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Sarvak Reservoir Facies Characteristics in One of the South West Field in Iran

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Open Journal of Geology 2017年第3期7卷 279-294页

作者： Somayeh Pakparvar nader kohansal ghadim.and Davood Jahani Department of Geology Faculty of Sciences Islamic Azad University Tehran North Branch Tehran Iran

Sarvak Formation (Late Albian-Early Turonian) as main reservoir in the field is one of the carbonate units of Bangestan Group in Zagros Basin with average thickness of 640 m. This formation conformably overlays the Kazhdumi Formation while the upper boundary is an erosional unconformity which is covered by Ilam Formation. There is a significant lateral and vertical heterogeneity in the reservoir layers that causes main challenge in reservoir characterization. In this paper, reservoir properties evaluation and construction of depositional model have been done based on lithotype study, sedimentary environment classification, petrophysical interpretations and SeisWorks. Five facies types (lithotypes) in the Sarvak Formation with particular rock properties are identified in 8 wells and 200 thin sections. The main facies association elements and relevant depositional settings have been interpreted by extracted Paleolog, facies and fossil association data which are related to depositional setting variations.

关键词： Lithotype Heterogeneity Paleolog Depositional System

Analyzing Factors Affecting Erosion and Sedimentary Deposits Using the Empirical Method of PSIAC

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Open Journal of Geology 2017年第8期7卷 1078-1093页

作者： Abdolreza Alijani Armita Alijani nader kohansal ghadim.and Mohsen Aleali Geology-Sedimentary Lithology and Sedimentology Department of Geology Science and Research Branch Islamic Azad University Tehran Iran Offshore and Marine Structure Engineering Science and Research Branch Islamic Azad University Tehran Iran Department of Geology North Tehran Branch Islamic Azad University Tehran Iran Department of Geology Science and Research Branch Islamic Azad University Tehran Iran

PSIAC empirical method is considered as one of the methods calculating and estimating the amount of erodibility and sedimentation of sedimentary deposits in sedimentary basins and dams’ reservoirs. This method is based on analyzing nine influential factors including: surface geology, solid, weather, runoff, unpaved area, limited plant coverage, land usage, high lands erosion, river erosion and sediment transportation. These factors are rated according to their level of importance. The case study of this research is Lali Water Catchment, Khuzestan, Iran. The amount and intensity of adorability will be ranked as low, moderate and high. This research is based on field work, laboratorial studies and analyzing results obtained from statistics. Results indicated that the unpaved area and high land erosion are identified as the most effective factors, respectively. In contrast, runoff and surface geology are considered as the lowest rate. Other factors reflect moderate effects. Since any significant studies have not been done in this regard, the current research can present a new method to scrutinize the empirical effects of these factors. It is noteworthy to highlight that different methods are compared with each other in order to scrutinize the amount of erodibility in most studies, but the present study has analyzed the influential factors of the sub-methods of one major method. This essay focuses on the affectability of each one of the nine factors, independently. In conclusion, the outcomes of this research can contribute to identify and determine suitable alternatives to stabilize sedimentary basins and increase the life span of dams and watershed management projects and also reduce the destructive effects of floods. Additionally, it contributes civil projects in such lands.

关键词： Erodibility Sedimentation PSIAC Empirical Method Sedimentary Basins Dams’ Reservoir

Sedimentology and depositional environment of the Kazhdumi Formation Sandstones in the northwestern area of the Persian Gulf

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Open Journal of Geology 2016年第11期6卷 1401-1422页

作者： Bijan Noori nader kohansal ghadim.and Bahram Movahed Mohammadreza Yousefpour North Tehran Branch Islamic Azad University Tehran Iran Iranian Offshore Oil Company Tehran Iran

Kazhdumi is one of the Bangestan Group formations aging late early Cretaceous (Albian). Three subsurface sections of the sandstone bearing part of Kazhdumi in the studied area located at northwest of the Persian Gulf are assessed for determining sedimentary facies and depositional environment. Based on the recognized facies, the sandstone bearing zones of Kazhdumi and their relevant paleoenvironments can be addressed as: first one is the B sandstone zone containing thick sandstone layers alternating with shale and siltstone thin layers which are deposited by river influenced conditions because of the characteristics like: cross bedding, oxidized constituents and palesol. The second one, the A sandstone zone which is deposited under a key limestone layer, is composed of sand/sandstone layers with marine features and presents the interaction of marine-river condition in deltaic channels. This zone, is a transition interval showing the changes of river-dominated condition to marine one. The third one is the A sandstone zone deposited above the key limestone layer containing fine grained laminated siliciclastic and chemical sediments. Alternation of distal channel facies and green marine shale of delta containing glauconite, pyrite and organic matter residuals, all confirm the reduction condition in estuarine environment. Applying facies analyses results, isopach maps, porosity distribution maps and sandstone grain size study, the paleocurrent pattern is determined from the southwest to northeast.

关键词： Kazhdumi Formation Sedimentary Facies Paleoenvironment Paleocurrent Persian Gulf

Provenance and Tectonic Setting of Late Lower Cretaceous (Albian) Kazhdumi Formation Sandstones (SW Iran)

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Open Journal of Geology 2016年第8期6卷 721-739页

作者： Bijan Noori nader kohansal ghadim.and Bahram Movahed Mohammadreza Yousefpour North Tehran Branch Islamic Azad University Tehran Iran Iranian Offshore Oil Company Tehran Iran

Provenance and tectonic setting of the Late Lower Cretaceous (Albian) sandstones in SW Iran have been interpreted on the basis of geochemistry (major and trace elements) of 35 samples from Iranian offshore oil fields (Soroosh, Nowrooz, Foroozan and Hendijan). Geochemically, trace-element concentrations, such as La, Th, Sc and Zr, and ratios, such as La/Sc, Th/Sc, La/Co, and Th/Co, of sandstones from Kazhdumi Formation at four localities indicate that they were derived from felsic source rocks and deposited in a passive continental margin. Most major and trace element contents of Kazhdumi sandstones are generally similar to upper continental crust (UCC) values. However, some samples are depleted in major and trace elements (such as K2O, Na2O, Sr and Ba) relative to UCC, which is mainly due to absence or smaller amount of Na-rich plagioclase and K-feldspar and also paucity of clay minerals, which is possibly due to intense weathering and recycling. Enrichments in Zr, negative Sr anomalies and Th/U ratios higher than 4 for Kazhdumi sandstones are further evidence for recycled sources. The study of paleoweathering conditions based on chemical index of weathering (CIW) indicates a moderate to intense weathering of first cycle sediments, or it may alternatively reflect recycling under semi-arid to semi-humid climate conditions in Kazhdumi sandstones. The results of this study suggest that the main source for the Kazhdumi sandstones is likely located in uplifted shoulders of a rifted basin (Neo-Tethys) in its post-rift stage (Arabian basement).

关键词： Provenance Geochemistry Tectonic Setting Albian Kazhdumi Formation Burgan SW Iran

Reservoir Characterization and Geostatistical Modeling of Ilam &Sarvak Formations in One of Oil Fields in Southwest of Iran

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Open Journal of Geology 2017年第6期7卷 789-795页

作者： Neda Sasaninia Davoud Jahani Bahram Habibnia nader kohansal ghadim.and Department of Geology Tehran North Branch Islamic Azad University Tehran Iran Department of Petroleum Exploration Petroleum University of Technology Abadan Iran

Exploration and exploitation of hydrocarbon reservoirs have been always time consuming with high risk and high cost. In this regard, assessment of reservoir characterizations and information about spatial distribution of its parameters play an important role in adaptation of suitable strategies for hydrocarbon resources management. There are only few numbers of oil wells cored in every oil field due to high cost, time-consuming process, and other drilling problems. Therefore, it is required to use alternative estimation methods in order to achieve the petro-physical parameter in total space of reservoir. In this research, geostatistical methods have been applied as a new approach to calculate and estimate porosity and permeability of reservoir in one of southwestern oil fields of Iran. The information obtained from 86 wells in one of southwestern oil fields of Iran has been available in this study. Physical parameters of porosity and permeability are vital parameters that should be estimated in studied reservoir. This study indicated that Gaussian Variogram Model is the best model to predict porosity and permeability values in field. Error means of actual values of porosity are equal to 6.9% and for permeability are 11.21% using Gaussian Model. Also, after prediction of porosity and permeability values for field, distribution of these parameters in field was illustrated in two-dimensional and three-dimensional modes besides distribution and location of wells in field in order to determine the best drilling spots and reduce risk of drilling operations.

关键词： Porosity Permeability Geostatistics Krigging

Facies Interpretation, Depositional Environment and Sequence Stratigraphy of the Sartakht Formation in the Bakhshi Section, Located in Kalmard Block, East-Central Iran

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Open Journal of Geology 2016年第5期6卷 314-329页

作者： Bibi Haniyeh Emraninasab Mohammad Hossein Adabi Mahmoodreza Majidifard nader kohansal ghadim.and Department of Geology North Tehran Branch Islamic Azad University Tehran Iran Department of Geology Faculty of Earth Sciences Shahid Beheshti University Tehran Iran Research Institute for Earth Sciences Geological Survey of Iran Tehran Iran Department of Geology Islamic Azad University North Tehran Branch Tehran Iran

Permian rocks in Kalmard block are recognized with Khan Group, enjoying various characteristics in different outcrops. This group is made up of three informal formations, namely Chili, Sartakht and Hermez. Middle Permian deposits (Sartakht formation) are composed chiefly of sandstone and carbonate rocks. This formation is composed of 58.6 m sandstone and dolomitic limestone in the Bakhshi section. Lower Permian carbonate deposits (Chili formation) unconformably underlie this formation while lateritic paleosols of upper Permian (Hermez formation) are depicted overlying an erosional unconformity above this formation. According to lithologic and microscopic investigations, the deposits of Sartakht formation can be divided into 2 siliciclastic petrofacies and 12 carbonate microfacies. Field observations, along with microscopic examinations, have resulted in identifying tidal flat, lagoon, shoal and open marine environments in the rocks of the studied formation. Vertical changes of microfacies and depth variation curve point to the high thickness of the microfacies of lagoon and shoal environments and low thickness of the microfacies of tidal flat and open marine environments. The carbonate-siliciclastic sequence of Sartakht formation is made up of a third-order depositional sequence, separated from carbonate depositions of lower Permian (Chili formation) and lateritic paleosols of upper Permian by type 1 sequence boundary (SB1). Siliciclastic deposits include LST system tract, and carbonate microfacies involve TST and HST system tracts, separated from each other by MFS. Sartakht formation rocks in Bakhshi section are deposited in a low-angle homoclinal ramp, mostly in the inner ramp, located in the south of Paleotethys Ocean. The depositional sequence identified in Sartakht formation points to the age of middle Permian, conforming to middle Absaroka II supersequence. The upper erosional boundary between Sartakht and Hermez formations conforms to the global-scale sea lev

关键词： Middle Permian Kalmard Block Sartakht Formation Depositional Environment Sequence Stratigraphy

Facies Interpretation, Depositional Environment and Sequence Stratigraphy of the Gachal Formation in the Madbeiki Section, Kalmard Block, East Central Iran

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Open Journal of Geology 2016年第6期6卷 439-458页

作者： Soheil Erfani Mohammad Hossein Adabi Mahmood Reza Majidifard nader kohansal ghadim.and Department of Geology North-Tehran Branch Islamic Azad University Tehran Iran Department of Geology Faculty of Earth Sciences Shahid Beheshti University Tehran Iran Research Institute for Earth Sciences Geological Survery of Iran Tehran Iran Department of Geology Islamic Azad University North-Tehran Branch Tehran Iran

Deposits of Lower Carboniferous rocks in Kalmard block are recognized by Gachal informal formation, showing various characteristics in different outcrops. Lower Carboniferous deposits (Gachal formation) are composed chiefly of carbonate, evaporite and siliciclastic rocks. This formation is composed of 198 m sandstone, limestone and dolomite as well as a small amount of shale, marl and gypsum in the Madbeiki section. This formation unconformably underlies Precambrian metamorphic deposits (Kalmard formation) while lateritic soils of lower Permian (Chili formation) are depicted overlying an erosional unconformity above this formation. According to lithologic and microscopic investigations, the deposits of Gachal formation can be divided into 1 siliciclastic petrofacies, 1 evaporite microfacies and 16 carbonate microfacies. Field observations, along with microscopic examinations, have resulted in identifying tidal flat, lagoon, shoal and open marine environments in the rocks of the studied formation. Vertical changes of microfacies and depth variation curve indicate the high thickness of the microfacies of tidal flat, lagoon and shoal environments and low thickness of the microfacies of open marine environment. The carbonate-evaporite-siliciclastic sequence of Gachal formation is made up of three third-order depositional sequence, separated each other by type 1 sequence boundary (SB1). Siliciclastic and evaporite deposits include LST system tract, and carbonate microfacies involve TST and HST system tracts, separated from each other by MFS. Gachal formation rocks in Madbeiki section are deposited in a low-angle homoclinal ramp, mostly in the inner ramp, located in the southern Paleotethys Ocean. The depositional sequence identified in Gachal formation points to the age of Lower Carboniferous, conforming to upper Kaskaskia super sequence. The upper erosional boundary between Gachal and Chili formations conform to the global-scale sea level fall.

关键词： Lower Carboniferous Kalmard Block Gachal Formation Depositional Environment Sequence Stratigraphy

Evaluating the Amount of Erodability and Sedimentation by Comparing Sediment Weight Model and PSIAC Experimental Model (Case Study: Lali Water Catchment, Khuzestan, Iran)

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Open Journal of Geology 2016年第8期6卷 692-702页

作者： Abdolreza Alijani nader kohansal ghadim.and Mohsen Aleali Mohammad Reza Espahbod Ali Meysami Department of Geology Science and Research Branch Islamic Azad University Tehran Iran Department of Geology North Tehran Branch Islamic Azad University Tehran Iran North Tehran Branch Islamic Azad University Tehran Iran Department of Geology Shahr-e-Ray Branch Islamic Azad University Tehran Iran

The upstream water catchments are the main source providing sediments in rivers and sedimentary basins. The balance between the erosion phenomenon and the amount of sediment entering into the basin relies on the geometrical specifications and the morphology of the river along the water catchment direction and the amount and type of the sediments. The sedimentary feed of rivers and basins are changed for the sake of natural factors or human disturbances. The river and basin react against this change in that their shape, morphology, plan and profile get changed due to the increase or decrease of the input sediment into the basin. It is essential to know the sediment amount produced by erodability and sedimentation of upstream basins and effects of projects and also to evaluate the amount of sedimentary load in base studies, civil projects, optimizing rivers and dam construction studies specially calculating the amount of sediment amount entering into the dams’ reservoirs in order to take engineering decisions and related alternatives. Sediment Weight Model and PSIAC Experimental Model are recognized as two common methods calculating the amount of the produced sediment caused by erosion applied in this research. Holistically, these methods have been used and compared. Although the results are almost close to one another, more sediment load has been produced in PSIAC method. As more affective parameters are used to cause erosion and produce sediment in PSIAC experimental model, it is recommended to refer to the results of this method because they are closer to reality.

关键词： Erodability Sedimentation Water Catchment Sedimentary Basin The Sediment Weight Model PSIAC Experimental Model

Evaluating Sediment Production Caused by the Lithology of the Geological Formations in Sedimentary Basins (Case Study: Lali Area, Khuzestan, Iran)

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Open Journal of Geology 2016年第9期6卷 996-1013页

As sediments are produced and accumulated in sedimentary basins especially in dams’ reservoirs and they highly affect the reservoirs life span, it is essential to scrutinize the effect of lithology and types of geological formations of an area on the life span of reservoirs specifically from the viewpoints of the erodability of these formations due to their lithology type. Lali area, Khuzestan, Iran and the water catchment of the intended area (based on geological situation and Taraz dam situation) are placed in the sedimentary-structural zone of the folded Zagros. The method of this research is based on analyzing the topography and geology maps and field work in order to identify the lithology of the geological formations. In fact, the amount of its erodability has been characterized by the type of the geological formations. The current research aims at putting the geological results, lithological data of the formations types and the outcrop of the soil-lithological units together in order to evaluate the sedimentary and erosive factors of these units and precisely identify the area’s geological formations to remove the ambiguities in this issue. Studies indicate that formations made of looser gypsum and marl like Pabde-Gurpi and Gachsaran are exposed to more sedimentation and erosion than the formations made of compacted lime stone and conglomerate with silica-lime cement such as Bakhtiary and Asmari formations and the sand stones of Aghajari formation reveal the moderate to high resistance. Thus, the lithological identification of the formations, the type of sediments and their looseness and hardness contribute to detect the amount and type of deposits entering into the dam reservoir. The type and amount of these transported and deposited sediments are assessed to predict more suitable optimized ways to exploit dams’ reservoirs.

关键词： Geological Formations Lali Area (Khuzestan) Sedimentation Settlement Lithology