Enayatallah Haghfarshi; Peyman Rezaee; Seyed Reza Moosavi Harami; Mohammad Faridi
Abstract
Lignite Beds of Tabriz are among of the Neogene formations in the northwestern area of the Iran, which is spread in the eastern suburb of Tabriz. Its sedimentary facies includes facies groups of fine grains clastics, sandstones, limestones and facies of lignite, tuff and microfacies and petrofacies under ...
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Lignite Beds of Tabriz are among of the Neogene formations in the northwestern area of the Iran, which is spread in the eastern suburb of Tabriz. Its sedimentary facies includes facies groups of fine grains clastics, sandstones, limestones and facies of lignite, tuff and microfacies and petrofacies under them. In this study, two stratigraphic sections of these sediments in the eastern part of Tabriz were studied and 171 samples and 42 thin sections were collected and studied. XRD analysis for mineralogy and SEM electron microscopy for 3-dimensional studies were used to identify microfossils. Identified fossils include the genera and species of gastropods, Pelecypods, ostracods, fish, diatoms, charophyte algae, and foraminifera. The studied fossil assemblages includes species from freshwater to euryhaline and marine. The identified sedimentary environments include the lake basin environment, the shallow coastal environment and the marshy lake environment. In the studied sedimentary strata, strong fossil evidence and sedimentological evidence of the marine environment are not observed, at least during its lifetime. Therefore, it is concluded that the marine taxis in these deposits remain and are adapted from a former marine environment.
Stratigraphy and Palaeontology
Ali Asaadi; Ali Imandoust; Mehdi Sarfi; Mehdi Ghane Ezabadi
Abstract
The Lower Cretaceous Fahliyan Formation is one of the main oil reservoirs in the Persian Gulf. In this study, for investigating facies characteristics, depositional environment, diagenetic features, sequence stratigraphy and describing factors controlling reservoir quality, the integration of the results ...
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The Lower Cretaceous Fahliyan Formation is one of the main oil reservoirs in the Persian Gulf. In this study, for investigating facies characteristics, depositional environment, diagenetic features, sequence stratigraphy and describing factors controlling reservoir quality, the integration of the results from core description, petrographic studies, and petrophysical data was utilized. Nine main facies were recognized and grouped in four facies belts of lagoon, shoal, patch reef and shallow open marine, indicating deposition of the formation in a carbonate ramp platform. Various diagenetic processes that influenced facies, occurred in marine, meteoric, and burial diagenetic realms. Four main pore types have been identified in the reservoir that include interparticle, moldic, vuggy, and microporosity. From the sequence stratigraphy point of view, three third-order sequences which are correlatable within the Fahliyan Formation were identified. The development of grainstone and algal rudstone/floatstone in shoal/ patch reef sub-environment played an important role in developing the high reservoir. In view of their controls on reservoir quality and pore system, diagenetic features can be categorized into two classes: (1) diagenetic processes enhancing reservoir quality that include dissolution and fracturing, and (2) diagenetic processes reducing reservoir quality that include cementation and compaction.
Sedimentology
Samira Akbarzadeh; Abdolhossein Amini; Vahid Tavakoli; Khosro Heydari
Abstract
The Oligo–Miocene Asmari Formation is the most important reservoir rocks of the Dezful embayment oil fields. This study interpret sedimentary environments and sequence stratigraphy of the Asmari Formation in Karun oil field based on changes in facies, gamma-ray log morphology and change in concentration ...
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The Oligo–Miocene Asmari Formation is the most important reservoir rocks of the Dezful embayment oil fields. This study interpret sedimentary environments and sequence stratigraphy of the Asmari Formation in Karun oil field based on changes in facies, gamma-ray log morphology and change in concentration of thorium, potassium and uranium elements of the natural gamma- ray spectrometry. In this regard, 1 evaporate, 9 carbonate facies and 1 mixed facies were recognized. The thorium to uranium ratio used to analyze the oxidation, reduction condition. Based on the vertical distribution of the facies in the sequence stratigraphy framework, three 3rd order sequences were determined. Changing the trend of logs in time reflects the decreasing trend of gamma- ray in the sequence boundary and increasing trend at maximum flooding surface. Five main morphologies including left Box Car shape, Right Box Car shape, Serrated Bell shape, Serrated Funnel shape and serrated shape have been recognized. The conformity of this morphologies with the sequence stratigraphy leads to the relationship between the Left Box Car shape with Low stand system tract, Serrated Bell shape and Right Box Car shape with Transgressive system tract and Serrated Funnel shape with High system tract.
F. Shirezade Esfahani; A. Bayet-Goll; N. Kohansal Ghadimvand; A. Kangazian; A. Akbari Mohammadi; M. Sadri
Abstract
The carbonate successions (Tournaisian-Visean) exposed in the Tang-e-Darchaleh and Banarizeh sections from Sanandaj-Sirjan Zone (SSZ), Iran, have been used to generate a facies model. From the analysis of facies and their associations, four depositional zones are recognized on the Tournaisian-Visean ...
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The carbonate successions (Tournaisian-Visean) exposed in the Tang-e-Darchaleh and Banarizeh sections from Sanandaj-Sirjan Zone (SSZ), Iran, have been used to generate a facies model. From the analysis of facies and their associations, four depositional zones are recognized on the Tournaisian-Visean ramp: basinal environments, outer ramp (FA1 and FA2; deep subtidal associations), mid ramp (FA3, FA4 and FA6; shallow subtidal to lower intetidal associations), and inner ramp (FA5; shoal). The gradual transitions between facies and facies associations, as well as the depositional profile of the shelf transect indicate a low gradient ramp. The observed sedimentary features in the facies associations portray a transgressive, proximal-to-distal, wave-dominated combined flow marine ramp sequence, as recorded in stratigraphic changes in character of storm bed sequences and the spatial arrangement of types of storm bed along the depth related environmental gradients. This study suggests that during the Lower Carboniferous, a broad shelfal platform covered the southern margin of the Palaeotethys, which was characterized by dominantly shallow carbonate ramp.
E Khazaei; M.H Mahmudy Gharaie; A Mahboubi; J Taheri
Abstract
The studied section in SW Kashmar located in Tabas block of central Iran sedimentary - structural zone. According to field observations and petrography, two sets of siliciclastic and carbonate facies were distinguished. Three lithofacies were identified based on the field parameters such as lithology, ...
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The studied section in SW Kashmar located in Tabas block of central Iran sedimentary - structural zone. According to field observations and petrography, two sets of siliciclastic and carbonate facies were distinguished. Three lithofacies were identified based on the field parameters such as lithology, geometry, sedimentary structures, layering surfaces and bedding contacts. Three lithofacies including conglomerate (Gcm, Gp), Sandstone (St, Sr, Sh, Sl, Sm), muddy (Fl), four petrofacies (polymictic orthoconglomerate 1 and 2, arkosic wacke, and subarkose as well as four microfacies associations of open marine, shoal, lagoon, tidal flat were identified based on microscopic features such as grain type, grain size and texture. Based on finning upward Bouma cycles, erosional surface and greywacke composition, siliciclastic sediments of upper part of the Shirgesht Formation are deposited in turbidity conditions. Present of hummocky stratification, finning upward cycles with shellbeds at the base of units revealed that carbonate rocks of lower part of the Niur Formation are deposited in a shallow ramp storm - dominated. The regional tectonic, expansion of glaciers and melting led to environmental changes during Upper Ordovician – Early Silurian transition in the studied region.
Stratigraphy and Palaeontology
M. Allameh; A. Mahboubi; R. Moussavi-Harami; M. Khanehbad
Abstract
The Aitamir Formation (Albian-Cenomanian) composed of siliciclastic rocks and several carbonate horizons. In order to study depositional environment and sequence stratigraghy, two stratigraghic sections studied in east Koppeht Dagh basin near the Baghak and Shurijeh villages. Field and petrograghic studies ...
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The Aitamir Formation (Albian-Cenomanian) composed of siliciclastic rocks and several carbonate horizons. In order to study depositional environment and sequence stratigraghy, two stratigraghic sections studied in east Koppeht Dagh basin near the Baghak and Shurijeh villages. Field and petrograghic studies led to siliciclastic and carbonate facies that deposited in lagoon, barrier, shoreface and open marine environments. Sequence stratigraghy analysis led to identification of three depositional sequences in both sections. Comparision of interpreted sea level curves at studied area with Albian-Cenomanian global curve shows similarities and differences that can be relatedto tectonic setting and sedimentation rate.
N Kohansal-Ghadimvand; Sh Gholipouri; P Ghazanfari; R Mahari
Abstract
The aim of this study is to determine microfacies and diagenetic processes of the Mobarak Formation with the age of early Carboniferous in Valiabad section, at Karaj-Chalus road. The thickness of the formation at this section is 339 m and consists of limestone with intercalations of shale and marl. ...
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The aim of this study is to determine microfacies and diagenetic processes of the Mobarak Formation with the age of early Carboniferous in Valiabad section, at Karaj-Chalus road. The thickness of the formation at this section is 339 m and consists of limestone with intercalations of shale and marl. According to lithological characteristics, the MobarakFormationis subdivided into 8 rock units and is disconformably overlain by the Lalun Formation and underlain by Dozdeband Formation. Thirteen microfacies have been recognized on the basis of depositional texture and petrographic analysis. These carbonate facies belong to four major sub- environments including beach/tidal flat, lagoon, barrier/sand shoal and open marine. The formation deposited in a homoclinal carbonate ramp.
H Amin-Rasouli; Y Lasemi; S Zaheri
Abstract
The middle Cambrian-early Ordovician transgression in the AlborzMountains resulted in the deposition of members 1 through 3 of the Mila Formation showing an overall transgressive trend. This succession is bounded unconformably by the Top-Quartzite of the Lalun Formation at the below and member 4 of the ...
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The middle Cambrian-early Ordovician transgression in the AlborzMountains resulted in the deposition of members 1 through 3 of the Mila Formation showing an overall transgressive trend. This succession is bounded unconformably by the Top-Quartzite of the Lalun Formation at the below and member 4 of the Mila Formation at the top. It consists of tidal flat to open marine facies, which have been deposited in an extensive ramp on the Proto-Paleotethys passive margin of northern Gondwana. It is composed of six depositional sequences aged middle to early- late Cambrian, related to Sauke 2 supersequence. These sequences are correlated with those recognized in other parts of the world including Oman, China, and North America suggesting that they were formed as the consequence of global relative sea level fluctuation.
A. Kakouei; M. Masihi; M. Shirani
Abstract
Determination of different facies is one of the important and basic tasks of geological engineering characterization of reservoir rocks from well logs and core data. Our objective is to identify and determine different facies of the South Pars Field using RBF and PNN neural networks in order to perform ...
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Determination of different facies is one of the important and basic tasks of geological engineering characterization of reservoir rocks from well logs and core data. Our objective is to identify and determine different facies of the South Pars Field using RBF and PNN neural networks in order to perform static and dynamic simulation. These networks are utilized to identify facies of the South Pars Field for the first time in Iran. In this study, we use different parameters of mentioned networks such as ‘spread’ and ‘goal numbers’ to improve networks operation. In this regards, the optimum values of these two parameters were 0.01-10 and 0.02-0.04 respectively. The results show that the RBF and PNN neural networks are robust means to determine and model the facies of the South Pars Field in Iran.
F. Gharib; Y. Lasemi; M. H. Emami
Abstract
The clastic facies of Kahar Formation were identified in the studied sections of coastal, deltaic and fluvial and also carbonate facies in shallow marine environments. The vertical displacements of Kahar Formation in these study sections show an overall major transgressive upward cycle. The petrography ...
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The clastic facies of Kahar Formation were identified in the studied sections of coastal, deltaic and fluvial and also carbonate facies in shallow marine environments. The vertical displacements of Kahar Formation in these study sections show an overall major transgressive upward cycle. The petrography of plutonic and semi- plutonic igneous rocks indicate that they consist mainly of monzogabbro- diorite and in some cases, alkaline syenite. According to the results of Kahar Formation's plutonic rocks petrography and studies of related facies, the basin of this formation was a continental rift.