محیط رسوبی

Open Access Article

1 - Cruziana ichnofacies from Nayband Formation (Late Triassic) in the Parvadeh section, Southwest Tabas, East central Iran
Nasrollah Abbassi Mohammad ghavidel Morteza Yosefi Navid Navidi Izad

Nayband Formation is composed of sandstone, coal bearing shales, siltstone, and fossiliferous limestone in the southwest Tabas section, east central Iran. In this section, it is 1410 m in thickness and Late Triassic in age. A divers trace fossils have been found in the More

Nayband Formation is composed of sandstone, coal bearing shales, siltstone, and fossiliferous limestone in the southwest Tabas section, east central Iran. In this section, it is 1410 m in thickness and Late Triassic in age. A divers trace fossils have been found in the middle parts of sequence as 400-600 m. These trace fossils include Lockeia isp., Palaeophycus tubularis, Palaeophycus striatus, Planolites beverleyensis, Rhizocorallium isp., Rosselia isp., and cf. Treptichnus isp. This ichnoassemblage is attributable to Cruziana ichnofacies with presence of Lockeia isp., Rhizocorallium isp., and, Rosselia isp. This part of Nayband Formation was deposited in low energy conditions below fair-weather wave base. Manuscript profile

Open Access Article

2 - Microfacies, Sedimentary Environment and Sequence Stratigraphy of the Qom Formation, Deh Namak, Northwest of Garmsar
Jahanbakhsh Daneshian Asadi Mehmandosti yousef ramezani

Deh Namak section is exposed along the most northern point of the Qom Formation, where the Central Iran zone and Alborz zone come together. The study of microfacies, sedimentary environments and sequence stratigraphic features of the Qom Formation in this area can h More

Deh Namak section is exposed along the most northern point of the Qom Formation, where the Central Iran zone and Alborz zone come together. The study of microfacies, sedimentary environments and sequence stratigraphic features of the Qom Formation in this area can help to understand the situation of the Qom sedimentary basin in the northern part, bordering the Alborz zone. 166 samples of the Qom Formation in Deh Namak section in the northwest of Garmsar are investigated. Microfacies analysis of these sedimentary rocks indicates that according to sedimentary environment they consist of nine microfacies belonging to four facies belts including tidal flat, agoon, shoal/reef sediments and slope of platform. Due to the absence of the gravitational and turbidity sediments and abundance of reef/shoal sediments, a rimmed carbonate shelf depositional environment is suggested in which more sediments were precipitated in shallow water. In this model, deep facies of the basin did not spread and the deepest facies belong to the slope. Also, sequence stratigraphic studies show that the Deh Namak section is composed of four sedimentary sequences of third- order, two types II and one type I sequence boundaries were recognized in this formation. Manuscript profile

Open Access Article

3 - Microfacies and sedimentary environment of Lower Cretaceous deposits in Qumenjan section, south west of Qayen
Hourieh Zarei Seyed Naser Raisossadat M. Mortazavi M. Yazdi

In order to study the Lower Cretaceous deposits, Qumenjan section has been selected and measured. Field and lab studies of the Lower Cretaceous deposits in this section reveal a gradual change of the depositional setting, from a fluvial depositional system (continental More

In order to study the Lower Cretaceous deposits, Qumenjan section has been selected and measured. Field and lab studies of the Lower Cretaceous deposits in this section reveal a gradual change of the depositional setting, from a fluvial depositional system (continental environment) to a mixed siliciclastic- carbonate ramp (marine environment). The continental deposits of the studied section include conglomerate and sandstone lithofacies that are deposited in a proximal gravel- bed braided river. In the studied sedimentary sequence, the marine siliciclastic- carbonate facies associations are formed in three tidal flat, lagoon and shoal facies belt in the inner and mid ramp setting. Manuscript profile

Open Access Article

4 - Geochemical Investigation and Effect of Sedimentary Environment Changes on Pabdeh Formation Hydrocarbon Potentiality in Mansuri Oilfield
بهرام علیزاده ندا جنت مکان هرمز قلاوند محمد حسین حیدری فرد

Pabdeh Formation is one of the most important probable source rocks in Mansuri oifield being under investigation . In this study, hydrocarbon potential of pabdeh formation is evaluated. Also effect of sedimentary environment changes on geo More

Pabdeh Formation is one of the most important probable source rocks in Mansuri oifield being under investigation . In this study, hydrocarbon potential of pabdeh formation is evaluated. Also effect of sedimentary environment changes on geochemical and hydrocarbon potential variation is studied ,To achieve this , hydrocarbon potential of Pabdeh Formation with Rock Eval Pyrolysis was investigated .Besides that, gas chromatography and gas chromatography-mass spectrometry data were utilized . Based on this study , in the Late Eocene age , relative sea level had raised , while in the Oligocene age, falling in sea level was occurred .Variation in sea level caused Pabdeh Formation to be heterogeneous in hydro carbon potential . Pabdeh Formation in Mansuri oilfield from geochemical aspects is divided into three divisions. Lower ad Upper zones I this formation, have fair (0.5-1%TOC) to good (1-2%TOC0 hydrocarbon potential and contain Kerogen type III. These zones have gas production potential . Middel zone, has very good (2-4%TOC) to excellent (TOC>4%) potential and contains Kerogen type II and III.Middel zone has oil production potential . Rock Eval data as well as thermal history modeling demonstrate that; Pabdeh Formaion is in early oil window, started yielding petroleum since 5-6 million years Manuscript profile

Open Access Article

5 - Geochemical Investigation and Effect of Sedimentary Environment Changes on Pabdeh Formation Hydrocarbon Potentiality in Mansuri Oilfield
بهرام علیزاده ندا جنت مکان هرمز قلاوند محمد حسین حیدری فرد

Pabdeh Formation is one of the most important probable source rocks in Mansuri oifield being under investigation . In this study, hydrocarbon potential of pabdeh formation is evaluated. Also effect of sedimentary environment changes on geo More

Pabdeh Formation is one of the most important probable source rocks in Mansuri oifield being under investigation . In this study, hydrocarbon potential of pabdeh formation is evaluated. Also effect of sedimentary environment changes on geochemical and hydrocarbon potential variation is studied ,To achieve this , hydrocarbon potential of Pabdeh Formation with Rock Eval Pyrolysis was investigated .Besides that, gas chromatography and gas chromatography-mass spectrometry data were utilized . Based on this study , in the Late Eocene age , relative sea level had raised , while in the Oligocene age, falling in sea level was occurred .Variation in sea level caused Pabdeh Formation to be heterogeneous in hydro carbon potential . Pabdeh Formation in Mansuri oilfield from geochemical aspects is divided into three divisions. Lower ad Upper zones I this formation, have fair (0.5-1%TOC) to good (1-2%TOC0 hydrocarbon potential and contain Kerogen type III. These zones have gas production potential . Middel zone, has very good (2-4%TOC) to excellent (TOC>4%) potential and contains Kerogen type II and III.Middel zone has oil production potential . Rock Eval data as well as thermal history modeling demonstrate that; Pabdeh Formaion is in early oil window, started yielding petroleum since 5-6 million years Manuscript profile

Open Access Article

6 - Interpretation of sedimentary environment and factors affecting reservoir quality in upper Sarvak Formation in one the oil fields of Abadan plain
Mohammad Hossein Saberi Bahman Zarenezhad الهام اسدی Nasim Rahmani

The Sarvak Formation of the Albian-Turonian Formation is one of the most important hydrocarbon reservoirs in south and southwest of Iran. In this study, in order to assess the reservoir quality, from a petrographic study and porosity and permeability data, an important More

The Sarvak Formation of the Albian-Turonian Formation is one of the most important hydrocarbon reservoirs in south and southwest of Iran. In this study, in order to assess the reservoir quality, from a petrographic study and porosity and permeability data, an important 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 Four facies tidal flat, 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 diagenetic 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 diagenetic 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 studies identified third order sedimentary sequences of the age of Turonian, Late Cenomanian, and Middle Cenomanian, and studied the facies and diagenetic processes within its framework. Correlation of porosity and permeability data of the core showed that the reservoir quality in this formation was influenced by facies and diagenetic processes. So that the microfacies containing the rudist have the highest reservoir quality. Due to the diagenetic processes, sedimentary and porosity and permeability data, the facies shoal and open marine to the land have the best reservoir quality. Manuscript profile

Open Access Article

7 - Interpretation of sedimentary environment and factors affecting reservoir quality in upper Sarvak Formation in one the oil fields of Abadan plain
Arad Kiani Mohammad Hossein Saberi Bahman Zare nejad Elham Asadi Nasim Rahmani

The Sarvak Formation of the Albian-Turonian Formation is one of the most important hydrocarbon reservoirs in south and southwest of Iran. In this study, in order to assess the reservoir quality, from a petrographic study and porosity and permeability data, an importan More

The Sarvak Formation of the Albian-Turonian Formation is one of the most important hydrocarbon reservoirs in south and southwest of Iran. In this study, in order to assess the reservoir quality, from a petrographic study and porosity and permeability data, an important 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 Four facies tidal flat, 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 diagenetic 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 diagenetic 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 studies identified third order sedimentary sequences of the age of Turonian, Late Cenomanian, and Middle Cenomanian, and studied the facies and diagenetic processes within its framework. Correlation of porosity and permeability data of the core showed that the reservoir quality in this formation was influenced by facies and diagenetic processes. So that the microfacies containing the rudist have the highest reservoir quality. Due to the diagenetic processes, sedimentary and porosity and permeability data, the facies shoal and open marine to the land have the best reservoir quality. Manuscript profile

Open Access Article

8 - (Biostratigraphy and microfacies of the Asmari Formation in south flank of Mish anticline (northeast of Gachsaran
Saber Ahmadi Ali seyrafian Hosyen vaziri-Moghadam

Asmari Formation at the section of the south flank of Mish anticline (northeast of Gachsaran), located 22 km northeast of Basht city, in vicinity village Kalagh ¬Neshin is investigated and has a thickness of 281 meters. In this research, biostratigraphy and microfacies More

Asmari Formation at the section of the south flank of Mish anticline (northeast of Gachsaran), located 22 km northeast of Basht city, in vicinity village Kalagh ¬Neshin is investigated and has a thickness of 281 meters. In this research, biostratigraphy and microfacies of the Asmari Formation in this section were studied and the results were compared with 5 section of Asmari Formation in similar regions and close to it. By studying on 172 microscopic sections, 3 the biozone for Asmari Formation in the section the study was carried out and the section studied given that is: Lepidocyclina – Operculina – Ditrupa assemblage zone. Archaias asmaricus – Archaias hensoni – Miogypsinoides complanatus assemblage zone. Indeterminate zone. According to the study of benthic foraminifera and biozones, the cut off age is from the late Oligocene (Rupelian-Chattian) to the early Miocene (Aquitanian). Microfacies studies led to identify 10 microfacies and 4 subfacial belonging to the open marine and lagoon (semi-closed and enclosed) environments, which includes the external, intermediate, and interior parts of a hemocalinal ramp. Manuscript profile

Open Access Article

9 - Microfacies analysis, Sedimentary Environment and Sequence Stratigraphy of the Qom Formation in the Naraq area
Alireza Ashouri Asma Aftabi arani Jahanbakhsh Daneshian Abbas Ghaderi Mohammad Reza Aria Nasab

Naraq section is located at the South of the Qom sedimentary basin in Central Iran. The study of microfacies sedimentary environments and sequence stratigraphic features of the Qom Formation in this area can help to understand the situation of the Qom sedimentary basin. More

Naraq section is located at the South of the Qom sedimentary basin in Central Iran. The study of microfacies sedimentary environments and sequence stratigraphic features of the Qom Formation in this area can help to understand the situation of the Qom sedimentary basin. In this study, 111 samples of the Qom Formation in Naraq section in the northwest of Naraq are investigated. Based on field observation and thin-section studies, 6 microfacies related to the lagoon, reef and slope parts of carbonate platform have been recognized.Due to the presence of slope microfacies and skeletal and non-skeletal grains that are transported from the shallow to this environment and the existence of SMF9, bioturbation, Also the presence of barrier / reef sediments, a carbonate shelf depositional environment is suggested for the Qom Formation in Naragh section. In this model, marls of b member of the Qom Formation show more relative depth. Also sequence stratigraphic studies show that the Naraq section is composed of three sedimentary sequences of third- order three types I and one type II sequence boundaries were recognized in this formation. Manuscript profile

Open Access Article

10 - Investigating the role of microfacies, depositional conditions and diagenesis on the quality of the reservoir section, Ilam Formation (Santonian-Campanian) in one of the fields in southwestern Iran, Dezful embayment
Seyedeh Akram Jooybari Peyman Rezaei Majid Mehdipour

10.52547/ispg.39683.11.21.16

The Ilam formation is one of the important carbonate oil reservoirs of the Zagros and Dezful embayment basins. In order to identify the microfacies and depositional conditions and diagenesis processes, 100 microscopic thin sections from one well of this reservoir in on More

The Ilam formation is one of the important carbonate oil reservoirs of the Zagros and Dezful embayment basins. In order to identify the microfacies and depositional conditions and diagenesis processes, 100 microscopic thin sections from one well of this reservoir in one of the Dezful embayment oil fields were evaluated. Porosity and permeability data were used to check reservoir quality. The petrographic study led to the identification of 9 microfacies belonging to the facies belts of lagoon, barier, middle ramp and outer ramp, which were deposited in the homoclinal ramp environment. The most important diagenesis processes identified in Ilam reservoir include cementation, dissolution, fracture, micriteization, stylolitization, and dolomitization. Based on the qualitative classification of the reservoir and Lucia's petrophysical diagrams, the lagoon facies and the middle ramp have an average reservoir status, and the carbonate barier facies and the outer ramp have a weak reservoir status. The reservoir quality of the lagoon and middle ramp facies is related to the existence of interconnected and channel porosities. Due to strong cementation and the presence of unrelated porosity such as mold porosity, the carbonate barier facies has low permeability and has a poor reservoir status. In general, the Ilam Formation in the studied field is in a weak state in terms of reservoir, which can be important in addition to the facies controllers in relation to the lack of expansion of fracture and dolomitization and the excessive expansion of cementation in these facies. Therefore, the Ilam Formation in the studied field has a weak reservoir performance due to diagenetic processes, despite having more shallow sequences than deep ones. Manuscript profile

Open Access Article

11 - 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

12 - Reconstruction of Asmari Formation Sedimentary Environment in Asmari and Gurpi Anticlines in the oil field of Masjed Soleiman (Southwest of Iran)
Navab Varnaseri Davood Jahani Nader Kohansal Ghadimvand Mohsen Pourkermani

In this research, the process of lithological changes and diagenetic processes of Asmari formation with Oligo-Miocene age has been investigated. For this purpose, 400 samples were selected and collected from a section of the Masjid Suleiman oil field and the surface sec More

In this research, the process of lithological changes and diagenetic processes of Asmari formation with Oligo-Miocene age has been investigated. For this purpose, 400 samples were selected and collected from a section of the Masjid Suleiman oil field and the surface section of the Asmari anticline in the Dezful depression and the Gurpi anticline in the Izeh zone. Petrographic studies revealed 18 sedimentary microfacies that were deposited on a ramp-type carbonate platform. Among the significant diagenetic processes in the region are the process of micritization, bioturbation and the influence of burrowing organisms, cementation (types of cement related to marine, meteoric and burial diagenesis environments), dissolution (meteoric and burial dissolution), dolomitization (in different phases), silicification, pyritization, phosphatization, mechanical compaction, chemical compaction, fracture and porosity. Based on the identification of the sequence boundaries and following the facies depth changes, the carbonate sequence of the Asmari formation in the subsurface section and the Asmari anticline section are introduced in the form of 3 sedimentary sequences of the third order shallowing upwards, which are the former Aquitanian, the late Aquitanian and Bordigalin belong. Among the dominant porosities in the Asmari Formation, we can mention the hole, mold and fracture porosities. Manuscript profile

Open Access Article

13 - Depositional Environmental Analysis of Shally Units of Pabdeh-Gurpi Formation and Clay Minerals Effect on Wellbore Stability, Aghajari Oil Field
بهمن سلیمانی Zahra Dehghani

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<span style="font-size: 10.0pt; mso-bidi-font-size: 11.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: Calibri; mso-bidi-theme-font: major-bidi; mso-bidi-language: FA; mso-bidi-font-weight: bold;">This research is related to detect of clay minerals and geochemical changes of Pabdeh-Gurpi shale formations and their role in borehole instability in Aghajari oil field. For this purpose, these formations were investigated using NGS well log (one well ring), X-ray diffraction method (XRD) and XRF analytical method (11 samples from two wells). In the NGS log, the detected minerals are illite, montmorillonite, mixed layer, glauconite and feldspar. In the XRD method, clay minerals illite, montmorillonite, mixed layer, chlorite and kaolinite were identified in order of abundance.These minerals due to their sensitivity to react with water causes the instability of the borehole. The high ratio of Si/Al and changes of Ti and high level of Fe3+ and Mg are also a sign of the widespread presence of illite, chlorite and montmorillonite in the mentioned formations.   <span style="font-size: 10.0pt; mso-bidi-font-size: 11.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: Calibri; mso-bidi-theme-font: major-bidi; mso-bidi-language: FA; mso-bidi-font-weight: bold;">The changes of major and trace elements compared to Al2O3 except for MnO, CaO, and P2O5 showed a positive linear relationship. The changes in the amount of Fe2O3 show the oxidizing conditions in the upper part of the base, but the reducing conditions towards the upper side. Based on the amount of iron, manganese and vanadium, the sediments were formed under conditions of reduction, non-sulphide reduction Eh and medium to low pH. Variations in Th/U ratio (1-4.5) indicate marine to transitional environments. The existence of horizons rich in organic matter (more than 2%) confirms the reduction conditions.   <span style="font-size: 10.0pt; mso-bidi-font-size: 11.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: Calibri; mso-bidi-theme-font: major-bidi; mso-bidi-language: FA; mso-bidi-font-weight: bold;">Based on the low values of the Zr/Rb ratio, the sediments in the upper and lower parts are finer than the middle part of the grain. The relative accumulation of biogenic carbonate along with the shale is periodic and is reflected in the changes in the (Zr+Rb)/Sr ratio. Based on the Sr/Ba ratio, marine conditions prevail in the lower part and continental and metamorphic and sometimes marine conditions prevail in the upper part of the formation. Oxidation-reduction conditions were also investigated. The values of the V/(V + Ni) ratio of the semi-reduction region, the Ni/Co ratio of the reduction region and the V/Cr diagram show the almost reduction region and in some cases the oxidant conditions. Paleoclimatic conditions at the time of sedimentation based on low values of Rb/Sr ratio (less than 0.14) were completely hot and dry.   Manuscript profile

Open Access Article

14 - Stratigraphy, facies and depositional conditions of the Asmari Formation (Rupelian-Burdigalian) in the south-eastern folded Zagros, Bandarlengeh embayment (Khamir salt mountain section)
Peyman Rezaei Seyedeh Akram Jooybari Abdullah Najafi

Asmari Formation (Rupelian-Burdigalian) is one of the most well-known formations in Iran. In order to investigate the stratigraphy and sedimentary environment, a section of this formation was selected in Khamir salt mountain section in Bandarlengeh embayment. In this nu More

Asmari Formation (Rupelian-Burdigalian) is one of the most well-known formations in Iran. In order to investigate the stratigraphy and sedimentary environment, a section of this formation was selected in Khamir salt mountain section in Bandarlengeh embayment. In this number, 70 limestone microscopic thin sections and 3 marl samples (XRF) were evaluated to identify the microfacies and the sedimentation conditions.The petrographic study led to the identification of 10 microfacies belonging to the facies belts of tidal, lagoon, carbonate bar, open marine, which were deposited in the homoclinal carbonate ramp environment. The composition of marl facies oxides also indicates the presence of carbonate minerals, quartz and clay minerals, which along with field observations and alternating calcareous facies suggest that this facies was deposited in an open marine environment. Finally, it seems that the facies and fossil diversity of the Asmari Formation in the mentioned section is such that during the Aquitanian stage, this formation was located closer to the coast line and during the Rupelian and Chattian-Burdigalian times, it was located at a further distance from the coast line. Manuscript profile

Open Access Article

15 - 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

Open Access Article

16 - Reservoir quality evaluation of the Asmari Formation in the framework of sequence stratigraphy in one of the Iranian SW oilfield
Ebrahim Sfidari A. Hakymi-Zanuz

The Oligo-Miocene Asmari Formation forms the main reservoir rock of many Dezful Embayment fields. Microfacies analysis, diagenetic features, and sequence stratigraphic evaluation of the Asmari Formation were carried out based on the petrographic investigation, petrophys More

The Oligo-Miocene Asmari Formation forms the main reservoir rock of many Dezful Embayment fields. Microfacies analysis, diagenetic features, and sequence stratigraphic evaluation of the Asmari Formation were carried out based on the petrographic investigation, petrophysical logs, and core measurement porosity and permeability data. Petrographic analyses led to the identification of twelve microfacies indicating five subenvironments including tidal flat, lagoon, barrier (belonging to inner ramp), middle ramp, and outer ramp, all of which are representing a homoclinal ramp. Tidal flat, lagoonal, and barrier microfacies are mostly present in the upper parts of the Asmari Formation, while middle and outer ramp microfacies were largely developed in the middle part. Cementation, compaction, dolomitization, dissolution, and fracturing are the main diagenetic processes in this formation. Compaction and cementation have negatively affected reservoir quality while fracturing, dolomitization, and dissolution contributed to reservoir quality enhancement. The sequence stratigraphic studies represent three 3rd order sequences of early Aquitanian, late Aquitanian, and early Burdigalian age based on the main features of microfaces, their depositional environments, and shallowing and deepening-upward trends. Microfacies of the Transgressive System Tract (TST) have been affected by compaction, dissolution (moldic), cementation, and slightly dolomitization in the middle to outer ramp parts. The Highstand System Tract in the inner ramp part has been affected by dolomitization, dissolution, and fracturing close to the sequence boundaries, and has a better reservoir quality than the Transgressive System Tract. Manuscript profile

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