A GENERALIZED THERMODYNAMIC MODEL FOR PREDICTING THE PHASE BEHAVIOUR OF GAS HYDRATES IN RESERVOIR FLUIDS
Authors: Antonin Chapoy, Hooman Haghighi, Bahman Tohidi, Centre for Gas Hydrate Research, Institute of Petroleum Engineering, Heriot-Watt University, Riccarton, Edinburgh, United Kingdom
Abstract: The formation of hydrates is a substantial hindrance in the production of oil and gas through subsea pipelines. The cost of hydrate prevention is a significant obstacle to development of offshore hydrocarbon resources in deep water. Thus accurate knowledge of hydrate phase equilibrium is crucial to avoid gas hydrate formation problems and to design/optimize production, transportation and processing facilities. Although there is an obvious pressing requirement to study and understand gas hydrates, the existing experimental data are relatively limited for real petroleum reservoir fluids. It is therefore necessary to generate reliable experimental data as well as developing reliable predictive technique for such systems. In practice, thermodynamic inhibitors are widely used to reduce the risks associated with gas hydrate formation. The addition of these additives such as alcohols (methanol, ethanol), glycols and electrolytes causes inhibition of the hydrate formation conditions by altering the state of the liquid phase. In such mixed inhibitor systems, both co-solvents and strong electrolytes are present in the aqueous phase, making the thermodynamic modelling of these highly non-ideal systems challenging.