الفهرس 
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Abstract
The aim of the study is to delineate the structural features affecting Bahariya section of Khalda oil field using the available seismic reflection data and to determine the reservoir parameters of the pay zone using well logs and core data. The reservoir characteristics are presented using litho-saturation cross plots and contour maps.
Geologically, Khalda Field belongs to Shushan Basin and is situated 450 km west of Cairo and 50 km south of the Mediterranean coast and the Bahariya Formation is the main producing zone.
Twenty-two lines of 2-D seismic sections were utilized in this investigation covering about 329 km of total length. Logging data of ten wells and core analysis results from four wells were used for evaluating the petrophysical parameters and hydrocarbon potentialities of Bahariya Formation.
from seismic analysis, it is clear that the general dipping of the studied formation is to the South and Southeast direction and the southern part of the area is the steepest. Two-way time values range from 1.060 sec to 1.4 sec, while depth values range from 5250 ft (near the central and northern parts) to 6750 ft (at the southern parts). The structural setting of top of Bahariya Formation is defined by folding and normal faulting that most of them have NW-SE trends where only one has NNE-SSW trend. The main highest closure is located in the west of the central part of the area (where depth reaches 5250 ft) and is faulted by numerous NW-SE faults. These structural features constitute the main structural traps characterizing the Bahariya Formation. The structure contour map shows an area, to the northern extension of the drilled area, which could be considered as favorable for future drilling and exploration.
from well logs analysis, sand content distribution increases in eastern and southeastern parts in Upper Bahariya formation and western and southwestern parts in Lower Bahariya Formation. In contrast, clay volume decreases towards East and South directions in Upper Bahariya Formation and decreases towards the center of the area and south directions in Lower Bahariya Formation. Silt volume increases towards North and decreases towards East and West in Upper Bahariya Formation, while in Lower Bahariya Formation it decreases towards North direction and increases towards South, East and West.
The total porosity of Upper Bahariya Formation increases towards East, West and in the center of the area and decreases towards North and West while the effective porosity distribution increases in the east-southeast directions. In the Lower Bahariya Formation, the total porosity increases towards Southeast direction and decreases towards East direction while the effective porosity increases in the west-southwest direction.
Hydrocarbon and moveable hydrocarbon saturation parameters concentrate generally, in the southeastern and southwestern parts in Upper and Lower Bahariya formations, respectively.The results of litho-saturation cross-plots, columnar charts and maps of the Upper and Lower Bahariya Formations, particularly at wells located near the highest parts of the structure, show that sandstone volume, effective porosity, net pay, hydrocarbon saturation and movable hydrocarbon values of Lower Bahariya Formation are more than those of Upper Bahariya Formation while siltstone and clay volumes in the first are lower than those in the second. The maps of petrophysical parameters reveal that the center of the southeastern and southwestern parts of the study area is the most favorable part for oil accumulation and production.
It is shown that the lithological and petrophysical characteristics and consequently the hydrocarbon potentiality of the Lower Bahariya Formation is better than that of the Upper Bahariya Formation, particularly at wells located near the highest parts of the folding structure of the study area.
The obtained high values of porosity derived from core analysis data indicate that the Bahariya Formation is a high quality reservoir while the standard deviation results indicate that the porosity of Bahariya Formation is heterogeneous. Generally, the horizontal permeability show higher values than the vertical permeability. The Lower Bahariya Formation has a fair to very good reservoir characteristics in the studied wells in terms of horizontal permeability where 45.05% of samples have fair permeability, 35.26% have good permeability and 19.69% have very good permeability while vertical permeability (Kv) shows 79.28% with fair permeability values, 16.09% with good permeability and 4.63% with very good permeability values. The obtained high values of correlation coefficients in some wells indicate that the derived equations could be helpful for the reservoir evaluation of nearby wells.The correlation coefficient between porosity and horizontal permeability increases toward the northeast, south and southwest while increases toward east and southeast between porosity and vertical permeability. The maximum value of correlation coefficient between horizontal and vertical permeability lies in the center of the studied area.
The petrophysical properties of Bahariya Formation reflect the ability of the formation to store and produce oil.