(476h) Insights into the Deep-Sea Gas Hydrate Dissociation in the Indian Offshore: An Integrated Study of the Mechanistic, Environmental, and Economic Dynamics

Natural gas, a relatively cleaner burning fuel, is abundantly stored within natural gas hydrate reserves in the proximate Indian offshore. This attributes these reserves as a potentially sustainable energy prospect for developing nations like India which majorly imports natural gas for its needs. This study aims to develop a model based on first principles to comprehend the deep-water hydrate dissociation dynamics and gauge the gas production rates. Building on the analysis, the study further delves into exploring the environmental and economic ramifications through a detailed Life-cycle assessment (LCA) followed by a comprehensive economic analysis. This undertaking exemplifies a unique attempt to develop such multi-dimensional comprehensions aimed at facilitating the commercialization of the process in the future.

In contrast to most studies in the literature that use commercially available simulators, the modelling methodology in this study uses an equation-based approach that integrates conduction-convection coupled with pressure drawdown for the calculation of dissociation parameters. Furthermore, this study considers the geological and hydrological parameters specific to deep-sea Indian reserves, particularly in the Krishna-Godavari Indian basin. The developed model is simulated by applying the finite-difference technique followed by a sensitivity analysis to evaluate the parametric influence of different hydrological and geological parameters. The results indicate a significant gas recovery potential of approximately 51000 m³/day over 20 years with a notable sensitivity towards sediment permeation and conductivity.

Conceptualizing a cradle-to-gate scope, the LCA findings for the gas production through hydrate dissociation indicate that the CO₂ emissions is around 1.01 tonnes per tonne of natural gas. Moreover, replacing current natural gas imports (47%) entirely with gas coming in from hydrate dissociation can potentially reduce around 62.5 % of CO₂ emissions. The contribution of such CO₂ emission savings, considering a 100% replacement, can be a significant 4.2% towards the commitment pledged by the Government of India to reduce the country’s emissions by 1 billion tonnes by the year 2030. Furthermore, this study discusses several economic aspects of the process through scenarios wherein imported natural gas, procured at spot pricing which is vulnerable to geopolitical fluctuations, is replaced with gas from hydrate reserves, result in savings of about 25 USD/MMBTU.