Changes

Northeastern Iraq, contiguous with Iran and Turkey, is part of the Zagros foldbelt, consisting of two zones ([[:file:M106Ch12Fig03.jpg|Figure 3]]). The High Zagros Nappe zone is a topographically high region characterized by tightly folded rocks and by ophiolite which was obducted onto the Arabian plate in the Late Cretaceous ([[:file:M106Ch12Fig04.jpg|Figure 4]]). Cretaceous and older sedimentary rocks and a suite of igneous and metamorphic rocks crop out in this region ([[:file:M106Ch12Fig05.jpg|Figure 5]]). There are no oil and gas discoveries in the High Zagros Nappe zone, although rocks containing bitumen and organic-rich rocks are exposed.

Northeastern Iraq, contiguous with Iran and Turkey, is part of the Zagros foldbelt, consisting of two zones ([[:file:M106Ch12Fig03.jpg|Figure 3]]). The High Zagros Nappe zone is a topographically high region characterized by tightly folded rocks and by ophiolite which was obducted onto the Arabian plate in the Late Cretaceous ([[:file:M106Ch12Fig04.jpg|Figure 4]]). Cretaceous and older sedimentary rocks and a suite of igneous and metamorphic rocks crop out in this region ([[:file:M106Ch12Fig05.jpg|Figure 5]]). There are no oil and gas discoveries in the High Zagros Nappe zone, although rocks containing bitumen and organic-rich rocks are exposed.

[[file:M106Ch12Fig04.jpg|thumb|300px|{{figure number|4}}Regional geologic cross section, which extends NE across central Iraq, from the Arabian platform of southwestern Iraq, at the border with Saudi Arabia, across the Mesopotamian Foredeep and Zagros foldbelt in eastern Iraq and adjacent Iran, and ending at the Sirjan-Sanandaj zone in Iran.]]

file:M106Ch12Fig04.jpg|{{figure number|4}}Regional geologic cross section, which extends NE across central Iraq, from the Arabian platform of southwestern Iraq, at the border with Saudi Arabia, across the Mesopotamian Foredeep and Zagros foldbelt in eastern Iraq and adjacent Iran, and ending at the Sirjan-Sanandaj zone in Iran.

The main part of the Zagros foldbelt is topographically lower and is characterized by large anticlines trending to the northwest. In the southwestern part of the foldbelt, synclinal areas are covered by Neogene sediments. In the northwestern part of the foldbelt, Paleogene strata are exposed in synclines. The Zagros foldbelt forms a large structural embayment, called the Kirkuk embayment, in the overall Zagros foldbelt. Many oil and gas fields occur within this zone, as shown in [[:file:M106Ch12Fig03.jpg|Figure 3]], including the super-giant Kirkuk field.

The main part of the Zagros foldbelt is topographically lower and is characterized by large anticlines trending to the northwest. In the southwestern part of the foldbelt, synclinal areas are covered by Neogene sediments. In the northwestern part of the foldbelt, Paleogene strata are exposed in synclines. The Zagros foldbelt forms a large structural embayment, called the Kirkuk embayment, in the overall Zagros foldbelt. Many oil and gas fields occur within this zone, as shown in [[:file:M106Ch12Fig03.jpg|Figure 3]], including the super-giant Kirkuk field.

The central portion of Iraq is the Mesopotamian foredeep, an area of relatively deep-water deposition in the Mesozoic and Cenozoic that formed in front of, and which is less deformed than, the Zagros foldbelt ([[:file:M106Ch12Fig06.jpg|Figure 6]]). Structural features trend to the northwest in the Mesopotamian foredeep, parallel to the Zagros foldbelt trends, and are formed by both detached and basement-involved faults ([[:file:M106Ch12Fig04.jpg|Figure 4]], [[:file:M106Ch12Fig06.jpg|Figure 6]]). Bouguer-gravity values are low in this foredeep ([[:file:M106Ch12Fig02.jpg|Figure 2]]), reflecting the thick sedimentary section. There are many oil and gas fields in the Mesopotamian foredeep ([[:file:M106Ch12Fig03.jpg|Figure 3]]), including the large East Baghdad field.

The central portion of Iraq is the Mesopotamian foredeep, an area of relatively deep-water deposition in the Mesozoic and Cenozoic that formed in front of, and which is less deformed than, the Zagros foldbelt ([[:file:M106Ch12Fig06.jpg|Figure 6]]). Structural features trend to the northwest in the Mesopotamian foredeep, parallel to the Zagros foldbelt trends, and are formed by both detached and basement-involved faults ([[:file:M106Ch12Fig04.jpg|Figure 4]], [[:file:M106Ch12Fig06.jpg|Figure 6]]). Bouguer-gravity values are low in this foredeep ([[:file:M106Ch12Fig02.jpg|Figure 2]]), reflecting the thick sedimentary section. There are many oil and gas fields in the Mesopotamian foredeep ([[:file:M106Ch12Fig03.jpg|Figure 3]]), including the large East Baghdad field.

==Oil and gas fields==

==Oil and gas fields==

Table 1 lists the discoveries in Iraq (information in part from Jassim and Goff<ref name=Jassimandgoff_2006 />; Verma et al.<ref name=Vermaetal_2004>Verma, M. K., Ahlbrandt, T. S., and Al-Gailani, M., 2004, Petroleum reserves and undiscovered resources in the total petroleum systems of Iraq: Reserve growth and production implications: GeoArabia, v. 9, no. 3, p. 51–74.</ref>), along with the hydrocarbon type and age of the main reservoir. The numbers refer to the locations of the fields as shown in [[:file:M106Ch12Fig03.jpg|Figure 3]]. Table 2 lists the fields by hydrocarbon type, structural province, structural style and trap type, source name, age and strata type, and volumes of in-place, estimated ultimate recoverable (EUR), produced, and remaining ultimate recoverable (RUR) oil and gas. The volumes data for oil and gas come mainly from Verma et al.<ref name=Vermaetal_2004 /> and Jassim and Goff,<ref name=Jassimandgoff_2006 /> except as noted in other references in this article.

Table 1 lists the discoveries in Iraq (information in part from Jassim and Goff<ref name=Jassimandgoff_2006 />; Verma et al.<ref name=Vermaetal_2004>Verma, M. K., Ahlbrandt, T. S., and Al-Gailani, M., 2004, Petroleum reserves and undiscovered resources in the total petroleum systems of Iraq: Reserve growth and production implications: GeoArabia, v. 9, no. 3, p. 51–74.</ref>), along with the hydrocarbon type and age of the main reservoir. The numbers refer to the locations of the fields as shown in [[:file:M106Ch12Fig03.jpg|Figure 3]]. Table 2 lists the fields by hydrocarbon type, structural province, structural style and trap type, source name, age and strata type, and volumes of in-place, estimated ultimate recoverable (EUR), produced, and remaining ultimate recoverable (RUR) oil and gas. The volumes data for oil and gas come mainly from Verma et al.<ref name=Vermaetal_2004 /> and Jassim and Goff,<ref name=Jassimandgoff_2006 /> except as noted in other references in this article.

Table 3 lists the reservoir horizons and seals in fields that have produced oil and gas. The same information is shown for undeveloped fields in Table 4 and for small discoveries and wells with shows in Table 6.

Table 3 lists the reservoir horizons and seals in fields that have produced oil and gas. The same information is shown for undeveloped fields in Table 4 and for small discoveries and wells with shows in Table 6.

There are 107 oil discoveries and nine gas discoveries in Iraq. The majority of these are in the Zagros foldbelt (53), the Mesopotamian foredeep (22), and the Gotnia Basin (18), and they account for over 98% of the oil and gas discovered.

There are 107 oil discoveries and nine gas discoveries in Iraq. The majority of these are in the Zagros foldbelt (53), the Mesopotamian foredeep (22), and the Gotnia Basin (18), and they account for over 98% of the oil and gas discovered.