Gas Hydrate Occurrence and Saturation in the Barents and Norwegian Sea Using Industry Well Logs and Seismic Data

Identifying and quantifying gas hydrate systems remotely not only improves understanding of global distribution and architecture, but also allows us to estimate the influence of gas hydrate on past and current climate change. Herein, we incorporate 125 petroleum industry well logs into extensive seismic dataset from the Barents and Norwegian Sea to strengthen hydrate identification and support calculations of gas hydrate saturation. The Barents Sea has unique geologic morphology distinguished by recent ( 2.7 m.y.) proglacial erosion which has enhanced hydrocarbon migration from deeper reservoirs. A regional erosional unconformity indicates the base of glacigenic sediments, which may host gas hydrates. The Norwegian Sea, a warmer and deeper sea than the Barents, also displays favorable hydrate conditions. Previous seismic studies in both areas have suggested gas hydrate, as shown by the presence of both bottom simulating reflections and free gas accumulations in the upper sediment cover. Gas vents and chimney features are observed on water column and seismic data in both areas, indicating significant fluid advection and a possible thermogenic source for gas hydrates.

We obtained the industry well logs, core and drilling reports through the open access database maintained by the Norwegian Petroleum Directorate. Gas hydrate stability is calculated using bottom water temperature, geothermal gradients, and gas composition where possible. In order to remain within the gas hydrate stability zone, we limited the wells to those drilled with a water depth of at least 350 meters. We systematically evaluate each of these wells for gas hydrate occurrence and estimate saturation using the caliper, gamma ray, porosity, compressional velocity, and resistivity well log measurements within the gas hydrate stability zone. Where possible, we tie in 2D and 3D seismic data available through the Centre for Arctic Gas Hydrate Environment and Climate (CAGE, The Arctic University of Norway) and provide a spatial interpretation of gas hydrate distribution. Utilizing both well logs and seismic data allows for the integration of regional and local datasets, thus broadening and refining our understanding of gas hydrate systems.