The authors have presented an argument for the possibility of REFPROP software package application for thermophysical properties control of the liquefied hydrocarbon mixtures depending on the composition including design and measured data of phase states of the hydrocarbon mixtures. The studies were carried out by the example of the Chayandinskiy oil and gas condensate field. The presented results of the phase state of mixtures of an oil and gas condensate field using the example of the Chayandinskiy field allow us to predict the behavior of liquefied hydrocarbons at low temperatures, as well as determine the parameters for further transportation in a single-phase liquid state through low-temperature pipelines. Also the task of thermophysical properties control during transportation of the liquefied hydrocarbon mixtures has been analysed. The composition changing of methane and light hydrocarbon mixture allows one to enlarge the mixture density greatly and to change its other properties at acceptable temperatures and pressures. In the article it is shown that the mixture usage is energetically more efficient than the liquefied gas.