Paleozoic Stratigraphy and Petroleum Systems of the Western and Southwestern Deserts of Iraq

Aqrawi, Adnan A.M.

doi:10.2113/geoarabia0302229

Cited by 72 publications

(1 citation statement)

References 26 publications

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“…The deposition was paused in Late Silurian twice due to the Caledonian orogeny, and in the Carboniferous-Permian due to the Hercynian orogeny. The Kaskaskia marine transgression event resulted in the formation of the Devonian Pirispiki Red Beds and Chalki Volcanics along with the limestone and Ora Shale formations [57]. The Ga'ara and the Chia Zairi Limestone formations were formed during the Permian time.…”

Section: Geological and Hydrogeological Settingmentioning

confidence: 99%

Monitoring Mass Variations in Iraq Using Time-Variable Gravity Data

2022

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Iraq is facing a water shortage due to water scarcity and anthropogenic activities. The recent advance in technologies in geophysical methods has made groundwater monitoring possible. Time-variable gravity data and outputs of the climatic model, as well as rainfall data, are integrated to investigate the spatio-temporal mass variations caused by groundwater changes over Iraq. The findings are: (1) For the entire study period (04/2002–12/2020), Period I (04/2002–12/2006), Period II (01/2007–12/2017), and Period III (01/2018–12/2020), the study region had an average annual precipitation rate of 223.4, 252.5, 194.2, and 311.6 mm/y, respectively. (2) The average Terrestrial Water Storage variations (ΔTWSs) varied from −5.79 ± 0.70 to −5.11 ± 0.70 mm/y based on the three different gravity solutions with a mean of −5.51 ± 0.68 mm/y for the entire investigated period. (3) For Periods I, II, and III, the average ΔTWS fluctuation was calculated to be +6.82 ± 1.92, −6.20 ± 1.17, and +28.58 ± 12.78 mm/y, respectively. (4) During the entire period, Periods I, II, and II, the groundwater fluctuation was averaged at −4.86 ± 0.68, +2.47 ± 2.20, −3.79 ± 1.20, and −4.63 ± 12.99 mm/y, respectively, after subtracting the non-groundwater components. (5) At the beginning of the 2007 drought during Period II, a decline in rainfall rate, and significant groundwater withdrawal during Period III all appear to have contributed to groundwater depletion. The Euphrates and Tigris Rivers, as well as the Mesopotamian plain, receive water from the running streams created by the ground relief. The area of the Mesopotamian plain, which has a thicker sedimentary sequence that can reach 9000 m, is found to have a positive TWS signal, indicating that its groundwater potential is higher. The integrated approach is informative and cost-effective.

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Section: Geological and Hydrogeological Settingmentioning

confidence: 99%

Monitoring Mass Variations in Iraq Using Time-Variable Gravity Data

2022

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Facies and depositional environments of the Devonian–Carboniferous succession of Iraq

Al-Juboury

Al-Hadidy

2008

Geological Journal

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Facies associations and depositional environments of the Late Devonian-Early Carboniferous succession in Iraq have been studied in several boreholes from north and northwestern Iraq. The >400 m-thick succession comprises the Kaista, Ora, Harur and Raha formations which are composed generally of mixed siliciclastic-carbonate facies. The Kaista Formation consists of sandstones intercalated with siltstones and calcareous shale that were deposited in a mixed fluvial-marine environment. The Ora Formation is composed dominantly of black shale with subordinate sandstone and dolomite deposited in a shallow-marine, sub-tidal shelf environment. The Harur Formation is composed mainly of dolomite with subordinate shale and was deposited in a deep sub-tidal environment. The Raha Formation consists mainly of marine shales intercalated with sandstones and concluded the Kaskaskia megasequence. The depositional setting is considered as a subsiding basin with a wide geographic distribution. It extended from the Ora region in the extreme north of Iraq to west and southwestern Iraq and reflects an epicontinental or epeiric sea setting on a homoclinal ramp inclined to the southeast.

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Identification of facies‐controlled eogenetic karstification in the Upper Cretaceous of the Halfaya oilfield and its impact on reservoir capacity

et al. 2018

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Penecontemporaneous dissolution has been considered as the dominant origin of reservoir formation, whereas epigenetic dissolution has also played certain roles in the improvement of reservoir capacity in the Upper Cretaceous Mishrif Formation in the Middle East. Here, we report a possible new reservoir origin based on a case study in the Halfaya oilfield of Iraq, that is, facies-controlled eogenetic karstification. The most representative evidence is that early selective dissolution is not only present in relative high-energy categories of rocks but also in low-energy ones in the cored intervals. Meanwhile, the occurrence frequency of karstification varies among different environments and associated lithologies. In grainstones and packstones, spongy-like dissolution pores and irregular karst channels are widely developed, with fillings and massive plastic breccias. In contrast, in wackestones, lots of high-angle karst channels are developed based on biological burrows, and the karst is more frequently observed in the shoal environment than in the low-energy environments. These characteristics are indication of eogenetic karstification.The model of this karstification can be attributed to a multiple superimposition of short-term exposure during the penecontemporaneous stage and the medium-term exposure after the shallow burial stage. The karst has impact on reservoir capacity, according to which 3 areas are divided in the increasing order, namely, the tight bedrock area, spongy-like dissolution pores area, and karst channels and vugs-filled area, among which the karst channels and vugs-filled area is the most favourable for oil accumulation. This understanding might be general to the Mishrif reservoirs in the entire Middle East.

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Paleozoic Stratigraphy and Petroleum Systems of the Western and Southwestern Deserts of Iraq

Cited by 72 publications

References 26 publications

Monitoring Mass Variations in Iraq Using Time-Variable Gravity Data

Monitoring Mass Variations in Iraq Using Time-Variable Gravity Data

Facies and depositional environments of the Devonian–Carboniferous succession of Iraq

Identification of facies‐controlled eogenetic karstification in the Upper Cretaceous of the Halfaya oilfield and its impact on reservoir capacity

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