Phase Behaviour Measurement for High CO2 Content Natural Gas Hydrates

In this work, the effects of highly concentrated carbon dioxide (CO2) on methane hydrate formation are investigated through measurement of phase behaviour. The experimental apparatus, called Hydreval, includes a high temperature sapphire cell (20 MPa) with standard reservoir temperature operational range between –21.15 oC and 248.85 oC, a magnetic driven stirrer and 360o fully visual cell with attached camera for recording purposes. CO2 is a non-organic compound found in abundance within most reservoirs in Malaysia. Due to the high concentration of CO2 content, more accurate experimental data is needed. A generalized isochoric (constant volume) with step-heating process is used for obtaining reliable gas hydrate phase diagrams. The results show that the phase behaviour of high CO2 content natural gas hydrates is alike that of pure CO2 natural gas hydrate. At temperatures between 5-12 oC, the pressure required for hydrate dissociation points increase slowly. However, at high temperatures above 12 oC, the shift becomes more apparent with a significant amount of pressure being required for hydrate dissociation.