Methane Recovery from Hydrate-Bearing Sediments and Simultaneous Carbon Dioxide Sequestration through a Localized Heat Transfer Process

Global demand for natural gas is rising as it plays a crucial role in the energy transition. Unlocking the vast, untapped reserves of natural gas hydrates could revolutionize the global energy supply. Conventional gas production methods alone would not be a sustainable approach for natural gas extraction from hydrate reservoirs. Therefore, this work focuses on a new hybrid approach, wherein one can extract natural gas by destabilizing the existing natural gas hydrates and simultaneously sequestrating carbon dioxide (CO2) in the form of solid hydrates. In this direction, we design a new reactor facility that aims to mimic the hydrate reservoir and offer the localized heat transfer required for methane hydrate dissociation, while simultaneously stabilizing the CO2 hydrates. Natural subsea sediments and seawater collected from the Arabian Sea are used to form methane hydrate at ∼65 bar pressure and ∼1.5 °C temperature. CO2 was injected into the methane hydrate-bearing sediment at ∼30 bar after releasing gaseous CH4 from the reactor. An in-house-produced biosurfactant, rhamnolipid, is used to promote the CH4 hydrate formation and CH4–CO2 replacement kinetics. Additionally, its performance is compared with commercially available hydrate promoters, sodium dodecyl sulfate surfactant, and L-tryptophan amino acid. CH4 recovery from hydrate-bearing sediments is measured at the sediment temperature range of 2–6 °C (the corresponding heating probe temperature range is 5–10 °C) while using a gas chromatography analysis of the gas phase at different time intervals. Our results showed significant CH4 recovery (40–45%) at a sediment temperature ranging between 2 and 3 °C. However, an anomalous behavior of L-tryptophan (TP) was revealed with a substantial reduction in CH4 recovery.