/or methane plus a heavy hydrocarbon. In the initial phase of this program, which forms this article, the choice was made to experimentally determine the phase diagram of the binary system: carbon dioxide + diphenylmethane within the temperature range 293.15–378.15 K. In addition, the data were compared with those modeled using a predictive version of the Peng-Robinson equation of state (PPR78).