الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The main purpose of the current study is to determine the
different reservoir parameters characterizing the reservoir zones
utilizing core data and well logging analysis in the Obayied
field.
The available data for the current study are:
I. Well-logging data of five wells including Composite logs
of gamma-ray logs, formation density compensated logs,
neutron compensated logs, resistivity logs, and borehole
compensated sonic logs.
II. Core data of three wells including core porosity logs for
chosen depths at Upper Safa Member and Lower Safa
Member.
III. Structure map of Lower Safa Member.
The different well logging data of five wells in the
Obayied field were used to study the different petrophysical
parameters of the Upper and Lower Safa reservoirs. The Well
log analysis allows for the following conclusions:
The Upper Safa reservoir in the interval 3553.33-3757.05 m
depth (Total vertical depth subsea) has been shown four
hydrocarbon bay zones based on the well logs correlation.
The average values of the petrophysical parameters of thus
zones have been measured. The nature of the fluids in the
permeable pay zones is determined by the analysis of the
porosity and resistivity logs. The interpretation of both the
response of the resistivity tools and the neutron-density log
response through the Upper Safa zones show that the
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92
hydrocarbons will be mainly oil while the deepest pay zone
of wells (Well-1, Well-3, and Well-5) shows gas
occurrence.
The Lower Safa reservoir in the interval 3723.47-3936.72 m
depth (Total vertical depth subsea) has been shown several
hydrocarbon bay zones based on the well logs correlation.
The interpretation of both the response of the resistivity
tools and the neutron-density log response through the
Lower Safa zones show that the hydrocarbons will be
mainly gas.
The lithological identification of the Upper Safa Member
shows a majority of slightly calcareous to calcareous shale
with streaks of slightly calcareous sandstone and
argillaceous limestone. The Upper Safa reservoir have total
net pay thickness range from 4.72 to 17.22 m with total
porosity range from 6.75 to 8.84 % that is very close to its
core porosity data and has been largely affected with the
shale volume that ranged from 9.52 to 18.88 % and has
resulted in relatively small effective porosity ranged from
4.27 to 5.81 %, and relatively high water saturation ranged
from 43.72 to 70.11 %. Consequently, the hydrocarbon
saturation is relatively small with a range from 29.89 to
56.28 %, and the effective bulk volume of hydrocarbon
(BVHE) about 2.41%.
The lithological identification of the Lower Safa Member
shows a majority of sandstone with streaks of shale. The
Lower Safa reservoir have net pay thickness range from
42.37 to 81.53 m with total porosity range from 7.83 to
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93
11.44 % that is very close to its core porosity data and has
been little affected with the shale volume that ranged from
6.07 to 14.08 % and has resulted in relatively good effective
porosity ranged from 6.56 to 8.52 %, and relatively low
water saturation ranged from 32.97 to 47.84 %.
Consequently, the hydrocarbon saturation is relatively high
with a range from 52.16 to 67.03 %, and the effective bulk
volume of hydrocarbon (BVHE) about 4.99%.
The lateral distribution of hydrocarbon occurrences has
been explained through several iso-parametric maps. These
maps show the effect of some important petrophysical
parameters such as the total porosity, the effective porosity,
and the water saturation for Upper and Lower Safa
reservoirs. These iso-parametric maps complete the picture
of hydrocarbon potentiality and delineating the areas for
hydrocarbon accumulation. These maps illuminate the
lateral variation of these petrophysical parameters which
may be due to the lateral facies heterogeneity, where facies
change from place to place without consistent trend or due
to the complex structure affecting the study area or both of
them.
The hydrocarbon discoveries in the studied area proved that
the Middle Jurassic shales of the Khatatba Formation
indicate an excellent source rock in the Shoushan Basin. The
organic-rich shales of Khatatba Formation also act as a seal
for the Upper Safa reservoir. Also, Kabrit shale and
limestone represent a good cap rock of the Lower Safa
reservoir where it covers the reservoir all over the field;
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94
thus, this formation represents a typical hydrocarbon
vertical seal (Cap Rock), reservoir, and source.
The results of this study showed improvement in the
reservoir characterization of the Upper and Lower Safa
reservoirs, help to identify potential hydrocarbons present, and
hence will aid increasing the cumulative reserves in the
concerning area. The integrated data has been used to support
the exploration and development in the future field planning by
doing more explorations in both the northwestern direction
(where has more hydrocarbon bulk volume at the Upper Safa
Member and has the highest formation pressure values) and the
southwestern direction (where has more hydrocarbon bulk
volume at the Lower Safa Member and has the highest
formation pressure values) of the study area