Facies

Open Access Article

1 - Robustness of fuzzy c-mean method for delineation of hydrochemical facies distribution of groundwater in Varamin Plain
Mohammad Nakhaei Mehdi Talkhabi Meysam Vadiati

In this paper, classification of a large hydrochemical data set from Varamin plain is done by using fuzzy c-means (FCM) and hierarchical cluster analysis (HCA) clustering techniques. Then its application to hydrochemical facies delineation is discussed. Groundwater samp More

In this paper, classification of a large hydrochemical data set from Varamin plain is done by using fuzzy c-means (FCM) and hierarchical cluster analysis (HCA) clustering techniques. Then its application to hydrochemical facies delineation is discussed. Groundwater samples were grouped into three classes according to the optimum number of the classes and fuzziness exponent by using the fuzzy c-mean. The data set includes 90 deep and moderate deep well samples from groundwater data set and 9 hydrochemical variables were used. Results from both FCM and HCA clustering produced cluster centers that can be used to identify the physical and chemical processes creating the variations in the water chemistries. The optimum cluster in FCM method determined by optimization function, but in HCA method by trial and error. The FCM method is potentially useful in establishing hydrochemical facies distribution and may provide a better tool than HCA for clustering large data sets when overlapping or continuous clusters exist. Plotting the cluster membership value contours on a map demonstrated the existence of three spatially continuous, well-defined clusters of groundwater samples. The results showed that the FCM method is more sound for investigating threshold data rather than HCA method (that represents sharp and abrupt variations). Manuscript profile

Open Access Article

2 - Microfacies and petrofacies analysis, diagenetic characteristics and environmental condition of the Faraghan Formation in the central part of the Persian Gulf
J. Amraei Peyman Rezaei A.H. Amini Seyed Mohammad Zamanzadeh V. Tavakoli

<p>Clastic deposits of the Faraghan Formation (Late Permian, Sakmarian) are present in different outcrops in the Zagros area and some wells in the Persian Gulf Basin. The presence of these clastics represents the existence of an extended clastic system on the north-east More

<p>Clastic deposits of the Faraghan Formation (Late Permian, Sakmarian) are present in different outcrops in the Zagros area and some wells in the Persian Gulf Basin. The presence of these clastics represents the existence of an extended clastic system on the north-east of the Arabian plate. The Faraghan Formation unconformably overlies Zakeen sandstone (Devonian) and grades upward into Dalan carbonate (Upper Permian). To study the Faraghan Formation some thin sections were prepared from cuttings of some wells in the central part of the Persian Gulf and then they were studied. Results show of this study that the Faraghan Formation consists of quartz arenite, sandy siltstone and sandy claystone petrofacies and carbonate mudstone, bioclast wackestone and bioclast packstone microfacies. Based on sedimentary characteristics and spatial relationships between the petrofacies, this formation was deposited on a linear shoreface environment (floodplain, shoreface and offshore sub-environments). Main diagenetic processes consist of compaction, dissolution, cementation, neomorphism, sericitization and dolomitization. Heterogeneity of the Faraghan Formation lithology and variety of environmental conditions and diagenetic features make this formation a good candidate for hydrocarbon reservoir studies.</p> Manuscript profile

Open Access Article

3 - Geomechanical zonation of the Faraghan, Zakeen and Sarchahan formations based on incorporation of rock mechanical and sedimentological studies, in one of the Persian Gulf oil fields
Mehran Kalhori Hooshang Mehrabi Ebrahim Sefidari Hasan Eshraghi Behnam Vaez Livari

Geomechanical studies have important applications in various topics such as wellbore stability, well completion, well orientation, hydraulic fracturing plans and operations, sand production and hydrocarbon fields subsidence. It is necessary to prepare earth mechanical m More

Geomechanical studies have important applications in various topics such as wellbore stability, well completion, well orientation, hydraulic fracturing plans and operations, sand production and hydrocarbon fields subsidence. It is necessary to prepare earth mechanical model of the well in the field. In addition, one of the necessary subjects to prepare mechanical earth model (MEM) is providing continuous rock mechanical parameters in the well. Rock mechanical parameters change by any variation in lithology. In this study, rock mechanical parameters are provided in continuous form, for Faraghan, Zakeen and Sarchahan formations for a field in the Persian Gulf and these parameters are clustered. Clustering resulted in recognizing six clusters with various rock mechanical characteristics. Petrographic study (i.e. determining facies, cementation and diagenesis) recognized five facies with different petrographic and cementation characteristics. These facies include quartz arenite and arkosic sandstones, shales, red mudstone and carbonates. A correlation between sedimentary and geomechanical facies was found. According to petrographic and geomechanical studies, the studied interval was divided into 7 sections. Accordingly, variation of rock mechanical parameters with regard to change in lithology was investigated. In addition, the impact of rock composition, cementation and compaction changes on rock mechanical parameters were evaluated as well. Manuscript profile

Open Access Article

4 - Facies and depositional model in siliciclastic Chelken Formation, South Ghaemshahr City
هوشنگ مهرابی عبدالحسین امینی وحید توکلی مرتضی فرخی Seyed Mohad Zamanzadeh

Siliciclastic Chelken Formation (Lower and Middle Pliocene) with a siliciclastics nature in Javarom Section (south of the Ghaemshahr city) was studied. This formation comprises three sets of conglomerate, sandstone and mudstone, which are usually arranged in fining upwa More

Siliciclastic Chelken Formation (Lower and Middle Pliocene) with a siliciclastics nature in Javarom Section (south of the Ghaemshahr city) was studied. This formation comprises three sets of conglomerate, sandstone and mudstone, which are usually arranged in fining upwards sequences. According to the nature of fining upward sedimentary sequences, sedimentological characteristics and structural features, it is proposed that Chelken Formation deposited in a fluvial environment. Conglomeratic facies are mainly grain-supported in nature, sandstone facies are represented by quartz arenite and lithic arenite in nature and Mudstone facies are carbonate in nature. The paleo-currents analyses represent a north and northeastward direction Manuscript profile

Open Access Article

5 - Facies studies and depositional environment of Sahand volcanic complex (NW of Iran)
Farhad Pirmohammadi alishah Ahmad Jahangiri

Sahand volcanic complex is located in the south of Tabriz and east of Urmia Lake and includes an alternation of lava, igneous materials and clastic sediments that were affected by many folds and fractures. Sahand volcano is relatively young in age (Miocene to Pliocene) More

Sahand volcanic complex is located in the south of Tabriz and east of Urmia Lake and includes an alternation of lava, igneous materials and clastic sediments that were affected by many folds and fractures. Sahand volcano is relatively young in age (Miocene to Pliocene) and its structure is somewhat intact. Consequently, where there is a good lateral continuity, facies and volcanological studies can be carried out in the upper part of the complex. Based on these studies, it was determined that the Sahand volcanic structure can be divided into four central, near, medium and distant facies. Facies studies show that the structure of Sahand Volcano was created by several explosive phases, some of which were associated with water intrusion and there was not much time between eruptions. Characteristics, such as severe welding and discoloration of pyroclastic deposits show that these units had a high temperature at the time of formation and were formed on land. Overall, Sahand volcanic eruptions were more explosive, and thus, the number of pyroclastic deposits is much higher than lava flows. In the central, near and middle facies of Sahand, no traces of younger hydrothermal activities can be found, and only in the distant facies, there is a hot spring (Bostan Abad), the relationship of which needs further study to prove the connection of these springs with the Sahand Volcano. Manuscript profile

Open Access Article

6 - Electro-Facies and Rock Type Comparison in the One of Gas Field’s Kangan, (Iran)
حیدر صائمی

Abstract Kangan Formation in the Study Area is about 444 meters thick and is mainly composed of Limestone and dolomite with randome interbeds of Anhydrites. In this article, Rock Types are determind by Electro Facies and Hydrolic Flow Units (HFU) method using the Core More

Abstract Kangan Formation in the Study Area is about 444 meters thick and is mainly composed of Limestone and dolomite with randome interbeds of Anhydrites. In this article, Rock Types are determind by Electro Facies and Hydrolic Flow Units (HFU) method using the Core data, Gamma -Ray, Density and Neutron Porosity petrophysical logs of one of the Field’s wells. Rock Types determination can be a practical solution for categorizing reservoir’s facies aiming assesment of reservoir rock’s petrophysical properties and diffrentiating high potential producer zones from low potential ones. Hence clustering method based on Multi Resolution Graph-Based Clustering (MRGC) which is a “Non Parametric” statistical method, of umpteenth near value and graphical presentation of data, was implyed on Neutron Porosity, Density and Gamma-Ray logs to re-construct equivalent electro facies to the ones obtained from core. At the end, final clusters are formed by combining small clusters where five facies were recognized. The used method in this research eleminates the need of repeated coring and leads to a major cost and time saving. More over the Rock Types were also determind by Hydrolic Flow Units method. Hydrolic Flow Units is a method for categorizing the variety of Rocks according to their flowing properties based on geological and physical flow in pore scale. Five Rock Types were determind by this method also, which had good conformity with the ones from previous method in many locations. In some locations of course the results were not as good which could be as a result of non uniform sampling and human error. Manuscript profile

Open Access Article

7 - Electro-Facies and Rock Type Comparison in the One of Gas Field’s Kangan, (Iran)
حیدر صائمی وحید توکلی حسن اشراقی

Abstract Kangan Formation in the Study Area is about 444 meters thick and is mainly composed of Limestone and dolomite with randome interbeds of Anhydrites. In this article, Rock Types are determind by Electro Facies and Hydrolic Flow Units (HFU) method using the Co More

Abstract Kangan Formation in the Study Area is about 444 meters thick and is mainly composed of Limestone and dolomite with randome interbeds of Anhydrites. In this article, Rock Types are determind by Electro Facies and Hydrolic Flow Units (HFU) method using the Core data, Gamma -Ray, Density and Neutron Porosity petrophysical logs of one of the Field’s wells. Rock Types determination can be a practical solution for categorizing reservoir’s facies aiming assesment of reservoir rock’s petrophysical properties and diffrentiating high potential producer zones from low potential ones. Hence clustering method based on Multi Resolution Graph-Based Clustering (MRGC) which is a “Non Parametric” statistical method, of umpteenth near value and graphical presentation of data, was implyed on Neutron Porosity, Density and Gamma-Ray logs to re-construct equivalent electro facies to the ones obtained from core. At the end, final clusters are formed by combining small clusters where five facies were recognized. The used method in this research eleminates the need of repeated coring and leads to a major cost and time saving. More over the Rock Types were also determind by Hydrolic Flow Units method. Hydrolic Flow Units is a method for categorizing the variety of Rocks according to their flowing properties based on geological and physical flow in pore scale. Five Rock Types were determind by this method also, which had good conformity with the ones from previous method in many locations. In some locations of course the results were not as good which could be as a result of non uniform sampling and human error. Manuscript profile

Open Access Article

8 - Electro-Facies and Rock Type Comparison in the One of Gas Field’s Kangan, (Iran)
حیدر صائمی وحید توکلی حسن اشراقی

Abstract Kangan Formation in the Study Area is about 444 meters thick and is mainly composed of Limestone and dolomite with randome interbeds of Anhydrites. In this article, Rock Types are determind by Electro Facies and Hydrolic Flow Units (HFU) method using the Co More

Abstract Kangan Formation in the Study Area is about 444 meters thick and is mainly composed of Limestone and dolomite with randome interbeds of Anhydrites. In this article, Rock Types are determind by Electro Facies and Hydrolic Flow Units (HFU) method using the Core data, Gamma -Ray, Density and Neutron Porosity petrophysical logs of one of the Field’s wells. Rock Types determination can be a practical solution for categorizing reservoir’s facies aiming assesment of reservoir rock’s petrophysical properties and diffrentiating high potential producer zones from low potential ones. Hence clustering method based on Multi Resolution Graph-Based Clustering (MRGC) which is a “Non Parametric” statistical method, of umpteenth near value and graphical presentation of data, was implyed on Neutron Porosity, Density and Gamma-Ray logs to re-construct equivalent electro facies to the ones obtained from core. At the end, final clusters are formed by combining small clusters where five facies were recognized. The used method in this research eleminates the need of repeated coring and leads to a major cost and time saving. More over the Rock Types were also determind by Hydrolic Flow Units method. Hydrolic Flow Units is a method for categorizing the variety of Rocks according to their flowing properties based on geological and physical flow in pore scale. Five Rock Types were determind by this method also, which had good conformity with the ones from previous method in many locations. In some locations of course the results were not as good which could be as a result of non uniform sampling and human error. Manuscript profile

Open Access Article

9 - Study of Petrography & Petrophysics of Permian- Triassic carbonate sediments in Qatar –South Pars Arch
Ali reza Bashari

Abstract Dalan and Kangan Formations are major gas reservoirs in the Persian Gulf and surrounding area. Several supper giant gas fields has been found in the region. In this study reservoir rock types were identified and were divided into four lithostratigraphic zo More

Abstract Dalan and Kangan Formations are major gas reservoirs in the Persian Gulf and surrounding area. Several supper giant gas fields has been found in the region. In this study reservoir rock types were identified and were divided into four lithostratigraphic zones: K1 to K4. Each of the four succeeding zones have been divided into different subzone. This Studies identified different facies-types on the Dalan and Kangan formation in this region. Petrophysical & Petrographycal studies indicate that the best reservoir unites are found in: Dolo-grainstones, Dolowakestones/Packstones and Grainstones. Isopach maps and Depth maps show variations in thickness and depth of different zones in this region. Depth map on top of Kangan formation shows this formation getting deeper toward north- west and south east in the Persian Gulf. Continuity of marker beds in Permian/Triassic sediment and paleontological evidence support diachroneity of these sediments. Manuscript profile

Open Access Article

10 - Using information entropy theory and bayesian decision method to identify appropriate parameters for evaluating and discriminating oil facies (mansuri oil field, south of Iran)
حسین معماریان

Due to subsurface heterogeneity and existing vagueness in geophysical interpretation, identifying and interpretation of facies in wellbores is always prone to uncertainty and risk. Nowadays several methods have developed for quantitative facies interpretation. These met More

Due to subsurface heterogeneity and existing vagueness in geophysical interpretation, identifying and interpretation of facies in wellbores is always prone to uncertainty and risk. Nowadays several methods have developed for quantitative facies interpretation. These methods are generally divided into deterministic and stochastic categories. Deterministic methods, in spite of their simple modeling procedure, cannot expose the amount of error or accuracy of the model. On the other hand, stochastic methods, in addition to quantifying the error of the model, can provide the probability of the model’s accuracy in each point of the reservoir. The Bayesian approach is one of the stochastic methods that use conditional probabilities for modeling. This approach, as well as probabilistic modeling of hydrocarbon facies, quantitatively computes the effect of additional data in decreasing the error of the classification. Information entropy theory, by quantifying the intrinsic uncertainty in each model input parameter, can easily provide the selection of valuable parameters. The present study was carried out on one of the wells of Mansuri oil field, south of Iran. After generation of training data by using rock physics techniques and Gassmann’s relation, the value of each input parameter was identified by entropy analysis. Then, by use of Bayesian analysis and valuable parameters, oil facies classification and discrimination was implemented. The five optimum parameters were elastic impedance, compressional wave velocity, shear wave velocity, density and porosity .The amount of error in this method is approximated to be 11 percent. This investigation also showed that gamma ray parameter does not have a drastic positive effect on identification and discrimination procedure of oil facies, which has a good agreement with the results of entropy analysis . Manuscript profile

Open Access Article

11 - Facies, thickness variations and reservoir characterisation of Arab formation (Surmeh) in the Eastern part of the Persian Gulf
Ali reza Bashari

The Kimmerigian-Tithonian) Arab Zone are the prolific hydrocarbon bearing resrvoirs in the eastern part of the Persian Gulf,offshore,Iran.They were deposited in an arid climate which dominate during late Jurassic. The Berriasian to Thitonian Hith formation wich o More

The Kimmerigian-Tithonian) Arab Zone are the prolific hydrocarbon bearing resrvoirs in the eastern part of the Persian Gulf,offshore,Iran.They were deposited in an arid climate which dominate during late Jurassic. The Berriasian to Thitonian Hith formation wich overlies the Arab reservoir constitutes the cap rock,wich just to the east gradually pinches out and form a N-S feather adge. The study reveals that Arab zones form a massive to interbedded anhydrite with varying proportion of limestone and dolomite and generally have regressive units which was deposited on a broad carbonate platform .This formations are thick in center (Salman field) and mostly consist of intertidal pack/grainstones with high porosity/permeability,good cap rock and also close to the source rock,which has the most hydrocarbon potential, but towards east the layers getting thinner with unsuitable cap rock and are away from source rock ,so as a result Arab formation in this part of the Persian Gulf doesn,t seem to be attractive. This study reveals that there is still some undrilled structure within this area which could be attractive for further Exploration drilling. Manuscript profile

Open Access Article

12 - Basic steps in determining the provenance of terrestrial sedimentary sequences, with examples from central and north west of Iran
عبدالحسین امینی

By stating the fundamental differences between terrestrial and detrital facies, this paper emphasizes on the limitations of provenance studies in terrestrial facies. Considering the presence of coarse-, medium- and fine-grained facies in most of terrestrial sedimentary More

By stating the fundamental differences between terrestrial and detrital facies, this paper emphasizes on the limitations of provenance studies in terrestrial facies. Considering the presence of coarse-, medium- and fine-grained facies in most of terrestrial sedimentary sequences, the differences in textural and mineralogical characteristics, their study methods and possible differences in the provenance of these facies, the basic and necessary steps in studying these facies for determining the sedimentary provenance was investigated. In explaining these steps, some examples from terrestrial formations of Central Iran (Upper Red Formation) and north west of Iran (Zivar Formation) are presented. The role of diagenesis, structural deformation and paleogeography in the provenance study and their importance in this type of studies are explained. Finally, it is discussed how to proof the accuracy of the interpretations for the studied sedimentary sequences. Manuscript profile

Open Access Article

13 - An investigation on sedimentary facies and hydrochemistry characteristics of carbonate deposits in the Ab-e Ask region, Southeast of Damavand volcano
S. Rahmani Javanmard Mohsen Ranjbaran V. Amiri

Calcareous springs of Ab-e Ask are located 85 km northeast of Tehran, in the southern range of the Damavand volcano. Microscopic studies represent the existence of four abiotic and two microbialite facies in the Ab-e Ask travertines. The travertines are the main deposit More

Calcareous springs of Ab-e Ask are located 85 km northeast of Tehran, in the southern range of the Damavand volcano. Microscopic studies represent the existence of four abiotic and two microbialite facies in the Ab-e Ask travertines. The travertines are the main deposit types of these springs. Based on sedimentation sequence and lithofacies these travertines are categorized as first type (vent and channel), second type (pound, dam, and cascade), and third type (laminated) travertines. On a δ18O versus δ13C plot (VPDB), these travertines are plotted in the oncoid and crystalline crust lithofacies fields. These facies show the character of hydrothermal spring and set the spring in the thermogenic group. Positive values of the Langelier Saturation Index (LSI) for Pashnak, Nadaali, and Zagh springs indicate that these water samples are supersaturated with respect to calcium carbonate, which leads to considerable sedimentation around the springs. In contrast, a negative LSI value at the Sare Pole spring indicates the water is undersaturated with respect to calcium carbonate. Therefore, this spring has a lesser role in travertine deposition compared to the other springs. Also, the position of the samples on the modified Gibbs and Van Wirdum diagrams, suggests that the interaction of water with carbonate and to some extent silicate rocks is considered as the most important source of Ca and Na. Manuscript profile

Open Access Article

14 - Facies analysis and sedimentary environment of the Jeirud Formation in Garmabdar section, central Alborz: with emphasis on paleoredox conditions during deposition of black shales
Nahid Karimi Najmeh Etemad-Saeed Aram Bayet-Goll Afshin Zohdi Tomas Kumpan

The late Devonian has been associated with major global climate changes, widespread anoxia events, and the Hangenberg Crisis. The main aim of this study is to explore the relationship between paleoenvironment and paleoredox condition during deposition of the lower Devon More

The late Devonian has been associated with major global climate changes, widespread anoxia events, and the Hangenberg Crisis. The main aim of this study is to explore the relationship between paleoenvironment and paleoredox condition during deposition of the lower Devonian Jeirud Formation in the Garmabdar section, northeast of Tehran. The Jeirud Formation in the Garmabdar section, with a thickness of about 280 m, is composed of siliciclastics, carbonates, carbonate-siliciclastic hybrids and phosphorite deposits. Sedimentary facies analysis led to recognition of three siliciclastic facies associations related to estuarine environments under the influence of waves, shoreface and offshore and two carbonate facies associations related to intertidal and subtidal environments. Moreover, the geochemical paleoredox proxies (such as U/Th and V/Cr) also suggest prevailing anoxic conditions during deposition of black shales and phosphorites in the studied section. In overall, these results suggest that there is a good agreement between the depth of the depositional environment and anoxic conditions during deposition of black shales of the Jeirud Formation. Manuscript profile

Open Access Article

15 - The history of deposition and post-deposition and their effects on the reservoir quality of Asmari Formation in Ahvaz oilfield
Akbar Heidari Milad Faraji Narges Shokri

The carbonate interval of the Asmari formation along with sandstone deposits were deposited in most areas of the Zagros sedimentary Basin, including the Ahvaz area, in Oligo-Miocene. In this study, the effects of depositional and post-depositional environments on the re More

The carbonate interval of the Asmari formation along with sandstone deposits were deposited in most areas of the Zagros sedimentary Basin, including the Ahvaz area, in Oligo-Miocene. In this study, the effects of depositional and post-depositional environments on the reservoir quality of zone A7 of the Asmari Formation in well No. 4 in Ahvaz oil field were studied. The study of the sequences of the Asmari Formation in this section led to the identification of 11 carbonate facies, one evaporite facies, one mixed carbonate-siliciclastic facies, and one siliciclastic facies. Sedimentary environments of tidal zone, lagoon, coral reef and open sea were introduced for the depositional environment of identified facies. Due to the absence of sudden changes, it seems that the studied deposits were deposited in a ramp-type carbonate platform that was influenced by siliciclastic sediments from the Zagros river systems. The immature sedimentary texture of the sandstone facies indicates the proximity of the origin of the quartz sources to the carbonate basin. Among the diagenetic processes that have affected the examined sequences, the following processes can be mentioned: micritization, cementation, neomorphism, physical and chemical compaction, dissolution, fracture development and filling, dolomitization, and anhydritization. These diagenetic processes occurred in post-depositional marine, meteoric and burial diagenetic environments. Many fractures were filled with petroleum, which indicates that fractures, along with dolomitization, chemical compaction, and fenestral pores, are among the most important post-sedimentation complications to increase reservoir quality. While cementation and anhydritization resulted in reducing the reservoir quality by closing the pore spaces . Manuscript profile

Open Access Article

16 - Reconstruction of Jeirud Formation depositional environment in Aro Section (Central Alborz)
Seyed Mohammad Zamanzadeh M. Ranjbaran K. Ghaffari

In this paper it is attempted to reconstruct the depositional environment of the Jeirud Formation in Aro section. The Jeirud Formation (Late Devonian) is composed of about 45 meters of clastic sedimentary units in the southwest of Firoozkuh city, southern Alborz area. T More

In this paper it is attempted to reconstruct the depositional environment of the Jeirud Formation in Aro section. The Jeirud Formation (Late Devonian) is composed of about 45 meters of clastic sedimentary units in the southwest of Firoozkuh city, southern Alborz area. To carry out this research a field work was done during which a precise and detailed sedimentary log of the section was prepared and 52 samples from different lithologies of the formation were collected. Thin sections were prepared from all conglomeratic and sandstone samples, besides some thin sections were prepared from mudrocks and just 1 sample of paleosoil and then all were petrographically studied. In the study area, both basal and top boundary of the Jeirud Formation is disconformable with Mila and Mobarak formations respectively. All facies in the section include clastics (conglomerates, sandstones, mudstones and a paleosoil horizon). The facies were classified based on Miall classification so that conglomeratic facies comprise Gcm and Gmm; sandstone facies comprise Sh, Sp and Sm and mudrocks include Fl and Fm facies. Combined field and lab studies resulted in identification of two sedimentary facies associations including channel fill and flood plain facies associations. The reconstructed sedimentary environment of the Jeirud Formation in the Aro area represents a braided river depositional environment. The lower parts of this formation represent a finning-upward sequence which indicates deposition within a braided river channel subenvironment (conglomerates and sandstones) and the upper part is dominated with mudrocks with a paleosoil horizon representing deposition in a flood plain subenvironment. Manuscript profile

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