فهرست مطالب

  • Volume:8 Issue: 3, 2012
  • تاریخ انتشار: 1391/07/11
  • تعداد عناوین: 8
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  • M. Aghajarian *, M. R. Kamali, A. Kadkhodaie, S. Fathollahi Page 193
    Permeability and effective porosity are the most important characteristics of a reservoir which can be used as input for creating petrophysical models of reservoir. The relationship between porosity and permeability in the form of hydraulic flow units can be used in describing heterogeneous reservoir rocks. Identifying hydraulic flow units can be used for evaluating reservoir quality based on relationship between porosity and permeability. Porosity and permeability are measured by injecting helium and air into the core samples respectively. In addition, these parameters can be measured by NMR well logging. Furthermore, well testing is another way for measuring permeability parameter. Although these measurement methods are accurate, they have some drawbacks. These methods are time-consuming and expensive.Therefore, they are used only occasionally. In this study, we estimated porosity and permeability by back propagation error Artificial Neural Network method (BP-ANN) using extensive dataset achieved by well logging in the field.Finally, after estimating parameters by using SSE method and K-means analysis, we improved the relationship between porosity and permeability in the Asmari Formation by dividing data from three studied wells into nine hydraulic flow units. Results showed that the Neural Network method predicted reservoir parameters successfully.
    Keywords: Asmari Formation, K-means analysis, petrophysical models, reservoir, SSE method, well testing
  • M. Poorkermani, M. Mohajjel, A. Solgi, M. Arian, R. Nadri Page 203
    Qom province as part of central Iran exhibits specific characteristics of seismic activity with zones of varied relative seismicity. Historical and instrumentally recorded earthquakes show indications of substantial seismic activity of the faults. These faults include complex systems of reverse and strike-slip faults and play a crucial role in continental deformation and structural pattern of the region. Using satellite images as well as doing field work, several faults were identified in the study area. The faults are potentially active and capable of creating destructive earthquakes. Contributing to structural pattern and active tectonics of Qom region, these faults are actively changing topography and morphological features. Since new residential construction projects are under way in this area, it is highly recommended that seismic potential of faults be taken into consideration.
    Keywords: new residential, seismic activity, seismic potential, structural pattern
  • S. H. Khatami Shal *, M. A. Mackizadeh, H. Shamsabadi Page 215
    The bentonite mine of Chahriseh Abgarm anticline is located in the topmost part of the Lower Red Formation in the Chahriseh region and attached to Qom Formation. In terms of structural-sedimentary zonation, it is located in the edge of Sahand-Bezman band. This mine is nonlaminated and can be seen as mounds close to the yellowish limestones of the Qom Formation. Analysis of XRD results showed that clay mineral Montmorillonite forms over 88% of the bentonitic sample volume. Based on the data obtained from sectional microscopic analysis, the parent rock of this mine consists of volcanic ash that is composed of andesite. Following its deposition in a closed pool environment, the volcanic ash has altered into bentonite inorganic matter as a result of digenetic reactions after burial by sand and conglomerate sediments. This clay deposit is classified as halmyrolysis clay. This mine is one of the largest and most important of the bentonite mines in Isfahan region.
    Keywords: andesite, Chahriseh, halmyrolysis clay, Lower Red Formation, montmorillonite
  • A. Davoudi *, R. Lak Page 225
    Titanium is an element that exists in nature in combination with other elements. It has many applications. Regarding the fact that the Caspian Sea coastal area is a suitable environment for placer deposits, this study was performed with the aim of identifying the source of titanium. In this study, 11 samples of Larym and Farahabad sediments were taken and in the laboratories of the Geological Survey, granulometry and ICP analysis were done. By using statistical parameters such as the indicators of central tendency, the indices of dispersion, normal distribution, the various correlation coefficients, cluster and factor analysis were obtained. Statistical calculations showed that the concentration mean of this element in the studied area is higher than the average earth's crust. The results indicated that in sediments of the studied area the maximum value of titanium which can be found in gravely deposits and can be considered as an economic potential is higher than the economic threshold of other elements.
    Keywords: Caspian Sea, economic threshold, statistical parameters, Titanium
  • K. Shabani Goraji * Page 233
    Petrography and geochemistry of the Eocene turbidite sandstones of the Zaboli unit in southeastern Iran were studied. These sandstones are fine to coarse grain, poorly to moderately-sorted, sub-angular to sub-rounded feldspatic litharenite. They contain mono- and poly-crystalline quartz grains, feldspar, volcanic, sedimentary and metamorphic rock fragments and represent Q55F14.5L30.5 proportion. Diagenetic features include physical and chemical compaction, cementation (calcite, silica and clay mineral), replacement by calcite and chemical alterations (kaolinite and sericite formation). Major oxides and trace element concentrations and key trace element ratios (Th/Sc, La/Sc, Co/Th, La/Yb, La/Sm) indicate that the sources of these sediments were intermediate to felsic igneous rocks. Modal analysis revealed a recycled orogen tectonic provenance and major and trace element discrimination plots indicated a depositional basin in an active continental margin and continental arcs.
    Keywords: diagenetic features, Modal analysis, mono-, poly-crystalline quartz grains, metamorphic rock fragments
  • S. Tabasi *, R. Ghavami Riabi, F. Doulati Ardejani Page 245
    The accuracy of an exploration method depends on the accuracy of anomaly determination and anomaly separation techniques. This paper investigates the results of gravity anomaly separation in an area with regular survey grid net using fractal method. The full logarithmic diagram of gravity values versus area was used to evaluate the threshold values and to determine the fractal dimension. The data distribution, spatial and geometric characteristics of exploration data are important parameters in the fractal model. So these results were compared with the concentration- area fractal model for stream sediments geochemistry data (in a gold mineralized area) with irregular network survey. A few data with high anomalous values in irregular network survey were shown fractal dimension variations that were not referred to real anomalies. Based on the current research, the network of the survey is another item, which affects the accuracy of the anomaly separation and the systematic network survey was shown better results in anomaly separation based on the fractal methods.
    Keywords: full logarithmic diagram, gravity anomaly, gravity values versus area, spatial, geometric characteristics, threshold limit
  • N. Ebadati *, K. Shafiei Motlaq Page 255
    During recent years, high exploitation from the aquifer declines the quantity and quality of this water resource. In this regard, it seems that the hydrogeology cal management studies are needed for this aquifer. Hydro geological aspects of the Kalachoo plain are studied using the results of the pumping test, geological logs of the observation and exploration wells, and field observation. The unit hydrograph of the aquifer is drowning using the information of the 12 observation wells. Because of non suitable distribution of observation wells, central part of the plain is selected for model design.Then water level through October 2002 is selected for steady state condition in the aquifer at (2002-2004). Using the available data, needed packages by VISUAL MODFLOW 2.6 are completed and conceptual model is constructed. Then this conceptual model is calibrated, manually, for steady state condition while the considered parameters are hydraulic conductivity, inflow and outflow of margins as virtual wells. In order to optimize the value of specific yields and recharge parameters, calibration process is continued under unsteady state condition. Calibration period length is one year (October 2002 to October 2003). Model verification is performed for five years. Verification results indicate that the calibration model is capable for management practices. After the artificial recharge on the Tang-e-Hygoon and Tang-e-Sapoo in model, the result has been showed the positive effects on the recovery of ground water level in Kalacho plain.
    Keywords: ground water, observation wells, Tang-e-Hygoon, Tang-e-Sapoo
  • M. H. Ghobadi, Y. Mohebi Hassanabadi, Y. Abdilor, R. Babazadeh Page 265
    In this study, improvement in geotechnical characteristics of fine grained soils of Faghireh village in Hamadan region has been studied by using lime. Investigated parameters include plasticity characteristics, uniaxial compressive strength, optimum water content and maximum dry density of soil, which were studied by adding lime of 1%, 3%, 5% and 7% of soil weight and providing curing time periods of 7, 15, 30 and 45 days. The aggregation test resulted in increasing the percentage of lime in the soil after 7 days, decreased percentage of fine grains and increased coarse grains. Also the result of the plasticity test shows increasing the percentage of lime, and curing time decreased the plasticity index of samples until finally the soil would be nonplastic. The result of uniaxial compressive test shows that increase in lime percentage and curing time increases resistant properties of improved soil. According to the results, the percentage of optimum lime and curing time to improve fine grained soils in Faghireh village is recommended as 7% and 30 days respectively,. Also, in order to investigate the relationship between lime-treated geotechnical properties and lime percentage and curing time, the multivariate regression analysis has been carried out, which demonstrates high regression coefficients for the proposed relationships.
    Keywords: fine grained soils, geotechnical characteristics, plasticity index, regression coefficients, soil strength, uniaxial compressive strength