الفهرس 
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Abstract
Jade oil field study area lies in the northern part of Matrouh basin which located in the northern of the Western Desert of Egypt which is confined between Latitudes 300 30’ N and 310 00’ N and Longitudes 260 25’ E and 270 00’ E. The study zone covers around 2000 km2. The main objectives of the present study are the following points:
1- Outlining the regional subsurface geological structures affecting on the study area and delineating their main tectonic trends.
2- Estimating the petrophysical properties of the main reservoir and, consequently the potential parts of the area for oil exploration, then evaluating the hydrocarbon potential inside the interested reservoirs (Alam El Bueib 3D, 3E, 3G and 6 members), and finally
3- Locating promising plays for hydrocarbon accumulations.
The available data used in the present study are:
1) Seismic data comprises (shot-point location map of the study area, twenty seismic lines, velocity measurements, in the form of sonic logs for only one well (Jade 04)
2) Well logging data for four wells distributed in the area which comprises (composite logs, formation density compensated logs, borehole compensated sonic logs, neutron logs, resistivity logs, spontaneous potential logs, gamma ray logs).
To achieve these objectives the following geophysical methods were used seismic interpretation and well logging analysis.
Twenty seismic lines were interpreted by identifying of reflectors using well data (for well-to-seismic tie and well correlation), picking and correlation of reflection horizons, closing loops, detecting fault locations, constructing time structure maps and conversion of reflection times into depth structure maps. This was done by using software computer program (Petrel, 2013) developed by Schlumberger Services Company.
Well logs analysis is used to evaluate the productive zones in terms of depths, thicknesses and petrophysical properties of these zones within the interested reservoirs for the evaluation of the hydrocarbon potentiality using Interactive Petrophysics (IP) developed by LR Senergy Company.
The interpreted seismic sections display very well the subsurface geologic structural configuration of the study area. Petrel (2013) software was used for picking the reflection events of the interested formation tops as well as picking their dissecting faults. These formation tops are: Abo Roash 3G Member, Alamein Formation, and Zahra Member of Khatatba Formation. Close view of these seismic sections shows that the area is affected by three sets of normal faults with different heaves and throws dissecting the interested formation tops building tilted fault-blocks and horst and graben structures.
Three time structure maps were constructed on the tops of these interested formations showing low and high time values that reflect the locations of structural highs and lows for the upthrown and downthrown blocks separated by different sets of normal faults arranged from old to young as follows:
The first set of fault elements is the northeast-southwest (NE- SW) trending faults that are formed during the Syrian Arc System (late Cretaceous). There are two major faults resents this first set. The hanging wall downthrown side of one of these two faults is cut by several minor faults that are perpendicular to the major one with smaller heaves and throws dividing the area into smaller tilted fault blocks of several structural highs and lows.
While the second set of these elements are the northwest-southeast (NW-SE) direction, which it is the dominant trend creating a series of fault patterns presenting graben and horst structures that are formed during the Gulf of Suez (Oligo-Miocence).
Then, the third set is East-West (E-W) direction which is located in the northwest side of the study area and it has been exited during Tertiary (Mediterranean fault system).
The depth maps on tops of the studied geologic formations that were constructed show almost the same geologic features identified in the interpretation of the two-way time maps because a constant average velocity value was used for each formation.
Post-stack seismic inversion approach indicated a pattern can greatly add to conventional direct hydrocarbon interpretation. It has proven to be very useful theory in the detection of the hydrocarbon occurrences and lithological definition in the area of study. Using the results of the inversion by showing the lower acoustic impedance anomaly has a great impact to confirm the hydrocarbon existence at the zone of interest in our study area, which is Alam El Bueib 3G reservoir member.
Also, this approach was very helpful by showing of higher acoustic impedance anomaly at the level of Alamein Formation due to the presence of dolomite and shale as seal rocks.
The main reason for this study is utilizing post-stack seismic inversion to help hydrocarbon discovery. Evaluation is basically in the light of utilizing the well-logging and seismic data.
Seismic attributes (unconventional seismic interpretation) techniques have been extracted from seismic measurements to display data in different viewpoint that is a very helpful to assist seismic interpretation in detecting fault element locations.
Data logging analysis carried out for four wells in the study area by using a petrophysics computer program (IP, 2011) developed by Schlumberger. The procedure includes the determination of water resistivity by using third party. The volume of shale (Vsh) is calculated by using GR log as a single indicator and Neutron-Density log as a double indicator. Also, the corrected porosity was calculated by: Sonic, Density and Neutron logs.
The determination of fluid saturations was carried out for both clean and shaly zones. In the clean formation Archie equation was applied, and in the shaly formations Indonesian method was used. Then, the lithology was determined analytically by IP software and graphically by using many crossplots (Neutron-Density cross plots and M-N cross plots). The vertical and horizontal distributions of hydrocarbon occurrences have been exhibited from the litho-saturation cross plots for four evaluated wells and through Iso-parametric maps of the study area show the following:
A. Vertical Distribution of the Petrophysical Parameters:
The vertical distribution of hydrocarbon occurrences is presented and explained through the litho-saturation crossplots. These plots for the available four wells show that the main lithology of the Alam ElBueib member (3D) is sandstone, shale, siltstone and streaks of carbonates with average porosity value 10% and water saturation ranging in values from (22 % to 55 %), while Alam ElBueib member (3E) is mainly composed of Sandstone with streaks of siltstone with average porosity value 12% and water saturation ranging in values from 27 % to 92%., Also Alam ElBueib member (3G) is mainly composed of sand stone with calcareous cement and streaks of carbonates with average porosity value 12% and water saturation ranging in values from 14% to 70% . And Alam ElBueib 6 Formation is mainly composed of Sandstone, calcareous cement, Limestone and Dolomite with average porosity value 10% and water saturation ranging in values from 13 % to 25%.,
B. Horizontal Distribution of the Petrophysical Parameters:
The horizontal distribution of hydrocarbon occurrences was studied and explained through a number of porosity and saturation maps for Abu Roash Member (A), Bahariya Formation and Kharita Formation.
For Alam Elbueib Memeber (3D), mainly composed of sand stone, shale, silt stone and streaks of carbonates., Alam El bueib Member (3D) has a good porosity values which increase in southwestern directions as bed thickness and movable hydrocarbons saturations and decreases of water saturations in these directions, it is considered to be as productive reservoir due to high movable hydrocarbon saturations and low shale volume.
For Alam Elbueib Member (3E), mainly composed of sand stone with streaks of silt stone, Although Alam El bueib Member (3E) has a good porosity values which increase into the northeast directions as bed thickness and movable hydrocarbons saturations and increase of water saturations in these directions, it is considered to be as nonproductive reservoir due to low movable hydrocarbon saturations and high water saturation.
For Alam ElBueib Member (3G), mainly composed of sand stone with calcareous cement and streaks of carbonates., Alam ElBueib Member (3G) has a good porosity values which increase in central and southwest getting the highest value in the middle of the area as bed thickness and movable hydrocarbons saturations and decreases of water saturations in these directions, it is considered to be as productive reservoir due to high movable hydrocarbon saturations and low shale volume.
For Alam ElBueib Formation (6), mainly composed of Sandstone, calcareous cement, Limestone and Dolomite, Alam ElBueib Formation (6) has a good porosity values which increase towards the center of the area as bed thickness and movable hydrocarbons saturations and decreases of water saturations in these directions, it is considered to be as productive reservoir due to high movable hydrocarbon saturations and low shale volume.
The tectonic regime was acting upon this area in the form of both lateral compressions and released extensions providing both folding and faulting systems that were clearly indicated by structural highs and lows and normal faults in seismic sections, time and depth structure maps. This tectonic system helped the hydrocarbon migration paths and fluid flows from structural lows to structural highs.
Finally, it can be concluded that the Jade Oil Field is characterized by several structural highs of minor anticlines and horst blocks building mainly three-way dip closures, sometimes four-way dip closures, suitable for hydrocarbon accumulations representing good structural traps. Source rocks are represented by Khatatba Shale Formation. Reservoir rocks are represented by of Alam El Bueib Members (3D, 3G, 3E and 6) of Alam El Bueib Formation. Post-stack seismic inversion has declared two separated lower acoustic impedance zones representing good impact as promising zones for hydrocarbon potential at Alam El Bueib Members (3D and 3G) of Alam El Bueib Formation and Khatatba Formation (Upper and Lower Safaa Members). Seal rock is represented by Alam El Bueib 3C Shale Member.