Abstract Beaufortian strata (Jurassic - earliest Cretaceous) in NPRA have become a focus of exploration since the 1994 discovery of the nearby Alpine oil field. Interpretation of sequence stratigraphy and depositional facies from a regional 2-D seismic grid and well data has resulted in the definition of four major depositional sequences that each display unique stratal geometries and thickness trends across NPRA. Sequence K1 (Lower-Middle Jurassic) accumulated in a depocenter in northcenteral NPRA. Constituent depositional sequences include lowstand (LST), transgressive (TST), and highstand (HST) systems tracts. Sequence K2 (Oxfordian-Kimmeridgian) is a composite of higher-order depositional sequences that each reflects a forced regression, which caused widespread erosion across northcentral NPRA and accumulation of the derived sediment at the shelf margin in lowstand systems tracts. Subsequent flooding of the shelf resulted in deposition of transgressive systems tracts that commonly include well-winnowed, upper shoreface sandstones capped by a condensed section of fissile shale, forming good stratigraphic trapping potential. Sequence K3 (Valanginian) displays relatively distal facies character, suggesting high relative sea level during most of the depositional history. An important exception is the presence of a transgressive systems tract at the base of K3 that contains winnowed, shoreface sandstones. Sequence K4 (Hauterivian) is a shelf-margin wedge that developed as the result of tectonic uplift along the Barrow Arch. It comprises lowstand and transgressive systems tracts that display stratal geometries suggesting dynamic incision and synsedimentary collapse of the shelf margin. Cores of Beaufortian strata from NPRA exploration wells display a variety of key stratigraphic surfaces and depositional facies. When integrated with the regional grid of public domain seismic data, these provide a unique opportunity for interpreting the sequence stratigraphy and depositional systems oil-prospective strata in a frontier province.

Abstract Alaska, the least explored of all United States regions, is estimated to contain approximately 40% of total U.S. undiscovered, technically recoverable oil and natural-gas resources, based on the most recent U.S. Department of the Interior (U.S. Geological Survey and Minerals Management Service) estimates. Northern Alaska, including the North Slope and adjacent Beaufort and Chukchi continental shelves, holds the lion’s share of the total Alaskan endowment of more than 30 billion barrels (4.8 billion m 3 ) of oil and natural-gas liquids plus nearly 200 trillion cubic feet (5.7 trillion m 3 ) of natural gas. This geologically complex region includes prospective strata within passive-margin, rift, and foreland-basin sequences. Multiple source-rock zones have charged several regionally extensive petroleum systems. Extensional and compressional structures provide ample structural objectives. In addition, recent emphasis on stratigraphic traps has demonstrated significant resource potential in shelf and turbidite systems in Jurassic to Tertiary strata. Despite robust potential, northern Alaska remains a risky exploration frontier—a nexus of geologic complexity, harsh economic conditions, and volatile policy issues. Its role as a major petroleum province in this century will depend on continued technological innovations, not only in exploration and drilling operations, but also in development of huge, currently unmarketable natural-gas resources. Ultimately, policy decisions will determine whether exploration of arctic Alaska will proceed.

Abstract The NPRA is a significant part of the north Alaskan petroleum province, a lightly explored region that is estimated to hold more than one-third of total U.S. undiscovered, technically recoverable, oil and natural gas resources based on the most recent U.S. Department of the Interior (USGS & MMS) estimates ( Bird, 1999 ). The NPRA is a geologically complex region that includes prospective strata within passive margin, rift, and foreland basin sequences. Multiple source rock horizons have charged several regionally extensive petroleum systems. A variety of plays are present involving extensional and compressional structures and stratigraphic traps in shelf and turbidite systems.