الفهرس 
Tectonic settingOnly 14 pages are availabe for public view
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Abstract
This study is aimed to r’le delineation and interpretation of the subsurface ceologica! L configuration in the area northwest to Qattara Depression. \i-cstern Desert. Egypt. The interpreted geological evolution has been used to eLaluate the hydrocarbon potentialities in this area both in txme and space. These objectives have been accomplished by the integrated analysis of all available geological. geophysical. and geochemical data. The data set included 24 unrnigrated seismic lines. the composite and electric logs of eight wells. and measured maturity indicators (Ro and Tmax) and kerogen types. The methods of study included three approaches. Seismic analysis has been applied to delineate the structural and stratigraphic configuration. Qualitati1.e and quantitative evaluation of well logs has been performed to determine the petrophysical parameters and main rock components of geological intervals that could be potential reservoir rocks. Basin analysis has been camed out using the burial and thermal history of the study area to evaluate the prospective source rock maturity and their hydrocarbon generating capabilities. These analyses have been facilitated by the use of three computer sohvares; MIRA. QLA2, and BasinMod, in addition to the well logs digitizer RAT. The penetrated sedimentary succession in the study area has been discussed in relation to the subsurface geology of the Northern b’estern Desert. A correlation chart has been constructed to investigate the vertical and horizontal variation of both lithology and thicknesses of the stratigraphic units in eight wells. The stratigraphy of the study area is characterized by cycling of sedimentary facies. Marine carbonates and shales are dominated at the end of each cycle. These marine carbonates are good marker horizones for correlation. The selected lines used in the seismic analysis are forming a p d and passing by or close to the studied wells. The seismic analysis included the application of different techniques which are: spectral analysis. synthetic seismograms creation. ~-eloc~n. correlation. n.ing i?-nther~: seismogr?ms to seismic sections. srlsmic stratigraphic analysis. and seismic structural interpretations. The results of each step has been utilized in the next step. The spectral ar,alysis is done to get the frequency spectral content of the reflections encountered in the seismic lines. The spectral plots for different traces showed that the frequency content ranges from 6 Hz to 35 Hz. uith an average peak frequency of 23 HZ. The obtained frequency range represents the actual seismic data frequency. It has been used to desiy a bandpass filter which was applied in creating the synthetic seismograms. The bandpass filter of 6-12-24-35 Hz has been designed to obtain a zero-phase wavelet in time domain. Ths wavelet was presumed as the source wavelet . The input data for creation of synthetic seismograms were the velociv and density logs. The end product is the zero-offset artificial seismic trace for each of the studied well. The technique involved calculation of the acoustic impedance log, calculation of the reflection coefficients log, and convolution of the reflection coefficient log with the zero-phase wavelet to yield the qnthetic seismogram. A correlation chart, using the velocity logs of the studied wells, was made to investigate the velocity variations of the geologic section. Ths chart confirmed the correlation results of the stratigraphic boundaries. The correlation shows that the Tertiary section has erroneous low velocities due to bad hole condition. The Khoman chalk has velocity range from 10000 to 11200 ftlsec. The velocity pattern of Abu Roash Formation (seven rock units) is composed of alternating low and high velocity intervals which are laterally continuous. The shale intervals has low velocity (10000 Wsec), whereas the limestone intervals velocity is about 14200 ftlsec. On the other hand, Alarn El Bueib Formation (five rock units) does not pertain such velocity contrast between its units, in addition to thickness variation of each unit. Both weak velocity contrasts, and transmission loss of seismic enerE with depth. yields to weaker seismic reflection events. Alarn El Bueib velocity is about 15000 ft/sec. There is no clear velocity contrast across the boundary of Haharl?a and Kharita Formation. The veloci~ increases graduaiiy tiom 12500 5 sec in Bahariya sandstones to 13800 ftisec in the lower Oarita sandstones These sandstone velocities indicates good porosities . The velocity decreases to about 10200 ftlsec in the upper shaly pan of Bahariya ~ormat;on. It is clear, in this chart, that Alamein Formation has much higher inten.al velocity (18000 fi/sec) compared to those of overlying and underlying units. Ths hgh velocity is continuous in all wells. The minimum thckness to resol~.e the upper and lower boundaries of Alamein Formation on seismic lins would be 196 feet. The thckness of this unit averages around 200 feet in most of the wells. These criteria make Alamein Formation an excellent seismic marker in studying the seismic sections. Tying synthetic seismograms to seismic lines gave satisfactory match, and was achieved using MIRA software. The approach of interpreting the studied seismic lines involved the tracking of seismic reflector markers, the description of geometrical relationships of the encountered sequences, and the delineation of the structural deformation.