Shahram Sherkati - Academia.edu (original) (raw)

Papers by Shahram Sherkati

Iranian Journal of Oil and Gas Science and Technology, 2014

A synthesis of well logs was carried out and drilling mud weight data were analyzed to figure out... more A synthesis of well logs was carried out and drilling mud weight data were analyzed to figure out anomalous high fluid pressure within the Triassic evaporitic cap rock (the Dashtak formation) and study its impact on the geometry of anticlinal traps in the gas rich Gavbandi province located in the southeast part of the Zagros Mountains. The results indicated that the location of anticlinal traps at the depth in which the Permian Dehram Group reservoir unit exists is horizontally displaced with respect to surficial crest of many anticlines within the Gavbandi area. This crestal shift may be induced by abnormally high fluid pressure in the “An evaporate “member of the Dashtak formation, detected in many exploration wells across the area. When fluid pressure increases due to compaction during shortening, the higher shaliness could probably cap more fluids and consequently increase the fluid pressure within the Dashtak formation. Anomalous high fluid pressure decreases internal friction ...

Developments in Structural Geology and Tectonics, 2019

Abstract Spatially widespread and extended periods of sedimentation coupled with distinct phases ... more Abstract Spatially widespread and extended periods of sedimentation coupled with distinct phases of tectonism resulted in complex stratigraphic relationships on the northeast margin of the Arabian Plate. The Mesozoic and Cenozoic strata were incorporated into the Late Jurassic to present-day tectonic events. This tectono-stratigraphic evolution led to the formation of promising petroleum systems. Most of the explored Zagros areas are structural traps; after more than a century of hydrocarbon exploration, stratigraphic traps have become the focus of exploration. Consolidation of knowledge of regional tectono-stratigraphic evolution of the region is crucial to unlock the remaining potential. The regional architecture of sedimentary basins in central Zagros shows major changes that occurred from the Late Jurassic to the present. Coupled sedimentary and tectonic processes exerted significant controls on the facies and distributions of the strata and associated hydrocarbon systems. Sedimentary architecture and the timing of structural events on the northeast margin of the Arabian Plate were analyzed in this study using seismic profiles, well data, and gross depositional environmental maps. A tectono-sedimentary evolution of the Zagros shows a correlation with changes in the rates and vectors of displacement for the hosting and surrounding plates. Increases in rates and changes in the displacement vectors of the African and Indian Plates since opening of the Atlantic Ocean produced distinct tectonic events together with reactivation of inherited structures on the northeast margin of the Arabian Plate that induced facies changes and stratal variations. Sedimentary processes controlled the strata architectures, sequences, and facies during tectonically quiescent periods that favored the development of intrashelf basins along the margin.

GSA Bulletin, 2020

The integration of biostratigraphy, strontium isotope stratigraphy, and magnetostratigraphy allow... more The integration of biostratigraphy, strontium isotope stratigraphy, and magnetostratigraphy allowed for the precise dating of the >3.0-km-thick marine to non-marine foreland sedimentary succession within the Dowlatabad growth syncline along the Frontal Fars arc in the Zagros Fold Belt that extends from eastern Turkey to southern Iran. This area was the missing link to complete the dating of syntectonic deposits in the Fars arc and quantify the migration of sedimentary belts as well as the propagation of folding across the entire Mesopotamian foreland basin. Both are essential for defining the interplay of basin evolution and sequence of folding. Deposition of the foreland marine marls in the Mishan Formation started at ca. 11.5 Ma. The transition to a non-marine basin infill occurred at 4.9 Ma by the progradation of thick fluvial deposits of the Aghajari Formation with a fast accumulation rate of 63 cm/k.y. The beginning of growth strata deposition and thus the onset of folding i...

International Journal of Earth Sciences, 2021

The role of pre-existing structures during the building of the Zagros fold-and-thrust belt is a m... more The role of pre-existing structures during the building of the Zagros fold-and-thrust belt is a matter of debate. The orientation of the pre-existing basement faults varies in different parts of the Zagros belt. Major directions of the basement faulting in the Arabian plate and Zagros are N–S, NE–SW, NW–SE and E–W. Reactivation of these inherited pre-existing faults occurred at the Cretaceous. In this study, analogue modelling was constructed to test the effect of various orientations of the pre-existing basement faults on the deformation style in the northern boundary of Dezful Embayment. The model consisted of sand layers that partly overlay a viscous layer of silicon above wooden plates. Model results explain the development of deflection in the deformation front and the incompatibility location of faults in the basement and surface. The presence of the basal décollement horizon between the basement and overlying sedimentary sequences separated faulting geometry in the basement from sedimentary cover. Model results suggest that the flexure of the Zagros Mountain Front Faults (ZMFF) in the north part of Dezful Embayment is resulted by reactivation of pre-existing Bala Rud fault (BRF) which is an oblique ramp. The close similarity between the major structures produced during the analogue experiments and those observed in nature, suggests that BRF as a pre-existing basement fault has a major role in the deformation of the structures in the study area.

Journal of Asian Earth Sciences, 2020

Abstract Subsidence analysis of 42 exploration wells in the Zagros foreland basin indicates the t... more Abstract Subsidence analysis of 42 exploration wells in the Zagros foreland basin indicates the tectonic evolution of the basin since Early Cretaceous. The impact of inherited basement structures on the basin evolution is documented in this study. Subsidence maps show that the architecture of the basin dramatically changed during the Cretaceous. In the Central Zagros, the Hercynian palaeo-high (i.e. Wadi Al Batin palaeo-high), which affected sedimentation until the Early Cretaceous time gradually disappeared and the South Pars palaeo-high within the central Persian Gulf started to show more impact on sedimentation. The palaeo-highs in the Zagros basement have different geometrical characteristics and origin. The Hercynian and South Pars are wide-wavelength palaeo-highs with a regional-scale impact on subsidence. In contrast, the Hendijan, Kharg-Mish and Kazerun palaeo-highs with different orientations and quite smaller wavelengths show different impact on the subsidence pattern. These kinds of palaeo-highs could be related to re-activation of pre-existing basement faults. Whereas South Pars and Hercynian paleo highs are possibly related to thermal expansion or contraction of the crust. The Hendijan and Kharg-Mish palaeo-highs with the NE-SW orientation were intensively re-activated during Turonian time. On the contrary, the Kazerun Fault with the N-S orientation became more active and considerably influenced sedimentation during the last 20 Ma. Selective re-activation of deep-seated faults might have taken place as a result of changes in the orientation of the far-field stress in the region. Understanding the complexities of inherited structures and their impact on reservoir characteristics can support future exploration activities in the Zagros foreland basin.

Http Www Theses Fr, 2004

Quatre coupes structurales regionales ont ete construites a travers le Zagros Central Iranien, de... more Quatre coupes structurales regionales ont ete construites a travers le Zagros Central Iranien, depuis l'avant-pays jusqu'a la zone interne. Elles sont fondees sur des observations de terrain, sur les cartes geologiques et sur les donnees de sub-surface. Elles montrent que la geometrie des plis change de facon significative dans les directions horizontale et verticale. Le style structural est etroitement lie aux variations du comportement mecanique des unites lithostratigraphiques. Une nouvelle subdivision structurale du Zagros Central est proposee, qui illustre cette variation du comportement mecanique de la colonne sedimentaire. Elle est basee sur la presence de plusieurs niveaux de decollement, actives durant la compression. Pour etudier l'influence d'un niveau de decollement intermediaire sur le style de plissement et de chevauchement, nous avons realise des experiences analogiques en changeant la profondeur de ce niveau de decollement. En sus de cette reconstruction cinematique experimentale, l'evolution cinematique d'un pli est reconstruite a partir d'observations de terrain : les evolutions de differents plis, de plus en plus internes et de plus en plus deformees, sont interpretees comme un indicateur de la cinematique de deformation. Dans la zone d'etude, le principal style de deformation est represente par les plis de detachement, au moins pour les phases initiales de deformation, lesquelles sont suivies par la formation de plis de rampe. Nous discutons aussi d'autres aspects du pli de detachement, lies a la mobilite du sel, a des niveaux de decollement multiples et au controle tardif par implication du socle. L'evolution de la couverture sedimentaire, depuis l'episode obductif du Cretace Superieur jusqu'a la collision du Miocene Inferieur, est decrite grâce a des cartes isopaques et a des courbes de subsidence. Cette analyse montre une compression continue et des mouvements le long de failles de socle de direction N-S et NW-SE. Les mouvements, qui precedent le plissement Neogene du Zagros, ont influence l'histoire de la sedimentation. Les mouvement des failles de socle, relies aux episodes tectoniques regionaux, ont declenche la croissance discontinue de diapirs de sels. Dans le Zagros Central le rifting permo-triasique de la Neo-Tethys, le long de la faille du High Zagros ainsi que l'obduction cretacee-paleocene et ses evenement compressifs associes, avec la reactivation des directions arabiques N-S, pourraient avoir active des episode de diapirisme salifere. L'analyse des deformations par modele analogique suggere que l'initiation des chevauchement et des decrochements est influencee par les domes de sel preexistants. Le moteur de l'halocinese et de l'extrusion du sel d'Hormuz a ete l'ecrasement des domes de sel preexistants ainsi que les mouvement de pull-apart sur les failles decrochantes. La modelisation du systeme petrolier dans la zone d'Izeh est basee sur la presence hypothetique de roches-meres dans les formations de l'Albien, du Jurassique et du Paleozoique Inferieur. Cette modelisation montre que l'interaction entre sedimentation et deformation, qui varie suivant deux orientations, aurait eu un impact direct sur la maturation et l'expulsion des hydrocarbures des roches meres de l'Albien et du Jurassique. Cependant, les roches-meres du Paleozoique Inferieur auraient expulse leurs hydrocarbures avant le plissement du Zagros. Ceci suggere que les principaux facteurs favorables pour l'exploration du gaz dans les reservoirs permiens du Zagros sont la presence de paleo-structures et d'une couverture triasique efficace. Ainsi, les carbonates permiens pourraient pieger les hydrocarbures expulses hors des roches mere du Paleozoique Inferieur, avant leur re-migration et leur piegeage dans les structures du Zagros.

This map will be published by the Commission for the Geological Map of the World (CGMW-Paris) Har... more This map will be published by the Commission for the Geological Map of the World (CGMW-Paris) Hard copies or good quality pdf files are available through the CGMW website: http://ccgm.free.fr/index_fr.html Presentation of the map: The project of a Structural Map of the Arabian Plate and surrounding areas was supported by CGMW in order to bridge the gap between the Tectonic map of Africa (Milesi et al., 2010) and the International Tectonic Map of Asia (in progress) and because the Arabian plate is a very critical area to understand the geodynamic processes, which led to the collision between Africa and Eurasia. From a pedagogic point of view, the map can also help to illustrate a lot of tectonic features. The Arabian plate is very well defined between a southern divergent boundary, the Red Sea and Gulf of Aden, and a northern convergent boundary, the Zagros Fold-Thrust Belt. It is flanked by two major transform fault zones: the left lateral Levant Fault to the west and the right-late...

Proceedings, 2011

Curvature and strain analysis are two most important and well developed parameters in the anticli... more Curvature and strain analysis are two most important and well developed parameters in the anticline scale for fracture prediction (distribution and intensity). Asmari formation from Gachsaran giant oil field in the Zagros folded belt with sufficient seismic(2D) and well data(more than 350 drilled wells up to now), is one of the best case for comparing this two methods. Fracture intensity indictor map on the basis of each method has been produced and then get in the exam with production index data in some wells. Map that produced based on the 3D strain analysis and with special attention to the structural situation, structural evolution and also fracture's position related to local stress direction, is more compatible with production index than map on the basis of curvature analysis. Also it was illustrated that one of the best advantages of 3D strain analysis versus curvature analysis is variation in vertical direction and volumetric result instead of map. So there is a good possibility for correlating this result with other data such as facies, lithology and porosity models and so on, which is not involved in this paper.

SEG Technical Program Expanded Abstracts 2009, 2009

EAGE Workshop on Naturally and Hydraulically Induced Fractured Reservoirs – From NanoDarcies to Darcies, 2011

Fracture distribution in a naturally fractured reservoir is related to many different parameters.... more Fracture distribution in a naturally fractured reservoir is related to many different parameters. These parameters include fracture drivers such as tectonic phenomenon, fracture controllers such as lithology and porosity and fracture indicators such as mudloss and production data. Each of these parameters is related to fracture distribution in a specific point of view. This study is focused on Asmari Formation in Gachsaran oil field is which is the most famous naturally fractured reservoir in Iran. The main goal of this work is comparison and integration of all of the fracture signs and controller parameters to generate a comprehensive fracture intensity model. 3D strain is calculated and integrated in fracture intensity modeling as a tectonic fracture driver. Distance to fault was also contributed as a second driving factor to the modeling process. On the other hand, the mudloss was normalized and converted to fracture permeability and its 3D model was generated to be added in the intensity modeling. Productivity Index map was another indicator that was involved in modeling. The result fracture intensity model includes the effect of all of the fracture controllers, drivers and indicators and this is the main advantage of integration approach for modeling.

Salt Sediment Interactions and Hydrocarbon Prospectivity: Concepts, Applications, and Case Studies for the 21st Century: 24th Annual, 2004

... Sherkati, Shahram NIOC Yaghma Allay-Jomhuri Avenue Teheran Iran Abstract ... 3) is the result... more ... Sherkati, Shahram NIOC Yaghma Allay-Jomhuri Avenue Teheran Iran Abstract ... 3) is the result of the opening and closure of the Neo-Tethys ocean realm along the northeastern border of the Ara-bian plate (Berberian and King, 1981; Alavi, 1994). ...

Journal of Petroleum Exploration and Production Technology, 2015

Vuggy porosity is a type of porosity in carbonate rocks. This kind of porosity significantly affe... more Vuggy porosity is a type of porosity in carbonate rocks. This kind of porosity significantly affects the permeability, pressure drop and recovery factor in the reservoir. Therefore, their identification and modeling is important for the reservoir characterization and history matching. Image logs, RCAL and SCAL tests are main tools to determine vugs, though all are costly and sometimes unavailable. Thus, development of a generalized approach to recognize vugs in reservoirs will be significant. In this paper, a combined majority voting-Parzen-wavelet based algorithm is developed using gamma ray (GR), neutron porosity (NPHI), bulk density (RHOB) and sonic (DT) logs for identification of vugs in frequency domain. The agreement between the core tests results and the results of this newly developed method confirms the application of proposed new method.

Carbonates and Evaporites, 2014

ABSTRACT Vuggy porosity is a key pore space type associated with the characterization of any carb... more ABSTRACT Vuggy porosity is a key pore space type associated with the characterization of any carbonate reservoir. This porosity has significant influence on many parameters in reservoirs such as permeability, oil recovery, pressure drop and production. In this paper, two data-driven methods (i.e., Bayesian and Parzen classifiers) are used to identify vuggy porosity zones from well logs. Four well logs namely gamma ray (GR), neutron porosity (NPHI), bulk density (RHOB) and sonic (DT) from three oil wells drilled in Sarvak Formation, west of Iran, were integrated to examine the capability of the methods. The results show that the Parzen classifier gives better results than Bayesian in terms of classification accuracy. The Parzen technique classifies the given depth with an average accuracy of 77.7 % in single-well analysis and average accuracy of 67.3 % in generalization step.

$Research paper thumbnail of A combined Parzen-wavelet approach for detection of vuggy zones in fractured carbonate reservoirs using petrophysical logs$

Journal of Petroleum Science and Engineering, 2014

Saint Petersburg 2008, 2008

The aim of the paper is to discuss the role of pre-existing salt structures on the Zagros folds d... more The aim of the paper is to discuss the role of pre-existing salt structures on the Zagros folds development, within the Southern Zagros fold and thrust belt, which is characterized by the large extend of the Hormuz salt layer. We based our interpretations on geological observations, with comparison with analogue sand box experiments. Folds formed on top of a preexisting diapir display a peanut like shape on map view with a strong focusing of strain at the location of the former salt body.

Tyumen 2009 - EAGE International Conference and Exhibition, 2009

Identification and description of subsurface structures in petroleum reservoirs is a vital import... more Identification and description of subsurface structures in petroleum reservoirs is a vital importance. For this purpose there are many sources of data. One of these is borehole imaging technology. In this study we have characterized geological features and structures such as fractures, cross bedding, paleocurrent direction, borehole breakouts and in-situ stress orientation of Ilam and Sarvak Formations in southwestern Iran using Fullbore Formation MicroImager (FMI). The results show that image logs have many applications in integrated hydrocarbon exploration (geological, geophysical and geomechanical studies) especially in wells without any core available.