Modeling of Gas Hydrate Accumulations at the Alaska North Slope using PetroMod

Elena Pinero

Within the German project SUGAR – Submarine Gas Hydrate Reservoirs, a new tool for the 3-D prediction of gas hydrate accumulations has been developed and included in the commercial petroleum systems modelling software PetroMod. 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 new module calculates the evolution of the gas hydrate stability under marine or permafrost conditions as a function of pressure and temperature over time. PetroMod also includes the kinetics for methane hydrates formation, as well as the permeability reduction due to the decrease of available pore space during gas hydrate accumulation. With the aim of calibrating the new gas-hydrate module and test its validity, we use the available geological model of the Alaska North Slope, originally developed by the USGS and Schlumberger Aachen (formerly IES). The extension of the area with suitable pressure and temperature conditions for the formation of gas hydrates is mainly controlled by the thermal conditions and by the expansion of the permafrost during the last 1.5 Ma. The model predicts specially enriched gas-hydrate accumulations at the Brookian sequence near the main fluid migration pathways, as faults. Gas hydrates are modeled between 450-700 m and 450-920 m at the Mount Elbert and Ignik Sikumi test wells, respectively, which is in good agreement with direct measurements at these wells. Averaged saturations of gas hydrates of up to 13% (of pore volume) are predicted, which is also in good agreement with the available test-well data. During the meeting we will present further details of our model results in comparison to the main data measured on the test wells, as well as regional quantifications including the potential total accumulation of gas hydrates in the Alaska North Slope.

AAPG Search and Discovery Article #90177©3P Arctic, Polar Petroleum Potential Conference & Exhibition, Stavanger, Norway, October 15-18, 2013