Summary geologic report for petroleum lease sale #100, Kodiak Shelf, Alaska
No abstract available.
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Research about Kodiak Shelf
Source-linked reports with geographic coverage including Kodiak Shelf.
Geology and geochemistry of gas-charged sediment on Kodiak Shelf, Alaska
Methane concentrations in some sediment cores from the Kodiak Shelf and adjacent continental slope increase with depth by three or four orders of magnitude and exceed the solubility in water at ambient conditions. Acoustic anomalies in seismic-reflection records imply that methane-rich sediment is widespread. Molecular composition of hydrocarbon gases and isotopic composition of methane indicate gas formation by shallow biogenic processes. Stratigraphic positions of acoustic anomalies in Quaternary glacial and posttransgressive sediments suggest that these units are likely sources of gas. A seep along the extension of a fault may be gas venting from a deeper thermogenic source.
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Petroleum geology of Kodiak Shelf, Alaska.
Organic geochemical data show that Cenozoic rocks on Kodiak Island, in Albatross basin, and under the continental slope generally contain less than 0.5 wt. % organic carbon. Moreover, kerogen from all rocks analyzed is predominantly (60 to 100%) herbaceous; woody and coaly kerogens are present in secondary (20 to 40%) amounts. Most strata in shelf basins are thermally immature; however, Eocene and Oligocene strata, which probably floor the shelf basins, are mature on the basis of comparison with coeval strata onshore. Eocene and Oligocene rocks have poor reservoir properties; the best reservoirs are probably in upper Miocene or Pliocene and younger rocks. Potential traps for hydrocarbons include Tugidak uplift, parts of Albatross Bank, structures in the central-shelf upli t, and Portlock anticline. Overall, unless hydrocarbon source rock properties improve offshore, gas and gas condensate are the most likely hydrocarbons to have been generated.
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