Experimental investigation on the phase behaviour for gas hydrates in CO2 rich gas mixtures & multiphase system

Abstract

Almost 40% of undiscovered hydrocarbon reserves have high CO2 and H2S concentrations around the globe. So it is crucial to understand these hydrocarbon systems’ thermophysical properties for the excellent design of production facilities. An experimental investigation is conducted in this study to understand and evaluate the thermodynamic conditions of gas hydrate formation in natural gas systems with high CO2 levels gas and dominant multiphase (high CO2 level gases, deionized water, and crude oil). Three gas mixtures were chosen in this study to simulate natural gas with high CO2 content. The experiments are conducted within the critical pressure of the selected gas to avoid any phase change due to pressure. The impact of high CO2 levels in gas systems on the thermodynamic conditions of the gas hydrates was first explored. Then, the effect of a multiphase system was investigated after the addition of the oil phase into the system. The thermodynamic equilibrium conditions obtained from experiments were used to construct the Hydrate liquid–vapour Equilibrium (HLVE) curves, and the phase behaviour was studied. The details about the temperature variance and enthalpy are also clearly discussed. It has been discovered that gas mixtures with a higher CO2 content tend to promote compared to the pure methane gas system but inhibit compared the pure CO2 system. But in the multiphase system, all the gases show an inhibition effect compared to their respective pure gas system results.

Keywords

• Thermodynamic conditions
• CO2
• Phase behaviour
• Gas hydrate
• Multiphase pipelines