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Tolokonnikova Z.,Kuban State University | Yazdi-Moghadam M.,NIOC Exploration Directorate
Geologos | Year: 2013

Four bryozoan species are described from the upper member (Shishtu II) (Visean, Early Carboniferous=Mississippian) of the Shishtu Formation of central Iran: Nikiforovella ulbensis Nekhoroshev, 1956, Nicklesopora elegantulaformis (Nekhoroshev, 1956), Primorella cf. iranica Gorjunova, 2006, and Nikiforopora intermedia (Nikiforova, 1950). This Visean assemblage shows close palaeogeographical affinities of Iran with Kazakhstan and Russia (eastern Transbaikalia, Kurgan region).

Dehbozorgi M.,University of Tehran | Pourkermani M.,University of Tehran | Arian M.,University of Tehran | Matkan A.A.,University of Tehran | And 2 more authors.
Geomorphology | Year: 2010

Neotectonics is a major factor controlling landform development in tectonically active regions, and it has significantly affected fluvial systems and mountain-front landscapes in the Sarvestan area of the central Zagros, Iran. The area is located along the simply folded belt of the Zagros, and is an outcome of the SW-NE oriented tectonic conversion that initiated in the Late Cretaceous and strengthened during the Early Miocene due to the collision of the Arabian and Eurasian plates. To assess tectonic activities in the area, we analyzed geomorphic indices: the stream-gradient index (SL), drainage basin asymmetry (Af), hypsometric integral (Hi), valley floor width-valley height ratio (Vf), drainage basin shape (Bs), and mountain-front sinuosity (J). These indices were combined to yield the relative active tectonics index (Iat) using geographic information systems (GIS). Based on Iat values, the study area was divided into four parts: Class 1 (very high relative tectonic activity, 1.0% in area); Class 2 (high, 20.0%); Class 3 (moderate, 67.0%), and Class 4 (low, 12.0%). The results are consistent with field observations on landforms and geology. © 2010.

Pireh A.,Research Institute of Petroleum Industry RIPI | Alavi S.A.,Shahid Beheshti University | Ghassemi M.R.,Geological Survey of Iran | Shaban A.,NIOC Exploration Directorate
Journal of Petroleum Science and Engineering | Year: 2015

Shale-gas production depends on natural and hydraulic fractures to flow it to well. A major part of source rocks in the Zagros Fold Belt was deposited during Neocomian time; the lowermost part of the Garau Formation has charged the Early Cretaceous Petroleum System of the Lurestan subzone, which has a potential of being as a shale-gas resource. These source rocks are widely distributed in the Lurestan Depression and in the NW part of the Dezful Embayment. Knowing factors which control fracture intensity and fracture length in each area are important in drilling into shale-gas resources. In this regard, a very dense and accurate field data acquisition on fracture sets, orientation, length, as well as bedding thickness, texture and lithology was carried out in Early Cretaceous Garau Formation and basal Sarvak Formation within two anticlines with different structural settings (Kabir-Kuh and Khoram-Abad). According to our analyses, we have identified 2 fracture systems: (1) an orthogonal fracture system: set A in Khoram-Abad anticline and sets A and B in the Kabir-Kuh anticline and a longitudinal fracture set: set B in Khoram-Abad anticline and sets C and D in the Kabir-Kuh anticline, (2) an oblique fracture system: sets C and D in Khoram-Abad anticline and set E in the Kabir-Kuh anticline. The normal faults and stylolites (prior to stylolitization) in the study area of Kabir-Kuh anticline had formed in response to extension stress regime and the transverse fractures in the study area of Khoram-Abad anticline are Early Cretaceous to Late Oligocene in age, then the transverse fractures and their orthogonal stylolites in Kabir-Kuh anticline and longitudinal and oblique fracture systems in the Khoram-Abad anticline have formed from Early Miocene to Middle Late Miocene, while longitudinal and oblique fracture sets in the Kabir-Kuh anticline have formed since Middle Late Miocene. We suggest that there have been two phases of counterclockwise rotations in orientation of the stress fields that had produced these fractures. The rotations in the stress field have probably occurred due to rotation of the Arabian plate during its convergence to the Eurasian plate which had changed the orientation of fractures. These rotations forming some range of fractures with different attitudes, that now with recent direction of impression apply by the Arabian plate those fractures which generate in the past would have shown different reaction. In our study area in addition to transverse fracture sets which originated near parallel to maximum horizontal stress, one set of oblique fractures is the second normal fracture set which is reactivated in response to fluid pressures, prior to origination of new hydraulic fractures. In the Lurestan structural province, deformation intensity is increased from the Kabir-Kuh anticline in the southern part of the Lurestan structural province to the Khoram-Abad anticline in the northeastern part of the province. In the Kabir-Kuh anticline, lithology has played the most important role in fracture intensity, so that in some places even with increasing bedding thickness, we observe an increase in fracture intensity instead of the expected decreasing fracture intensity. While in Khoram-Abad anticline bedding thickness has the most important effect on fracture intensity, and lithology has a minor role. In both investigated areas, fracture length is increased with changing texture from mudstone to wackstone and also from wackstone to packstone. © 2014 Elsevier B.V.

Tavakoli M.,South Pars Gas Complex SPGC | Nejati Kalateh A.,University of Shahrood | Ghomi S.,NIOC Exploration Directorate
Journal of African Earth Sciences | Year: 2016

The thick sedimentary units in Central Iran contain structures that form oil traps and are underlain by a basaltic layer which is amenable for study using its magnetic susceptibility. The study and modeling of such sedimentary structures provide valuable exploratory information. In this study, we locate and interpret an underground magnetic susceptibility interface using 3D non-linear inverse modeling of magnetic data to make a better judgment in the context of hydrocarbon existence. The 3D structure is reconstructed by making it equal to a number of side by side rectangular hexahedrons or prisms and calculating their thicknesses such that the bottoms of the prisms are corresponding to the magnetic susceptibility interface. By one of the most important mathematical tool in computational science, Taylor series, the non-linear problem changes to a linear problem near to initial model. In many inverse problems, we often need to invert large size matrices. To find the inverse of these matrices we use Singular Value Decomposition (SVD) method. The algorithm by an iterative method comparing model response with actual data will modify the initial guess of model parameters. The efficiency of the method and subprograms, programmed in MATLAB, has been shown by inverse modeling of free noise and noise-contaminated synthetic data. Finally, we inverted magnetic field data from Garmsar area in Central Iran which the results were acceptable. © 2015 Elsevier Ltd.

Ghafouri A.,NIOC Exploration Directorate
32nd Asian Conference on Remote Sensing 2011, ACRS 2011 | Year: 2011

Remote sensing is an efficient tool for the assessment and monitoring of natural resources. Image classification is the most general method of information extraction through remotely sensed images. Mixed pixels, however may lead to inaccurate classification results in most conventional image classification algorithms. Subpixel image classification is a process which tries to extract the proportions of the pure components of each mixed pixel. In traditional image classification methods which are called pixel-based methods in this article, each pixel is assigned to a single class by assuming all pixels within the image are pure. Therefore, acknowledging surface heterogeneity during image classification is important. This can be done by using spectral unmixing techniques. It is a technique that has been developed to derive fractions of spectrally pure materials that contribute to observed spectral reflectance characteristics of a mixed pixel using endmember spectra. Image classification results is the basis of many judgments and decisions in remotely sensed projects, afterward its precision must be evaluated as well to remove any inaccuracy or errors that distorts accuracy and accurateness of process to get the process improved in further projects. There are many pixel unmixing and subpixel image classification methods however they have some common aspects in procedure. In this paper three methods of these methods are selected and applied. Using the aforementioned method makes the process of petroleum exploration faster and to some extents easier. The best situations that this method is highly recommended are: oil exploration in very large areas to make a general decision in the process of exploration and the other situation doubtlessly is in control procedure of the petroleum exploration process.

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