This work explores the morphologic characteristics of aeolian dune sand in the southeastern part of Western Desert of Egypt. It aims to assess the movement of barchan dunes and evaluate their ...environmental influence on the Toshka Project. Morphometric investigation of barchan dunes in the Toshka area revealed that most barchans have high length/width (a/c) ratios (fat to pudgy), while one-fifth of the studied barchans have lower a/c ratios and so appear normal in their morphologic forms. Statistical analysis of the main parameters of barchan dunes in Toshka and other desert regions in the Kharga (Egypt), Kuwait, Southern Morocco, California and Southern Peru demonstrates that barchans of the Toshka area are distinctive in their appearance. They are characterized by distinct aspect with higher values of length and width and greater growth in height. The high-energy wind environment in addition to the large amount of drifting sand are principal factors responsible for the unique shape of Toshka barchans.
The migration rate of barchan dunes in four chosen test locations, within the central and western Toshka area, ranges from about 3 to 10.82m/year. The calculated average migration rate of these dunes is about 6m/year in a SSW direction. Sand encroachment is more extensive in the central and western parts of the investigated Toshka area. Risk evaluation of sand dune movements in the southeastern part of the Western Desert points to medium to high sand encroachment risk values. These may represent serious hazards to the newly-established Toshka Project, threatening roads, as well as cultivated lands in the area.
•Most of Toshka barchans are fat and pudgy while normal barchans are less dominant.•Toshka barchans are unique in their shape compared with other barchans in the world.•The average migration rate of Toshka dunes is about 6m/year in the SSW direction.•The risk assessment of the Toshka sand dunes ranges from a medium to high index.
Paleozoic sedimentary succession research is valuable for better understanding the global petroleum province and future hydrocarbon reserves. Paleozoic rocks are the prime source of the enormous ...hydrocarbon fields in North Africa. Despite the Western Desert of Egypt being part of the North African Platforms and having similar depositional, tectonic, and diagenetic constraints, the hydrocarbon system for Paleozoic rocks in the Siwa Basin is indeed not characterized. Forty-five Paleozoic samples were collected from the Siwa Basin to evaluate the source rock characteristics using Rock-Eval pyrolysis, vitrinite reflectance, stable carbon isotopes, biomarkers, headspace gas, and palynofacies analyses. Additionally, the burial and thermal histories of these rocks were investigated by 1D basin modeling. The Paleozoic succession is represented by the Silurian (Basur Formation), Devonian (Zeitoun and Desouqy formations), and Carboniferous (Dhiffah Formation). The routine bulk geochemical analysis of the studied samples indicates poor to good source rock potential. The studied samples contain mostly kerogen type III with some kerogen type II, whereas the Carboniferous samples contain mostly kerogen type IV. The organic matter of the Devonian samples is suggested to have originated from marine and terrigenous sources, with a dominant upward terrigenous source. The lower part of the Devonian is deposited in more reduced marine conditions than the upper part. The organic matter is found to be mature, as indicated by Rr%, Tmax, and biomarker data. The composition of collected headspace gases in Paleozoic rocks suggests their thermogenic origin. Moreover, the similarity of the molecular composition between Paleozoic source rocks and crude oil in reservoir rocks supports the same hydrocarbon sources. Accordingly, the petroleum system in the Siwa Basin is based on active Paleozoic source rocks that charge and accumulate hydrocarbons in the sand reservoirs of the Desouqy Formation. The Paleozoic section entered the oil window in the Early Cretaceous (∼101 myr) based on its burial history. Thus, this study gives improved insights into the petroleum system in the Siwa Basin. Additionally, the Siwa Basin's lesser thickness and burial depth in comparison to other North African basins most likely contributed to its poor petroleum potential.
•Paleozoic rocks have poor to good source rock potential.•Organic matter is derived from marine and terrigenous sources.•Source rocks were deposited in a reducing environment.•Paleozoic rocks in Siwa Basin have active source rocks.
Jurassic rocks comprise the main source rocks in the Western Desert of Egypt. In this study, a rare case of Jurassic oil shale occurrence is recorded and studied as an extension of the Khatatba ...Formation. The study is based on an integrated model for oil shale deposition using seismic data, organic geochemical analyses, and palynomorph thermal alteration assessment to determine the hydrocarbon generation potential of these rocks. The seismic data were used to construct structure and lithofacies models and to relate the facies distribution with the geochemical parameters of the different rock units in addition to examining the lithofacies changes between the study wells adding value to the understanding of the environment of deposition and the structure of the study area. The Zahra, U. Safa, and L. Safa members are affected by two sets of normal faults, the first of which has a downthrown side to the east while the second set has downthrown westward sides. The 3D facies models show that the Zahra Member is composed mainly of limestone encountered in the central parts of the basin, while shale is mostly found in the north. The U. Safa consists mainly of sandstone and the L. Safa consists of sandstone and siltstone. The geochemical evaluation shows organic richness ranging from poor to good for the Zahra, while the Safa shows poor to excellent richness. Kerogen is Type III and IV in most samples. The Zahra samples are immature in the TUT-21X well and mature in only one sample from the AMOUN NE-2X well. The U. Safa samples are immature to marginally mature while the L. Safa samples are marginally mature to mature in the TUT-21X well and immature in the SHAMS-15X well. Palynomorph thermal alteration data confirm the above maturation levels. The bulk and biomarker composition of two oils samples from U. and L. Safa, AMOUN NE-1X well, are similar and indicate a terrigenous source of the kerogen. The oils are not biodegraded but are normal mature oils generated by kerogen that was deposited under oxic conditions. Data integration from this study can be used to show the variation in organic richness (TOC) and thermal maturity (Tmax) in the area between the four wells, which will help define the exploration risk and provide for a new vision for more exploration activity.
•Jurassic Khatatba Formation geochemical evaluation performed in Western Desert.•Organic richness varied from poor to good (Zahra Member) and from poor to excellent (Safa Member).•Kerogen types are Type III and IV for most samples.•Oils were generated from terrestrial organic matter deposited in oxic depositional environment.•The oils are normal oils, mature, with no evidence of biodegradation.
The Cenomanian fluvio-estuarine Bahariya Formation was investigated as an example for estuarine complexes at Aghar oilfield. A facies-constrained 3D-static reservoir geocellular modeling and 1D basin ...modeling were performed in this study for the purpose of adequately identifying the architectural elements, and charge timing, of such an important reservoir. We utilized a range of datasets, from basin to microscopic scales, such as seismic lines, well log data, conventional and special core data, thin sections and SEM images. The results show that Bahariya Formation is stratigraphically subdivided into a lowstand systems tract (LST) represented by the Lower Bahariya fluvial system and a transgressive one which is represented by the Upper Bahariya estuarine system. Five sedimentary facies assemblages were assigned for Bahariya Formation. Based on the petrographical description, SEM and XRD data, the studied samples are summed up into four microfacies associations. The available core data includes bulk density, helium porosity, vertical and horizontal permeability, and capillary pressure data. Applying the porosity-permeability plot, Dykstra-Parsons, discrete rock type, the reservoir quality index (RQI)-flow zone indicator (FZI) plot, effective pore radius of Winland (R35), and the stratigraphic modified Lorenz technique, it is indicated that the studied Bahariya samples can be grouped into eight reservoir rock types (RRTs). Among them, four RRTs are considered prospective, whereas the others are non-prospective. Besides, the Bahariya Formation is subdivided into two compartments with very high heterogeneity, due to the alternation between conductive and non-conductive hydraulic flow units (HFUs), which is attributed to the differential impact of the digenetic features including cementation, compaction and presence of authigenic minerals. The present tidal sandstone inlets case study deserves a special concern, for running the future oilfield development plans, and consideration in similar geologic settings.
•Pre-identified facies assemblages constraining 3D-static reservoir models for better illustrating heterogeneities.•TOC estimation and basin modeling confirming hydrocarbon charging.•Hydrocarbon-promising tidal inlets acting as best reservoir facies.•Based on the petrophysical behaviour and the porosity cutoff, eight reservoir rock types (RRTs) were assigned.•Four RRTs are prospective and the others are non-prospective; and all are summed up into 11 flow units (HFUs).
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•The estuarine architecture is just depicted via facies-constrained 3D modeling.•Heterogeneity of Khatatba complex reveals five sedimentary facies associations.•Basin modeling ...confirms hydrocarbon charging from Khatatba shales to reservoirs.•Bars comparison with modern-ancient analogues verifies sufficient characteristics.•Given best reservoir quality, estuarine bars deserve testing in similar settings.
Inadequate delineation of reservoir-heterogeneities, along with charge-timing confirmation, can considerably mislead exploration-development phases of petroleum. Therefore, precisely depicting the reservoir-architecture is crucial for avoiding exploration failures. To this end, integrated approach of various facies analysis and modeling-related disciplines; e.g. seismic facies, and GR-log motifs; was applied, in this study, to develop a depositional-model capable of aiding in stochastically-mapping reservoir heterogeneity and quality of the Jurassic estuarine depositional-system at JG-Field. To overcome the issue of sparse well control and scarcity of promising discoveries from deep-buried intervals in the study area, stochastic 3D-geocellular reservoir modeling, constrained by seismic attribute analysis, was performed to render a lateral prediction of different facies constituting the Jurassic succession. Predicting organic maturities and retrieving past geologic processes controlled sedimentary basin evolution were also a matter of importance to confirm hydrocarbon-charging to reservoir intervals. Accordingly, 1D-basin model was established so as to complete the story of petroleum system analysis in the area. We utilized dataset of seismic, log, core, and thin-section data; and applied both object-based and pixel-based, SIS (Sequential Indicator-Simulation) and SGS (Sequential Gaussian-Simulation), stochastic modeling algorithms upon simulating rock and fluid properties. The results show that the Jurassic succession constitutes a third-order depositional sequence of fluvio-estuarine units, subdivided into five sedimentary facies-associations. Fluvial and tidal-bar facies associations enrich medium-grained sandstones, deposited in subaerial and subaqueous conditions respectively, featuring significant reservoir quality. Given best reservoir-quality, and considerable thickness, the tidal sand-bars ought to catch attention of future development strategies and be considered for investigation in similar settings.
The Albian-Cenomanian succession in the Western Desert of Egypt represents important source/reservoir rocks. This succession comprises the Kharita and Bahariya formations in addition to the G Member ...of the Abu Roash Formation. These rock units were studied here using extensive sequence stratigraphic modeling. This model was based on high resolution statistical and time series analyses of electric logs from three well sections in the Meleiha Basin. This is a novel approach in this type of studies in this region. These well sections are the Safir N-2X, Hayat-4X, and Tut-1X arranged from south to the north direction in the study area. The statistical investigation included constrained single linkage and principal component analyses of characteristic lithological electric logs. The time series analysis was conducted using continuous wavelet transform (CWT), Morlet wave transform, and evaluative short-wave Fourier transform. Sixteen (16) short term sequences and 4 long term sequences were identified in the studied well sections and they were correlated with the global sea level curve. This is the highest resolution model identified in this area to the date. The time series analysis provided a cyclicity ratio that was used in the astronomical tuning of the identified sequences to the orbital time scale. Additional Fisher plots and palynofacies analyses were carried out to explore the paleoenvironmental settings. The Fisher plots revealed changes in the accommodation size that is in accordance with long term stratigraphic changes. The accommodation space increased significantly up-section in the Bahariya Formation and Abu Roash G Member. The application of statistical classification of palynofacies by cluster and correspondence analyses led to the identification of three palynofacies types (palynofacies type A, B and C) and proximal-distal trend that was determined by the correspondence values. The depth stacking of palynofacies and proximal –distal trend were attributed to long term stratigraphic changes and correlate well to the accommodation calculated from the Fisher plots. The integrated sequence stratigraphic modeling accomplished in the present study increases our understanding of the source/reservoir distribution in the Albian Cenomanian succession and will be of great benefit for current and future exploration plans in the Meleiha basin. In addition, the approach used in this study provides sequence boundaries and maximum flooding surfaces that could be used for regional and global correlations.
•The Albian Cenomanian succession represents important source/reservoir rock in Western Desert.•The succession comprises Kharita and Bahariya units from three well sections in Meleiha Basin.•Stratigraphic classification is based on high resolution statistical and time series analyses.•The study resulted in identification of 16 short term sequences and 4 long term sequences.•Complementary analysis of sea level is achieved by fisher plots and palynofacies.
In order to document the depositional environments of the Kurkur Formation in Southwestern Desert, Egypt, four surface sections measured in this region from north to south as follows: Gebel Garra, ...Wadi Abu-Sayal, Kurkur Oasis, and Sinn El-Kaddab. Planktonic foraminifera indicate that the age of Kurkur Formation in the study area is Danian to Selandian. Microfacies analysis shows graduation from wackestones, floatstones, and packstones in the lower part to oolitic and bioclastic grainstones in the upper section. The lower part of Kurkur Formation characterized by calcareous foraminifera assemblages, whereas arenaceous types are concentrated toward the uppermost part. Bivalves, gastropods, and echinoids are the most abundant macrofossils. Using the microfacies analyses and fossil content, the Kurkur Formation in the studied area deposited in middle neritic zone for the lower part, which is synchronous with the beginning of the Cenozoic transgression in the study area, and changed upward to inner neritic and supratidal environments.
