Equilibrium Conditions of Methane Hydrates in Seawater From Krishna-Godavari Basin, India

Abstract

Abstract Immense gas hydrate reservoirs have been reported in the Krishna-Godavari Basin, India. They mostly constitute methane gas and could serve as an alternative energy source. For efficient exploitation of methane from hydrates, it is crucial to know the region's stability conditions. The present study reports the stability and equilibrium conditions of methane hydrates, synthesized with seawater obtained from the Krishna-Godavari Basin. At Station MD161/02/GH, the water samples are collected at depths ranging from 500 to 1,500 m. The influence of salinity on methane hydrate formation and dissociation in the presence of seawater is established. The hydrate dissociation patterns in seawater and saline water (4 wt% NaCl) are similar and follow the phase equilibrium around 6 wt% NaCl. The identical dissociation behavior of the two systems ascertains seawater to have ~4 wt% salinity. The salinity concentration varies little with depth because the hydrate dissociation temperatures are the same for all the samples collected at the three depths. Using the Clausius-Clapeyron equation, dissociation enthalpies are calculated. The dissociation enthalpy in saline systems is about 6% higher. The hydrate growth kinetics is marginally faster in the saline system.