الفهرس 
CHAPTER I GEOLOGIC SETTINGOnly 14 pages are availabe for public view
 |  | from | 159 |  |  |
| | | from | 159 | | |
Abstract
The aim of this work is to evaluate the petrophysical parameters of Lower Bahariya Formation utilizing subsurface geology ,well logging data and pore pressure evaluation to spot some light on hydrocarbon saturation for the studied area.
The studied rock unit (The Bahariya reservoir) is penetrated by eight drill holes distributed in the area of study “El Nada wells” (nada-1x , nada-2x , n-nada-3x , n-nada-4x , n-nada-5x , n-nada-6x , n-nada-7x , n-nada-8x ) These wells located between latitude 30° 36” and 30° 54’ 18” N and longitudes 27 00 and 27 12 E
The structural map of Lower Bahariya Formation was affected by a number of major faulting extending from north west to south east direction the area was subjected to doubly plunging anticline located at the central part of the studied area
The logging data of eight drill holes distributed in the area of study “El Nada wells” (nada-1x , nada-2x , n-nada-3x , n-nada-4x , n-nada-5x , n-nada-6x , n-nada-7x , n-nada-8x ) of Bahariya Formation are used for evaluating the petrophysical parameters and hydrocarbon potentialities of Bahariya Formation. The used data are obtained and licensed from Agiba Petroleum Company.
The present work deals with the computerized well logging analysis by using Interactive PetrophysicsTM (IP), where The studied rock unit ( Bahariya Formation ) is penetrated by seven drill holes distributed in the area of study .
The available well logging data used in this work include the gamma-ray logs, porosity tools (sonic, density and neutron logs) and resistivity logs (deep and shallow) In the form of (LAS Format). The well logging technique followed is started by entering the data raw and determine the formation temperature. Then correcting the fluid and rock resistivities, and also for the other environmental corrections.
Volume of shale contents are calculated using the Neutron, Gamma-ray and Resistivity, in which the produced results are corrected through clavier et al., equation (1971) and steiber equation (1973).
The way shaliness affects a log reading depends on the manner of shale distribution in the formation .These types are dispersed ,laminated and structural shales .Generally, the dispersed shale reduces the permeability of the formation, while the laminated shale decreases overall average effective porosity and the structural shale has nearly the same properties as the laminated shale
By applying Interactive Petrophysics (IP) Software to calculated of the volume of shale of the studied reservoir in the area. According to schlumberger teqniques to depended on the minimum value of volume of shale. The shale distribution map illustrate the horizontal distribution of shale in the study area it show that, the shale has minimum value at central area of the map where maximum value is represented in east and west directions.
. Litho–saturation cross plot is a representation, zone wise, for the contents of rocks and fluids with depth of the well. The materials content includes the shale and matrix (limestone and sandstone), while the fluids content involves the water (reducible and irreducible) and hydrocarbons. However, the following is a brief about these rock lithologies and fluid saturations in the studied wells. he litho-saturation cross plot of Bahariya Formation in N.NADA-2X well shows that, the rock unit is composed of sandstone as the major lithologic constituent especially at the upper part of the formation. The shale is found through the rock unit and increases at the upper part of the formation . limestone increase in middle and lower part. The oil are noticed in the upper and middle parts of the formation (Lower Bahariya Formation) .The Litho-saturation cross plot of Bahariya Formation in N.NADA-3X well reflects that, the rock unit is composed of sandstone of the formation and the shale increase in along formation. limestone begins to decrease toward the upper part and increase in lower part. The oil appears in the middle part of formation.
Regarding to the litho-saturation cross plot of Bahariya Formation in N.NADA-8 well shows that, the rock unit is composed of sandstone and shale and thin layer of limestone. Sandstone begin to increase in the middle and lower part. The oil appears along formation.
The total porosity distribution map shows a gradual increase toward central area of the map and northwest directions. While it decreases to the east . While the effective porosity distribution map reflects a gradual increase to the central area of the map and northwest directions, where decreases towards the east. The maximum porosity wasat well Nada 2x which was 0.27%
The water saturation of the study area is determined where Archies’s formula (1942) is used to determine the water saturation in the clean formation but in the presence of the different types of shales water saturation is determined by INDONESIA equation.
The iso-parametrics map of water saturation shows that the value of water saturation decrease in the north area while it exhibits the gradual increase in south direction
Also, hydrocarbon saturation mapexhibit increase in north and northeast direction and decreases in south direction where maximum value in N.NADA-8. The maximum value of hydrocarbon saturation around well Nada-8 (0.68%).
Also a lithology identification with cross plots (Neutron-Density),(Sonic-Density)and (Sonic-Neutron) show that the main lithology is sandstone ,limestone, dolomite and shale .
Bahariya Formation is the main producing horizon in Nada oil field. It is represented by fine to very fine-grained sandstone, well sorted, sub-angular to sub-rounded, straight to concave-convex contact alternated with shales and limstones. It is divided into two zones, Upper and Lower, each zone is subdivided into two sub-zones. Bahariya Formation was deposited on a wide extensive shallow marine shelf .from litho saturation cross plots we noticed that the oil appear in upper Bahariya and show gradual increasing in Lower Bahariya.
Pore pressure evaluation in the studied area which depend on well logging analysis showing that high pore pressure values for pore pressure which reflects the considerable amount of Hydrocarbon saturation at these wells in the studied area .
By comparison the values of hydrocarbon saturation and Pore pressure , It was found that the hydrocarbon saturation distribution map exhibits increase in north and northeast direction (the same trend for increase porosity) and decreases in south direction where maximum value in N.NADA-8 While the Pore pressure distribution map shows an increase at the central parts around Nada- 3 well where the maximum thickness for Bahariya formation were showed at that well. Also these well is the deepest well which reflect the high overburden load at this well.
Also, it was found that, the distribution of pore pressure was affected with the structural setting in the studied area , where the maximum value of pore pressure was located at the double plunging anticline in the central parts of the studies area.
from this study it is interpreted why the Lower Bahariya is the main pay zone at Bahariya Formation, Nada field, Western Desert Egypt.
So the exploration and drilling activity could be directed to the central and the northern parts of the studied area.