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No 15
Vol. 15 No. 8
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In the present study, biostratigraphy, microfacies and sedimentary environment of the Asmari Formation in north flank of the Khami anticline in the north of the Gachsaran province is investigated. The Asmari Formation at the study section with a thickness of 276 meters is a thin, medium and thick to massive limestone, nodular limestone, marl, marly limestone, dolomite and dolomitic limestone. In this study 166 thin sections are studied and 23 genera and 24 species of foraminifera have been identified and 3 biozones are introduced. 1- Archaias asmaricus-Archaias hensoni-Miogypsinoides complanatus Assemblage zone. (Chattian) 2- Indeterminate zone (Aqutanian) 3- Borelis melo curdica-Borelis melo melo Assemblage zone. (Burdigalian) Thus, the age of the Asmari Formation at the study area is Chattian to Burdigalian (Oligo-Miocene). Based on study of thin sections and by considering the sediment texture, distribution of skeletal and non-skeletal grains, 12 microfacies are recognized which were deposited in open marine, bar, semi-restricted and restricted lagoon. Four platform types for the Asmari Formation at the study area in comparison with the recent studies on Asmari Formation including: 1-Rupelian-lower Chattian: Distally steepend ramp, 2-middle Chattian-upper Chattian: open shelf, 3-Aqiutanian: homoclinal ramp, 4-lower Burdigalian: carbonate platform.
Mona Rahim Abadi - Hossein Vaziri-Moghaddam - Ali Seyrafian
Keywords : Asmari Formation Khami anticline Oligocene-Miocene Microfacies Large benthic foraminifera
In this study, biostratigraphy, micofacies and sedimentary environment of Dariyan Formation in Anneh Anticline, near Hosein-Abad village (east of Gachsaran city) were investigated. Dariyan Formation at this study were consisted of 196 meters of thick, medium and thin layers of limestone, with orbitolinids, marl and marly limestone. The Daryian Formation is divided into the upper and lower parts, based on the existence of tongue with thin layer of limestone and laminated shale along with interlayer chert, with a large amount of radiolarids and planktonic foraminifera. In study area, Dariyan Formation conformably overlies the Gadvan Formation and is overlain by Kazhdumi Formation. A total of 114 thin sections were extracted from the study area and 22 benthonic foraminifera and 3 planktonic foraminifera have been identified in 4 biozones and 1 subzone: Praeorbitolina cormyi zone, Palorbitolinoides cf. orbiculata subzone, Hedbergella spp. Assemblage zone, Mesorbitolina texana zone, Mesorbitolina gr. subconcava zone. Based on identified zones in the study section, the age of Dariyan Formation is designated between Early Aptian to Albian. Sedimentary environment study of Dariyan Formation in Anneh Anticline led to identification of 9 microfacies related to open marine and lagoon. Due to the lack of a barrier facies, slumping and storm deposits, lump and grapston, an open shelf sedimentary environment was suggested for deposition of the Dariyan Formation in Anneh Anticline.
samaneh soleimani ahmadi - Hosyen Vaziri moghadam - ali seyrafian
Keywords : Dariyan Formation ، Anneh Anticline ، Biostratigraphy ، Aptian ، Orbitolina
The depressed basins of northwest central Iran are located in the structural Step and between Soltanieh-Ipac-Koshk-e-Nosrat and Qom –Zefreh system (the Indes - Qom –Khurabad faults). The main process of deformation within the basin with extension and compression of specific structures are comparable and verifiable using experimental models. The extensional structures include roll-over folds and normal faults, resulting in deep sedimentary basins during deposition of the lower and upper red formations. The younger structures, includes back-thrusts and for-thrusts, shortcut, and pop up structures represents the reversal of tectonic of primary extensional basin. These sedimentary basins have been created in relation to the growth faults and hanging wall blocks So In the presence of roll-over fold and antithetic and synthetic faults therefore are suitable for entrapment of hydrocarbons during migration. The active structural features have been identified using combination of geomorphic characteristic and seismic reflection data. Accordingly, none of the old normal faults in the Saveh- Qom and Aran basin show at the present any extensional movement and the fault activity of boundary faults and extensional folding are compressional. The active parts are: hanging wall of Saveh, restraining bending at the end of Indes fault that has stream Length-Gradient (SL) index and high value hypsometric index (Hi). The central part of Saveh-Qom and Aran basin, although show high Hi but the SL is low. This situation is due to the moderating effects of the thick lower and upper red formations and evaporative layer within the basin. In the Aran basin due to incomplete coverage of seismic lines the absence of normal faults cannot be definitively confirmed. However, the center of Aran basin as of Qom-Saveh formed push up which marks the compression of this basin and also activity of reverse and thrust faults. Based on the existing surface and subsurface data set, active deformation in this area now is transpression basin and the interior domains are in the uplift.
Mohammad Mokhtari - S.Ahmad Alavi - Leila Mahshadnia
Keywords : Active tectonic ، Positive Inversion ، Extensional Basin ، Northwest Central Iran
Sarvak Formation at the age of Albian-Turonin is one of the most important reservoirs of hydrocarbons in the south and southwest of Iran. In this study, in order to assess the reservoir quality, from a petrographic study and porosity and permeability data, a key well in one of the oil fields of Abadan plain has been used. Based on microscopic studies, 13 microfacies have been identified in the form of 4 tidal flat belt, lagoon, shoal and open marine for Sarvak Formation deposits in the studied oil field, indicating that the upper part of the Sarvak Formation is deposited in a homoclinal carbonate ramp. Among the identified diagenesis processes, dissolution, cementation, dolomitization, fracturing, Compaction, Neomorphism, Micritization, Bioturbation, Pyritization, Hematitization, phosphatization and silicification are mentioned. Diagenetic processes of Sarvak Formation occurred in three marine, meteoric and burial environments. Among the dissolution and fracturing diagenesis processes, the most important role has been in increasing the reservoir quality, and cementation and compaction have been the most important factors in reducing reservoir quality. Sequence stratigraphy investigations of 3rd degree sedimentary sequences were identified and the facies and its diagenesis processes were investigated. Correlation of porosity data and permeability of the core showed that the reservoir quality in this formation was influenced by facies and diagenesis processes. So that the microfacies containing the rudist have the highest reservoir quality. Due to the diagenesis, sedimentation and porosity and permeability data, the Facies Shoal and open marine to the land have the best reservoir quality.
Arad Kiani - Mohammad Hossein Saberi - Bahman Zare nejad - Elham Asadi Mehmandosti - Nasim Rahmani
Keywords : Sarvak Formation ، Abadan Plain ، Sedimentary Environment ، Diagenesis Processes ، Sequence Stratigraphy ، Reservoir Quality
Investigating potential source rocks in oilfields is important. In this study, in addition to evaluating the hydrocarbon potential, the Arrhenius kinetic model was used to more accurately assess the source rock maturity status as well as the percentage of oil generation in the Parsi oilfield. In the Arrhenius model, the rate of kerogen decomposition is very important. In this research, some source rocks that have been tested by thermal pyrolysis were kinetically analyzed and the source rock conversion ratio (TR) was determined. Based on the results of burial history and thermal modeling, it was found that Kazhdumi and Pabdeh formations were in the oil window well while Gurpi formation did not enter the oil window due to poor organic matter content (TR = 0). Therefore, among the Kazhdomi, Gurpi and Pabdeh formations in the Parsi oilfield, Kazhdumi formation is considered as the main and most effective source rock of this oilfield with high TTI and TR = 100.
Abuzar Bazvandi - Bijan Maleki - Saeedeh Senemari - parviz armani
Keywords : Kinetic evaluation ، Source rock ، Arrhenius model ، Burial history ، Pars oil field

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