Thesis (M.Sc.) -Cairo University, 2023.

Bibliography: pages 104-118.

Faghur Basin is a mature petroliferous district in the farthest west of the northwestern Desert of Egypt. The rift initiated in the Late Jurassic. The petroleum system in the basin is attributed to a single source rock deposited in the early rift phase.
The present work selected West Kalabsha area; the greatest part of the Faghur Basin with aims of studying its structural architecture, petroleum system in relation to tectonic evolution. 3D seismic survey and borehole data of West Kalabsha area are used in tracing structural architecture and evolution of defined structural forms. Detailed interpretation of 3D seismic cube has been achieved with detailed mapping of different geological reflectors tied with the available well data. In a favor of reaching a satisfactory understanding of Faghur Basin,
1 D model was applied along with the different interpreted maps, fault strike and dip relations.
The penetrated stratigraphic succession in study area ranges in age from Middle Miocene to Paleozoic, basement was penetrated in Waha platform. No Triassic sediments are known in the Faghur basin so far. Waha major fault is the basin bounding fault, defining the basin boundary to the North, at the down thrown to the south of the fault, complete section ranging from Late Jurassic to Miocene, at Waha platform, the up thrown side of the fault, part of the early Cretaceous is directly lying on Paleozoic. The Jurassic rocks are subdivided, from base to top, into Safa, Zahra and Masajid formations. Safa member is represented by continental sediments and consists of mainly sandstone and siltstone intercalations. The overlying Zahra member, which consists mainly of shale, siltstone, and minor limestone beds, containing the main source rock, concentrating at the bottom, directly above the main reservoir in the area of study; the Safa sandstone, forming both source and seal for the Safa member.
Masajid Formation consists mainly of limestone with minor shale interbeds. Masajid Formation is overlain by the Neocomian-Barremian Alam El Bueib Formation, which consists of shale and sandstone section with occasional limestone beds. Alamein Formation is of Aptian age, and it overlies the Alam El Bueib Formation and consists mainly of limestone. Upper Aptian Dahab Formation overlies Alamein Dolomite and is composed shales with thin interbeds of siltstones and sandstones. Dahab Formation is overlain by Albian Kharita Formation which consists of fine-coarse-grained sandstones with subordinate, siltstone, shale, and carbonate beds. Bahariya Formation of Lower Cenomanian age is overlying the dominantly continental sandstone unit of Kharita Formation. Late Cenomanian had witnessed a rifting, and a major marine transgressive cycle, of carbonates with some elastics (shale) of Abu Roash Formation. The formation extends to Early Senonian and includes seven rock units from "A to G". The overlying Khoman Formation, of Upper Senonian age, unconformably overlies Abu Roash Formation. Open marine conditions prevailed during the Khoman time; a carbonate platform continue to deposit mainly limestone until Middle Miocene Marmarica formation which is found at surface.
Detailed seismic interpretation of key reflectors in Faghur basin revealed a multi-history structural deformation through time with resolution of the main tectonic events that affected study area mainly during Mesozoic. The structural interpretation incorporated all available seismic and geologic data in the area of study. The first step was the correlation and tying between seismic reflectors and stratigraphic boundaries that were defined from available well penetrations, synthetic seismogram was utilized. Six key horizons were picked and interpreted, and they are equivalent to the top surfaces of Khoman formation, ARA Formation, Bahariya Formation, Alamein Formation, Masajid Formation, and top Paleozoic.
Top Jurassic surface is crossed by a several ENE-WSW to E-W trending normal faults, most of the faults are dipping to the South, and the rift was initiated in Late Jurassic as small dis-connected sub basins (half grabens), small thickness variation is observed at the first phase. The second rift phase was the major one, the small basins were connected at ~135 ma, the fault trends didn’t change and a variation in thickness is now more obvious, a third rift phase at 116 ma, with shifting in polarity, the fault trends now NW-SE super imposed on the older E-W fabric, re-activation of the major older fabric E-W faults is observed as well, the fourth rift phase started at 94 ma, with same fault trend like the third one; NW-SE.
The different rift phases are locked by limestone deposition on top of each, at a very slow rate of sedimentation.
The Waha platform bounding fault trending ENE-WSW was re-activated during all the rift phases.
The re-activation of the older, only major E-W faults during the latest phase played a major role in providing access to charge for exploring the shallower reservoirs and hence defining the sweet spots.
Faghur can be considered as a continental rift basin. Multi-stage rift events made the structure architecture of the basin. The super imposed NW-SE younger fault trend on the older E-W made the trap geometries mainly three-way dip closures with crystal shift due to the growth of new trending faults or re-activation of some of the older ones. Few Four-way dip closure geometries were identified along the basin axes as well. Some stratigraphic/combined Traps were defined at AEB-6 level as well.
In Late Cretaceous time, Egypt was subjected to a compressional tectonic phase known as "Syrian Arc". These tectonics had a very small deformation in the study area.
The Oligocene-Miocene extension phase of deformation was not remarked in the study area, this could be partially due to lack of Apollonia mapping due to the absence of a variable acoustic impedance as Dabaa is represented by limestone in the area of study.
Burial model indicate that the oil window of Khatatba source rocks has been reached during Late Cretaceous (92 Ma) and oil migration started at a variable burial depth between 10,500 -13,000 ft.
Reservoir rocks ranging from the Paleozoic Desouky sandstone (average net pay porosity of 8%) to the Albian Kharita sandstone (average net pay porosity of 23%), the main producing reservoir is the Jurassic Safa sandstone with average thickness of 80 ft. and average porosity of 9%.
The Late Jurassic Khatatba Formation strata deposited in broad fluvial flood plains, in which there are overbank swamps and small lakes transitional to estuarine or lagoonal settings, best match the depositional environments predicted by the oil chemistry.
The geochemical study of crude oils from the Faghur Basin defines a family of genetically related oils that were generated from thermally mature and organic-rich shale of Late Jurassic age, Khatatba.
The exploration strategy in Faghur basin is focused on the deeper Jurassic section, however, the re-activation of some of the older major E-W faults during the fourth rifting phase is providing the access to charge and hence defines the sweet spots for exploring the shallower AEB or Kharita formations with higher success rate, as the migration is the main risk factor in this case.

تقع منطقة غرب كلابشه فى شمال غرب الصحراء الغربيه بمصر. وتحتل الجزء الاكبر من حوض فاجور الترسيبى.
تتضمن الرساله نتلئج الدراسات الجيولوجيه التحت سطحيه التى اجريت على منطقة غرب كلابشه. وتهدف الى دراسة الطرز البنائيه واليات المصائد فى الجزء الاكبر من الحوض.
تم عمل تفسير للمسح اليزمى ثلاثى الابعاد مع نموج ترسيبى احادى الابعاد لبئر واقعى. تم ايضا الاستعانه بتسجيلات الابار فى المنطقه قيد الدراسه مع عمل العديد من الخرائط للأسطح المختاره بدقه بناءا على مكان وجودها الزمنى فى التتابع الجيولوجى وما تمثله من تغيرات فى اعادة التشوه الممكن بعد ترسيبها. تم ايضا عمل خرائط لتبين السمك بين هذه الطبقات فى المدى الزمنى لدراسة تطور الحوض عبر العصور الجيولوجيه ابتداءا من العصر الجوراسى العلوى حينما تم ترسيب أول الصخور نتيجه لطور الفتق الاول فى حقبة الحياه الوسطى.
يعتبر حوض فاجور الجزء الاكثر بعدا نحو الغرب فى شمال الصحراء الغربيه بمصر وقد زادت أهميته فى الفتره الاخيره بعد نتامى الانتاج ليكون اخر حوض منتج للزيت الخام والغاز فى صحراء مصر من ناحية الغرب.
تمت دراسة نمو حوض الترسيب مع بداية الفتق الاول حيث ترسبت الصخور الخازنه ثم صخور المصدر. وقد خلصت الدراسه الى التالى:
تكون حوض فاجور بدأ فى العصر الجوراسى العلوى حيث تم ترسيب ما يقارب سبعما
قدم من الصخور مع تكون فتوق وصدوع ضعيعة التطور باتجاهات مضربيه شرقيه-غربيه وهو الطور الأول للفتق.
تكون الطور الثانى فى عصر الكريتاسى السفلى وهو ما ادى الى ترسيب سبعة الاف قدم من الصخور مع نمو قوى للفتوق والصدوع السابقه بنفس الاتجاه. يعتبر الطور الثانى هو الطور الرئيسى والاعنف فى تطور حوض فاجور.
تكون الطور الثالث فى عصر الكريتاسى السفلى الى العلوى وهو ما ادى الى ترسيب خمسة الاف قدم من الصخور مع نمو قوى للفتوق والصدوع باتجاه جديد وهو الشمال الغربى مع اعدة تنشيط لبعض الفتوق الرئيسيه الاقدم.
تكون الطور الرابع فى عصر الكريتاسى العلوى وهو ما ادى الى ترسيب ثلاثة الاف قدم من الصخور مع نمو اقل قوه للفتوق والصدوع باتجاه الشمال الغربى مع اعدة تنشيط لعدد أقل من الفتوق الرئيسيه الاقدم.
تعتبر صخور العصر الجوراسى الاعلى هى صخور المصدر الوحيده المسئوله عن النظام البترولى وعن انتاج الزيت والغاز فى حوض فاجور نتيجه لعدد اطوار نمو الحوض السابق ذكرها فان الطرز البنائيه لمعظم المكامن ذات طابع محكم بالصدوع وعادة ما تميل فى ثلاثة اتجاهات.
يعتمد اسكتشاف الصخور الاحدث فى حوض فاجور على اعادة تنشيط الصدوع الاقدم فى الاماكن التى حددتها الدراسه.

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