Sequence stratigraphy of the Triassic Period: Case from the Dashtak and Khaneh-Kat formations, the Zagros Basin, Iran

Rahmani, Omeid; Khoshnoodkia, Mehdi; Mohseni, Hassan; Hajian, Mahmoud

doi:10.1016/j.petrol.2018.03.092

Cited by 10 publications

(5 citation statements)

References 13 publications

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“…Whereas, in Bakirman‐1, Bjeel‐1,2,3,7, Bekhma‐1, and Gulak‐1 wells toward the southwest of Warte area, it was deposited in a tidal flat, lagoonal, and evaporitic environment, which formed from dolomite and dolomitic, silicified and oolitic limestones with green shales and anhydrite replacements (Csató et al, 2014) that refers to a shallower and more restricted setting than the Warte area. Regional correlation of the Baluti Formation with surrounding areas shows that the Late Triassic Dashtak Formation which is mainly comprised of shallow water carbonate–evaporite sediments consisting of dolomite, evaporite, and shale rare in fossil content was deposited in a supratidal and tidal flat to lagoonal environment within the Neo‐Tethys Ocean in the eastern Zagros Fault and Thrust belt in Iran (Rahmani, Khoshnoodkia, Mohseni, & Hajian, 2018). It differs from the Baluti Formation in the Warte Section by containing multiple evaporate intervals which were thought to have been deposited during the second Triassic infilling‐subsidence event (Rahmani et al, 2018).…”

Section: Discussionmentioning

confidence: 99%

“…Regional correlation of the Baluti Formation with surrounding areas shows that the Late Triassic Dashtak Formation which is mainly comprised of shallow water carbonate–evaporite sediments consisting of dolomite, evaporite, and shale rare in fossil content was deposited in a supratidal and tidal flat to lagoonal environment within the Neo‐Tethys Ocean in the eastern Zagros Fault and Thrust belt in Iran (Rahmani, Khoshnoodkia, Mohseni, & Hajian, 2018). It differs from the Baluti Formation in the Warte Section by containing multiple evaporate intervals which were thought to have been deposited during the second Triassic infilling‐subsidence event (Rahmani et al, 2018). While in southeastern Turkey, the Çanakli Formation which forms the base of Cudi Group is mainly comprised of dolomite (Fortuny et al, 2015), which was deposited in a lagoonal shallow marine carbonate environment during the Late Triassic age (Ziegler, 2001).…”

Section: Discussionmentioning

confidence: 99%

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Sedimentology of the Baluti Formation (Late Triassic) in the Warte area, northeastern Iraqi Kurdistan region

et al. 2021

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A detailed sedimentological investigation of the Baluti Formation (Late Triassic) in the Warte section, Imbricated Zone, northeastern Kurdistan region of Iraq has been undertaken for the first time. The formation is comprised of 34 m of dolomitic limestone, marly limestone, and marly dolomitic limestone which is partially brecciated and all interbedded with shale and several beds of marl in the lower part. Based on the field observations and petrographic inspections, four different lithostratigraphic units were identified in the studied section, which are, in ascending order: marly dolomitic limestone interbedded with marl and shale unit, brecciated marly dolomitic limestone interbedded with shale unit, fractured marly dolomitic limestone unit, and marly limestone interbedded with shale unit. The petrographic study of 19 thin sections of Baluti carbonates shows that the majority are composed of carbonate mud (micrite). The skeletal grains include ostracods, calcispheres, benthonic foraminifera, gastropods, bivalves, clasts, and bioclasts. While non‐skeletal grains include peloids, intraclasts, and extraclasts. The results of X‐ray diffraction (XRD) of five samples and scanning electron microscope (SEM) of three samples of the shale and marl of the studied formation show that the main clay mineral is illite, whereas non‐clay mineral is dolomite. The carbonate rocks of the Baluti Formation were subjected to different diagenetic processes, such as micritization, dolomitization, cementation, compaction, solution, pyritization, neomorphism, and fracturing. Three main microfacies were identified in the Baluti carbonates and according to their environmental interpretation, they are grouped into one basic type of facies association—subtidal‐semi restricted lagoon. Field observation, petrographic, microfacies, and textural analysis indicate that the Baluti Formation in the Warte section was deposited in a shallow marine, subtidal (lagoon) environment with semi‐restricted conditions.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Sedimentology of the Baluti Formation (Late Triassic) in the Warte area, northeastern Iraqi Kurdistan region

et al. 2021

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“…The rather complex carbonate cap rock pore structures are probably a consequence of the abundant presence of nanometer-to micrometer-sized pores and throats (Chalmers et al, 2012;Cao et al, 2015). This results from the influence of the sedimentary environments in which the sediments forming these rocks were deposited together with the complex diagenetic alterations they underwent (Ross and Bustin, 2009;Anovitz et al, 2013;Lai and Wang, 2015;Liu et al, 2018;Rahmani et al, 2018).…”

Section: Relationships Between Pore Size Proportion and Sealing Capacitymentioning

confidence: 99%

“…Pervasively distributed carbonate cap rocks acting as effective sealing layers play a significant role in the preservation of hydrocarbons within carbonate reservoir strata (Lü et al, 2014;Zhang et al, 2015;Rahmani et al, 2018). Accordingly, these cap rocks have received increasing attention, especially the carbonates of the Ordovician Yingshan Formation, because they are considered one of the key sealing rocks in the Tarim Basin (Jin, 2014;Lü et al, 2017;Wu et al, 2019a).…”

Section: Introductionmentioning

confidence: 99%

Fractal characteristics of pore networks and sealing capacity of Ordovician carbonate cap rocks: A case study based on outcrop analogues from the Tarim Basin, China

Wu¹,

Tang²,

Gomez‐Rivas³

et al. 2021

Bulletin

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. Jun Wu is grateful to the China Scholarship Council (201806400037) for supporting his study as a joint Ph. D. candidate at the University of Barcelona. Enrique Gomez-Rivas acknowledges funding 2 by the AGAUR-Agència de Gestió d'Ajuts Universitaris i de Recerca of the Generalitat de Catalunya ("Beatriu de Pinós" fellowship 2017SGR-824), and the Spanish Ministry of Science, Innovation and Universities ("Ramón y Cajal" fellowship RYC2018-026335-I). We are grateful to Editor-in-Chief Prof. Robert Merrill, Associate editor Prof.Barry Jay Katz and two anonymous reviewers for their thoughtful suggestions and critical comments that significantly improved the manuscript.Abstract：Understanding and predicting the main controls on the sealing capacity of carbonate cap rocks is of great significance for ultra-deep carbonate reservoir exploration and production. This study focuses on revealing the pore networks and sealing capacity of the Ordovician carbonate cap rocks in the Tarim Basin, by analyzing samples from outcrop analogs using optical and scanning electron microscopy and a combination of mercury intrusion capillary pressure and nitrogen gas adsorption. Three classes of cap rocks are defined here according to their pore throat structure, fractal dimension and sealing capacity. These carbonate cap rocks are dominated by limestones and dolomitic limestones. Four pore types are identified: microfracture, intragranular pore, intercrystalline pore and intracrystalline pore. Six pore structure types show multiscale variability from macropores to micropores. The pore structures present multiple fractal behaviors, with fractal dimensions showing an increasing trend as the pore diameter decreases. The cover coefficient, a parameter that allows characterization of the cap rock sealing performance, shows an increasing trend along with increasing the fractal dimension of pore structure. The average cover coefficients of six pore 3 structure types not only show good correlations (either exponential or linear) with certain fractal dimensions, but they also demonstrate a strong positive correlation with the average fractal dimension. These results suggest that the sealing capacity of the studied rocks increases with increasing fractal dimension. The sealing performance of cap rocks significantly decreases with increasing the amount of macropores. This work provides a relevant case study for further understanding of pore structures and sealing capacity of carbonate cap rocks.

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“…The Lower-Middle Triassic Dashtak Formation is a formation in the Kazerun Group with lithologies of do-lomite, shale, anhydrite, Argilaceuos dolomite, etc. The lithologies of this formation consist of 6 sequences alternately, such as the section of shale Agar evaporative part A, evaporative part B, evaporative part C, the Sefidar dolomite part, and evaporative part D. Due to the presence of thick anhydrite layers, this formation is considered as an important cap rock in the Zagros Basin for gas reservoirs of the Dahrom Group (Dalan and Kangan) in the south of Iran (Khoshnoodkia et al, 2010;Hajian-Barzi et al, 2015;Rahmani et al, 2018;Habibnia et al, 2016). In this study, petrophysical and geological information of two wells has been used for modelling.…”

Section: Geology Of the Regionmentioning

confidence: 99%

Drill Bit Selection in a Formation With Different Sedimentary Facies Using the Markov Chain: A Case Study at One of the Oil Fields in the South of Iran

Rad¹,

Negahban²,

Tokhmechi³

et al. 2021

MBPB

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The selection of a drill bit is an essential issue in well planning. Furthermore, identification and evaluation of sedimentary rocks before well drilling plays a crucial role in choosing the drill bit. Moreover, the Markov chain as a stochastic model is one of the powerful methods for identifying lithological units, which is based on the calculation of the transition probability matrix or transition matrix. The Markov chain experiences transitions from one state (a situation or set of values) to another according to specified probabilistic rules. In this paper, the Markov chain was implemented for bit selection in a formation with different sedimentary facies (such as the Dashtak Formation). Therefore, the proper drill bit was proposed by utilizing the transition matrix of rock facies and the available bits. This process was carried out in two wells where the thicknesses of the Dashtak Formation are 960 meters and 1410 meters. Consequently, the results indicate that the Markov chain is a practical method for selecting bits in a sequence of rock facies based on an acceptable matching between the reality mode (the used bits in the well) and the Markov chain results. Besides, in the case of using an improper bit in a well, and using a bit in a washing and reaming operation, there were differences between the used bits and the Markov chain outputs.

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Sequence stratigraphy of the Triassic Period: Case from the Dashtak and Khaneh-Kat formations, the Zagros Basin, Iran

Cited by 10 publications

References 13 publications

Sedimentology of the Baluti Formation (Late Triassic) in the Warte area, northeastern Iraqi Kurdistan region

Sedimentology of the Baluti Formation (Late Triassic) in the Warte area, northeastern Iraqi Kurdistan region

Fractal characteristics of pore networks and sealing capacity of Ordovician carbonate cap rocks: A case study based on outcrop analogues from the Tarim Basin, China

Drill Bit Selection in a Formation With Different Sedimentary Facies Using the Markov Chain: A Case Study at One of the Oil Fields in the South of Iran

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