PHDtheses :Petroleum
Permanent URI for this collectionhttps://repository.neelain.edu.sd/handle/123456789/4967
Browse
2 results
Search Results
Item Groundwater hydrogeological investigation in basement and sedimentary aquifers in El Obeid–Bara area, North Kordofan State; Sudan(Al-Neelain University, 2008) Ahmed Babiker El HajAbstract The study area is situated in the North Kordofan State-western Sudan the region is characterized by semi-arid and poor savannah climatic zone, where acute shortages of water are experienced. The purpose of this study is to assess the groundwater quantity and quality, through testing the hydraulic properties of the aquifer and geological setting. Using remote sensing techniques and geophysical electrical methods combined with the hydrogeological methods to study the potentialities of the groundwater resources. The study area is covered by the basement complex (Precambrian age) which is overlain by superficial deposits in the southern part, where the northern part is covered by sedimentary rocks (Tertiary to Quaternary age) under the overburden of superficial deposits. The remote sensing studies were done to define some geological features in the study area. Lineament-length density and frequency ranges from 0.02 to 0.3 km-1, and from 0.01 to 0.19; drainage-length density and frequency are 0.006 to 0.1 km-1, and from 0.004 to 0.06 respectively. Therefore, in the hard rocks terrains based on lineament studies the target zones were indicated by the overlap of the high-intensity lineament contours and the low-intensity drainage contours, and by intersection of a stream channel, that was observed on major lineaments restricted at zones (10, and 11) that provide better targets for groundwater prospecting. The geophysical electrical resistivity and electromagnetic methods were applied to define the anomalies, thickness and lateral lithological variation of the sedimentary and basement aquifers. The results show that these methods useful to locating boreholes sites. Geophysical logs (electrical resistivity and self-potential) were applied in five wells located at the sedimentary aquifer in order to provide better guideline for the water bearing formation. The present hydrogeological investigations have revealed two inhomogeneous and anisotropic water-bearing formations: the sedimentary basin consists of two aquifers called upper and lower, mainly comprising of sand and a few amounts of gravels and clays. However, the other aquifer weathered / fractured basement consist of clay and fragment of rocks. The results of pumping test and grain size analysis revealed the variation in hydraulic properties depending on geological formation. Where, the average transmissivity ranges between 124 and 937 m2 /d, hydraulic conductivity was estimated to be 1.8 and 19.5 m/d, and storativity vary from 4.5x10-6 to 1.9x10-3, indicating higher hydraulic XIV properties of the sedimentary aquifer and lower in the basement complex one. The present investigation has brought to light the fact that the area promising in term of groundwater resources estimated to be 52.5x109 m 3 in the sedimentary basin, and 3.1x109 m 3 for basement complex. The fluctuation in the static water level depending mainly on the annual recharge and discharge rates range between 0.5 to 3.0 m. The volume of annual recharge estimated to be 40% with compared to annual discharge. On the other way, the total annual extraction values of groundwater resources equal about 1.3 x109 m 3 , which is more than the annual recovery rates. In term of chemical composition of groundwater, the TDS values range from 300 to 3060 ppm and EC values ranges between 415 and 4400 microohms/cm. Hydrochemical analysis using standard diagrams to classified hydrochemical characteristics of both aquifers. Groundwater is predominantly of sulphate- chloride alkaline-earth water (Ca-Mg-SO4-Cl type) in the basement complex, while Ca-HCO3 to Na-Cl type of hydrochemical facies presented in the sedimentary and it is apparently suitable for drinking demands.Item Assessment and Evaluation of the Water - Bearing Formations in Central North Kordofan and West White Nile States(Al-Neelain University, 2012) Mohamed Ahmed El HadiABSTRACT The study area lies in central North Kordofan and west White Nile areas. It represents a part of White Nile Rift Basins. The area encompasses the Bara and Kosti Basins which are subdivided into sub-basins. In the present study the VES and electrical logs were used to detect and delineate the extensions of the water bearing formations in the light of boreholes information. The Basement rocks represent the oldest geological unit which crop out in the area in form of Jebels (Hills). These rocks are overlain by the Nawa Series in areas around Er Rahad or by the Mesozoic sediments of the Nubian Sandstone Formation at the base of the basins. The Mesozoic sediments of the Nubian Sandstone Formation are overlain by the Umm Rawaba Formation. The Umm Rawaba Formation represents the main sedimentary unit in the study area. It is mainly composed of unconsolidated sediments of sands, granules and clays. The thickness of the formation exceeds 500 m at Bara. It is overlain by the superficial deposits of sand dunes. The results of the study indicated that the area involved three aquifers: upper, lower and deep aquifers. The depth to the water table varies from about 20 m west of Bara to more than 100 m south of Umm Rawaba. The thickness of the upper and lower aquifers together reaches about 150 m as in Umm Balagei. The hydrogeological and lithological evidence of the boreholes indicate that the upper aquifer extends in the southern parts of the area. They also indicate that the deep aquifer is not a part of the lower aquifer as believed previously. It is clear that there is no problem in water supply in Bara Basin and around the western side of Khor Abu Habil where low salinity was recorded (375 – 1000 ppm). The increase of the salinity represents the main problem of water quality around Magrour ridge, Jebel Kon, east of Jebel Zalata and in Kosti Basin which exceeds 5000 ppm. The source of recharge and flow direction in the area are from the North, Northwest and East directions. Higher transmsisivity, hydraulic conductivity and storage coefficient for the aquifers are recorded in Umm Rawaba Sub-basin (16 m 2 / day, 13.32 m / day and 4.75 x 10-2) respectively whereas the lower values were recorded north of Tendelti. The facies analysis indicated that the ratio of the permeable rocks decreases from more than 60 % in Umm Rawaba and El Basheri Sub-basins to less than 20 % in the East direction. Porosity estimation indicated an increase in the porosity values from 17 % as west of Umm Rawaba to about 30 % east of Jebel Kon. الخلهصه تقع منطقة الدراسة فى وسط شمال كردفان وغرب النيل اليبيض وتمثل جزءًا من أحواض النيل اليبيض التصدعية (الفالقية). تضم هده المنطقة حوضى يبارا وكوستي المقسمان الى شبه أحواض. أنجز ت هده الدراسة يباستخدام السبر الكهريبي الرأسي وسجل ت اليبار الكهريبية لستكشاف وتحديد إمتدادا ت التكوينا ت الحاويه للمياه الجوفيه فى ضوء معلوما ت اليبار المحفورة فى منطقة الدراسة. تـعد صخور مجمع الساس أقدم الوحدا ت الجيولوجية فى منطقة الدراسة والتى تظهر على السطح فى هيئة مكاشف صخرية مثل جبل مقنص، جبل ظلطة، جبل هبيكة وجبل كون. تـطغطى هده الصخور يبرواسب سلسلة ناوا فى مناطق حول الرهد أو يبرواسب حقبة الميزوزوي من تكوين الحجرالرملي النويبي فى قاع الحواض. يعتبر تكوين أم روايبه والدي ُيطغطي تكوين الحجرالرملي النويبي من أهم الوحدا ت الجيولوجية من الناحية الهايدروجيولوجية. يصل سمك هدا التكوين الى حوالى 500 متر حول منطقة يبارا. ُيطغطى هدا التكوين يبالرواسب الحديثة المسماة يبالقيزان الرملية و التى تلعب دورًا هام ًا فى عمليا ت التطغدية المباشرة. أظهر ت النتائج أن منطقة الدراسة تضم ةثلةثة خزانا ت جوفيه (خزان علوي، خزان سفلي وخزان عميق) . تتراوح أعماق المياه لتلك الخزانا ت من حوالى 20 متر غرب يبارا لكثر من 100 متر جنوب أم روايبه. يصل سمك الخزانين العلوي و السفلي مع ًا لحوالي 150 متر فى منطقة أم يبالجي. أظهر ت الدلة الجيولوجية والهايدروجيولوجية من اليبار المحفورة إمتدادًا اقليميًا للخزان العلوي فى الجزاء الجنويبية لمنطقة الدراسة، كما أكد ت أدلة أخرى أن الخزان العميق يمثل وحدة هايدروجيولوجية فى منطقة حوض كوستي فقط ول يمثل جزءًا من الخزان السفلي كما كان ُيعتقد سايبق ًا. أكد ت النتائج عدم وجود مشكل ت فى مخزون المياه الجوفية فى مناطق حوض يبارا (يبارا - أم روايبه) والجزء الطغريبي من خور أيبوحبل ودلك يبسبب صلحية المياه حيث تتراوح كمية جزءً الملح الصلبة يبين 375 – 1000 ا فى المليون، ولكن الزدياد الملحوظ للملح الصلبة المؤدي لرتفاع الملوحة شكل أهم مشكل ت المياه فى مناطق حول كل من حديبة مجرور و جبل كون ، شرق جبل ظلطة وفى منطقة حوض كوستي حيث تصل نسبة الملح الصلبة لكثر من 5000 جزءًا من المليون. تتم عمليا ت التطغدية للخزانا ت أما يبواسطة الدخول المباشر (التطغلطغل) من خلل الطغطاء الرملي أو من خلل الجريان الداخلي ودلك من مصادر عديدة من إتجاها ت الشمال (الحوض النويبي) ، الشمال الطغريبي (منطقة الخيران) ومن الشرق (النيل اليبيض). أظهر ت نتائج الختبارا ت التجريبية إمتياز الخزانا ت الجوفية فى حوض يبارا حول منطقة أم راوايبه يبخواص هايدروليكية أعلى من خواص إمتدادا ت تلك الخزانا ت شرق ًا. أوضحت تحاليل السحنا ت إزدياد نسب الصخور المنفدة فى حوض يبارا (حول أم روايبه والبشيري)عن %60 وتراجع تلك النسب لقل من %20 فى إتجاه الشرق ، كما أشار ت نسب المسامية الى إزديادها من حوالي %17 فى حوض يبارا لحوالي %30 شرق جبل كون.