كلية النفط والمعادن

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    MULTI-GEOPHYSICAL TECHNIQUES FOR HYDRO-GEOPHYSICAL INVESTIGATIONS IN WESTERN OMDURMAN KHARTOUM STATE-SUDAN
    (Al-Neelain University, 2018-12) Nada Al Derdere Adroos
    ABSTRACT The area under present consideration is located in the central part of the Sudan is generally bounded by latitudes (16º - 16.8º N)and longitudes(31º - 33º E)it comprises the Khartoum state and North Kordofa. The present study will be focused in Wadi El Mugaddam basin. The geological unites in the study area are, sedimentary rocks. The sedimentary rocks included: Nubian sandstone Formations and superficial deposits (clays and sand dunes). The annual rainfall ranges between 100mm to 150mm and occurs intermittently during the period from July to October. The geophysical methods applied are Electrical Resistivity Method - Vertical- Electrical Sounding (VES) to determine the groundwater occurrences, aquifers extensions, thickness and depths and calibrated with boreholes lithological data. The ranges of resistivity are used to construct geo-electrical sections forthe study area. Apparent resistivity models have been generated in depth; the intention was to use the model in the static and dynamic modeling. 3D model of apparent resistivity generated form VES calibrated data and wells marker. Groundwater in the study area occurs into two aquifers; the shallow aquifer ranging between 60 -120m and the deep aquifer vary between 130m to 250mbelow ground surface. Groundwater quality in the study area is very good with total dissolved solids (T.D.S) in the range of 245 to 848 mg/liter. الخلاصــة تقع منطقة الدراسة في الجزء الاوسط من السودان وتتبع لولايتي الخرطوم و شمال كردفان بين دائرتي عرض (16.8º- 16º) شمالا وخطي طول(31º - 33º)شرقا. وجيولوجيا تغطي المنطقة الصخور الرسوبية وهي صخور متكون الـــــــــــــــــحجر النوبي الرمــــــــــــــــــــــــــــــــــــــــــــــــــــــــلي والرسوبيـــــــــــــــــــــــــــــــــــــــــــــــــــات الحديثــــــــة (الطين والكثبان الرملية ). تم تطبيق طريقة السبرالراسي الكهربي لتحديد تواجد المياه الجوفية, امــــتدادات الخزانات الجوفية , سمك وعمق الخزانات ومقارنتها بمعلومات الابار من العينات الصخرية well logs)). تم عمل قطاعات جيوكهربية من معدلات المقاومية الكهربية الظاهرية لمنطقة الدراسة . تم انشاء نماذج المقاومة النوعية ثلاثية الابعاد 3Dباستخدام نماذج النمذجة الاستاتيكية والديناميكية بمعلومات VES,s ومعايرة بيانات الابار. توجد المياه الجوفية في حوضين جوفيين تفصل بينهما طبقة طينية ولكنهما متصلان مع بعضهما من الناحية الهايدروجيولوجيه . يتراوح عمق الحوض الجوفي العلوي حوالي 70-160 متر تحت سطح الأرض وتحده طبقه طينية وبالتالي تفصله من الحوض الجوفي الأسفل الذي تتراوح اعماقة إلي أكثر من 270 متر. يتدرج منسوب المياه الجوفية من حوالي 50 متر (تحت سطح الأرض) عند الحدود الشرقية لأرض المشروع والي حوالي 62 متر عند الحدود الجنوبية و الوسطي لمنطقة الدراسة. ويلاحظ أن منسوب المياه الجوفية ينخفض بمعدل 1.1 متر كل واحد كيلو متر غرباً من النيل. تتميز الطبقات العميقة الحاملة للمياه بنفاذيه عاليه الي متوسطه مما يبشر بإنتاجية مياه جوفيه عاليه تصل الي حوالي 200-400 متر مكعب في الساعة وفق ماابانت بعض الآبار التي حفرت بالمنطقة. تختص المياه الجوفية بدرجة عاليه من العذوبة وفق كميه الأملاح الذائبة التي تتراوح كمياتها بين 245 الي 848 ملغرام في اللتر.
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    Integration of Geophysical Techniques for Archaeological Prospection in Sudan.
    (Al Neelain University, 2007-05) Mohamed Abdelwahab Mohamed Ali
    The geophysical data in the current study have been measured in four archaeological sites in Sudan. The studied sites include Meroe city, Domat Al-Hamadab, Musawwarat es Sufra and Jebel Barkal. The geophysical methods, which are suitable for each site, were selected on base of the physical contrast of the specific parameter of each method. This parameter represents magnetic susceptibility in magnetic method, electrical resistivity in resistivity method and dielectric permittivity in ground penetrating radar. The magnetic data in the studied archaeological sites in Sudan have been measured using three different magnetometers. The first one (caesium magnetometer with accuracy 1 0.01 nT) measures the total magnetic fields. The second one (Overhauser magnetometer :t: 0.1 nT) measures the vertical gradient of the total magnetic field and the third one (Fluxgate gradiometer :\: 0.1 nT) measures the vertical gradient of vertical component of the magnetic field using portable magnetometer/gradiometer. The magnetic surveys were complemented by resistivity mapping to investigate the archaeological features horizontally when these features have contrast in_ the magnetic susceptibility and resistivity to their surroundings. The complementary magnetic and resistivity mapping surveys have been integrated with electrical resistivity imaging (ERI) and ground penetrating radar (GPR) data, in profiles with locations selected on base of the magnetic and resistivity results. The ERI and GPR profiles provided complementary information about the variation of the anomalies related to the archaeological features with depth. The integrated interpretation of these methods leads to better understand the target features and accordingly helps the archaeologists witl1 some hints for correct conclusions. The integrated prospection results (chapter 5) convinced the archaeologist to replace some of the archaeological excavation by geophysical surveys to complete the missing parts of the site maps. Test excavations have been carried out for field check of the geophysical interpretation. This study shows how it is successful using geophysical processing techniques to improve signals of the geophysical data from archaeological sites so as to extract the maximum information from these data, and then gives better chances for successful interpretations. Basic theory and algorithms of the geophysical methods and processing techniques are used not only for explaining the successful techniques, but also for defining the problematic ones and introducing and recommending methods to overcome the encountered problems. It is demonstrated that geochemical analysis and magnetic susceptibility measurements can give some indications for explaining the success and failure of archaeological prospection using magnetic surveys. The magnetic gradient revealed the presence of some fairly clear archaeological building structures in the different studied sites. It is shown that such measurements are more effective to detect the shallow archaeological features than the total magnetic field measurements, which enhance the anomalies'of deeper sources. The geochemical analysis and magnetic susceptibility results of the collected samples, which represent the construction and the surrounding materials in the studied sites, indicate that sandstone as non-magnetic material can be detected successfully, when it is embedded in magnetic background. The fired-bricks may have higher magnetic susceptibilities. Therefore, they are shown in the magnetic images very clearly. Depending on the scale of the prospected features, comparison between coarse sampling pattern (e.g. 0.5 m) and fine sampling pattern (0.25 m) has been done. The first one was used in the reconnaissance‘ survey, but small-scale sampling pattern was required to resolve the small-scale anomalies more clearly. 3D modeling and inversion of the magnetic data of the studied area have been done using a priori infonnation, which were of great help to select a good starting model for the inversion process and then ending in a plausible model for the modeled anomalies with low rms error. ' 1D vertical electrical sounding (ID-VES) measurements have been used to give general estimation of the vertical extension of the prospected features. Furthermore, it helps to describe geological conditions of the archaeological features and their surroundings. 2D resistivity imaging profiles with small electrode- spacing (0.25 m, 0.5 or l m -depending on the scale of target anomalies) have been carried out along locations selected on base of magnetic, 1D-VES and resistivity mapping results. The resistivity inversion results of these profiles helped to estimate the vertical extensions of the archaeological targets more precisely. The applicability of combining 2-D electrical resistivity imaging (2D-ERI) profiles in 3-D data set for inversion using a 3-D resistivity inversion code is also demonstrated. High frequency (500 MHZ) ground penetrating radar (GPR) replaced 2D-ERI in arid and semi-arid area, where conditions favor the use GPR. The integrated interpretation of these methods leads to better understand the target features and accordingly helps the archaeologists with some hint for correct conclusions. This study can be used to pave the way for an increased use of geophysical techniques in the cultural heritage management of archaeological sites in Sudan.