North Field, Qatar
North field, also known as the North Dome, located in the Persian Gulf, Qatar, is the world's biggest offshore gas project. The giant gas field covers 6,000km2 in water depths of about 65m and contains estimated recoverable gas reserves of 900 trillion cubic feet (tcf). North field alone accounts for about 13% of the world's total proven gas reserves.
The offshore gas field is jointly owned and operated by RasGas and Qatargas. The North Field is currently operated with 14 liquefied natural gas (LNG) trains with a total production capacity of 77 million tonnes per annum.
RasGas, a consortium owned by QP (70%) and ExxonMobil (30%), operates seven of these production trains. The remaining seven trains are operated by Qatargas, a consortium comprising QP, Total, ExxonMobil, Mitsui, Marubeni, ConocoPhillips, and Royal Dutch Shell. The Barzan gas project scheduled for completion in 2015 is the latest North Field project under construction.
South Pars, Iran
South Pars, the geographical extension of the North Field into Iran's territorial waters in the Persian Gulf, holds 635tcf of estimated recoverable gas reserves, making it the world's second biggest offshore gas project. The Iranian field is expected to produce 27.9 billion cubic feet of gas per day when all its development phases are brought on-stream.
The South Pars gas field is operated by Pars Oil and Gas, a subsidiary of National Iranian Oil Company (NIOC). The offshore gas field Pars, occupying an area of 3,700km2, is being developed in 24 phases, with 11 phases having already been completed.
The 12th phase, designed to produce 500 million cubic feet of gas per day, is scheduled for commercial production in early 2014.
The Shtokman gas and condensate field located about 600km north-east of Murmansk in the Barents Sea, Russia, contains 137tcf of gas and 56 million tons of gas condensate.
Lying in water depths between 320m and 340m, the field was discovered in 1988 and is currently under development in three phases. Shtokman Development, a special-purpose company comprising Gazprom (51%), Total (25%) and Statoil (24%) was created in 2008 to develop the field.
The front-end engineering design (FEED) study and construction of two semi-submersible drilling rigs for the first phase development of the field began work in 2008. However, Gazprom postponed the phase I development in February 2010. Production from the field is now expected only after 2016. The offshore field is expected to produce 2.5tcf of gas a year upon full completion.
Mamba Complex, Mozambique
The 75tcf Mamba Complex located in Area 4 in the Rovuma Basin offshore Mozambique ranks as the world's fourth biggest offshore gas project. The Mamba Complex comprises of Mamba South, Mamba North, Mamba North East and the Coral 1 natural gas fields discovered between 2011 and 2012.
The development of the Mamba offshore gas project is estimated to cost approximately $50bn. The Italian national oil company ENI operates the Mamba Complex and holds 50% working interest in Area 4 of the Rovuma Basin.
The other stake holders of the offshore area include China National Petroleum Corporation (CNPC, 20%), Portugal's Galp Energia (10%), South Korea's Kogas (10%), and Empresa Nacional de Hidrocarbonetos de Mozambique (10%).
Iran's Kish gas project located below the Kish Island in Persian Gulf wit estimated recoverable gas reserves of 66tcf is the world's fifth biggest offshore gas project and the second biggest offshore gas field in Iran after South Pars.
National Iranian Oil Company (NIOC) discovered the gas field in 2006. Petroleum Engineering and Development Company (PEDEC) has been developing the field in three phases since 2012.
The first phase of the Kish gas project is expected to be operational in the first quarter of 2014 and is expected to produce 100 million cubic feet of gas a day. The field is expected to produce three billion cubic feet of gas and 30,000 barrels of gas condensates per day when fully operational.
North Pars, Iran
The North Pars gas field, located 120km south east of Bushehr in water depths of 2m to 30m in the Persian Gulf, Iran, contains recoverable gas reserves of 47.2tcf making it the world's sixth biggest gas project under development.
The offshore gas field was discovered in 1965 and received approval for operation in 1977 after the completion of 17 drilling wells. However, the development was abandoned for a long time due to the Islamic Revolution in 1979.
The field is being freshly developed with a four-phased development plan targeting 3.6 billion cubic feet of gas production per day. A $16bn contract was signed between NIOC and China National Offshore Oil Corporation (CNOOC) in 2007 to build a 20 million tonnes per annum (mtpa) LNG project at North Pars.
East Natuna, Indonesia
With estimated gas reserves of 46tcf, the East Natuna gas field located in the Greater Sarawak Basin in the South China Sea approximately 1,100km north of Indonesia's capital Jakarta, is the seventh biggest offshore gas project under development.
The Indonesian offshore gas field, formerly known as the Natuna D Alpha, was discovered in 1970. Indonesia's state-owned petroleum company Pertamina formed a 50-50 joint venture with Exxon Mobil in 1980 to develop the East Natuna field. However, the development could not progress due to high CO2 content (70%) in the gas.
The project was resumed in December 2010 when Pertamina and ExxonMobil signed a preliminary agreement to co-develop the field. France's Total and Thailand's PTT Exploration and Production (PTTEP) later joined the consortium to develop the field, which is expected to start production in 2020. Peak gas production from the field is estimated to be four million cubic feet per day.
Shah Deniz, Azerbaijan /Greater Gorgon, Australia
The Shah Deniz gas project located 70km south-east of Baku, Azerbaijan, in the Caspian Sea, in water depths between 50m and 500m, and the Greater Gorgon gas field located about 130km off the north-west coast of Western Australia, containing 40tcf of recoverable gas reserves each, rank as the world's eighth biggest offshore gas projects.
The Shah Deniz offshore gas field was discovered in 1999 and is being developed by a joint venture of BP (25.5%), Statoil (25.5%), LUKoil (10%), NIOC (10%), SOCAR (10%), Total (10%), and TPAO (9%). The first stage development of the field, namely Shah Deniz Stage 1, has been operational since 2006.
The Gorgon offshore gas project in Australia is being developed by the Gorgon Joint Venture (GJV) comprised of Australian subsidiaries of Chevron, ExxonMobil, Shell, Osaka Gas, Tokyo Gas and Chubu Electric. The Gorgon and Jansz-Io gas fields are being developed in the initial phase of the project. The start of LNG production from Gorgon is expected in 2014, while the delivery of domestic gas to the mainland is expected to begin before the end of 2015.
Plataforma Deltana, Venezuela / Sakhalin III, Russia
Plataforma Deltana gas project located in the Atlantic Ocean, adjacent to Venezuela's border with Trinidad & Tobago, and the Sakhalin III gas project in Russia comprising three blocks in the Sea of Okhotsk, with estimated recoverable gas reserves of over 38tcf each, rank as the world's ninth biggest offshore gas projects.
Plataforma Deltana offshore area, divided into five blocks, is being developed by Venezuela's national oil company PDVSA in partnership with foreign companies including Total, Statoil, Chevron, and Gazprom. In addition to the 38tcf gas reserves in the Venezuelan portion, the Trinidad and Tobago side of the field is estimated to contain 21tcf of gas reserves but is currently not being developed.
The Sakhalin III offshore gas project being developed by Gazprom includes the Kirinsky, Ayashsky and Vostochno-Odoptinsky blocks. The Kirinsky block, comprising the Kirinskoye, Yuzhno-Kirinskoye and Mynginskoye gas and condensate fields, is being developed on priority. The first gas was produced from the Kirinskoye field in October 2013.
The Troll gas field lying about 65km west of Kollsnes, Norway, in the northern part of the North Sea, with estimated recoverable gas reserves of 36tcf, is the world's tenth biggest offshore gas project. The gas field, comprising two main structures namely Troll East and Troll West, accounts for approximately 40% of the total gas reserves in the Norwegian continental shelf (NCS).
The Troll gas field was discovered 1983 and was initially developed by Norske Shell after receiving approval in December 1986. The gas field was brought on-stream in February 1996 and Statoil took over as the operator of the field from Norske Shell three months later.
A three-phased development approach has been followed for the field. Phase I focused on gas reserves in Troll East, Phase II focused on the oil reserves in Troll West, and Phase III will focus on the development of the gas reserves in Troll West.