3-D Numerical Modelling of Gas Hydrate Accumulations at the Alaska North Slope

The petroleum systems modelling software PetroMod has been extended by a new module simulating the basin-wide accumulation of methane hydrates under marine and permafrost conditions. This new feature includes kinetics for the production of methane by microbial degradation of organic matter at low temperatures and predicts the evolution of the thermodynamic stability zone of gas hydrates through geologic time. In combination with the proven capabilities for calculating oil and gas generation and flow paths for their migration based on the input geological information, PetroMod is now also able to predict the formation of gas hydrate reservoirs.The 3-D geological model of the Alaska North Slope developed by the USGS and Schlumberger is used to test the new PetroMod gas hydrate module. Model results are compared to published well-log and geochemical data from drill sites at Mt. Elbert and the Ignik Sikumi field test site, which are part of the Eileen gas hydrate accumulation. The simulations indicate that today’s gas hydrate accumulations started to form ~0.5 Ma ago with highest amounts near the major faults. The predicted extent and thickness of the gas hydrate stability zone matches well with the observations from the 148 wells in the area.