South Pars/North Dome Gas-Condensate field
The South Pars/North Dome field is a natural-gas condensate field located in the Persian Gulf. It is by far the world's largest natural gas field, with ownership of the field shared between Iran and Qatar. According to the International Energy Agency (IEA), the field holds an estimated  of in-situ natural gas and some  of natural gas condensates. On the list of natural gas fields it has almost as much recoverable reserves as all the other fields combined. It has significant geostrategic influence.

This gas field covers an area of , of which  (South Pars) is in Iranian territorial waters and  (North Dome) is in Qatari territorial waters.

Field geology
The field is  below the seabed at a water depth of , and consists of two independent gas-bearing formations: Kangan (Triassic) and Upper Dalan (Permian). Each formation is divided into two different reservoir layers, separated by impermeable barriers. The field consists of four independent reservoir layers K1, K2, K3, and K4.

The K1 and K3 units are mainly composed of dolomites and anhydrites, while K2 and K4, which constitute major gas reservoirs, comprise limestone and dolomite. A massive anhydrite (the Nar member) separates the K4 from the underlying K5 unit which has poor reservoir qualities. The gross pay zone in the South Pars field is approximately 450 m thick, extending from depths of approximately 2750 to 3200 m. Reservoir strata dip gently to the NE. The average thickness of the reservoir units declines from South Pars (some  ) to North field (). As in other reservoir structures in neighboring areas, the reservoir in the Qatar Arch is cut by a set of NNW-SSE trending faults. Diagenesis has a major effect on reservoir quality of the field.

The field is a part of the N-trending Qatar Arch structural feature that is bounded by the Zagros fold and thrust belt to the north and northeast.

In the field, gas accumulation is mostly limited to the Permian–Triassic stratigraphic units. These units known as the Kangan–Dalan Formations constitute very extensive natural gas reservoirs in the field and Persian Gulf area, which composed of carbonate–evaporite series also known as the Khuff Formation.

Permian–Early Triassic has been divided into Faraghan (Early Permian), Dalan (Late Permian) and Kangan (Early Triassic) Formations.

Reserves

According to International Energy Agency (IEA), the combined structure is the world's largest gas field.

In-place volumes are estimated to be around  gas in place and some  of natural gas condensate in place. With in place volumes equivalent to  of oil (310 billion boe of gas and 50 billion boe of natural gas condensate) the field is the world's biggest conventional hydrocarbon accumulation.

The field recoverable gas reserve is equivalent to some  of oil and it also holds about  of recoverable condensate corresponding of about  of oil equivalent recoverable hydrocarbons.

The gas recovery factor of the field is about 70%, corresponding of about  of total recoverable gas reserves which stands for about 19% of world recoverable gas reserves.

The estimates for the Iranian section are  of natural gas in place and around  of recoverable gas which stands for 36% of Iran's total proven gas reserves and 5.6% of the world's proven gas reserves.

The estimates for the Qatari section are  of recoverable gas which stands for almost 99% of Qatar's total proven gas reserves and 14% of the world's proven gas reserves.

Table 1 - South Pars/North Field gas reserves

Note: 1 km³ = 1,000,000,000 m³ = 1 Billion m³ = 1 Trillion Liters

However, since the field is a common field and the reservoir is highly homogenous, the ultimate recoverable reserves of each country may vary from this technical assessment which only considers the static data and does not include rate of gas migration. So, it is better to say that the ultimate recoverable reserves of each country would be a factor of cumulative gas production by each of them.

The Iranian section also holds  of condensate in place of which some  are believed to be recoverable, while Qatari section believed to contains some  of condensate in place and at least some  of recoverable condensate.

The field is rich in liquids and yields approximately  of condensate per  of gas. It has also very high level of well productivity which in average stands for  per day per well.

Reserve uncertainties
In 2005, Qatar Petroleum became worried the North Dome's reserves were being developed too quickly, which could reduce reservoir pressure and possibly damage its long-term production potential. In early 2005, the government placed a moratorium on additional development projects at the North Dome pending a study of the field's reservoirs. This assessment is not expected to end until after 2009, meaning new projects are unlikely to be signed before 2010. However, this did not affect projects approved or underway before the moratorium.

The 2005 moratorium by Qatar and the subsequent extension of that raised some questions about the actual proven reserves in Qatari side of the field. There was some news in 2006 that ConocoPhillips drilled unexpectedly dry holes in the North Field and this event was at least a partial catalyst for a revamped perspective on the North field structure and potential. Further supporting evidence for skepticism about the real scale of Qatari's reserves came from the 2008 exploration round in Qatar to target exploration of gas in the pre-Khuff formation. Even one of the blocks is exactly located beneath the North Dome Field.

On 29 October 2007, Qatargas CEO Faisal Al Suwaidi stated that the 5-year moratorium on new North Field gas development projects, imposed in 2005, could be extended to 2011 or 2012. The exploration moratorium was lifted by Qatar in April 2017 with the announcement of a new gas project in the southern part of the field.

South Pars development

The South Pars Field was discovered in 1990 by National Iranian Oil Company (NIOC). The Pars Oil and Gas Company, a subsidiary of NIOC, has jurisdiction over all South Pars-related projects. Field development has been delayed by various problems - technical (i.e., high levels of mercaptans and foul-smelling sulfur compounds), contractual issues and, recently, politics.

Gas production started from the field by commissioning phase 2 in December 2002 to produce  of wet gas. Gas is sent to shore via pipeline, and processed at Assaluyeh.

Condensate production from South Pars is currently , and by 2010, could increase to over . As of December 2010, South pars gas field's production capacity stands at  of natural gas per day. Gas production at South Pars rose by nearly 30% between March 2009 and March 2010. The field's reserves are estimated at  of natural gas and  of natural gas condensates. Production at South Pars gas field will rise to  per day in 2012.

NIOC is planning to develop the field in 24 to 30 phases, capable of producing about  to  of natural gas per day. Each standard phase is defined for daily production of  of natural gas,  of condensate, 1500 tonnes of liquefied petroleum gas (LPG) and 200 tonnes of sulfur, however some phases have some different production plans. Each of the phases is estimated to have an average capital spend of around US$1.5 billion, and most will be led by foreign oil firms working in partnership with local companies.

Development of a South Pars phase by the Norwegian Statoil company has become infamous after extensive report of misconduct and bribery to the Horton Investments, an Iranian consultancy firm owned by Mehdi Hashemi Rafsanjani, son of former Iranian President Hashemi Rafsanjani. Statoil committed to spending US$300 million to construct three production platforms and a pipeline. The government of Mr Ahmadinejad, who came to power in 2005, has favoured local firms over foreign companies in the energy and other sectors.

By the beginning of 2008, phases 1, 2, 3, 4 and 5 have been brought to production and by the end of 2008, phases 6, 7, 8, 9 and 10 will be on stream. Phases 12, 15, 16, 17, 18, 19, 27 and 28 are under different development stages.

Project finance

Financing is expected to come from a variety of sources including the Oil Ministry, withdrawals sources will come from a variety of sources including the Oil Ministry, withdrawals from the National Development Fund, the issuance of bonds both domestically and also internationally, and from domestic banks through an energy fund.

The Oil Ministry has called for the issue of more than $12 billion worth of bonds for a period of three years. Three billion euros will be allocated to the South Pars gas field and the rest will go to oil field development projects. As of December 2010, about $30 billion have been invested in South Pars gas fields' development plan. It is estimated that the amount will reach over $40 billion by 2015. The Ministry of Petroleum in Iran said in a revised statement in 2011 that Iran will invest some $90 billion between 2011 and 2015 ($60 billion will be allocated to the upstream sector and the rest to the downstream sector).

Once the eight remaining phases are fully developed by 2014, the facility will produce a total of  of natural gas condensates and 4 million tons of sulfur as well as an annual sum of 4.4 million tons of LPG and 4 million tons of ethane gas. Economic studies show with the operation of each South Pars phase, one percent is added to the country's gross domestic product (GDP), while phase 12 will add more than three percent of GDP.
By 2015, the annual revenue of the field will soar to $100 billion, raising Iran's gas output to  per day.

South Pars phases

As at 2012, some 400 Iranian companies were taking part in the development of the South Pars gas field through supplying equipment to related projects.

Phase 1 was developed by Petropars to produce  per day of natural gas,  of condensate, 1500 tons of LPG per day  plus 200 tons of sulfur per day.
Phases 2 and 3 were developed by a consortium of Total S.A., Petronas and Gazprom to produce  per day of natural gas,  of condensate, 3000 tons of LPG per day plus 400 tons of sulfur per day. It came online in March 2003.
Phases 4 and 5 were developed by Eni and Petropars, to produce  per day of rich natural gas,  per day of ethane,  of condensate, 3000 tons of LPG  per day  plus 400 tons of sulfur per day.
Phases 6, 7 and 8 being developed by Petropars and Statoil to produce lean gas for re-injection into the Aghajari oilfield, and heavy gas and condensate for export. It involves construction of three offshore platforms in addition to the land based facilities. Statoil is developing the offshore platforms while Petropars is developing the land based facilities. A  pipe will be laid from each platform to the coast. These phases will produce  per day of natural gas,  of ethane,  of condensate, 4500 tons of LPG per day plus 600 tons of sulfur per day.
Phases 9 and 10 being developed by a joint venture of GS of South Korea, Oil Industries Engineering and Construction Company (OIEC Group) and Iranian Offshore Engineering and Construction Company (IOEC), in September 2002. The share of Iranian players in this contract exceeds 60%. These phases produce  per day of natural gas,  per day of ethane,  of condensate, 3000 tons of LPG per day plus 400 tons of sulfur per day. Phases 9 & 10 were inaugurated by President Ahmadinejad on March 2009.
Phases 11 will produce LNG through the Pars LNG project. The project was awarded to China National Petroleum Corporation in 2010 after that France's Total S.A. was excluded from the project by Iran. Finally in December 2016, the memorandum of understanding for development of this phase has been awarded to a consortium of Total from France, CNPC from China and Petropars from Iran.
Phases 12 development begin carried out by Petropars as a LNG project. This phase will produce  per day of rich natural gas,  of ethane,  of natural gas condensate, 3000 tons of LPG per day plus 400 tons of sulfur per day. Venezuela’s state-owned oil company Petroleos de Venezuela S.A. (PDVSA) will finance 10% of the $7.8 billion project. Angola’s Sonangol Group has also been awarded a 20% stake in phase 12 project.
Phase 13 and 14 development will be for Persian LNG production. Development was awarded to an Iranian company (Khatam-ol-Osea) for $5 billion. The Iranian Khatam-ol-Osea Consortium is made up of several large Iranian companies, namely Khatam al-Anbia Construction Headquarters, Oil Industries Engineering & Construction (OIEC), SADRA, ISOICO, IDRO, and NIDC. The contract to develop phase 13 was signed with a consortium comprising Mapna, SADRA and Petro Pidar Iranian companies and the phase 14 with another consortia consisting of Industrial Development and Renovation Organization (IDRO), National Iranian Drilling Company (NIDC) and Iranian Offshore Engineering and Construction Company (IOEC). Royal Dutch Shell and Repsol had been originally awarded phases 13 and 14 but were left out of the project by Iran due to their repeated delays.
Phases 15 and 16 development was awarded to Khatam al-Anbia. These phases will produce  per day of natural gas,  of ethane,  of natural gas condensate, 3,000 tons of LPG per day plus 400 tons of sulfur per day. In July 2010, the project was transferred to Iran Shipbuilding & Offshore Industries Complex. At that time, the $2 billion project was already 50% complete. Phase 15 & 16 will be completed by March 2012.
Phases 17 and 18 development was assigned to a consortium of Oil Industries Engineering and Construction Company (OIEC Group), Iran Offshore Engineering and Construction (IOEC) and Industrial Development and Renovation Organization of Iran (IDRO). These phases produce  per day of natural gas,  of ethane,  of natural gas condensate, 3,000 tons of LPG per day plus 400 tons of sulfur per day. Phases 17 & 18 were inaugurated by President Hassan Rouhani on April 2017.
Phase 19 development was awarded to Petropars. These phases will produce  per day of natural gas,  of ethane,  of natural gas condensate, 3,000 tons of LPG per day plus 400 tons of sulfur per day. As it is understood this phase is defined within phase 1 so it can be regarded as some kind of expansion for phase 1.
Phases 20 and 21 development was awarded to OIEC Group.  per day of natural gas,  of ethane,  of natural gas condensate, 3,000 tons of LPG per day plus 400 tons of sulfur per day. Phases 20 & 21 were inaugurated by President Hassan Rouhani on April 2017. 
Phases 22, 23 and 24 were awarded to Khatam al-Anbia, Petro Sina Arian and SADRA and are located in the north-eastern frontier of the field. The aim of phases 22, 23 and 24 development is to produce  per day of natural gas,  of natural gas condensate, and 300 tons of sulfur per day. The three phases also are designed to produce 800,000 tons of LNG and 750,000 tons of ethane per year.
Phases 25 and 26 are in tender.
Phases 27 and 28 development was assigned to Petropars on an EPC scheme. These phases will produce  per day of natural gas,  of ethane,  of natural gas condensate, 3,000 tons of LPG per day plus 400 tons of sulfur per day.

South Pars gas and condensate production plan

Table Sources: NIOC, Pars Oil & Gas Company, Shana and Media

Development delays and criticisms
While several phases of South Pars gas field are still waiting for development and the ongoing development phases are facing delays, NIOC authorities are conducting negotiations for development of other Iranian offshore gas fields like North Pars, Kish, Golshan, Ferdows and Lavan.

Many Iranian energy analysts believe that NIOC authorities should focus on full development of South Pars field prior to conduction of any new project for development of other undeveloped Iranian offshore gas fields.

The priority of South Pars full development is not only due to its shared nature with Qatar, but also with huge capability of the field to add significant liquid production to Iranian liquid export capacity.

On 27 February 2009, one of the members of Iranian Parliaments criticized lack of attention on the importance of acceleration of South Pars field development and the field development delays.

Scale and impacts of delays
By the end of 2008, Qatar's cumulative production from the field was two times higher than Iran's cumulative production from the field. Qatar produced about  of natural gas in the period of 1997 to 2008, while Iran produced about  of natural gas in the period of 2003 to 2008. The 2:1 ratio of Qatar's cumulative gas production from the field to Iran's is forecasted to continue at least for the short term: by the end of 2011, Qatar's total cumulative production from the field will reach  of natural gas, while Iran's will stand at  of natural gas in the same year. The ratio is maintained mainly because Qatar's annual production is almost twice the Iranian production level.

In 2011, Qatar will reach an annual production capacity  of natural gas per year, while in that year Iran's production capacity will reach  per year. If Iran could implement all of its South Pars planned development projects on time, then it would reach the production capacity of  of natural gas per year, not earlier than 2015.

The most important impact of delays and lower production in Iranian side would be migration of gas to the Qatari part and a loss of condensate yield due to decreased field pressure.

North Dome development
The North Dome, also known as North Field, was discovered in 1971, with the completion of Shell's North West Dome-1 well.

With falling oil and associated gas production, and depletion of the Khuff reserves, developing the North field became imperative. In 1984 it was decided that development would occur in phases. Phase 1 involved installing production, processing, and transport facilities for  of natural gas per day to serve local utilities and produce 5,000 tons per day of propane, butane, gasoline, and naphtha. In 1989 a gas sweetening plant and sulfur processing unit were added. Phase one was online by early 1991. Gas from North Field phase one has been primarily used for local demand, and injection into the Dukhan field. Phase two was expected to involve selling North Field gas to its neighbors, possibly through a Gulf Cooperation Council (GCC) gas grid. Phase three involved exporting to Europe and Asia.  Even before the Persian Gulf War, this phase ran into trouble. To justify the investment, Qatar Petroleum (QP) needed two large-scale long-term supply contracts. Despite efforts from QP managing director Jaber al-Marri, contracts were not forthcoming. This switched emphasis to domestic outlets. In 1988, a firm of international consultants presented a plan to QP for developing domestic projects to utilize Qatari gas. Suggestions included an aluminum smelter, a ferro-alloy production plant, methanol production facilities, and expansion of petrochemical and fertilizer operations.

Qatar rapidly expanded its production and exports from North Dome Field. Here are a number of milestones:

 1989: Qatar begins production from North Field phase one (Alpha) at rate of  of natural gas per day.
 1997: Qatar begins exporting by sending  (0.16 million tons) of LNG to Spain.
 2005: Qatar exports a total of  (27.9 million tons) of LNG. Of this,  went to Japan,  to South Korea,  to India,  to Spain, and  to the United States.
 2006: Qatar surpasses Indonesia as the world's largest LNG exporter.
 2007: In March QP solidifies its leading role when RasGas completes its fifth LNG production train, giving the country  of annual liquefaction capacity, the most in the world.

Subsequent phases of the North field development provided feedstock to LNG plants at Ras Laffan Industrial City.

Based on the current Qatar planned projects, production of LNG from North Dome Field may reach to  to  per day by 2012, any further increase in the production level of the Qatari side of the field is subject to the result of the ongoing study by Qatar Petroleum which is supposed to be released in 2012.

The prospects for further growth in Qatari gas production beyond 2012 are clouded by the uncertainty created by a moratorium on new export projects, which was imposed in 2005 while the effect of existing projects on North Field reservoirs was studied.

In order to monetize North Dome's vast resources of gas and liquids, Qatar has undertaken ambitious plans for establishment of the world's biggest LNG and GTL industry.

Qatar's LNG industry
Qatar has two LNG companies called Qatargas and RasGas and both are located in the Ras Laffan Industrial Port on the coast of Persian Gulf.

Since 1997, Qatar has been exporting LNG from the North Field. In 2006, Qatar surpassed Indonesia as the world's largest LNG exporter. Based on the massive gas resources of the field, Qatar is developing the world biggest LNG export facilities in order to reach the capacity of 77 million metric ton per year by 2012 (see table below).

Qatargas and RasGas are the two main companies responsible for Qatar's LNG projects.

Qatar's GTL industry

Oryx GTL (Sasol)

The ORYX GTL plant was commissioned in early 2007, as the first operational GTL plant in Qatar.  The plant nameplate capacity is , however, the plant has faced technical challenges and did not reach full capacity during the first year of operation. Modifications recommended by Sasol assist with overcoming this shortfall and production capacity was reached/ maintained from 2009 onwards. The plant uses  of natural gas from the Al Khaleej Gas project.  The ORYX GTL project uses Sasol's Slurry Phase Distillate (SPD) process.

Pearl GTL (Shell)

The project is under construction and will be the world's largest GTL plant which will have the capacity of  of middle distillates and significant quantities of LPG and condensate. The first of two  GTL trains is planned to start production in 2011. Around  of natural gas will be supplied from the North field to the project. Shell has 100% of the equity in the integrated upstream and plant project.

Table 3. North Field production plan (million cubic feet per day).

Table sources: QatarGas, RasGas, Qatar Petroleum and internet