Petroleum Engineering – Exploration
Bahram Alizadeh; Zollfaghar Eivazi Nezhad; Majid Alipour
Abstract
In this study, the hydrocarbon potential and depositional environments of the Coniacian Laffan formation were investigated in the Binak oilfield, SW Iran. With an average thickness of 80 m, the Laffan formation consists mainly of gray shales and thin argillaceous limestones in the study area. In order ...
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In this study, the hydrocarbon potential and depositional environments of the Coniacian Laffan formation were investigated in the Binak oilfield, SW Iran. With an average thickness of 80 m, the Laffan formation consists mainly of gray shales and thin argillaceous limestones in the study area. In order to investigate the hydrocarbon potential, 22 cutting samples from 5 wells of the Binak oilfield were analyzed by Rock-Eval 6 pyrolysis and organic petrographic techniques. The hydrogen index (HI) versus Tmax diagrams indicated mixed-type II/III kerogen with a maturity corresponding to the early stages of the oil window (Tmax ≈ 435 °C). In addition, plots of S1+ S2 versus TOC were consistent with a weak to excellent hydrocarbon potential for the Laffan formation. On the other hand, organic petrographic techniques indicated that the primary organic constituents of the Laffan formation are inertinite and bituminite with subordinate amounts of amorphous organic matter (AOM). In other words, the contained organic matter was mainly composed of inertinite and lacked significant hydrocarbon potential. An abundance of inertinite and the conspicuous absence of vitrinite macerals in the studied samples suggested that the Laffan formation was deposited under sub-oxic marine conditions. Furthermore, the presence of bituminite in the studied samples greatly influenced the Rock-Eval pyrolysis readings, so geochemical evaluation of the Laffan formation using only Rock-Eval pyrolysis data may lead to erroneous interpretations. Therefore, a combination of Rock-Eval and organic petrographic methods is necessary for reliable geochemical evaluation of the Laffan formation. The results of this study can be useful for a better understanding of the Cretaceous hydrocarbon system in the study area.
Petroleum Engineering – Exploration
Bahram Habibnia; Omid Vallipour; Majid Alipour
Abstract
The Qale-Nar oilfield is an asymmetric two-humped anticline located in the northernmost part of the Dezful embayment, in which the fractured Asmari carbonates are the primary reservoir rock. In this study, for the first time, the organic geochemistry of oils produced from the Asmari reservoir is used ...
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The Qale-Nar oilfield is an asymmetric two-humped anticline located in the northernmost part of the Dezful embayment, in which the fractured Asmari carbonates are the primary reservoir rock. In this study, for the first time, the organic geochemistry of oils produced from the Asmari reservoir is used to investigate the reservoir continuity and possible compartmentalization. To this end, geological information from the studied oilfield was combined with bulk geochemistry (e.g., °API gravity) and molecular characteristics (e.g., gas chromatography (GC) and gas chromatography–mass spectrometry (GC–MS) data) of the produced oils. Two oil samples obtained from wells 6 and 10 of the studied oilfields indicate significant differences in their bulk and molecular geochemical properties. Accordingly, a scenario was presented to better explain the reservoir charging and compartmentalization in the Qale-Nar oilfield. In this scenario, low-maturity hydrocarbon pulses first charge the eastern culmination of the Qale-Nar oilfield. The activity of a fault plane located between wells 6 and 10 could induce a barrier between the two wells. Consequently, the late hydrocarbon charges with higher maturity could only charge the compartment belonging to well 6. Therefore, well 10 could not receive these high-maturity hydrocarbon pulses due to the lack of lateral connectivity. The information obtained from this study can be of great help in future reservoir studies with important implications for field development projects and enhanced-recovery plans.
Petroleum Engineering
Majid Alipour; Bahram Alizadeh; Scott Ramos; Behzad Khani; Shohreh Mirzaie
Abstract
Chemometric methods can enhance geochemical interpretations, especially when working with large datasets. With this aim, exploratory hierarchical cluster analysis (HCA) and principal component analysis (PCA) methods are used herein to study the bulk pyrolysis parameters of 534 samples from the Persian ...
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Chemometric methods can enhance geochemical interpretations, especially when working with large datasets. With this aim, exploratory hierarchical cluster analysis (HCA) and principal component analysis (PCA) methods are used herein to study the bulk pyrolysis parameters of 534 samples from the Persian Gulf basin. These methods are powerful techniques for identifying the patterns of variations in multivariate datasets and reducing their dimensionality. By adopting a “divide-and-conquer” approach, the existing dataset could be separated into sample groupings at family and subfamily levels. The geochemical characteristics of each category were defined based on loadings and scores plots. This procedure greatly assisted the identification of key source rock levels in the stratigraphic column of the study area and highlighted the future research needs for source rock analysis in the Persian Gulf basin.
Petroleum Engineering
Majid Alipour; Bahram Alizadeh; Ali Chehrazi
Abstract
Commercial hydrocarbon discoveries in the Cretaceous of the southern Persian Gulf basin provide direct evidence that there is an effective petroleum system associated with the Cretaceous series. The revised models of thermal maturity in this region are needed to investigate lateral and stratigraphic ...
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Commercial hydrocarbon discoveries in the Cretaceous of the southern Persian Gulf basin provide direct evidence that there is an effective petroleum system associated with the Cretaceous series. The revised models of thermal maturity in this region are needed to investigate lateral and stratigraphic variations of thermal maturity, which have not so far been addressed in detail for this part of the Persian Gulf. Such thermal maturity models are required to delineate the existing play assessment risks and to predict properties in more deeply buried undrilled sections. This study uses two dimensional basin modeling techniques to reconstruct maturity evolution of the Cenomanian Middle Sarvak source rock, presumably the most likely source for these hydrocarbons. The results indicate that an estimated 900 meter difference in the depth of burial between the southeastern high and the adjacent trough tends to be translated into noticeable variations at both temperature (135 °C versus 162 °C) and vitrinite reflectance (0.91% versus 1.35%). Since the organic matter in the mentioned source rock is of reactive type II, these could cause a shift of about 18 million years in the onset of hydrocarbon generation over respective areas.
Bahram Alizadeh; Majid Alipour; Bahram Habibnia; Ahmad Reza Gandomi-Sani; Behzad Khani; Saber Shirvani; AmirAbbas Jahangard
Abstract
In an attempt to reconstruct the paleoenvironments of deposition for the Middle Jurassic Baghamshah formation, samples collected from six outcrop sections along the Shotori swell were subjected to detailed geochemical analyses. Bulk geochemical and biological marker data indicate a logical trend of the ...
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In an attempt to reconstruct the paleoenvironments of deposition for the Middle Jurassic Baghamshah formation, samples collected from six outcrop sections along the Shotori swell were subjected to detailed geochemical analyses. Bulk geochemical and biological marker data indicate a logical trend of the variation of organic input, salinity, and oxicity within Baghamshah paleoenvironments across the studied area. An increase in terrestrial character from southern end towards the central parts of the Shotori swell parallels with a uniform increase in the oxicity and a decrease in the salinity. The northernmost sections are characterized by less terrestrial impact, reduced oxicity, and elevated salinity compared to the central and southern sections. These variations are interpreted in the framework of past geometric configuration and a hypothetical paleogeomorphologic model is tentatively proposed for the Middle Jurassic of the area. According to these results, the depositional setting of the studied formation decreased in depth from Section-1 towards Section-4, suggesting that the proximity of the latter section to the Yazd Block may have had a strong control over the observed geochemical variations. The terrestrial organic input and the oxicity of the environment are conspicuously low for northern sections and their salinity shows a sharp increase compared to other sections. We hypothesize that a fault plan exists across the northern and southern Shotori Mountains that had played an active role in creating the current geochemical variations.
