The future of energy gases

The natural-gas hydrates of the Messoyakha field in the West sibenan basin of Russia and those of the Prudhoe Bay-Kuparuk River area on the North Slope of Alaska occur within a similar series of interbedded Cretaceous and Tertiary sandstone and siltstone reservoirs. Geochemical analyses of gaseous well-cuttings and production gases suggest that these two hydrate accumulations contain a mixture of thermogenic methane migrated from a deep source and shallow, microbial methane that was either directly converted to gas hydrate or was first concentrated in existing traps and later converted to gas hydrate. Studies of well logs and seismic data have documented a large freegas accumulation trapped stratigraphically downdip of the gas hydrates in the Prudhoe Bay-Kuparuk River area. The presence of a gas-hydratelfree-gas contact in the Prudhoe Bay-Kuparuk River area is analogous to that in the Messoyakha gas-hydratelfree-gas acc'umulation, from which approximately 5 . 1 7 ~ 1 0 ~ cubic meters (183 billion cubic feet) of gas have been produced from the hydrates alone. The apparent geologic similarities between these two accumulations suggest 'that the gas-hydrate-depressurization production method used in the Messoyakha field may have direct application in northern Alaska.