Iran's Crude Oil Reserves and Production
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GeoArabia, Vol. 12, No. 2, 2007 Iran’s oil reserves and production Gulf PetroLink, Bahrain Iran’s crude oil reserves and production Moujahed I. Al-Husseini ABSTRACT The Government of Iran estimates the country’s initial-oil-in-place and condensate- in-place are about 600 and 32 billion barrels (Gb), respectively. In 2004, the official estimate of the proved remaining recoverable oil and condensate reserves was about 132.5 Gb, of which crude oil accounted for about 108 Gb. Cumulative crude oil production is expected to cross the 60 Gb mark in 2007, implying that the estimated ultimate recoverable reserves of crude oil are about 168 Gb (cumulative production plus remaining reserves) and the total recovery factor is about 28%. The main Oligocene-Miocene Asmari and Cretaceous Bangestan (Ilam and Sarvak) reservoirs contain about 43% and 25%, respectively, of the total crude oil- in-place. Recovery factors for the Asmari range between about 10–60%, and for the Bangestan between 20–30%. Between 1974 and 2004 remaining recoverable reserves have increased from about 66 to 108 Gb, while the ultimate recoverable reserves have increased from 86 to 168 Gb. In contrast to 1974 when Iran’s production peaked at 6.0 Mb/d, production in 2005 averaged about 4.1 Mb/d. The 1974 peak occurred when production from most of the giant fields was ramped-up to very high but unsustainable levels. Current plans are to increase the crude oil production rate to 4.6 Mb/d by 2009. This is a significant challenge because this production capacity has to offset a reported total annual decline rate of 300–500,000 barrels/day (Kb/d). This high decline rate is attributed to the maturity of the giant fields, many of which attained their peaks in the 1970s and have produced about half or more of their estimated ultimate recoverable reserves. Therefore to achieve the 2009 production target within the next three years, Iran has to add about 680 Kb/d of capacity per year from its developed fields (infill drilling, recompletions, enhanced and improved oil recovery), while also adding net new surface facilities and well capacity from undeveloped fields and reservoirs. INTRODUCTION Iran is a major producer in the Organization of Petroleum Exporting Countries (OPEC) and was one of its founding members when it was formed in 1960. With an average production of about 4.1 million barrels of crude oil per day (Mb/d) in 2005 (Figure 1 and Table 1), Iran supplies approximately 5% of the world’s oil production of 81.1 Mb/d, and 12% of OPEC’s production of 33.8 Mb/d (BP, 2006; quantities include natural gas liquids – NGL and oil from unconventional sources). In mid-2004, the country reported that its proved remaining recoverable crude oil and condensate reserves were about 132.5 billion barrels (Gb) or about 11.3% of the world’s reported proved oil reserves of 1,200 Gb for end-2005 (BP, 2006). The estimated proved remaining crude oil reserves are about 108 Gb, and consist of both primary and secondary reserves (Table 2). At the June 2006 OPEC meeting in Caracas, Venezuela, Iran’s Petroleum Minister, K. Vaziri-Hamaneh, stated that the country planned to raise oil production to 4.6 Mb/d by 2009 (Middle East Economic Survey - MEES, 5 June 2006). It should be recognized, however, that such an increase represents a significant challenge because it has to overcome a production decline rate in the maturing fields of 300–400,000 (Kb/d) according to former Iranian Petroleum Minister, B. Zanganeh (MEES, 1 August 2005), or as much as 500 Kb/d according to the current Petroleum Minister Vaziri-Hamaneh (MEES, 18 September 2006). The production decline rate is not irreversible and is being overcome with infill drilling, recompletions, enhanced and improved oil recovery (e.g. gas injection programs) in many mature fields. Moreover, to achieve this 12% production capacity expansion, Iran is bringing on- stream several undeveloped fields and reservoirs. 69 Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/12/2/69/4570022/husseini.pdf by guest on 24 September 2021 Al-Husseini Iran’s Production History 7 6 80 5 1979 Revolution 60 4 3 40 1951 Revolution 2 Oil price/barrel (2006 US dollars) Production rate (Million barrel/day) World War II 20 1 Masjid-e-Sulayman production started (1913) 1980-1988 Iran-Iraq War 0 0 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2006 Year Figure 1: Iran’s daily production of crude oil from 1913 to end-2006. Also shown is the average price of a barrel of oil in 2006 dollars. Table 1 lists Iran’s estimated crude oil production capacity by field (Figure 2) for: • April 2004 (Arab Petroleum Research Centre – APRC, 2005); • end of 2005 (MEES, 13 February 2006); • end of 2010 and end-2015 (assuming current production rates). The planned production capacity increases are compiled from various sources and assume no delays in completing the projects (MEES, 13 February and 19 June 2006; McDonald, 2006; Petroleum Review, 2006; OPEC website). Production from the undeveloped Azadegan field (260 Kb/d after 2008, McDonald, 2006) and Kushk Hosseinieh field (300 Kb/d after 2008; McDonald, 2006) are shown as completed by 2010. The 100 Kb/d from the Azar field (announced as commercial in 2006, MEES, 19 June 2006) and 300 Kb/d from Yadvaran field (planned for 2012 or later, but may only be 180 Kb/d, Associated Press in Gulf News, 18 February, 2006) are shown in 2015. Also listed in Table 1 are the specific gravities for the oils in API units (as reconciled between various sources including: Beydoun, 1988; Alsharhan and Nairn, 1997; APRC, 2005; MEES, 13 February 2006; McDonald, 2006). This article reviews the crude oil and condensate reserves (Tables 2 and 3) and oil production capacities in the main fields and reservoirs of Iran (Table 1), and the country’s overall production history (Figure 1). It first clarifies the nomenclature and stratigraphy of Iran’s fields (Figures 3 and 4), and then explains the sources of the database (Tables 1 –16). One objective of this article is to provide a quantitative data base of Iran’s reserves and production that illustrates the relationships between initial-oil-in-place (IOIP), estimated ultimate recoverable reserves (EURR), remaining primary and secondary reserves (PRR, SRR), total remaining reserves (TRR), reserves growth, cumulative production (CP), recovery factor (RF), decline rates and production. A second objective is to show the relative importance of the reserves and production from the Asmari reservoir in Iran’s four supergiant fields (Agha Jari, Ahwaz, Gachsaran and Marun; Figure 2). 70 Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/12/2/69/4570022/husseini.pdf by guest on 24 September 2021 Iran’s oil reserves and production Table 1 Iran’s Crude Oil Production by Field for 2004 to 2015. MAIN CRUDE OIL x 1,000 barrels/day RESERVOIRS OF IRAN Field API Apr-04 end-05 2010 2015 Ab-Teymour 43 43 43 43 32.6° The onshore reservoirs in Iran are Abuzar 200 190 220 220 26.0° named after formations and groups in Agha Jari (Aghajari) 190 200 200 200 34.6° which they occur, as shown in Figure 3 Ahwaz-Asmari 800 700 700 700 32.6° (Stöcklin and Setudehnia, 1972; Szabo Ahwaz-Bangestan 160 155 220 220 25.5° and Kheradpir, 1978; NIOC, 1998). The Azadegan 0 0 260 260 Heavy offshore reservoirs are named after Azar 0 0 0 100 NR either Iranian or Arabian formations Bahregansar 65 65 65 65 29.8° (Figure 4). Alsharhan and Nairn (1997) Balal 40 40 40 40 42.0° provide a comprehensive review of Bibi Hakimeh 150 130 130 130 29.9° the petroleum systems covering the Binak 50 50 50 50 29.9° reservoirs, seals, source rocks and oil Cheshmeh Khosh 37 36 80 80 28.0° types. Chillinger 10 10 10 10 36.6° Darquain 0 50 160 160 38.5° Tables 2 and 3 provide an overview of Dehluran 9 9 25 25 35.5° the distribution of oil and condensate Doroud (Darius) 150 130 220 220 34.0° by field and reservoir, indicating Forouzan (Fereidoon) 35 35 100 100 28.5° a total crude oil in-place (IOIP) of Gachsaran 650 560 560 560 31.1° Haft Kel 40 40 40 40 31.1° about 600 Gb and condensate in-place Hendjian 8 8 8 8 23.0° (ICP) of about 32 Gb. The Asmari Karangan 5 0 0 0 NR and Bangestan reservoirs are found Karanj 125 150 150 150 34.4° in many fields and account for about Kilur Karim 10 0 0 0 NR 260 Gb and 150 Gb, respectively, Kupal 55 60 60 60 32.0° representing approximately 43% and Kushk Hosseinieh 0 0 300 300 Heavy 25% of initial-oil-in-place. The main Lab-e-Safid 40 40 40 40 35.3° reservoirs are briefly discussed in the Mansouri 60 50 100 100 27.5° following sections. Marun (Maroun) 570 520 520 520 33.0° Masjid-e-Sulayman 6 4.5 20 20 40.0° Oligocene-Miocene Asmari Nargesi 50 0 0 0 NR Reservoir Neft-e-Safid 25 25 25 25 44.5° Neft-e-Shar 15 0 0 0 43.0° Nowruz 90 90 90 90 21.0° The Asmari Formation contains the Par-e-Siah 2 0 0 0 31.7° most prolific and productive reservoir, Parsi (Paris/Faris) 200 100 150 150 33.9° holding some 43% of IOIP.