A Ramezani Akbari; H Rahimpor-Bonab; M.R Kamali; R Moussavi-Harami; A Kadkhodaie
Abstract
The Fahliyan Formation of Khami Group is hosting important hydrocarbon reserves in Iran and also is a main reservoir rock in the Abadan Plain oil fields which is Neocomian in age. In the studied wells its thickness is about 440 meters. In the Abadan Plain, the Fahliyan Formation transitionally overlies ...
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The Fahliyan Formation of Khami Group is hosting important hydrocarbon reserves in Iran and also is a main reservoir rock in the Abadan Plain oil fields which is Neocomian in age. In the studied wells its thickness is about 440 meters. In the Abadan Plain, the Fahliyan Formation transitionally overlies the argillaceous limestone of the Garau Formation and its upper boundary changes into marl and argillaceous limestone of the Gadvan Formation. According to thin sections examinations prepared from cuttings and cores plus electrofacies analysis 11 microfacies and 2 lithofacies are recognized. This formation consists of two carbonate and mixed carbonate-siliciclastic (mixed zone) members. The Lower Fahliyan was deposited in carbonate ramp environment while, the Upper Fahliyan was deposited in a mixed carbonate–siliciclastic environment. To determine electrofacies, the rock types were modeled with using MRGC method. Best correlation between petrographical and electrofacies is 12 cluster model (in MRGC method). These results suggest that the electrofacies model is in agreement with heterogenetic rock type such as mixed carbonate–siliciclastic environment observed in petrography. Also, in homogenous rock type such as carbonate ramp environment electherofacies can’t completely determine geological facies. Based on petrographical and electrofacies this formation is composed of three third order sequences with type sb2 sequence boundaries. But, the third sequence in mixed carbonate–siliciclastic zone is terminated with sb1 sequence boundary just below the Gadvan Formation.
N Mohammadi Akbari; M.R Kamali
Abstract
Sarvak Formation (with the age span of Cretaceous) is considered as one of the most prominent oil reservoirs in the south of Iran and a significant volume of oil accumulation in the Persian Gulf basin is attributed to this formation. In the present research plan, in order to evaluate the hydrocarbon ...
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Sarvak Formation (with the age span of Cretaceous) is considered as one of the most prominent oil reservoirs in the south of Iran and a significant volume of oil accumulation in the Persian Gulf basin is attributed to this formation. In the present research plan, in order to evaluate the hydrocarbon generation capacity of this formation, cores, cuttings and oil samples collected from fields’ wells located in block D underwent some investigations which were in the Iranian sector of the Persian Gulf. Correlation is defined as the geochemical comparison between hydrocarbons themselves, or also hydrocarbons with source rocks, and furthermore defining the quality of the genetic relation between them. In order to achieve this goal a variety of gadgets and parameters are used, some of them being biomarkers and stable isotopes.
The results obtained from geochemical analyses including primary analyses (pyrolysis rock-eval), bitumen extraction and separation, complementary analyses (gas chromatography), gas chromatography-mass spectrometry and stable isotope studies on samples indicate that kerogen of studied samples is a combination of types II and III and it implies that most organic matter generating hydrocarbon were formed in a marine environment along with a little entering from land. The hydrocarbons existing in Sarvak Formation were generated from a semi carbonated clastic source rock and were sedimented under a reduced or semi-reduced environment. The saturate sections of the Chromatograms samples indicate the lack of environmental biodegradation in the studied samples. The Oil and inter bed shaly-marl samples of the Sarvak Formation show a fair to good hydrocarbon potential. The set of under study samples are located in the beginning of the oil generation window (late diagenesis) and early catagenesis in terms of their maturity degree. Furthermore, hydrocarbons show a paraffinic-naphthenic characteristic. It seems the shaly-marl layers existing in some parts of the Sarvak Formation (Ahmadi member), in Block D, in the Persian Gulf, have been the cause for the generation of hydrocarbons available in the Sarvak reservoir.
S Parham; M.R Kamali
Abstract
The Dalan upper member is a gas reservoir in the Persian Gulf, which is important because of gas and condensates production. This unit has been affected by dolomitization. Dolomicrites is a type of dolomites identified in the studied interval. This investigation concentrates on dolomicrites from the ...
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The Dalan upper member is a gas reservoir in the Persian Gulf, which is important because of gas and condensates production. This unit has been affected by dolomitization. Dolomicrites is a type of dolomites identified in the studied interval. This investigation concentrates on dolomicrites from the point of view of its spatial distribution and reservoir zonation. This type of dolomite has been studied using thin section, RCAL, and isotopic analysis data. This type of dolomite is identified relying upon petrographical evidences such as very fine to fine unimodal, anhedral to subhedral crystals of dolomite. The texture is equivalent to xenotopic-A and nonplanar-A. Some features like fenestral fabrics, microbial filaments evaporitic cast, anhydrite nodules and mud cracks are also identified. The findings led us to the conclusion that dolomicrites pertains to fenestral dolomitic mudstone, which deposited in supratidal to arid upper intertidal. The result of isotopic analysis of oxygen revealed that this dolomite formed at temperature between 20.36ºC to 46.6ºC. This confirms deposition in sabkha environment so sabkha dolomitization model offered for dolomicrites. The diagenetic processes affected dolomudstones are dissolution, cementation, compaction, anhydrite replacement and fracturing.
Studies of the porosity and permeability data indicated that reservoir characterization is under the influence of texture. In mud-dominated facies like dolomitic mudstone, reservoir quality is poor to fair unless this part influenced by subsequent diagenetic processes like dissolution and fracturing.
M khanjani; S.R Moussavi-Harami; H Rahimpour-Bonab; M.R Kamali
Abstract
The Albian - Turonian Sarvak Formation, the second major reservoir formation in south and southwest Iran is composed of mainly carbonate rocks. In this study, the upper part of Sarvak Formation in Siri Oil Fields was studied to determine facies, depositional environments, diagenetic processes and sequence ...
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The Albian - Turonian Sarvak Formation, the second major reservoir formation in south and southwest Iran is composed of mainly carbonate rocks. In this study, the upper part of Sarvak Formation in Siri Oil Fields was studied to determine facies, depositional environments, diagenetic processes and sequence stratigraphy analysis. The facies analysis led to the recognition of 12 microfacies in 5 facies associations, which deposited in a homoclinal carbonate ramp environment. The main diagenetic processes affected carbonates of this formation are bioturbation, micritization, cementation, dissolution, dolomitization, stylolitization, pyritization and fracturing. The most important cements in this formation are fine equant calcite cement, drusy mosaic calcite cement, coarse blocky calcite cement and syntaxial calcite overgrowth cement. Three third order sequences recognized in sequence stratigraphic studies for the upper part of Sarvak Formation taking into account of facies and diagenetic events in a sequence stratigraphic framework.
M Sadeghi; M.R Kamali; R Ghavami Riabi; B Qorbani
Abstract
In this study, rock samples from the pabdeh and Gurpi formations of well#NH-01 in the Nosrat Oil Field subjected to geochemical evaluation techniques using Rock-Eval pyrolysis, bitumen extraction, Column Chromatography and gas chromatography. The result of geochemical study indicates Kerogen type II ...
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In this study, rock samples from the pabdeh and Gurpi formations of well#NH-01 in the Nosrat Oil Field subjected to geochemical evaluation techniques using Rock-Eval pyrolysis, bitumen extraction, Column Chromatography and gas chromatography. The result of geochemical study indicates Kerogen type II and III. However, most samples tend to related kerogen Type II suggesting that source rock was deposited in the anoxic to suboxic environments and most organic matter derived from marine and partly from terrestrial sources. The pabdeh Formation shows fair to good hydrocarbon potential and has already entered oil generation window, whereas the Gurpi Formation has Poor to fair hydrocarbon potential. The Gas chromatography conducted on these samples indicates that most samples are rich in saturated hydrocarbons and also suggests organic matter of the pabdeh and Gurpi formations are all indigenous.
S Parham; M.R Kamali
Abstract
The Dalan Upper member (Permian) with carbonates and evaporite interlayer is one of the most important gas reservoirs in the folded Zagros area and Persian Gulf. In this investigation porosity types, their genesis and controlling factors have been studied at Surmeh surface section and a subsurface section ...
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The Dalan Upper member (Permian) with carbonates and evaporite interlayer is one of the most important gas reservoirs in the folded Zagros area and Persian Gulf. In this investigation porosity types, their genesis and controlling factors have been studied at Surmeh surface section and a subsurface section in Persian Gulf. Based on the new genetic classification of Ahr (2008) for carbonate porosity, porosity is created or altered by hybrids of depositional processes, diagenetic processes and mechanical fracturing in the studied intervals. In subsurface samples, porosity is hybrid of depositional and diagenetic types. In grain-supported microfacies, like ooidgrainstone related to the shoal environment, interparticle porosity is created which is a type of depositional porosity. Moldic, vuggy and intercrystallineporosity, which are diagenetic types of porosity,were formed in the later stages of diagenesis. Therefore, porosity in this microfacies is facies-selective and facies map can be used as a proxy for porosity distribution map. In surface section, besides depositional and diagenetic porosity, fracturing and brecciation are also significant. Brecciationoccured as a result of dissolution of anhydrite of Nar Member and formed the solution collapse breccias. Active tectonic in the folded Zagros belt and folding are another possible sources of fracturing in the surface samples. The properm data of routine analysis shows that the reservoir characteristic of the studied interval is heterogeneous.So, it has been compartmentalized into six zones with different reservoir qualities from poor to very good.
S. Parham; M. R. Kamali; F. Fayazi
Abstract
The Dalan Formation (Upper Permian) is mainly composed of limestone and dolostone with minor evaporite interbeds. Upper carbonates of the Dalan Formation constitute one of the main gas reservoirs in the Zagros fold thrust belt especially in the Fars and the Persian Gulf. The upper part of the Dalan Formation ...
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The Dalan Formation (Upper Permian) is mainly composed of limestone and dolostone with minor evaporite interbeds. Upper carbonates of the Dalan Formation constitute one of the main gas reservoirs in the Zagros fold thrust belt especially in the Fars and the Persian Gulf. The upper part of the Dalan Formation consists of oolitic grainstone with high reservoir quality. Based on sedimentological studies in the upper Dalan unit, seven microfacies have been recognized. This microfacies have been deposited in warm, arid intertidal, lagoon and shoal. They deposited in a homoclinal ramp. Different diagenetic process affected this unit are bioturbation, micritization, neomorphism, replacement, dolomitization, anhydritization, mechanical and chemical compaction, cementation, dissolution and fracturing. Based on the evidence like widespread dissolution, formation of moldic and vuggy porosity and precipitation of different types of meteoric cements and based on paragenetic sequences, it can be concluded that the studied interval, have not buried after the deposition, but at least some parts like oolitic shoal exposed subearially and was affected by meteoric diagenesis that was followed by deep burial diagenetic environment.
M. Memariani; H. Kermanshahi; M. R. Kamali
Abstract
With respect to distribution of Surmeh Formation in Persian Gulf region, this formation may act as candidate source rock for hydrocarbon accumulation in this region. A comprehensive geochemical analysis including Rock-eval Pyrolysis, Gas Chromatography (GC), Gas Chromatography – Mass Spectrometry ...
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With respect to distribution of Surmeh Formation in Persian Gulf region, this formation may act as candidate source rock for hydrocarbon accumulation in this region. A comprehensive geochemical analysis including Rock-eval Pyrolysis, Gas Chromatography (GC), Gas Chromatography – Mass Spectrometry (GC-MS), were carried out on cuttings, in order to determine its hydrocarbon potentiality. Based on Rock-Eval data, the organic matter of the Surmeh formation is type II and III kerogen, with low maturity being at the end of diagensis stage. It exhibits a poor source rock characterization with low content of TOC. A close similarity can be seen, between organic matter extracted from Surmeh sample with that of oil sample collected from Upper Dariyan, Lower Dariyan and Maudud reservoir in the field. Biomarker results indicate that an open marine and few terrestrial input source rocks deposited in an anoxic condition with carbonate origin. Based on geochemical investigations Surmeh Formation isn't suitable source rock in the study area locally. Biomarker derived from rock extracts and trapped oils indicated that they share the same origin and were stained by laterally migrating oils from distant area.
