Abstract
Forecasting of phase behavior and PVT-properties of natural gas is one of the major tasks during the developing and operation of gas and gas condensate fields. Each stage – from an exploration to transportation and storage of gas is followed by continuous changes of thermobaric conditions. This causes changes of thermodynamic properties of gas, one of which is compressibility factor. The comparative study of the existing theoretical methods of compressibility factor determination is given in the presented work: based on the equation of state and empirical correlations. Besides, the alternative approach based on molecular dynamics simulations with the Lennard-Jones potential is offered. The analysis of the received results is carried out on the basis of 165 experimental data for 5 various mixtures of natural gas covering temperatures of 310.9 – 344.4 K and pressure range of 7.074 - 48.443 MPa. The statistical analysis shows that the molecular dynamics method shows the minimum error and is suitable for determination of z-factor of mixtures with methane content more than 90%. For mixtures with the high content of carbon dioxide the Peng-Robinson equation of state with shift-parameter shows the minimum error.
Highlights
Development and operation of gas and gas condensate fields is connected with continuous change of thermobaric parameters, in particular, of temperature and pressure
To compare different approaches we use the experimental values of compressibility factor from Buxton.[40]
Compressibility factor for them was calculated at temperatures of 310.9 K, 327.6 K and 344.3 K and pressure from 7.07 to 48.44 MPa
Summary
Development and operation of gas and gas condensate fields is connected with continuous change of thermobaric parameters, in particular, of temperature and pressure. Prediction of phase behavior of natural gas in such conditions becomes one of the main tasks at all stages: production, operating, transportation and sale of natural gas special attention is paid to determination of PVT properties of natural gas. In the majority of engineering calculations for the analysis of PVT properties and phase behavior of natural gas the compressibility factor is used. The most exact way of its definition is experimental.[1] natural gas production and transport deals with constant changes in composition and properties. In such conditions experimental studies become time consuming and expensive. There are more than 20 empirical correlations c00the most known of which are Papay,[2] Latonov-Gurevich,[3] Beggs and
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