Investigation of natural gas behavior in shallower geologic strata: natural analogue of leaked gas in the Mobara gas field, Japan

摘要

To observe a natural analog of geologically sequestered CO_2 leakage to the land surface, geological, geohydrological, and geochemical surveys have been conducted on gas seepage from the Pleistocene sedimentary rocks in the Sugaya area in the Mobara gas field, East Japan. In the resulting model, gas that separated from groundwater in the shallow part was stored by a fault trap and seal layer and then leaked via inclined sandstone layers, open cracks near the surface, and dragged sandstone in the fault damage zones.