Could Alaska coals have generated oil?

Alaska’s Division of Geological and Geophysical Services is working with the U.S. Geological Survey to assess whether coals in some Alaska geologic basins could have generated oil, if buried under the appropriate conditions, according to a note in the DGGS annual report for 2015. Previous investigations using a technique called Rock-Eval pyrolysis have suggested that certain coal samples from the Nenana, Susitna and Holitna basins, if buried deep enough to reach the right level of thermal maturity, might have the potential to generate liquid hydrocarbons, the note says.

The U.S. Geological Survey wants to try further tests using a technique called hydrous pyrolysis on selected coal samples from Alaska. The technique replicates realistic subsurface conditions.

“If liquid hydrocarbons are generated during these experiments, it will prove that some Alaska coals are capable of generating petroleum liquids,” the note says.

DGGS has submitted a small suite of coal samples from the Nenana and Cook Inlet basins to the U.S. Geological Survey for the new tests.

Although coal tends to be associated with the generation of natural gas rather than oil, there are petroleum provinces where coal is known to have acted as an oil source. Doyon Ltd. is currently exploring in the coal-bearing Nenana basin in Alaska’s Interior and has found evidence that the basin could hold undiscovered oil resources.

- ALAN BAILEY