A Ramezani Akbari; H Rahimpor-Bonab; M.R Kamali; R Moussavi-Harami; A Kadkhodaie
Abstract
The Fahliyan Formation of Khami Group is hosting important hydrocarbon reserves in Iran and also is a main reservoir rock in the Abadan Plain oil fields which is Neocomian in age. In the studied wells its thickness is about 440 meters. In the Abadan Plain, the Fahliyan Formation transitionally overlies ...
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The Fahliyan Formation of Khami Group is hosting important hydrocarbon reserves in Iran and also is a main reservoir rock in the Abadan Plain oil fields which is Neocomian in age. In the studied wells its thickness is about 440 meters. In the Abadan Plain, the Fahliyan Formation transitionally overlies the argillaceous limestone of the Garau Formation and its upper boundary changes into marl and argillaceous limestone of the Gadvan Formation. According to thin sections examinations prepared from cuttings and cores plus electrofacies analysis 11 microfacies and 2 lithofacies are recognized. This formation consists of two carbonate and mixed carbonate-siliciclastic (mixed zone) members. The Lower Fahliyan was deposited in carbonate ramp environment while, the Upper Fahliyan was deposited in a mixed carbonate–siliciclastic environment. To determine electrofacies, the rock types were modeled with using MRGC method. Best correlation between petrographical and electrofacies is 12 cluster model (in MRGC method). These results suggest that the electrofacies model is in agreement with heterogenetic rock type such as mixed carbonate–siliciclastic environment observed in petrography. Also, in homogenous rock type such as carbonate ramp environment electherofacies can’t completely determine geological facies. Based on petrographical and electrofacies this formation is composed of three third order sequences with type sb2 sequence boundaries. But, the third sequence in mixed carbonate–siliciclastic zone is terminated with sb1 sequence boundary just below the Gadvan Formation.
M Khanjani; S.R Moussavi-Harami; H Rahimpour-Bonab; M.R Kamali; A Chehrazi
Abstract
The Santonian – CampanianIlam Formation is one of the major reservoirs of Bangestan Group in the Zagros petroliferous basin. In the Siri Alvand Oilfield located in the Persian Gulf this formation with a total thickness of 130 m, consists of limestone. In this study, microfacies, depositional environments, ...
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The Santonian – CampanianIlam Formation is one of the major reservoirs of Bangestan Group in the Zagros petroliferous basin. In the Siri Alvand Oilfield located in the Persian Gulf this formation with a total thickness of 130 m, consists of limestone. In this study, microfacies, depositional environments, diagenetic processes and sequence stratigraphy of the Ilam Formaton in Siri Alvand oilfield was studied. Based on thin sections studies, 8 microfacies and 4 facies associations were identified that deposited in a homoclinal carbonate ramp environment. On the basis of petrographic studies, the main diagenetic processes affected these rocks include bioturbation, cementation, dissolution, dolomitization, stylolitization, pyritization and fracturing. The most important cement types in this formation are bladed calcite, fine equant calcite, drusy mosaic calcite, coarse blocky calcite and syntaxial calcite overgrowth. Sequence stratigraphic studies led to recognition of four third order depositional sequences in the Ilam Formation that all of them terminated to the type 1 sequence boundary. Finally, facies and diagenetic processes intensity were studied in each sequence.
L Abdi; H Rahimpour-Bonab
Abstract
The Meyghan Playa is an inland closed basin, which is located in center of the aquifer Arak plain. This playa is a seasonal lake and from hydrological point of view acts as erosional base level of region and is appropriate site for precipitation clastic and chemical deposits. For mineralogical and sedimentological ...
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The Meyghan Playa is an inland closed basin, which is located in center of the aquifer Arak plain. This playa is a seasonal lake and from hydrological point of view acts as erosional base level of region and is appropriate site for precipitation clastic and chemical deposits. For mineralogical and sedimentological investigations 94 sediment samples were collected from the playa. 19 samples from surface sediments in transect to the center of playa and 31 specimens from 7 cores were systematically collected and studied by X-ray diffraction (XRD) technique. The clay minerals include Illite, Chlorite, Kaolinite,Vermiculite and Smectite. Illite and Chlorite are the most important clay minerals in the playa. Origins of clay minerals in the Meyghan playa are generally detrital, occurred by physical weathering and indicate composition of bed rock. The study of surface sediments indicate that amount of clay minerals from margin to center of the playa such as another detrital mineral (Quartz) is decreased. In addition, amount of them towards depth is increased. Therefore it shows the presence of a high water level and cold - humid climate in the past (late Pleistocene).