Mechanical experiments and constitutive model of natural gas hydrate reservoirs

Dynamic behavior of hydrate dissociation for gas production via depressurization and its influencing factors

Mechanical properties of remolded hydrate-bearing clayey-silty sediments

Effects of methane-carbon dioxide replacement on the mechanical properties of natural gas hydrate reservoirs

Experimental study of natural gas hydrate dissociation can provide a theoretical basis and technical reserves for future hydrate exploitation. Hydrate dissociation includes the thermodynamic and dynamic processes. Once thermodynamic conditions of the dissociation are satisfied, the dynamics plays a significant role for hydrate dissociation. Here, we establish and describe the techniques and methods for hydrate dissociation research from both the macroscopic and microscopic views. Macroscopic dissociation experiments mainly focus on the reaction devices, detection methods, and technical approach, including methane hydrate and different natural gas hydrates dissociation in vacuum. Microscopic dissociation experiment introduces an experimental technique to observe the microprocess of THF hydrate dissociation in situ using nuclear magnetic resonance imaging, intending to investigate the micro-mechanism of hydrate dissociation.

Natural Gas Hydrate Dissociation

The formation and dissociation of methane hydrate in subsea sediments were experimentally studied in porous media under simulated hydrate stability zone conditions for subsea hydrate resources.The changes of pressure,temperature and gas-production rate during hydrate dissociation were investigated under various conditions of hydrate formation and dissociation.The driving force(drawdown pressure) for hydrate dissociation was studied using a step depressurization procedure.The cumulative gas production rates under different depressurization modes were compared to reveal the mechanism of gas production in hydrate-bearing sediments.The experimental results show that the dissociation rate of hydrate mainly depends on the pressure drop.High pressure-drop can result in high dissociation rate and gas recovery.A minimum driving force is required for hydrate dissociation under certain temperatures.The cumulative gas production rate is related with the total pressure drop,but not affected by the depressurization modes.

YU Hongmin

Papers

Experimental study on formation and dissociation of methane hydrate in porous media