Natural gas reserves

This page is about current and future world natural gas reserves. The main question is how much gas will ultimately be produced.


30 Jun 2013.

Total world proved reserves, as of the end of 2012, were 187 trillion cubic meters (TCM; or 6614 trillion cubic feet - Tcf). That would last, at current production rates, 56 years.

The five nations with the largest reserves are Iran (34 TCM), Russia (33 TCM), Qatar (25 TCM), Turkmenistan (18 TCM), and the US (8.5 TCM).

Over the last 20 years or so there has been a revolution in unconventional gas, with the US leading the way. Estimates of technically recoverable resources, over and above reserves, in the US range as high as roughly eight times reserves.

There is little doubt that world reserves will rise substantially. Most of the discussion has been around two new sources. The first is the Arctic, which the USGS estimates may contain about 1700 Tcf of technically recoverable, conventional, undiscovered reserves, with the largest share probably on Russian territory. The second is unconventional – most importantly shale – gas. There is little data to go on so far, but experts are guessing that unconventional sources could raise world reserves by 50-100%.


Clippings below covered through Jun 2010.

Technically recoverable resources (14 Feb 2010) Two topics have dominated the discussion of resources that could add to world reserves in the medium term:

  • Arctic (14 Feb 2010) In Jul 2008 the USGS assessed technically recoverable resources, not including unconventional gas, north of the Arctic Circle. Total TRR were 1,669 Tcf. Over 70% of the possible gas reserves were estimated to be in three regions: West Siberian Basin (Russia) 651 Tcf, East Barents Basins (Russia or Scandinavia) 318 Tcf, Arctic Alaska (US) 221 Tcf.
  • Unconventional gas (14 Jul 2010) Based on a 1997 survey of world hydrocarbon resources, different assumptions suggest that unconventional gas may increase world reserves by 50-100%. This is an area of great current interest and activity, however it will be a some years before we know how unconventional sources will actually impact reserves over the longer term. Environmental opposition is likely to be greater in Europe than in the US, as the US is one of the few countries where individual property owners have mineral rights.

Unconventional gas background (30 Jan 2010) The core definition of unconventional gas (sometimes called continuous) is that the gas is highly dispersed in the rock, rather than in a concentrated bubble over oil or water. The main types of unconventional gas are deposits in shale (“shale gas”), in sandstone (“tight gas”), in coal (“coalbed methane”), or in ice (“gas hydrates”).

Mining of unconventional gas is relatively new. It began with tight gas and coalbed methane in the 1980s and 90s, and has recently expanded into shale. The main enabling technologies are horizontal drilling and hydraulic fracturing, both aimed at connecting a large volume of fractured rock to the well.

Because the area is so new, there remain significant unknowns. The first is that the environmental impact, especially contamination of aquifers, is not well characterized. The second is that the long term productivity of wells, and hence the cost and size of ultimate recovery volumes, is unclear.

Units (14 Aug 2008) Trillions of cubic feet (Tcf) is the most common unit in the US. Trillions of cubic meters (TCM) in the rest of the world. Tcf = TCM * 35.31.

US natural gas reserves (30 Jun 2013) US proved reserves were about 300 trillion cubic feet (Tcf) as of end 2012, according to the BP statistical review of world energy. Gas prices affect this number, but it is fairly solid. Something between 1025 Tcf and 2384 Tcf will probably be added to proved reserves over time.

Technically recoverable resources”, TRR, is the most common concept applied in estimating total remaining gas that exists in addition to proved reserves. There are two fairly comprehensive estimates for US TRR, in addition to proved reserves: 1025 Tcf (2011 estimate, USGS), and 2384 Tcf (2012 estimate, Natural Gas Committee).

Different sources have somewhat differing definitions for TRR, and details are rarely given. The USGS aims to estimate what will be added to proved reserves in 30 years, so probably this is a conservative estimate. It is also rather out of date, so can be taken as a lower bound. The Natural Gas Committee estimate does not include economic considerations, and so is probably high.


Freely available sources include

(The USGS and US EIA are concerned mainly with the US, but note this international summary from the EIA:

Information is for sale, with various abstracts appearing publicly, from the consultancies (e.g. Advanced Resources International and PFC Energy), and from the International Energy Agency.

See also

Below are clippings used in the construction of this page

A frequently cited global assessment of resources

Nov 1997. Annual Review of Energy and the Environment 1997, Vol. 22, p217. Via EBSCO host.


“After a period of large additions to the resource base, price expectations tend to decline. Exploration activities are streamlined and concentrate on the most promising projects. Likewise, exotic technology development is abandoned. In the short run, the net effect is an increase in exploration and production pro- ductivity. This increase will further suppress price expectations, and eventually exploration activity bottoms out. The resource base stagnates and even begins to shrink. Periodical reserve estimates display declining reserves-to-production ratios, which raise future price expectations, and the cycle begins anew. …

Estimates of global conventional and, to a lesser extent, unconventional oil and natural gas occurrences are routinely published by many organizations … The respective industries and institutions tend to report their quantities using quite different terminologies, concepts, and boundaries. As shown above, the same terms may have distinctly different meanings in different organizations. …

[Rogner's classification system:] the commonly reported reserve-to-production ratios are based on Category I-type reserves. … Category II represents occurrences of undiscovered but presumably extant conventional oil and gas resources that have a reasonable probability of being discovered. … In this assessment, Category III reflects the difference between Masters et al’s 5% and 50% probability estimates of undiscovered oil and gas occurrences. … The remaining categories, IV–VIII, add increasing technological and economic uncertainty to decreasing geological assurance.

Category IV reflects the potential for enhanced recovery. …

Categories V–VIII encompass unconventional oil and natural gas. …

Category V contains the identified reserves of unconventional oil and gas. …

Categories VI and VII encompass unconventional oil and gas resource esti- mates; Category VIII contains all remaining conventional and unconventional in situ occurrences including the quantities remaining in situ after commercial production has been abandoned. …

While the undiscovered oil resources are considerably lower than the proved reserves, undiscovered natural gas resources exceed their proved counterpart. … Compared to oil, natural gas is a newcomer on the global energy scene. … The larger undiscovered natural gas volume is the result of the slow but definite process of gas’ liberation from oil.

In summary, the total resource base estimate of conventional natural gas amounts to 394 Gtoe …

Because of the wide availability of conventional natural gas, there has been little commercial interest in the delineation of unconventional natural gas occurrences. Consequently, resource estimates of unconventional gas are very sparse and primarily initiated by academic curiosity rather than by commercial necessity. Funds have been limited and therefore so are the data on unconventional gas occurrences. The data contained in the literature are fraught with geological uncertainty. Moreover, the technology implications for the eventual production of unconventional gas are poorly understood. In summary, the data in the following tables are speculative and should be read as such, particularly the regional distribution estimates, which in many cases are highly speculative. …

Appropriate techniques for the gas extraction from hydrates have not been developed, and it will be technically challenging to engineer methods so that the natural gas gains exceed the energy expenditures. In the foreseeable future, there will be little need for the development of gas hydrates. However, their in-place occurrence, estimated at more than 19,000 Gtoe (37, 38), is remarkable and should be acknowledged. Although these estimates have yet to be confirmed by drilling tests, if only 1% of the estimated volume becomes techno-economically recoverable, this resource volume would be larger than current identified global natural gas reserves. …

Although it is quite speculative, the ratio of the US estimates for natural gas from shale formations to the in-place shale volume was used as a guide to calculate the regional natural gas resource from fractured shale resource potentials. The resource data shown in Table 6 are based on the assumption that the shale oil occurrences outside the United States also contain the US gas value of 17.7 TCF/Gt (tera-cubic feet per gigatonne) of shale in-place.

Table 6. Estimates of unconventional natural gas in place by type, in Gtoe … coalbed methane 232; gas from fractured shales 411; tight formation 189; methane hydrates 18,647; remaining in-situ 117; total 19,595. …

Coal accounts for the majority of fossil reserves (60%), while crude oil and natural gas reserve quantities are practically identical (i.e. 20% of total reserves).”

[1 gigatonne of oil equivalent – the main unit here – is about 1.1 TCM. Considering the very rough estimates involved, one can read this with Gtoe=TCM and not be too far off. This paper is really aimed at resources in place; the brief analysis of what might actually be recovered is quite superficial.]

Australia gas resources about 144 Tcf

1 Apr 2008. Parliament of Australia Research Paper no. 25 2007–08.

“Australia’s natural gas: issues and trends. Mike Roarty”

“As at 1 January 2005, Australia’s Category 1 and 2 reserves[4] totalled just over 4 000 billion cubic metres (bcm) or 144 trillion cubic feet (tcf). (footnote: Category 1 comprises current reserves of those fields which have been declared commercial. It includes both proved and probable reserves. Category 2 comprises estimates of recoverable reserves which have not yet been declared commercially viable; they may be either geologically proved or are awaiting further appraisal.) …

The Greater Gorgon fields located to the south west and west of the NWS—including the massive Jansz field—contains somewhere in the order of 40 tcf, currently representing some 25 per cent of Australia’s total gas resources. …

Whilst Australia has limited reserves of crude oil, it is relatively well endowed with natural gas resources. The most recent assessments indicate Australia has some 144 trillion cubic feet of natural gas”


USGS arctic survey

23 Jul 2008. USGS web site.

“Circum-Arctic Resource Appraisal: Estimates of Undiscovered Oil and Gas North of the Arctic Circle. Kenneth J. Bird, Ronald R. Charpentier, Donald L. Gautier (CARA Project Chief), David W. Houseknecht, Timothy R. Klett, Janet K. Pitman, Thomas E. Moore, Christopher J. Schenk, Marilyn E. Tennyson, and Craig J. Wandrey”

“90 billion barrels of oil, 1,669 trillion cubic feet of natural gas, and 44 billion barrels of natural gas liquids may remain to be found in the Arctic, of which approximately 84 percent is expected to occur in offshore areas. …

This Circum-Arctic Resource Appraisal (CARA) evaluated the petroleum potential of all areas north of the Arctic Circle … The study included only those resources believed to be recoverable using existing technology, but with the important assumptions for offshore areas that the resources would be recoverable even in the presence of permanent sea ice and oceanic water depth. No economic considerations are included in these initial estimates … nonconventional resources, such as coal bed methane, gas hydrate, oil shale, and tar sand, were explicitly excluded from the study. …

The extensive Arctic continental shelves may constitute the geographically largest unexplored prospective area for petroleum remaining on Earth. …

the CARA relied on a probabilistic methodology of geological analysis and analog modeling. … More than 70 percent of the undiscovered natural gas is estimated to occur in three provinces, the West Siberian Basin, the East Barents Basins, and Arctic Alaska.”

Table 1 shows estimated resources by region. For the three just named: West Siberian Basin [Russia] 651 Tcf, East Barents Basins [Scandinavia or Russia] 318 Tcf, Arctic Alaska [US] 221 Tcf.

[Note: a May 2009 article in Science gives comparable results.]

[Note: a separate survey in Oct 2008 estimated US Alaskan gas hydrates. For a map that gives some idea of the likely politics of the East Barents Basin see]

BP statistical review on reserves

Jun 2009. BP website; prominent link on home page.

“Statistical Review of World Energy 2009”

“Notes: Proved reserves of natural gas– Generally taken to be those quantities that geological and engineering information indicates with reasonable certainty can be recovered in the future from known reservoirs under existing economic and operating conditions.”

From table of proved reserves, tn of cubic meters (*35.31 to get tn cubic feet).

Took subset as follows:

  • Top 4: Russia, Iran, Qatar, Turkmenistan
  • US, North America, OECD
  • Australia (re Chevron)
  • World
Region 1988 1998 2007 2008 Reserve/Production
Australia 1.11 1.65 2.41 2.51 (88.6) 65.6
Iran 14.20 24.10 28.13 29.61 (1045.7) > 100
North America 9.51 7.24 8.88 8.87 (313.1) 10.9
OECD 16.57 16.17 16.56 16.83 (587.3) 14.6
Qatar 4.62 10.90 25.46 25.46 (899.3) > 100
Russia n/a 43.51 43.32 43.30 (1529.2) 72.0
Turkmenistan n/a 2.51 2.43 7.94 (280.6) > 100
US 4.76 4.65 6.73 6.73 (237.7) 11.6
World 109.72 148.01 177.05 185.02 (6534.0) 60.4

Annual percent growth in world proved reserves (CAGR when for multiple years)

  • 1988-1998, 3.0%
  • 1998-2008, 2.3%
  • 2007-2008, 4.5%

A graph shows the ratio of world reserves to production for 1984 to 2008. The ratio varied between about 58 and 68 years over that period, with no obvious trend.

Note: comparison of BP and EIA numbers shows that the BP proved reserves do include unconventional.

Unconventional gas a large change in the reserve picture

10 Jun 2009. PFC Energy press release

“Unconventional sources promise rich natural gas harvest”

“Global natural gas resources could be more than quadrupled, helping tackle climate change, if the world adopted US technology and expertise to tap unconventional sources, according to a report by PFC Energy, a consultancy. …

PFC says that global unconventional natural gas resources, based on 1997 geological estimates that could rise with new technologies, total 3,250,000bn cubic feet. … [this must be a typo; see 1997 clipping]

“You're talking about massive new resources,” said Nikos Tsafos, PFC's upstream and gas group senior analyst. “Even if you only got 10 per cent of [the total resources], given the need for economic viability at each formation, you would increase the reserve base globally by 50 per cent.””

WEO 2009

Nov 2009. IEA website.

“World Energy Outlook 2009. Executive summary”

“The world’s remaining resources of natural gas are easily large enough to cover any conceivable rate of increase in demand through to 2030 and well beyond, though the cost of developing new resources is set to rise over the long term. Proven gas reserves at the end of 2008 totalled more than 180 tcm globally — equal to about 60 years of production at current rates. Over half of these reserves are located in just three countries: Russia, Iran and Qatar. Estimated remaining recoverable gas resources are much larger. The long-term global recoverable gas resource base is estimated at more than 850 tcm (including only those categories of resource with currently demonstrated commercial production). Unconventional gas resources — mainly coalbed methane, tight gas (from low-permeability reservoirs) and shale gas — make up about 45% of this total. To date, only 66 tcm of gas has been produced (or flared).”

Advanced Resources estimate of future world shale reserves

12 Dec 2009. Presentation at the United Nations Climate Change Conference in Copenhangen.

“Worldwide Gas Shales and Unconventional Gas: A Status Report. Vello A. Kuuskraa, Scott H. Stevens, ADVANCED RESOURCES INTERNATIONAL, INC.”

“How Big Are World Gas Shale Resources? All currently published resource estimates for world gas shales start with Rogner’s 1997 study (Rogner, H. H., 1997, ”An Assessment of World Hydrocarbon Resources”, Annual Review of Energy and Environment.”):

  • Gas Shale Resource Endowment: 16,110 Tcf (456 Tcm)

The International Energy Agency “World Energy Outlook (2009)” assumed that about 40% of Rogner’s resource endowment would become recoverable:

  • Gas Shale Recoverable Resource: 6,350 Tcf (180 Tcm)

While undoubtedly large, only basin- and play-level (“bottom up”) appraisals of the diverse gas shale basins of the world will build confidence on the size, quality and producibility of this natural gas resource.”

Future of shale gas in Europe quite unclear

8 Mar 2010. FTUSA p19.

“Europe the new frontier in shale gas rush. Carola Hoyos”

“Helge Lund, chief executive of Statoil of Norway, says his geologists evaluated hundreds of basins before focusing on 10 to 15 areas worthy of closer examination.

“It is far too early to conclude whether shale will make as much of an impact outside the US as it has done inside the US,” he says.

Like his competitors, who have secured positions in Austria, France, Sweden, Hungary and Poland, Mr Lund is being secretive about which basins Statoil has identified. …

[Extraction] requires the support of local residents who have to put up with dozens of rigs, kilometres of pipelines and hundreds of heavy trucks rattling down village lanes transporting equipment that will eventually pump thousands of litres of water and chemicals into the ground in an increasingly controversial extraction method known as fracking .

Analysts believe the hurdles that the industry has encountered in the US could prove even more daunting in Europe.

Equipment shortages represent one headache. The US has up to 2,000 onshore gas-drilling rigs operating at any one time, dwarfing the 50 or so that usually operate in Europe. This big discrepancy could prove crucial as shale needs continuous drilling to maintain production flows because each individual well tends to start with a gush and then loses 70 to 90 per cent of its volume within one to two years.

Local opposition to the technique could also prove a show-stopper. In the US, landowners generally do not mind the influx of trucks and workers as they stand to make money from the minerals rights they own. In almost every other country the state owns those rights, increasing the problem of opposition from locals who will feel the downside of such industrial development, but fewer of the benefits. …

Europeans tend to take environmental issues more seriously than their US counterparts.”

BP statistical review 2010

Jun 2010. BP website; prominent link on home page

Took subset as follows:

  • Top 4: Russia, Iran, Qatar, Turkmenistan
  • US, North America, OECD
  • Australia (re Chevron)
  • World

Reserves in TCM (Tcf).

Region 1989 1999 2008 2009 Reserve/Production (years)
Australia 0.96 1.99 3.08 3.08 (108.7) 72.7
Iran 17.00 25.00 29.61 29.61 (1045.7) > 100
North America 9.52 7.32 9.18 9.16 (323.4) 11.3
OECD 15.60 14.26 16.44 16.18 (571.2) 14.4
Qatar 4.62 11.16 25.37 25.37 (895.8) > 100
Russian Federation 42.44 43.30 44.38 (1567.1) 84.1
Turkmenistan 2.59 8.10 8.10 (286.2) > 100
US 4.73 4.74 6.93 6.93 (244.7) 11.7
World 122.40 148.55 185.28 187.49 (6621.2) 62.8

Note OECD fraction of world reserves fell from 13% in 1989 to 9% in 2009.

EIA/ARI global shale gas assessment

5 Apr 2011. EIA-commissioned report by Advanced Resources. or

“World Shale Gas Resources: An Initial Assessment of 14 Regions Outside the United States”

  • The EIA report consists of a 12 page EIA summary followed by the full 353 page report from Advanced Resources
  • The EIA asked Advanced Resources to do a quick and dirty assessment of technically recoverable resources in 48 shale gas basins impinging on 32 countries
  • This is by no means an exhaustive assessment; many basins were left out as having not enough information available
  • The methodology was to compare with similar known formations, first estimating the volume of workable deposits, then estimating recovery volumes
  • Total technically recoverable resources (including the already-estimated 862 tcf for the US) were 6622 tcf (just for the 48 basins, and just for shale gas)

The EIA says, “adding the identified shale gas resources to other gas resources increases total world technically recoverable gas resources by over 40 percent to 22,600 trillion cubic feet.”

European strategy paper on shale gas

6 May 2011. EUCERS.