الفهرس 
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Abstract
The study area is located in the north eastern part of the Western Desert in Qarun concession, between latitudes 29°:15´:00” to 29°:21´:00” N, and longitudes 30°:15`00” to 30°30`:00” E. It lies within the most productive oil fields in the Qarun concession (Qarun, North Qarun, SW Qarun, and Harun fields).
The present work clarifies the stratigraphy, structure characteristics and well logging interpretation to evaluate the oil source and reservoir potentialities of the area and for evaluation of the Petrophysical parameters of the encountered A/R (G) sand reservoir of Wadi Rayan field.
VII.1. Stratigraphy
The subsurface stratigraphic section penetrated by 10 wells scattered in the study area is similar to a great extent that of the North of the North Western Desert. It ranges in age from Pre-Pre-Cambrian to Middle Eocene.
In most wells the Late Cretaceous Cenomanian sandstone of A/R (G) is followed up by Turonian, Santonian, Campanian, Maastrichtian and Early to Middle Eocene sediments at the top.
VII.2. Subsurface Geology
Construction of stratigraphic and structural cross sections illustrate that the area is originated as an anticline structure extending over the Wadi Rayan field. Lately it was subjected to a number of normal faults in the direction of nearly ENE-WSW and reverse fault in NNE-SSW direction , which is the main controlling factors affecting the structural configuration of the study area . Wadi Rayan field is a well defined four way-dip closure at Abu Roash (G) level , its structure is being both reveres fault in the right limb of the field and some of normal faults at the basal part of the structures.
VII.3. Well Logging Analysis
The Formation evaluation technique Upper Cenomanian A/R (G) members were carried to out in the next steps :
1. Determination of the drilling mud fluid resistivity (Rm, Rmf ) and their correction to the Formation temperature.
2. Determination of Formation water resistivity (Rw) from Resistivity and porosity logs.
3. Determination of Uninvaded zone Resistivity Rt. (deep resistivity) from log curves such as, deep Phasor induction (PI) and Array induction (AIT) .
4. Determination of invaded zone resistivity (shallow resistivity), and its correction for the effect of borehole, adjacent bed and invaded resistive zones.
5. Determination of the completely flushed formation resistivity (Rxo) from micro-spherical focused log (MSFL) and the curve correction in the relations to the mud cake thickness and mud cake resistivity (Rmc).
6. Determination of shale content (Vsh) using Gamma Ray, Sonic and Neutron-Density tools.
7. Determination of matrix parameters.
8. Determination of rock properties in both clean and Shaly zones using Sonic, Neutron, and Density tools.
9. Determination of fluid saturation (water and oil) in both clean and Shaly zones.
The deduced Petrophysical parameters result from the previous steps are integrated and expressed in the form of Lithosaturation cross plot and isoparametric maps to show their variations in the vertical and horizontal extension and reflect their effect on the reservoir characteristics and consequently on the oil potentialities.
VII.4. Oil Generation
The geochemical analysis done on sum of wells in Wadi Rayan field, indicated that the origin of hydrocarbon is essentially has a marine environment, where the Abu Roash (F) is considered the main source rocks, Qarun Co., unpublished report, (1997).
VII.5. Oil Migrations
Oil movement from the source rock into the surrounding porous or fracture permeable reservoir rocks is well known as the primary migration. Hence the oil when complete its first movement into its reservoir, subsequent secondary migration due to the tectonic movement through the permeable rocks carries out into a coarse grained reservoir rock ( Abu Roash (G ) sand reservoir in our study area) , there are no evidence of more movement of hydrocarbon in rock matrix that happened in the studied reservoir .
VII.6. Oil Accumulation
The present study illustrates that the folding and faulting of the study area are responsible for the extraction of oil bituminous rocks .the hydrocarbons fluid moved horizontally and vertically and accumulated in the reservoir porous sand, that are capping by impervious rocks, so as an explanation obtained, oil is due to the structural movement migrate from the source rocks of A/R
( F) into the reservoir rocks of A/R ( G) sand.
VII.7. Oil Entrapments
Generally the oil accumulation may be trapped by either structure, stratigraphic or combined traps. Structural traps are displayed in the form of anticlines, fault and faulted anticlines. In the study area the structure is flanking both of the Gindi and Beni Suif basins in a favorable location to trap oil, as a structural and stratigraphic combination trap plays.
VII.8. Cutoff Recommendations
The net pay parameters of the studied reservoir sand bearing rocks in the all wells of Wadi Rayan field, as a result of formation evaluation cutoff study and analysis, it conclude that, for any more current or future drilling activities in the field should be used and recommended the numbers as follows:-
13% Porosity as a reservoir cutoff
35% volume of Shale as a reservoir cutoff
60% water saturation as a reservoir cutoff
The sand zone of A/R (G) in WR-3X well is very clearly under the oil water contact, so this well is considered to be a water-wet reservoir. While the other wells from WR-1 to WR-10 is oil wet reservoir, all of them is above the oil water contact, although each has a different oil column height, above the original oil water contact. The mainly source rock is the carbonate rocks of
A/R (F) as a completely marine transgressive during the Late Cenomanian age. The reservoir rocks are the A/R (G) detrital clastics sand with intercalation of thin beds of the clay rock materials. The maximum pay thickness in the field is in WR-1 well of 74 ft. of pay, while the minimum is around 16 ft. of pay in well WR-13, this is very clear and supported from the quite low water saturation percentage and minimum volume of clay.