A Cubic Equation of State for Reservoir Fluids

In this study we derived a new cubic equation of state with a hard sphere repulsive term proposed by Hajipour and Edalat [18]. The parameters of the new equation are calculated using critical properties and acentric factor. By using the repulsive term in the new equation liquid density of fluids can be accurately predicted. Since parameter alpha is considered to be a linear function of acentric factor this equation of state can simply be applied to heavy hydrocarbons and petroleum fractions. The proposed equation of state predicts vapor pressure of pure components as well as vapor-liquid equilibria properties of fluids within acceptable accuracy. The new equation of state predicts vapor pressure more accurate than other commonly used equations of state such as Guo-Du and Peng-Robinson equations for reservoir fluids. This equation of state predicts liquid density of normal alkanes from C-1 to C-20 in the range T-r = 0.45-0.99 with the mean average absolute deviation of less than 1 %.