The South Central Iran Block has experienced polyphase intensive deformation in the Cenozoic time. Large-scale superposed folds in South Rafsanjan document the Cenozoic tectonic events within the South Central Iran Block. In this study, a case study of this deformation More
The South Central Iran Block has experienced polyphase intensive deformation in the Cenozoic time. Large-scale superposed folds in South Rafsanjan document the Cenozoic tectonic events within the South Central Iran Block. In this study, a case study of this deformation inferred from regional-scale Rafsanjan superposed folds in the south of Central Iran is presented to reconstruct the deformation sequence and tectonic regime during crustal shortening. These data indicate that the superposed folds, dominated by a two-stage tectonic transpression regime which experienced two phases of superposed folding, leading to the orthogonal superposition of WNW–ESE-trending folds onto NE–SW trending folds. Structural analyses and fault kinematic analyses in the Rafsanjan Structural Belt indicate a two-stage syn-folding paleo-stress field during the Cenozoic. The early phase of tectonism is characterized by late Miocene NW-SE transpression, which led to the development of NE-trending fold structures and causing the occurrence of an orogeny perpendicular shortening. This tectonic event was most likely associated with progressive anticlockwise rotation of the Central Iran Block. Subsequent tectonic event from Late Miocene until Quaternary contributed to a phase of contraction that overprinted the early NNE–SSW shortening in the interior parts of the studied area and generated a large-scale NE-convex fold belt and the typical large-scale superposed folds within the South of Central Iran Block. In terms of geodynamics, the later tectonism is likely to have been related to the NE-directed convergence between the Arabian and the Eurasian Plates.
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Estimation of in-situ stress tensor in sedimentary basins using information obtained from exploration and development oil and gas wells during the drilling and logging process may be used for estimation of in-situ stress tensor in sedimentary basins. The in-situ stress More
Estimation of in-situ stress tensor in sedimentary basins using information obtained from exploration and development oil and gas wells during the drilling and logging process may be used for estimation of in-situ stress tensor in sedimentary basins. The in-situ stress magnitude and orientation and the resulting stress regime around the studied wells have been several application in secondary recovery programs from hydrocarbon reservoirs as well as wellbore stability analysis. In this paper, the magnitude of in-situ stress is estimated by using abovementioned data in some oil wells located in the south west of Iran. Increasing the oil production by hydraulic fracturing design and sand control in the multi-layer reservoirs such as the Marun giant oil field with loose sand horizons and also improving drilling performance in the Gachsaran formation¬ requires knowledge about the prevailing stress conditions. This research, tries to analyze the stress regime of the Asmari and Gachsaran Formations around the selected wells in the Marun and Lali fields using constructed Mechanical Earth Models (MEM) and their differences are discussed. The calculated stress magnitudes in studied wells indicate a significant drop in magnitude of horizontal stresses from the Gachsaran to Asmari reservoirs in the Marun oil field. The magnitudes of the three principal stresses resulted that SHmax is the maximum principal stress and the Shmin is the minimum principal stress, thus a strike-slip stress regime (SHmax>Sv>Shmin) dominates in the Gachsaran sequence and the Asmari formation of the Lali oil field. however, in the Gachsaran formation of Marun giant oil field, stress regime is reverse-strike slip but normal stress regime is dominated in it's Asmari reservoir. The In-situ stress condition indicates that the structural condition and the depth difference of these structures plays an important role in the tectonic stress regime changes.
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