الفهرس 
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Abstract
Summary
Nile Delta is one of complex and difficult province for hydrocarbon exploration. Despite that difficulty, it attracted the attention three decades ago, after discovering Abu Madi and Abu Qir gas fields. The studies have been doubled in the last three years, largely from successful deep water exploration for Pliocene slope-channel systems.
The Pliocene channel Prospect is located in the North Alexandria Block B concession and is a complex, elongated, highly sinuous, deeply incised, mature Pliocene turbidite channel system that extends 15 Km across the West Nile Delta
Description of the geology of the study area, including a summary of stratigraphy, structures and tectonism of the Nile Delta in general and especial focus on west offshore Nile Delta at which the study area is located. The study area is affected by three main faults have the followingtrends:1) NW-SE Misfaq- Bardawil (Temsah) (right lateral strike slip fault), 2) NE-SW Qattara-Eratosthenes (Rosetta) (left lateral strike slip fault), and 3) E-W fault (listric normal faults). The stratigraphy of the area indicates that the main sand reservoir in the study area is Kafr Elsheik Formation. Then studying the architectural hierarchy and anatomy of submarine slope channel complex) provided a clear image about the distribution of sand elements within this complex reservoir.
The study of reservoir system depended on the seismic data, either full stack volume or angle stack volumes (Near-Mid.-Far) and the well logs data; where there are two wells only in the study area that penetrated the Pliocene channel; one of them in the northern part (X1 well) and the other in the southern part of the channel (X2 well). The northern well only has core data.
The following paragraphs indicate the workflow that was done in this study and the results of the study.
Firstly, define the polarity (SEG normal polarity) and determine the phase of the seismic data (mixed or zero) then convert it to zero-phase by applying phase shift equal to 130°. The next step is to define the resolution of seismic data that represents at what extent the seismic data can resolve the studied channel and its internal
elements. The estimated tunning thickness (approximately 11.5 m) is equivalent to sand element, so the seismic data had the ability to resolve the sand element inside the Pliocene channel complex. Then seismic to well tie was an important step to identify the top and the base of the channel, then the mapping of the top and the base of the Pliocene channel.
The results indicated that the Pliocene channel splitted by the different fault trends into three main segments:
1- Segment 1 is defined by the northern termination of the Pliocene channel, while the southern end of segment 1 is defined by large fault which trends NW-SE. This segment shows more channel amalgamation and better reservoir potential than southern segments. Segment 1 was penetrated by X1 well. It drapes over the highest part of the structure.
2- Segment 2 is defined by two faults, which trend NE-SW. It falls in the Saddle (graben) between the two faults. At the base of the reservoir of this segment, there is a structural low which is a possible location for perched water.
3- Segment 3 is defined to the north by the fault which separates it from segment 2 and to the south by the southern termination of the channel. This segment is potentially highly compartmentalized by a series of NE-SW trending faults. Segment 3 is draped over the southern end of Pliocene channel anticline.
Secondly, The evaluation of the channel was carried out by using the different logs such as GR log, density- neutron log, resistivity log and sonic log to get the saturation and net to gross for the two wells. The results indicated that X1 Well consists of three pay zones from four sand packages; where the first pay zone form depth 1575 to 1583 m and its Net to Gross is 0.739, the second pay zone from depth 1587.5 to 1619 m and its Net to Gross is 0.442 and the third pay zone from depth 1640.8 to 1647.8 m and its Net to Gross is 0.331. While for the X2 Well that consists of one sand package, its pay zone from depth 1638 to 1639.6 m and its Net to Gross is 0.013. Finally the resulting GIIP was equal to 2.1462*1010 (SCF), and the Recoverable Resources was equal to 15.0234*109 (SCF). For the channel fill, it is classified according to three subenvironments; axis, off-axis, and margin. The
potential channel subenvironments and their heterogeneity patterns can be identified based on core data. The description focused on cores exist in X1 well only. The first subenvironment is the channel axis subenvironment that is located within the thickest part of the channel, and exhibits the greatest amount of amalgamation ( i.e., high sand content) and is characterized by the thickest sedimentation units that have the highest proportion of sand ( i.e., high NTG ratio) (as sand 1 and sand 4). In contrast, the margin subenvironment is located at the thinner edges of the channel element and has the least amalgamation (i.e., lowest sand content), the thinnest beds, and the lowest proportion of sandstone (i.e., low NTG ratio) (sand 3). The off-axis subenvironment is intermediate between the marginal and axial portions of the channel elements (sand 2). According to these definitions, the thickest net pay and good-quality, coarse-grained sand reservoirs are located within the channel axis subenvironment and the thinnest net pay and lower quality; fine-grained sand reservoirs are located within margin subenvironment. Each subenvironment has its own depositional elements that may have distinct geometries and characteristics.
Third, The Pliocene channel was identified by different attributes for defining the external geometry and internal architecture of reservoir bodies, these attributes are 1) Amplitude extraction (RMS and Maximum negative), Maximum Negative and RMS amplitude attribute maps of full-stack reflectivity cube were extracted between the top and the base of the Pliocene channel. The distribution of the sand within the channel on the Maximum negative amplitude map appeared clearer than its appearance on the RMS amplitude map. 2) Coherence Volume was generated using the semblance algorithm, coherence attributes time slices at 1900 ms and 2000 ms respectively were extracted from the generated coherence volume. The first time slice showed the Pliocene turbidite channel. While, the second one showed the faults distribution. The clarity would be difficult to decipher from the seismic reflectivity volume alone. With comparison to time slices derived from full-stack reflectivity coherence image enhance interpretation of fault. 3) Spectral Decomposition technique showed the channel and its internal geometry, it was done by choosing an interval of interest in time domain (interpreted Pliocene channel, i.e. 3D slab). The time-window of the channel was between 1000 ms-3000 ms. The software extracted and flatted this slab of data then applied discrete Fourier transform to it in order to produce the tuning cube. Animating through the tuning cube in z-direction, namely, frequency slices
(animating frequency from 10 to 60 Hz) these frequency slices represented the amplitude in a series of horizontal sections in the frequency domain. Finally, selection through the different frequency slices to display the best image for the Pliocene Channel complex. Clarification of Direct Hydrocarbon Indicators (bright, dim and flat spot) within the channel were done by the analysis of the north well which is brighter than the south well, where the two wells had gas water contact (flat spot).
Fourth, Amplitude versus offset technique was used to evaluate the Pliocene channel (depending on Rutherford and Wiliams classification), the class type was identified to be class 3; i.e. increasing of the amplitude with the offset in the negative direction and the lithology and the fluid were separated by using EEI technique where the fluid angle equal to 45° and the lithology was 90°.
Finally, through all the previous steps the Pliocene Channel was evaluated by using different qualitative seismic techniques and well logs to define the external geometry and internal architecture of reservoir bodies.