Imaging CO₂ hydrates under simulated seafloor conditions at macro and micro scale

Sequestering CO₂ in natural gas hydrate deposits through CH₄/CO₂ exchange is of global interest. The stability of CO₂ hydrates was examined at 3.2 MPa and between -1° to +2°C in the FISH unit. In a typical experiment, CO₂ was bubbled into 75 mL distilled water containing 300 ppm of dissolved sodium dodecyl sulfate (SDS) at 450 psig. The vessel cooling was initiated and cell pressure/temperature (P/T) values were visually monitored till the system equilibrated. The CO₂ hydrates accumulated in the aqueous phase, and the gas/liquid interface persisted throughout the formation event. Quantitative data were collected for hydrate formation time and P/T stability of formed hydrates. The data are being analyzed to design further runs and to establish key parameters that may allow for preferential release of CH₄ from natural hydrates through simple exchange with added CO₂.