Why It Matters
A new U.S. Geological Survey assessment places Alaska North Slope undiscovered conventional natural gas resources at an estimated 96 trillion cubic feet. The estimate adds to known reserves but does not determine whether extracting or transporting the gas would be economical.
What Happened
The USGS released the North Slope-wide assessment Wednesday, marking the agency’s first evaluation of conventional natural gas resources across the entire region. Earlier assessments examined separate portions of the North Slope.
The assessment estimates 96 trillion cubic feet of undiscovered conventional natural gas and 17 billion barrels of undiscovered oil. It also lists 35 trillion cubic feet in known North Slope gas reserves, most of them located within the Greater Prudhoe Bay Unit, which has produced oil since the 1970s.
Alicia Lindauer said the gas estimate is “roughly three times the size of the known gas accumulations on the Alaska North Slope.” William Craddock said the result was broadly consistent with previous views of the region’s petroleum potential.
USGS incorporated updated geological knowledge and technology, along with information from discoveries including Willow and Pikka. ConocoPhillips is developing Willow on the western North Slope, while Santos began production at Pikka this year.
The assessment covers conventional oil and gas. It excludes gas hydrates and coalbed methane and does not evaluate the cost or commercial feasibility of developing the resources.
By the Numbers
96 trillion cubic feet — mean estimate of undiscovered conventional natural gas.
35 trillion cubic feet — known North Slope natural gas reserves.
17 billion barrels — mean estimate of undiscovered North Slope oil.
17.3 trillion cubic feet — low end of the estimated undiscovered gas range.
276.6 trillion cubic feet — high end of the estimated undiscovered gas range.
Nearly three years — estimated duration the undiscovered gas could fuel the nation.
Zoom Out
The assessment divides the North Slope’s subsurface into three broad geologic sequences: the Brookian, Beaufortian and Ellsemerian. The Brookian sequence contains rocks approximately 140 million years old and younger, the Beaufortian sequence covers rocks from about 140 million to 200 million years old, and the Ellsemerian sequence includes rocks as old as about 350 million years.
The Brookian sequence is most relevant to current and future North Slope oil activity. The Sagavanirktok formation supplies oil produced at Prudhoe Bay and other fields, while the Nanushuk and Torok formations underlie newer western North Slope fields.
USGS said the assessment followed its regular process. Department of the Interior leaders said it aligns with President Donald Trump’s policies.
What’s Next
The estimated gas remains stranded alongside the known reserves because the North Slope is hundreds of miles from major markets. Oil has moved through the Trans Alaska Pipeline System since 1977, but proposed North Slope gas pipelines have not been deemed economically viable.
Proposals for an Alaska natural gas pipeline have continued for half a century, including a proposed 800-mile line to a tidewater liquefaction facility. The new assessment provides a resource estimate but does not establish a project, financing plan or construction schedule.