SEISMO-PETROPHYSICAL STUDIES OF APOLLONIA RESERVOIR, RAZZAK FIELD, ALAMEIN BASIN, WESTERN DESERT, EGYPT

Abstract

The area of study is located in Razzak oil field, the Early Cretaceous Alamein basin, the northern part of the Western Desert of Egypt. In the present study, integration occurred between geologic and log data of five wells (ERZK-110X, ERZK-15X, ERZK-100X, ERZK-77X, and ERZK-180X) wells, as well as geophysical data represented by 30 seismic sections, to study the structural setting, stratigraphic features and petrophysical parameters of the Apollonia, Abu Roash G, Baharyia, Alamein and AEB-1 Formations, using Schlumberger petrel 2015 and Tech log 2015.1 software. The evaluation of the seismic attributes and seismic reflection characteristics analysis of Razzak Field was undertaken by subdividing the evaluated rock units of the study area into four seismo-facies units of varying parameters from top to bottom. These units are comparable to the Apollonia and Khoman Formations; Abu Roash Formation; Baharyia Formation and Alamein Formation. The seismo-facies of unit 1 of the Apollonia and Khoman Formations reveals parallel to sub-parallel layering, with a thickness increased gradually northwards, the lithologic distribution shows limestone with minor clay intercalations, with a facies varied from middle neritic, graded to outer neritic. Unit 2 of the Abu Roash G Formation , exhibits divergent layering, with a thickness increased gradually northwards and eastwards, the lithologic distribution, reflects the predominance of carbonate and sandstone occur, with minor portion and laterally graded into shale, with littoral facies, graded to inner and middle neritic facies. Unit 3 of the Baharyia Formation reveals chaotic and oblique layering, with a time thickness increases towards the northeastern and southwestern parts, the lithologic distribution illustrates sand and shale, with minor limestone streaks, and facies varied from continental to inner-middle neritic. Unit 4 of the Alamein Formation shows variation from parallel-subparallel orientation to oblique and chaotic features with thickness increased northwards and eastwards, the lithologic distribution

represents dolomitic limestone, with minor streaks of limestone, and a facies varied from middle neritic to outer neritic and bathyal facies. Finally, the results are integrated to build up a seismo-stratigraphic model in the evaluated area of the north Western Desert of Egypt. The seismic interpretation involves the construction of structure contour maps. In terms of time and depth, on the tops of Apollonia, Abu Roash G, Baharyia and Alamein Formations. These maps show three structural closures, due to folding, that are dissected by NW-SE faults. The analysis of relevant structural and stratigraphic seismic attributes, such as; root-mean-square amplitude, local structural dip, variance, iso-frequency component, sweetness and acoustic impedance average energy applied on the reservoir tops, to enhance the visibility of faults, structural interpretation and the physical parameters of the subsurface related to lithology and stratigraphy for reservoir characterization. Finally, the results obtained are used, to construct a seismic structural model with, the integration of the obtained seismic stratigraphic model, that lead to building a geologic model of the north Western Desert of Egypt.