Gas Hydrate Systems: A Statistical and Geospatial Approach Using Industry Well Log Data

Global distribution of natural gas hydrate, a solid composed of CH₄and H₂0, is unconstrained. As a potential contributor to global climate change, it is important to evaluate gas hydrate storage as accurately as possible, however, robust global estimates are difficult given heterogeneities is stability and physical setting. Using a geographic information systems (GIS) framework and statistical analysis, paired with more traditional methods like well log interpretation to study gas hydrate systems, we compare potential gas hydrate volumes in three unique geographical regions with gas hydrate systems.

Instead of scientific ocean drilling data, we use open access petroleum industry well logs from the Barents, Norwegian, and North Seas spread across decades of drilling to determine occurrence and concentration of gas hydrate in marine sediments. Each well was evaluated for gas hydrate occurrence and an estimated saturation using a suite of well log measurements within the gas hydrate stability zone. Initial results show that 10 out of 25 wells in the Barents Sea and 28 out of 60 wells in the Norwegian Sea have potential hydrate accumulations, given resistivity increase above background values.

We apply an analysis of variance (ANOVA) of hydrate saturation percentages, calculated for each well using Archie's equation, and spatially map the distribution of mean saturation using kernel density analysis. These statistical and geospatial analyses are aimed to explore the extent and physical conditions of gas hydrate systems. The results will help determine if gas hydrate systems in the Norwegian continental margin are fundamentally similar in their mean saturation, regardless of location, or if specific factors like bottom water temperature, geologic setting, and lithology influence the likelihood and saturation of hydrates. The differences in hydrate distribution among the geologically diverse environments will be useful for understanding the nature of hydrate systems and the bounds of global hydrate volume.