Methane hydrates will be exposed to CO₂ to gain natural gas (methane) and to store CO₂ in hydrates. Gas swapping in hydrates is possible since CO₂ hydrates are thermodynamically more stable than methane hydrates under the pressure and temperature conditions prevailing below the seafloor.

Gas swapping in hydrates is, however, a slow reaction. The water cages enclosing the methane molecules need to be stimulated or destabilized by the addition of heat or chemicals to enhance the velocity of this gas exchange reaction. 

Project B2 will, thus, test various approaches on the laboratory scale in order to:

• Accelerate the conversion of methane hydrates into CO₂ hydrates
• Enhance the rate of natural gas production from hydrates
• facilitate the storage of CO₂ in hydrates. 

Methods

In a first step, methane hydrates will be produced in sand matrix. Subsequently, they will be exposed to CO₂, heat and various chemicals to gain methane gas, to form CO₂ hydrates and to accelerate the gas swapping in hydrates. The kinetics of gas swapping will be studied under controlled conditions (50 – 400 bar, 0 – 50°C) applying various detection methods (gas sensors, gas chromatography, Raman spectroscopy, solid state 13C-NMR spectroscopy, etc.). The following reagents and reactions will be studied experimentally:

• Methane hydrates + liquid CO₂
• Methane hydrates + liquid CO₂ + heat
• Methane hydrates + supercritical CO₂
• Methane hydrates + liquid CO₂ + additional gases (N2, Ar, …)
• Methane hydrates + liquid CO₂ + polymers

The heat will be provided by partial burning of methane or by the injection of warm surface waters using a mega pump approach.