Application of Lee-Kesler equation of state to calculating compressibility factors of high pressure condensate gas

Lee-Kesler (LK) Equation of State (EoS) is the most accurate enthalpy model for gases. The pressures at some condensate gas well heads are higher than 70 MPa. Accurate calculating the compressibility factors of the high pressure gas is essential to the enthalpy calculation of LK EoS. The basic parameters of the LK EoS are the reduced pressure and temperature which should be calculated based on mixing rules. This work researches the API, Plocker and Knapp, Lee and Kesler mixing rules, the combinations composed of Prausnitz and Gunn high pressure mixing rule and the above three rules. Comparisons of 11 experimental and calculated compressibility factors show the API mixing rule is the most accurate one when the pressure is lower than 20 MPa. Comparisons of 31 experimental and calculated compressibilityfactors show the API+PG mixing rule combination is the most accurate when the pressure ranges from 24 to 90.5 MPa, and the maximum relative deviation is less than 2%.