Impact of extremely low porosity on geothermal gradient and fluid migration in gas hydrate-bearing layers: A case study of South Shetland Islands, Antarctic Peninsula

Abstract

Numerical fluid flow models were employed for the first time to study gas hydrates in South Shetland Islands, Antarctic Peninsula. The complexity of its geology, added to the remote and environmentally sensitive characteristics, makes it a very unique natural laboratory, where studying processes that could influence gas hydrate stabilityremains highly challenging. Based on seismic data, a marine subsurface model was created and fluid flow simulations carried out with ANSYS Fluent. Key inputs like sediment thickness, in-situ faults, and fractures, and water column dimensions were obtained from seismic sections. The same value of thermal and physical rock properties was assumed for each geological unit; the mesh structure was developed using triangular discretization. Four numerical models were constructed to investigate how variations in porosity, particularly under extremely low-porosity conditions, might affect thermal and fluid flow behavior within hydrate-bearing sediments. Porosity values of 0.01, 0.05, 0.1, and 0.2 were systematically applied to represent the low-porosity regimes. The results highlight that, especially at extremely low porosity, porosity together with fault density and seafloor bathymetry can strongly shape the distribution of heat transfer and fluid migration patterns. While the models do not directly simulate gas hydrate dissolution, the findings suggest that localized thermal anomalies and structural complexities could potentially create conditions favorable to destabilization processes. These insights contribute to a better understanding of the geophysical and hydrodynamic factors that may influence gas hydrate systems in complex and sensitive geological settings.