List of Articles گرانی&#172

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  1 - Study of North West Sedimentary Basin of Iran by 3D Modeling of Gravity Data
  Mojtaba  Tavakoli Ali nejati
  Inversion of the gravity data is one of the most interesting numerical tools for obtaining three dimensional geological images. In this paper 3D nonlinear inversion of the gravity data is used to determine the basement topography. The basement was juxtaposed with the re More

  Inversion of the gravity data is one of the most interesting numerical tools for obtaining three dimensional geological images. In this paper 3D nonlinear inversion of the gravity data is used to determine the basement topography. The basement was juxtaposed with the regular array of rectangular prisms in which the thickness of each prism is determined by the inversion procedures. Prepared algorithm is based on singular value decomposition (SVD) method which ca modify the initial model by comparing observed and estimated gravity data. The SVD method is very popular with geophysical data analysts because it is mathematically robust and numerically stable. To illustrate effectiveness of the prepared codes and algorithm related to 3D inversion of gravity data, both synthetic and real data were tested by the mentioned algorithm. The real data were part of the gravity data which were acquired in Moghan area (located in the north-west of Iran). Because of being near to the Baku oil-rich regions and thick sedimentary rocks, the Moghan sedimentary basin is an interesting area from hydrocarbon exploration point of view. Determination of the sedimentary rocks thickness is an important factor in oil and gas exploration issues. The main goal of 3D inversion of the gravity data in the study area is to determine basement the sedimentary rocks thicknesses or the boundary of Ojagh-Gheslagh Formation and its volcanic basement. The modeled boundary of Ojagh-Gheshlagh Formation and its volcanic basement which is obtained by the inversion of gravity data, was previously confirmed by interpretation of seismic data. Manuscript profile
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  2 - Identification of Takab geothermal system reservoir by using gravity method
  Mohammad Mohammadzadeh Moghaddam Javad Nouraliee Soheil Porkhial لیلا ابراهیمی Saba Moradalivand
  The presence of hot springs, travertine outcrops, hydrothermal altered area and active tectonic in the north-east of Takab city in the West Azarbayjan province indicate that there is a geothermal system in the area. In order to characterize the geological structures ass More

  The presence of hot springs, travertine outcrops, hydrothermal altered area and active tectonic in the north-east of Takab city in the West Azarbayjan province indicate that there is a geothermal system in the area. In order to characterize the geological structures associated to the geothermal system in the region, a gravity survey was carried out in 140 stations which covered an area about 600 km2. Necessary modifications such as Bouguer, topography and free air were applied over data to obtain complete Bouguer anomaly field. Then, residual gravity anomaly field was calculated by subtracting the regional gravity field from complete Bouguer field. The regional gravity field was calculated by fitting a three-order polynomials surface over the complete Bouguer field. The calculated residual gravity map shows two negative anomaly zones (A1 and A2) in the study area. In geothermal exploration, negative gravity anomalies are considered as probable reservoir of geothermal systems. The horizontal and vertical derivative maps show complicated fracture zones in the study area. To obtain more information, the depth estimation carried out using Euler method. Estimated depth for the top of negative anomaly source in zone 1 is between 1000 and 2000 m. Finally, 3D inversion of the data was performed using Li and Oldenburg algorithm to show an image of the reservoir in the depth. The results of 3D inversion show a significant negative density contrast that occurred only in zone 1. Therefore, the reservoir of the Takab geothermal system is located in the depths between 3000 and 5000 m in A1 anomaly zone. Manuscript profile