Analysis of Near Surface Hydrocarbon Distribution Pattern Around the Eileen Fault zone, Alaska North Slope

Methane hydrate (a crystalline solid in which water molecules form an ice-like framework that trap gas molecules) is an attractive energy resource because of its high energy density as compared to other naturally occurring forms of methane, and its relatively close proximity to the Earth's surface and seafloor. Methane hydrate distribution on the Alaska North Slope (ANS) Prudhoe Bay region is thought to be controlled by the availability of migrated thermogenic methane gas from depth. The Eileen Fault Zone coincides with a known region of shallow (less than 1000m) gas hydrates, indicating possible control of the gas hydrates by the Eileen faults. Should the faults be controlling the migration of hydrocarbons from depth, one would expect higher concentrations of hydrocarbons in the proximity of the Eileen Fault zone. Geochemical concentrations of hydrocarbons, taken from shallow surface (3m depth) soil samples around the Eileen Fault zone, is evidence for such migration and indicate target for further gas hydrate research and development in the area. Initial results by the USGS revealed correlations between high concentrations of helium, methane, pentane and hexane. This study uses an Inverse Distance Weighted (IDW) technique to display interpolated surfaces between transect sample points of the same hexane, pentane, methane and helium concentrations. Buffers are also placed around the fault zone in order to show possible migration zones around the Eileen should the fault dip at 10 degrees or 30 degrees. Initial results show hexane and pentane display zones of high concentrations within the buffered zones. Helium and methane display several zones of high concentration outside the buffered areas. The significance of these results further supports the hypothesis that the Eileen Fault is a migration path way with several zones of seepage for hydrocarbons at depth. The anomalous concentration zones falling within the buffered zones are an indication of this seepage.