Oil reserves in the United States
Proven oil reserves in the United States were 26.5 billion barrels (4.21×109 m3) as of 2011, excluding the Strategic Petroleum Reserve. The 2011 data represent a 39% increase in proved reserves since 2008. The Energy Information Administration estimates US undiscovered technically recoverable oil resources to be an additional 198 billion barrels.
US proven oil reserves were 26.5 billion barrels (4.21×109 m3) as of 2011. The 2011 data represent a 39% increase in proved reserves since 2008, but is 32% lower than the 39 billion barrels (6.2×109 m3) of proven reserves in 1970, when the supergiant Prudhoe Bay field was found in Alaska.
United States crude oil production had been declining since reaching a smaller secondary production peak in 1988 (caused by Alaskan production). Total production of crude oil from 1970 through 2006 was 102 billion barrels (16.2×109 m3), or roughly five and a half times the decline in proved reserves. Since the oil price peaked about US$147.50 in summer 2008 many projects have been brought online. It takes a few years to develop an oil field. In 2012 the oil production of the USA increased by 800,000 barrels, the highest ever recorded increase in one year since oil drilling began 1859. Oil-bearing shales in North Dakota and Montana are producing increasing amounts of oil. As of April 2013, US crude production was at a more than 20-year high, since the shale gas and tight oil boom; production was near 7.2 million barrels per day. Experts think that the USA could pass Saudi Arabia as the largest oil producer.
The reserves-to-production ratio (R/P) equaled 11.26 years in 2007. The ratio was 11.08 years in 1970. It hit a trough of 8.49 years in 1986 as oil pumped through the Alaska pipeline began to peak.
Consumption and imports
The US consumption of petroleum products peaked in 2005; by 2012, consumption had declined 11% from the peak.
Net imports of oil and products account for nearly half of the US trade deficit. Because of declining production and increasing demand, net US imports of oil and petroleum products increased from 3.16 million barrels per day (502×103 m3/d) in 1970 to 12.04 million barrels per day (1.914×106 m3/d) in 2007, before declining. Its largest net suppliers of petroleum products in 2007 were Canada and Mexico, which supplied 2.2 and 1.3 Mbbl/d (350×103 and 210×103 m3/d), respectively. As of 2011, the US consumed 18.8 million barrels of petroleum products per day, and imported a net 8.4 million barrels per day; the EIA reported the United States "Dependence on Net Petroleum Imports" in 2011 as 45%. During 2008-2009 the USA became a net exporter of refined oil products; before the US bought gasoline, diesel and kerosene in Europe, and smaller amounts from other countries.
Strategic Petroleum Reserve
The United States maintains a Strategic Petroleum Reserve at four sites on the Gulf of Mexico, with a total capacity of 727 million barrels (115.6×106 m3) of crude oil. The maximum total withdrawal capability from the United States Strategic Petroleum Reserve is 4.4 million barrels (700,000 m3) per day. This is roughly 32% of US oil imports, or 75% of imports from OPEC.
Services under the U.S. Department of the Interior estimate the total volume of undiscovered, technically recoverable oil in the United States to be roughly 134 billion barrels (2.13×1010 m3). Over 1 million exploratory and developmental crude oil wells have already been drilled in the US since 1949.
The United States Geological Survey (USGS) estimates undiscovered technically recoverable crude oil onshore in United States to be 48.5 billion barrels (7.71×109 m3)   The last comprehensive National Assessment was completed in 1995. Since 2000 the USGS has been re-assessing basins of the U.S. that are considered to be priorities for oil and gas resources. Since 2000, the USGS has re-assessed 22 priority basins, and has plans to re-assess 10 more basins. These 32 basins represent about 97% of the discovered and undiscovered oil and gas resources of the United States. The three areas considered to hold the most amount of oil are the coastal plain (1002) area of ANWR, the National Petroleum Reserve of Alaska, and the Bakken Formation.
The Minerals Management Service (MMS) estimates the Federal Outer Continental Shelf (OCS) contains between 66.6 and 115.1 billion barrels (10.59×109 and 18.30×109 m3) of undiscovered technically recoverable crude oil, with a mean estimate of 85.9 billion barrels (13.66×109 m3). The Gulf of Mexico OCS ranks first with a mean estimate of 44.9 billion barrels (7.14×109 m3), followed by Alaska OCS with 38.8 billion barrels (6.17×109 m3). At $80/bbl crude prices, the MMS estimates that 70 billion barrels (11×109 m3) are economically recoverable. As of 2008, a total of about 574 million acres (2,320,000 km2) of the OCS are off-limits to leasing and development. The moratoria and presidential withdrawal cover about 85 percent of OCS area offshore the lower 48 states. The MMS estimates that the resources in OCS areas currently off limits to leasing and development total 17.8 billion barrels (2.83×109 m3)(mean estimate).
In 1998, the USGS estimated that the 1002 area of the Arctic National Wildlife Refuge contains a total of between 5.7 and 16.0 billion barrels (2.54×109 m3) of undiscovered, technically recoverable oil, with a mean estimate of 10.4 billion barrels (1.65×109 m3), of which 7.7 billion barrels (1.22×109 m3) falls within the Federal portion of the ANWR 1002 Area. In May 2008 the EIA used this assessment to estimate the potential cumulative production of the 1002 area of ANWR to be a maximum of 4.3 billion barrels (680,000,000 m3) from 2018 to 2030. This estimate is a best case scenario of technically recoverable oil during the area's primary production years if legislation were passed in 2008 to allow drilling.
A 2002 assessment concluded that the National Petroleum Reserve–Alaska contains between 6.7 and 15.0 billion barrels (2.38×109 m3) of oil, with a mean (expected) value of 10.6 billion barrels (1.69×109 m3). The quantity of undiscovered oil beneath Federal lands (excluding State and Native areas) is estimated to range between 5.9 and 13.2 BBO, with a mean value of 9.3 BBO. Most oil accumulations are expected to be of moderate size, on the order of 30 to 250 million barrels (40,000,000 m3) each. Large accumulations like the Prudhoe Bay oil field (whose ultimate recovery is approximately 13 billion barrels (2.1×109 m3)), are not expected to occur. The volumes of undiscovered, technically recoverable oil estimated for NPRA are similar to the volumes estimated for ANWR. However, because of differences in accumulation sizes (the ANWR study area is estimated to contain more accumulations in larger size classes) and differences in assessment area (the NPRA study area is more than 12 times larger than the ANWR study area), economically recoverable resources are different at low oil prices. But at market prices above $40 per barrel, estimates of economically recoverable oil for NPRA are similar to ANWR.
In April 2008, the USGS released a report giving a new resource assessment of the Bakken Formation underlying portions of Montana and North Dakota. The USGS believes that with new horizontal drilling technology there is somewhere between 3.0 and 4.5 billion barrels (480×106 and 720×106 m3) of undiscovered, technically recoverable oil in this 200,000 square miles (520,000 km2) formation that was initially discovered in 1951. If accurate, this reassessment would make it the largest "continuous" oil accumulation (The USGS uses "continuous" to describe accumulations requiring extensive artificial fracturing to allow the oil to flow to the borehole) ever discovered in the U.S. The formation is estimated to contain significantly more - figures in excess of 150 billion barrels (2.4×1010 m3) have been reported - but it is yet uncertain how much of this oil is recoverable using current technology. In 2011, Harold Hamm claimed that the recoverable share may reach 24 billion barrels (3.8×109 m3); this would mean that Bakken contains more extractable petroleum than all other known oil fields in the country, combined.
Unconventional prospective resources
The United States has the largest known deposits of oil shale in the world, according to the Bureau of Land Management and holds an estimated 2.175 trillion barrels (345.8 km3) of potentially recoverable oil. Oil shale does not actually contain oil, but a waxy oil precursor known as kerogen. There is no significant commercial production of oil from oil shale in the United States.
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