Shale gas in the United States is an available source of unconventional natural gas. Led by new applications of hydraulic fracturing technology and horizontal drilling, development of new sources of shale gas has offset declines in production from conventional gas reservoirs, and has led to major increases in reserves of U.S. natural gas. Largely due to shale gas discoveries, estimated reserves of natural gas in the United States in 2008 were 35% higher than in 2006.
In 2007, shale gas fields included the #2 (Barnett/Newark East) and #13 (Antrim) sources of natural gas in the United States in terms of gas volumes produced. The number of unconventional natural gas wells in the U.S. rose from 18,485 in 2004 to 25,145 in 2007 and is expected to continue increasing until about 2040.
The economic success of shale gas in the United States and rapid growth in the amount produced after 2009 has led to rapid development of shale gas in Canada, and, more recently, has spurred interest in shale gas possibilities in Europe, Asia, and Australia. It has been postulated that there may be a 100-year supply of natural gas in the United States, but only 11 years of gas supply is in the form of proven reserves.
Shale gas production
U.S. shale gas production grew rapidly after a long-term effort by the natural gas industry in partnership with the United States Department of Energy to improve drilling and extraction methods while increasing exploration efforts. U.S. shale production was in 2008, an increase of 71% over the previous year. In 2009, US shale gas production grew 54% to , while remaining proven US shale reserves at year-end 2009 increased 76% to .
In its Annual Energy Outlook for 2011, the US Energy Information Administration (EIA) more than doubled its estimate of technically recoverable shale gas reserves in the US, to from , by including data from drilling results in new shale fields, such as the Marcellus, Haynesville, and Eagle Ford shales. In 2012 the EIA lowered its estimates again to 482 tcf. Shale production is projected to increase from 23% of total US gas production in 2010 to 49% by 2035.
The availability of large shale gas reserves in the US has led some to propose natural gas-fired power plants as lower-carbon emission replacements for coal plants, and as backup power sources for wind energy.
In June 2011, The New York Times questioned the impartiality of some of the reports issued by the agency with optimistic projections of the reserves, noting that people involved in the preparation of the reports had investments in the petroleum industry.
The article was criticized by, among others, The New York Times own public editor for lack of balance, in omitting facts and viewpoints favorable to shale gas production and economics. Other critics of the article included bloggers at Forbes and the Council on Foreign Relations. Also in 2011, Diane Rehm had Ian Urbina; Seamus McGraw, writer and author of The End of Country; Tony Ingraffea, a professor of engineering at Cornell; and John Hanger, former secretary of Pennsylvania Department of Environmental Protection; on a radio call-in show about Urbino's articles and the broader subject. The associations representing the natural gas industry, such as America's Natural Gas Alliance, were invited to be on the program but declined.
In June 2011, when Urbina's article appeared in The New York Times, the latest figures for U.S. proved reserves of shale gas were 97.4 trillion cubic feet, as of the end of 2010. Over the next three years 2011 through 2013, shale gas production totaled 28.3 trillion cubic feet, about 29% of the end-of-2010 proved reserves. Contrary to concerns of overstated reserves quoted in his article, both shale gas production and shale gas proved reserves have increased. US shale gas production in June 2011 was 21.6 billion cubic feet per day of dry gas.
Since then, shale gas production has increased, and by March 2015 was 41.1 billion cubic feet per day, almost double the June 2011 rate, and provided 55% of total US dry natural gas production. Despite the rapidly increasing production, companies replaced their proved reserves much faster than production, so that by the end of 2013, companies reported that shale gas proved reserves still in the ground had grown to 159.1 TCF, an increase of 63% over the end of 2010 reserves.
Advances in technology or experience can lead to greater productivity. Drilling for shale gas and light tight oil in the United States became much more efficient from 2007 to 2014. Bakken wells drilled in January 2014 produced 2.4 times as much oil as those drilled five years earlier. In the Marcellus Gas Trend, wells drilled in January 2014 produced more than nine times as much gas per day of drilling rig time as those drilled five years previously, in January 2009.
History
Shale gas was first extracted as a resource in Fredonia, New York, in 1825, in shallow, low-pressure fractures.
The Big Sandy gas field, in naturally fractured Devonian shales, started development in 1915, in Floyd County, Kentucky. By 1976, the field sprawled over thousands of square miles of eastern Kentucky and into southern West Virginia, with five thousand wells in Kentucky alone, producing from the Ohio Shale and the Cleveland Shale, together known locally as the "Brown Shale." Since at least the 1940s, the shale wells had been stimulated by detonating explosives down the hole. In 1965 some operators started hydraulic fracturing the wells, using relatively small fracs: 50,000 pounds of sand and 42,000 gallons of water; the frac jobs generally increased production, especially from lower-yielding wells. The field had an expected ultimate recovery of two trillion cubic feet of gas, but the average per-well recovery was small, and largely depended on the presence of natural fractures.
Other commercial gas production from Devonian-age shales became widespread in the Appalachian, Michigan, and Illinois basins in the 1920s, but production was usually small.
U.S. shale natural gas production rapidly increased after 2008—termed the "shale gas revolution" or "fracking revolution" by energy scholars—leading to a reversal of decades where US natural gas production was falling. During the 2010s and early 2020s, the United States produced so much more natural gas that it moved to being a net exporter.
Federal government impact Federal government policy have had mixed effects on the production of natural gas. Some policies have disincented market-based innovation, while federal research and development expenditures have also advanced gas production techniques and supply alternatives.
Federal price controls on natural gas led to shortages in the 1970s.
Faced with declining natural gas production, the federal government invested in supply alternatives, including the Eastern Gas Shales Project, which lasted from 1976 to 1992, and the annual FERC-approved research budget of the Gas Research Institute, which was funded by a tax on natural gas shipments from 1976 to 2000. The Department of Energy partnered with private gas companies to complete the first successful air-drilled multi-fracture horizontal well in shale in 1986. Microseismic imaging, an important input to both hydraulic fracturing in shale and offshore oil drilling, originated from coalbed research at Sandia National Laboratories.
The Eastern Gas Shales Project concentrated on extending and improving recoveries in known productive shale gas areas, particularly the greater Big Sandy Gas Field of Kentucky and West Virginia. The program applied two technologies that had been developed previously by industry, massive hydraulic fracturing and horizontal drilling, to shale gas formations. In 1976, two engineers for the federally-funded Morgantown Energy Research Center (MERC) patented an early technique for directional drilling in shale.
The federal government also provided tax credits and rules benefiting the industry in the 1980 Energy Act. Gas production from Devonian shales was exempted from federal price controls, and Section 29 tax credits were given for unconventional gas, including shale gas, from 1980 to 2000.
Although the work of the Gas Research Institute and the Eastern Gas Shales Project had increased gas production in the southern Appalachian Basin and the Michigan Basin, in the late 1990s shale gas was still widely seen as marginal to uneconomic without tax credits, and shale gas provided only 1.6% of US gas production in 2000, when the federal tax credits expired. The Eastern Gas Shales Project had tested a wide range of stimulation methods, but the DOE concluded that stimulation alone could not make the eastern gas shales economic. In 1995, the United States Geological Survey noted that future production of gas from the eastern shales would depend on future improvements in technology. However, according to some analysts, the federal programs had planted the seeds of the coming shale gas boom.Alex Trembath,US government and shale gas fracking , Breakthrough Institute, 2 March 2012.
In 1991, Mitchell Energy (now Devon Energy) completed the first horizontal fracture in the Texas Barnett shale, a project subsidized by the Gas Technology Institute, which was funded by a federal tax on gas pipelines. The first Barnett horizontal fracture was an economic failure, as were Mitchell's later experiments with horizontal wells. The Barnett Shale boom became highly successful with vertical wells, and it was not until 2005 that horizontal wells being drilled in the Barnett outnumbered vertical wells. Throughout the 1990s, the Gas Technology Institute partnered with Mitchell Energy in applying a number of other technologies in the Barnett Shale. The then-vice president of Mitchell Energy recalled: "You cannot diminish DOE's involvement."
Barnett Shale Mitchell Energy began producing gas from the Barnett Shale of North Texas in 1981, but the results at first were uneconomic. The company persevered for years in experimenting with new techniques. Mitchell soon abandoned the foam fracture method that was developed by the Eastern Gas Shales Project, in favor of nitrogen gel-water fractures. Mitchell achieved the first highly economic fracture completion of the Barnett Shale in 1998, by using slick-water fracturing. According to the United States Geological Survey: "It was not until development of the Barnett Shale play in the 1990s that a technique suitable for fracturing shales was developed" Although Mitchell experimented with horizontal wells, early results were not successful, and the Barnett Shale boom became highly successful with vertical wells. 2005 was the first year that the majority of new Barnett wells drilled were horizontal; by 2008, 94% of the Barnett wells drilled were horizontal.
Since the success of the Barnett Shale, natural gas from shale has been the fastest growing contributor to total primary energy (TPE) in the United States, and has led many other countries to pursue shale deposits. According to the IEA, the economical extraction of shale gas more than doubles the projected production potential of natural gas, from 125 years to over 250 years.
In 1996, shale gas wells in the United States produced , 1.6% of US gas production; by 2006, production had more than tripled to per year, 5.9% of US gas production. By 2005, there were 14,990 shale gas wells in the US. A record 4,185 shale gas wells were completed in the US in 2007.
In 2005, energy exploration of the Barnett Shale in Texas, resulting from new technology, inspired an economic confidence in the industry as similar operations soon followed across the Southeast, including at Arkansas's Fayetteville Shale and Louisiana's Haynesville Shale.