Bristol Bay, Frontier Basin, Alaska Peninsula: Hydrocarbon Resources, Petroleum Reservoir Characterization, and Source Potential

Rocky R. Reifenstuhl and Emily S. Finzel
Alaska Division of Geological & Geophysical Surveys, Fairbanks, AK

More than 20 wells have been drilled on the Alaska Peninsula; most reported oil and gas shows, but none has produced. A three year collaboration between Alaska Division of Geological & Geophysical Surveys, Division of Oil and Gas, University of Alaska Fairbanks, Bristol Bay Native Corporation, and Alaska Energy Technology Development Laboratory is reassessing this frontier basin. State lease sales are scheduled for 2005.

New outcrop data (2004) addressing hydrocarbon resource estimates encompassing state owned onshore and three-mile-limit waters of Bristol Bay basin and Alaska Peninsula suggest reserves of 300–500 million barrels oil and 3–5 TCF gas. Unconventional gas resource evaluation (coalbed methane) awaits high-pressure gas adsorption.

Federal offshore waters reserve estimates are 230 million barrels of oil and natural gas liquids, and 6.8 TCF gas (mean values: U.S. Minerals Management Service report, Sherwood, 2000).

Oil seeps (½ BOPD, API ~18) from the Jurassic Shelikof Formation. Kamishak Formation (Triassic; shallow-water biohermal limestone) yields TOC to 2.4%; HI of 598 and 474, and OI averaging 21.5. The single Naknek Formation (Jurassic) sample yields 2.2% TOC, and locally includes tens of meters of oil-charged (dead) delta-front sandstone. Porosity and permeability analyses of the Bear Lake Formation, Miocene; to 9,000 feet thick range from 1 to 35% and 0.001 to 1,000 md: samples from both outcrop and North Aleutian COST #1 core (17,155 feet TD; all in Tertiary age rock). Measured sections (1,800 feet) of Bear Lake Formation indicate good reservoir properties, >33 feet of coal, and sand/shale ratio of 50/1.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005