Sedimentology
Alireza Rostami; Mohammad Hossein Adabi; Abbas Sadeghi; Seyed Ali Moallemi
Abstract
The Dariyan Formation with the Aptian age is the youngest reservoir formation of the Upper Khami group which is important in terms of hydrocarbon reservoir potential. This formation is 135 meters thick in the Kuh-e-Mish surface section and consists of thin, thick and massive limestone, marl and shale. ...
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The Dariyan Formation with the Aptian age is the youngest reservoir formation of the Upper Khami group which is important in terms of hydrocarbon reservoir potential. This formation is 135 meters thick in the Kuh-e-Mish surface section and consists of thin, thick and massive limestone, marl and shale. Petrographic studies led to the identification of 13 microfacies. These have been deposited in four types of depositional environments, including inner ramp, mid ramp, outer ramp and basin, in a ramp type carbonate platform. Based on petrography, lateral and vertical facies changes, 3 third-order cycles distinguished. An integrated multidisciplinary approach including, petrography, surface gamma-ray spectrometry and trace element analysis have been used for recognition of original carbonate mineralogy and stratigraphic interpretations of this succession. Geochemistry of minor and major elements reveal original aragonitic mineralogy of the Dariyan Formation. Bivariate plot of Mn versus Sr/Ca values illustrated that the Aptian carbonates were affected by semi close diagenetic system with moderate water/rock interaction. Trace elements (Fe and Mn) contents are compared with distribution of sedimentary facies and depositional sequences to investigate and correlate stratigraphic boundaries, which are determined by sequence stratigraphy in shallow marine carbonate platform of the Dariyan Formation. The elemental peaks coinciding with the sequence boundaries and elemental peaks are correlated with maximum flooding surfaces.
Sedimentology
Mohammad Shalalvand; Mohammad Adabi; Afshin Zohdi
Abstract
In this study, the Late Paleocene Taleh Zang Formation in the southwest of Kermanshah hasbeeninvestigatedfor elemental geochemistry and effective diagenetic processes during burial. The thickness of the studied section is 282 meters that mainly composed of shallow marine limestones with interbedded of ...
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In this study, the Late Paleocene Taleh Zang Formation in the southwest of Kermanshah hasbeeninvestigatedfor elemental geochemistry and effective diagenetic processes during burial. The thickness of the studied section is 282 meters that mainly composed of shallow marine limestones with interbedded of marl and dolomite. The main diagenetic processes affecting the TalehZangFormation include micritization, various types of porosity, cementation, dolomitization and compaction. Due to the texture and the abundance of unstable skeletal particles (green algae and bivalve), porosity and cementation aremorecommon among the identified processes. Microscopic and geochemical studies have shown that these processes have taken place in eogenesis and early mesogenesis stages in marine, meteoric and shallow burial environments. Evidences indicate that the carbonates of the TalehZangFormation didnot tolerate deep burial after the deposition during diagenesis. Fluids that affected the lower parts of the formation during burial were mainly marine. Moreover, tothetop ofthe sequence in addition to seawater less meteoric fluids have affected the marine carbonates of the Taleh Zang Formation during diagenesis. The high amounts of Sr/Mn (mean27/51) and Sr/Ca (mean 1/61) and also low Mn (mean 27ppm) and Fe (mean 78ppm) values indicate close digenetic system with low water/rock interaction for the carbonate samples of the TalehZangFormation.
Sedimentology
Seyedeh Zahra Pourheidar; Mohamad Hosein Adabi; Mir Reza Moussavi Tasooj; Abbas Sadeghi
Abstract
The Elika Formation forms the major part of the Triassic carbonate sediments in the Alborz basin. In this study, facies and sedimentary environments of this formation were studied in Shahmirzad section whith a thickness of 746 meters and in Zereshk-Darreh section whith a thickness of 756 meters in the ...
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The Elika Formation forms the major part of the Triassic carbonate sediments in the Alborz basin. In this study, facies and sedimentary environments of this formation were studied in Shahmirzad section whith a thickness of 746 meters and in Zereshk-Darreh section whith a thickness of 756 meters in the southern part of central Alborz. Based on facies studies, four carbonate facies associations (tidal tlat, shoal, lagoon and open marine) have been identified, including twelve carbonate microfacies and have been deposited in a carbonate ramp. Deposition of sediments in this sequence can be divided into three stages. In the first stage, most of vermiculate limestone deposits are composed of bioturbated mudstone and clotted peloidal mudstone. The high frequency of facies such as laminated stromatolite, intraclastic packstone-grainstone and laminated mudstone are characteristic features of the second stage of sedimentation (middle dolomite) and indicate a decrease in the depth of sedimentary environment. In the third stage, the environment was suitable for the expansion of barriers and formation of packstone-grainstone facies.
Sedimentology
Elmira Shahkaram; Mohammad Hosein Adabi; Davood Jahani; Seyed Hamid Vaziri
Abstract
The Dalichai Formation is the first rock unit of the Middle Jurassic in the Alborz sedimentary basin that has occurred in a marine environment. The boundary of the Dalichai formation with Shemshak Formation is erosional unconformable while it is concordant with Lar formation. Due to lithological similarity, ...
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The Dalichai Formation is the first rock unit of the Middle Jurassic in the Alborz sedimentary basin that has occurred in a marine environment. The boundary of the Dalichai formation with Shemshak Formation is erosional unconformable while it is concordant with Lar formation. Due to lithological similarity, the boundary of the Dalichai formation with the Lar formation is unclear. It is also very difficult to identify the primary carbonates mineralogy, due to the effects of diagenetic processes solely on the basis of petrographic studies. We studied a section of Sharaf mountain with a thickness of 1420m and 149 samples was studied. The study of the major and minor elements, the Oxygen and Carbon isotopes, and plotting of these values against each other represents that the Dalichai formation have had original aragonite mineralogy, and the nonmarine diagenesis have had the highest impact on them. Plotting the Sr/Ca ratio versus Mn value, shows that these carbonates are affected in a semi-closed to open diagenetic system. Using Sr, Sr/Na, Sr/Ca, Oxygen and Carbon isotopes, the boundary of this formation with the Lar Formation is recognized in thickness of 1200m. The diagenetic environment temperature for this section limestones is 32.9ºC.
Sedimentology
Umid Kakemem; Mohammad Adabi; Ehsan Dehyadegari
Abstract
Depositional texture, sedimentary structure and present fauna led to characterize twelve carbonate- evaporate facies. These facies were classified in three facies belts including tidal flat, lagoon and shoal. Developpment of tidal zones together with evaporate deposits and thrombolite facies (signs to ...
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Depositional texture, sedimentary structure and present fauna led to characterize twelve carbonate- evaporate facies. These facies were classified in three facies belts including tidal flat, lagoon and shoal. Developpment of tidal zones together with evaporate deposits and thrombolite facies (signs to a shallow depositional environment), the absence of continuous reef‐frame builders, high production of carbonate mud, absents of calciturbidite, tempestites deposits and slump structures are evidences for a homoclinal carbonate ramp setting. The facies based on petrophysical characteristics which is the results of depositional texture and diagenesis are classified in seven reservoir rock types. In which, the first rock type (RT1) has weak reservoir property and toward RT7 reservoir quality will increase. Facies variation related to sea level fluctuations led to subdivide the whole strata into two 3rd order sequences. Facies stacking patterns in the sequences characterized by subtidal facies (lagoon and shoal) tend to have the most reservoir quality that covered by evaporative (Mf1) and peritidal facies (Mf2 to Mf4) with low-reservoir quality. The most reservoir quality in both K1 and K2 reservoir zones is coincident with late TST, maximum flooding surface (mfs) and late HST in identified depositional sequences which is settled in high-energy shoal facies intervals.
Sedimentology
Yazdan Golestan; Umid Kakemem; Mohammad Adabi; E. Dehyadegari
Abstract
Carbonate-evaporate succession with siliciclastic sediments and mixed siliciclastic carbonate deposits of Asmari-Pabdeh reservoir in Karanj Oil Field with Oligo-Miocene in age was studied to determine diagenesis, microfacies and original carbonate mineralogy. Micritization, dissolution, compaction, neomorphism, ...
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Carbonate-evaporate succession with siliciclastic sediments and mixed siliciclastic carbonate deposits of Asmari-Pabdeh reservoir in Karanj Oil Field with Oligo-Miocene in age was studied to determine diagenesis, microfacies and original carbonate mineralogy. Micritization, dissolution, compaction, neomorphism, cementation and dolomitization are the main diagenesis processes that effect Asmari-Pabdeh successions. Petrographic studies led to identification of three types of dolomite such as dolomicrite, dolomicrosparite and dolosparite, in which dolomicrosparite and particulary dolospatite caused increase in reservoir quality. Eleven carbonate-evaporate microfacies were identified. These deposited in four major environments comprises of tidal flat, lagoon, carbonate shoal and open marine. Sedimentary environment of the Asmari Formation recognized as a homoclinal ramp. Diagenetic studies reveal impact of marine, meteoric and burial diagenesis on the deposits. Geochemistry of minor and major elements reveal original aragonite mineralogy for carbonates of the Asmari Formation. The high Sr/Mn and Sr/Ca and minor amounts of manganese implying close diagenetic system with low Water/Rock interaction for the Asmari Formation succession.
Sedimentology
Umid Kakemem; Mohammad Adabi; Bahman Gudarzi
Abstract
Investigating of dolomitization and its effects on reservoir quality of the Upper Dalan Formation with Permian-Triassic in age is the aim of this study. In this section, the Upper Dalan Formation consists of carbonates and evaporite rocks with a thickness of 265m. Eleven carbonate- evaporate microfacies ...
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Investigating of dolomitization and its effects on reservoir quality of the Upper Dalan Formation with Permian-Triassic in age is the aim of this study. In this section, the Upper Dalan Formation consists of carbonates and evaporite rocks with a thickness of 265m. Eleven carbonate- evaporate microfacies have been distinguished on the basis of depositional textures, petrographic analysis and present fauna. These microfacies were deposited in three facies belts including tidal flat, lagoon and carbonate shoal. Absents of turbidite (calciturbidite) and tempesties deposits, slump structures, large barrier reef, widespread tidal flat and lagoonal facies with aboundent of mud matrix indicated that depositional setting of this interval was a homoclinal carbonate ramp. Based on petrographic studies, 4 types of dolomite including dolomicrite, dolomicrosparite, dolosparite and dolomite cement are recognized. Porosity and permeability data in varies dolomites reveals that in most dolomite the amount of permeability is not directly related to whole porosity, but depends mainly on the amount of connected porosities through bottleneck holes and is associated with increasing in dolomite crystal sizes. Therefore, from the early stage of dolomitization in the form of dolomicrite toward increasing in the rate of dolomitization with larger crystal size and with the form of subhedral and euhedral crystals, the reservoir properties had a high visible improvement. Ultimately, by persisting of dolomitization and growth of dolomite crystals toward each other and disappearance of bottleneck holes and creation of dolomite cements, reservoir properties destroyed. Dolomitization increased reservoir quality in grain dominated dolo-packstones with planner crystal texture.
A. Amiri; I. Rassa; A. Khakzad; M. H. Adabi
Abstract
Stabilization of potentially sliding terraces and natural slopes are of great importance from view point of resident security, environment protection, river engineering and water and soil conversation. Soil reinforcement using tree toots is one of the methods being studied by many researchers. Most of ...
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Stabilization of potentially sliding terraces and natural slopes are of great importance from view point of resident security, environment protection, river engineering and water and soil conversation. Soil reinforcement using tree toots is one of the methods being studied by many researchers. Most of them have worked on the effect of root density and few of them on the root diameter leading to contradicting results. In this paper the combined effect of root diameter and density on the shear resistance of soil is investigated by series of in-situ direct shear tests. Eighteen tests were carried out on soil possessing Willow roots and the results compared with those of non rooted soil as reference. To explain the observations, a new parameter referred to as root diameter-density index (RDDI) was defined. The results reveal that an increase in RDDI causes a significant increase in the apparent cohesion of rooted soil, but a little decrease in the internal friction angle. In both cases the rate of variation decreases with increasing RDDI and tends to a little value; however the extreme values of 212% and -15% are observed respectively. As general conclusion for rooted soils, the dominance of variation of apparent cohesion with respect to that of internal friction angle results the shear resistance ameliorates within a range of RDDI, and for further values it tends to a stabilized value. Moreover, for practical purposes, a relation was developed to be used by designer engineers.
