The Alaska North Slope region includes the National Petroleum Reserve–Alaska, with the bulk of Alaska's known petroleum until the Prudhoe Bay Oil Field was discovered in 1968, followed by the Kuparuk River oil field in 1969. The region also includes the Arctic National Wildlife Refuge, which itself has been the subject of controversy surrounding the possibility of petroleum drilling within its boundaries. The petroleum extracted from the region is transferred south by means of the Trans-Alaska Pipeline System to Valdez on the Pacific Ocean. Under the North Slope is an ancient seabed, which is the source of the oil. Within the North Slope, there is a geological feature called the Barrow Arch – a belt of the kind of rock known to be able to serve as a trap for oil. It runs from the city ofUtqiagvik to a point just west of the ArcticNational Wildlife Refuge. The Arctic Alaska Petroleum Province, encompassing all the lands and adjacent Continental Shelf areas north of the Brooks Range-Herald arch were estimated by the USGS in 2005 to hold more than 50 billion bbl of oil and natural-gas liquids and 227 trillion cubic feet of gas. The source rock for the Prudhoe BayOil Field and neighboring reserves is also a potential source for tight oil and shale gas – possibly containing "up to 2 billion barrels of technically recoverable oil and up to 80 trillion cubic feet of natural gas, according to a 2012 U.S. Geological Survey report." Ira Harkey quotes Noel Wien as stating that in the 1920s, "To keep warm and to cook with, the Eskimo was burning hunks of dark stuff he just picked up on the ground all around his tent. This was oil from seepage under the tundra. The Eskimos had always known about the oil, long before there was any drilling for it."
Alaska North Slope (ANS) crude production
Alaska North Slope is a more expensive waterborne crude. Since 1987, Alaska North Slope crude production has been in decline.
Topography
Within the North Slope, only a surface "active layer" of the tundra thaws each season; most of the soil is permanently frozen year-round. On top of this permafrost, water flows to sea via shallow, braided streams or settles into pools and ponds. Along the bottom of the Landsat 7 image on the right, the rugged terrain of the Brooks Range mountains is snow-covered in places and exposed in others. Much of the region is located in North Slope Borough. On August 12, 2018, a 6.3 magnitude earthquake hit the region, the most powerful recorded for the Alaskan North Slope.
