We have employed Monte Carlo simulation in the NPT ensemble to determine th
e molar volume and the compressibility factor of naturally occurring hydroc
arbon gas mixtures, The simulation results were compared to experimental da
ta as well as to predictions based on both the Peng-Robinson and AGA 8 equa
tions of state. The mean error of the simulation results was roughly of the
same order as those of the equation of state values. For pressures higher
than the retrograde dew point pressure, systematic deviations were found es
pecially if the gases contained a high proportion of heavy components. The
quality of the simulation results increased with rising temperature. In the
region of retrograde condensation, we used the Gibbs ensemble technique to
determine the molar volume as well as the composition of the phases. Both
were in agreement with the results of flash calculations combined with the
Peng-Robinson equation of state. At pressures far from the retrograde dew p
oint pressure, the simulation results followed the experimental liquid drop
out curve. (C) 1999 Elsevier Science B.V. All rights reserved.