Класс Месторождения: Уникальное
Тип Месторождения: Нефтегазоконденсатное
Местоположение:
Местность:
Стадия разработки: Добыча
Год открытия: 1992
Источник информации:
Метод открытия:
Площадь: 2307.78 км²
South Pars field
South Pars (Fig. 1) is the Iranian part of the world’s largest nonassociated gas field (Aali et al., 2006). The Kazhdumi Formation lies above this gas accumulation and is not directly associated with it, but small quantities of oil have been discovered above and below the Kazhdumi Formation.
Fig. 1. Location of the South Pars field and the wells studied.
Geographical location
The South Pars field is located in the Persian Gulf at the border between Iran and Qatar, and is 100 km from the port of Asaluyeh on the southern coast of Iran, 105 km northeast of Qatar, and 330 km northwest of Dubai (Fig. 1). The Qatari part of the field (North Field) was discovered in 1971 (Konert et al., 2001) whereas the Iranian sector was detected only in 1990 with the drilling of well SP-1. This giant field has an estimated 3700 km2 extent and is located between 51050/ and 52040/ E, and between 26025/ and 2705/ N. The wells studied are SPO-2, SPO-3, SP-2, SP-6 and SP-10, and their positions are shown on Fig. 1B and C.
Geology
The South Pars–North Field petroleum field is the result of positive regional epeirogenic movements of the Qatar Arch (Fig. 1B). This uplifted arch has divided the Persian Gulf into two distinct sedimentary basins, one to the northwest and the other to the southeast, each with its own sedimentary regimes and styles of hydrocarbon reservoirs (Sharland et al., 2001; Aali et al., 2006).
Although various structural and geological factors have affected the shape and position of this region, the north–south trend of the Qatar Arch is accepted as being the most important factor in forming the South Pars–North Field structure. This geological structure has formed suitable packages of lithostratigraphic units containing source rocks, reservoirs of late Permian and early Triassic age, and cap rocks (Aali et al., 2006).
The Kazhdumi Formation lies above the main gas and condensate reservoirs at South Pars. This and its equivalents represent an influx of clastics during the Albian following emergence and erosion of shallow-water Aptian carbonates. At this time, alluvial plains covered most of Saudi Arabia, Kuwait and Iraq west of the Euphrates river, with deltas prograding to the east, beyond which were shallow-marine waters of the Fars Platform, or deeper anoxic waters of the Dezful Embayment (which corresponds approximately to the province of Khuzestan), and more distally the open waters of the southern Tethys beyond which now exists the Zagros Fault. The region was equatorial, and a humid climate prevailed (Bordenave, 2002). The Kazhdumi Formation is a distal equivalent of nearshore sandstones and shales of the Burgan Formation in Kuwait, and the Nahr Umr Formation in Iraq and Qatar (Alsharhan and Nairn, 1997; Ibrahim and Al-Hitmi, 2000; Alavi, 2004). In the Dezful Embayment the Kazhdumi Formation is a dark, organic-rich, ammonite-bearing argillaceous limestone and calcareous shale of open-marine facies. It is a principal source rock in this petroleum rich area.
In the South Pars field the Kazhdumi Formation is 40–50 mthick (Table 1) and comprises grey to greenish and brownish shales with occasional marl intercalations. A few sandstone layers occur in the lower parts of the formation in two of the wells studied in the western part of the field. These sandstones are quartzitic, mediumto coarse-grained, well-sorted and well-rounded to rounded, glauconitic, and contain some iron oxides and lignites (Tehran Energy Consultants, 2001).
Table 1. Summary of samples utilized in the present study of the Kazhdumi Formation
Although the South Pars field is known for the huge gas reservoirs it contains, some wells have revealed oil in the Daryan and Sarvak formations below and above the Kazhdumi Formation (Fig. 2). Indeed, wells SP-2, SP-6, SPO-2 and SPO-3 in the present study are oil-prone. Whether the Kazhdumi Formation, a wellknown source rock for oil in the Zagros Basin, has produced oil in the South Pars field is open to question.
Fig. 2. Jurassic–Cretaceous stratigraphy of South Pars, Iran (Tehran Energy Consultants, 2001).
The Kazhdumi Formation has not been dated biostratigraphically in the South Pars field, but elsewhere it, or its equivalents, is considered Albian or Albian–early Cenomanian in age based on foraminifera and palynology (El Beialy and Al-Hitmi,1994; Ibrahim and Al-Hitmi, 2000; Al-Ameri et al., 2001).
Data source: Palynology and petroleum potential of the Kazhdumi Formation (Cretaceous: Albian–Cenomanian) in the South Pars field, northern Persian Gulf. Ebrahim Ghasemi-Nejad, Martin J. Head, Mehrangiz Naderi. Marine and Petroleum Geology 26 (2009) 805–816
Следующее Месторождение: Sarha 1