Cook Inlet

Commentary

Prospectivity remains, and the looming gas shortfall in Southcentral Alaska has increased the incentive for new drilling. Federal policy is now supportive, but small field sizes, ageing infrastructure and the state's fiscal decisions remain key variables. Outlook: Neutral.

Updated

October 7, 2026

Location

Description

The Cook Inlet Basin is a northeast-trending collisional forearc basin that stretches from the Gulf of Alaska into South central Alaska, just east of the Matanuska Valley. It is located in the arc-trench gap between the Aleutian trench and the active volcanic arc, above the subduction zone where the Pacific Plate is subducting beneath the North American Plate, and contains roughly 80,000 cubic miles of sedimentary rocks. The basin fill comprises Jurassic and Cretaceous marine strata overlain by several kilometres of predominantly nonmarine Tertiary sandstone, conglomerate, siltstone and coal of the Kenai Group, which hosts the producing oil and gas fields. Organic-rich marine shales and siltstones of the Middle Jurassic Tuxedni Group are the principal source of oil, reaching maturity largely as a result of Paleogene and Neogene burial.

Summary

There has been a significant amount of exploration and development, the USGS postulates that pre-Tertiary unconformity may be significant in exploration for new oil reserves. However, recent price headwinds are creating a feeling of uncertainty for the basin.