Methane Hydrate Formation and Dissociation on Suspended Gas Bubbles in Water

Understanding gas hydrate formation on gas bubbles evolved from an oil/gas blowout and the stability conditions of the hydrates formed are key to controlling hydrates during a blowout and its containment. In this work, methane hydrate formation and dissociation conditions on suspended gas bubbles in water were studied. For the formation process, methane gas was gradually injected into a counter flowing water column until a full hydrate shell on suspended gas bubbles was observed. The hydrate shells were then dissociated by either depressurization or heating. The minimum methane concentration to form hydrate shells on suspended gas bubbles in water was determined for the pressure range of (7.0 to 17.3) MPa at 277 K. The dissociation pressures of hydrates are also reported for temperatures from (276 to 286) K. It is observed that the hydrate shells on gas bubbles formed and remained stable only when a minimum dissolved concentration (similar to 0.0013 mole fraction) of gas in water was reached. During dissociation, hydrate shells showed a unique morphology, ranging from solid shells, broken shells, plates, and crystals on the surface of the gas bubbles.