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العنوان
Integrated Geophysical Study of Subsurface Structure at Wadi El-Rayan- El Fayoum Area- Egypt /
المؤلف
Mostafa, Hader Kadry Ali.
هيئة الاعداد
باحث / هدير قدري علي مصطفي
مشرف / عبد الناصر محمد هلال
مشرف / أشرف ابراهيم احمد غالي
مشرف / أيمن شبل السيد
تاريخ النشر
2021.
عدد الصفحات
116 p. :
اللغة
الإنجليزية
الدرجة
ماجستير
التخصص
الجيوفيزياء
تاريخ الإجازة
1/1/2021
مكان الإجازة
جامعة عين شمس - كلية العلوم - الجيوفيزياء
الفهرس
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Abstract

Wadi El-Rayan occupies a depression in the northern part of the western desert of Egypt and lies between latitude 30° 00’ 00” and 30° 34’ 00” N and longitude29° 00’ 00” and 29° 24’ 11” E.\
The Wadi El Rayan block covers an area of about 1,287 km2 and located about 140 km southwest of Cairo and 70 km southwest of the Quran oil field. It was discovered in September 1996 through drilling well WR-1x which has been drilled to a total depth of 7740 ft in the basement.
The main purpose of this study is delineating the structure style and hydrocarbon trapping of the area under study using 2D seismic and available well data. In order to achieve this target, the current study started with the description of the geology of the area, including a detailed discussion of the stratigraphic rock units, structures and tectonic evaluation of the north Western Desert, where the study area is located.
The sedimentary sequence of the wadi El-Rayan field ranges in age from Lower Cretaceous to Middle Eocene. The study area is within wadi Rayan Platform. The majority of the drilled wells are characterized by the absence of the Paleozoic and Jurassic rocks as a result of non-deposition on the wadi El-Rayan platform.
The northeastern part of western desert, including study area exhibits tectonic evaluation through four main phases:
First phase (1a) (early rifting): deformation of the northeastern part of Western Desert that led to the development of the north and northwest dipping Jurassic half-graben basin.
Second phase (2a) (Inversion phase): deformation took place after the deposition of the Cenomanian-Turonian and Lower Sonoma rocks which show slight gradual changes in thickness.
Third phase (2b): The presence of angular unconformities, between the Abu Roash Formation and the middle or upper parts of Khoman Formation or between the lower and upper parts of the Khoman Formation, indicates that this phase of deformation was initiated at the Early Late Estonian.
Forth phase (3): folding and reverse faulting affected the Abu Roash Formation and older rocks as well as the lower part of Khoman Formation.
The structures of the study area include both folds and faults. Folds in the Wadi EL-Rayan platform is symmetric and have gentle dipping flanks and have NE-SW orientation. Faults of the study area have three main orientations. They are oriented ENE- WSW, NE-SW, and NW-SE. ENE-WSW oriented faults are common in the most northern and southern parts of the study area. These faults have an apparent normal slip and active in the Early and Late Cretaceous times.
The first objective is Petrophysical analysis, the different cross-plots of given data are utilized to predict the lithology for the Abu Rawash G member using the available well logs which reflect that the main lithology of Abu Rawash G is shale with little content of limestone and sandstone.
A comprehensive analytical formation evaluation system has been established to interpret the basic logging data for the deduction of the petrophysical parameters of the main reservoir rocks Abu Rawash ”G” Formations, such as porosity, shale content, water and hydrocarbon saturation based on a number of equations and empirical formulae. The bore-hole data analysis has been done using ‘‘Techlog” Software.
The Petrophysical properties derived from conventional well logging analysis are generally diverse vertically in the form of litho-saturation cross-plot (CPI). The results of petrophysical analysis shows that the effective porosity ranges in values from 19 % to 23%, the volume of shale ranges in values from 7.5 % to 17 %, the water saturation ranges in values from 35% to 50% and the hydrocarbon saturation ranges in values from 50% to 65% which indicate good quality reservoir. Based on the petrophysical data log, the rock of Abu Rawash “G” member is interpreted as good reservoir with promising exploration area located specially in northern part of the field.
The second objective in this study is the interpretation of seismic profiles and the use of the provided wells to build the structure geological model and understand the history of this area based on all the previous regional studies and resources
Subsurface geological features deduced from the interpreted seismic sections can be represented by mapping of all gained information to clarify the structural highs and lows anomalies and the structural trends existing in study area.
The time structure contour maps constructed on top Abu Rawash ”G”and u. Bahariya Formations showing the major fault trends which affected the study area is given. We can note the ENE–WSW trend and NE–SW and NW–SE nor-mal and reverse faults which reflect both tension and compressional forces affected the study area. The depth structural maps are similar to the time maps except in a slight variation due to lateral change in the velocity.

Abu Rawash (G) is the productive zone in the study area so, the thickness map is very important to understand the distribution of the reservoir. Isopach map showing the distribution of the gross thickness of the Abu Rawash (G) zone; where the map shows the thickness decreases in the middle of study area while increases at other locations.
The integrated interpretation of the seismic data which represented in the form of the interpreted seismic sections, two-way time structural contour maps and depth structural contour maps, reflect the prevalence of structural tectonic trends. These trends of local structures are believed to be produced as a result of comparable systems of regional tectonic deformations affecting the surrounding regions. The trends of the faults are: ENE–WSW trend and NE–SW and NW–SE normal and reverse faults which reflect both tension and compressional forces affected the study area.