Abstract: The accurate prediction of the critical condition of gas hydrate formation for effective prevention is difficult. This paper compares and modifies the existing prediction models, mainly considers the equilibrium among the hydrate, gas and rich water phases while forming the gas hydrate, thus the prediction model for the gas hydrate is more reasonable based on the predicted critical condition. The results show that for a certain component of natural gas and pressure, there is a critical point of hydrate formation temperature. Moreover, if gas temperature is lower or the pressure is higher or the relative density is larger, it is much easier to form hydrate. The maximum error between the calculated results and the experiment data is 0.385%, indicating this prediction model is so high in precision that it can provide important theoretical basis for the technical design of gas hydrate prevention used in fields.

Key words: natural gas, hydrate, condition, thermodynamics model, prediction