Three‐dimensional (3D) reservoir modelling and basin analysis were performed for the Siwa Basin in the North‐Western Desert of Egypt. An integrative study from the available data were done, including ...geochemical data to construct a 1D basin model, petrophysical data to realize the characteristics of the reservoir, and geological data to understand the subsurface geologic setting, has been undertaken. Basin modelling was done for the Siwa A1‐X well to determine the burial and thermal history, sedimentation rate, level of maturity, and finally the event chart for the petroleum system. Siwa Basin comprises one petroleum system. The source rock is represented by the Palaeozoic Dhiffah, Desouky, and Zeitoun formations, with fair to good organic richness, producing oil and gas, which entered the oil window in 143.91, 162.87, and 167.31 Ma, and entered the wet gas in 138.75, 141.82, and 143.63 Ma, with sedimentation rate varying from low to high 543.96, 22.79, and 1,404.46 m/Ma, respectively. The Safa Member (Khatatba Formation) is the main reservoir, with hydrocarbon saturation reaching up to 80%, and with a low subsidence rate of 76.43 m/Ma. The Original Oil In Place for the new prospects is 197.177 Stock Tank Barrel (STB), while for the oil reserve is 50.618 Stock Tank Barrel (STB).
Workflow chart illustrating the procedure of constructing the 3D reservoir modelling, in addition to the explanation of the steps to establish the 1D basin modelling for Siwa Basin, Egypt.
Discovering new natural resources is important for sustainable development of remote oases in arid regions of Africa and the Middle East. The first comprehensive assessment of geological heritage of ...the Siwa Oasis in the northwestern part of Egypt is based on field inventory of potentially unique geological features and analysis of literature data. Comparison to similar features in the other parts of Egypt and the world, including the Russian South, is essential to evaluate the uniqueness of the described geological phenomena. A total of nine geological heritage types are established in the Siwa Oasis. These include stratigraphical, palaeontological, sedimentary, palaeogeographical, hydrological and hydrogeological, geothermal, pedological, geomorphological, and economical types. The most high-ranked are features constituting sedimentary, palaeogeographical, and hydrological and hydrogeological types. The former can be found in the old Shali town built from evaporite stones experienced diagenetic changes, and the latter is local manifestation of the Eocene–Oligocene palaeoenvironmental transition different from the global cooling trend. Additionally, saline lakes and pools, as well as stratigraphical sections, landforms, and some other features demonstrate certain uniqueness. A series of geosites are identified in the oasis and vicinities. Taken together, the geological heritage of the Siwa Oasis is significant for conservation and exploitation for research, education, and tourism purposes. It is suggested that geological tourism there should be combined with archaeological, industrial, and "ordinary" to become efficient and to contribute to the local sustainable development. Examples from the Russian South (the Big Tambukan and Big Yashalta lakes) permit to realize that the consideration of salt and therapeutic mud resource indicates on the higher value of the discussed geological heritage features of the Siwa Oasis. Moreover, this resource, which is of big uniqueness itself, can contribute substantially to tourism development on the basis of unique geological phenomena.
Display omitted
•Geological heritage – a new resource for Siwa Oasis (NW Egypt).•Nine types of geological heritage and several geosites.•Saline lakes and pools as characteristic features.•Geological tourism to be combined with archaeological and industrial tourism.•Similar resource available in the Russian South is already exploited.
Waterlogging, soil salinization, and groundwater depletion in non-rechargeable aquifers are among the causes endangering the sustainability of Siwa Oasis. The water resources include the tertiary ...carbonate aquifer (TCA), Nubian sandstone aquifer (NSSA), springs, drains, and hypersaline lakes. Geophysical logs were used to identify various aquifer systems. Stable isotopes, major ions, and heavy metals were examined. K-means cluster analysis based on principal component analysis (PCA), hydrochemistry, stable isotopes, and mixing models using NETPATH were applied in order to understand the complex hydrogeological conditions in the different aquifer systems. The results showed that all water samples were under-saturated (SI < 1) with respect to anhydrite, halite, and gypsum minerals, indicating the water's ability to dissolve more from these minerals and increase water salinity.In contrast, calcite, dolomite, Ca-montmorillonite, and illite minerals were supersaturated in most water samples (SI > 1), showing their ability to precipitate these minerals. There is no recharge for the aquifer systems, and all the groundwater resources have paleo meteoric origin, where the maximum values of δ18O and δ2H are −8.45 and −65.63, respectively. All of the springs originated from the TCA, as indicated from the K-mean cluster analysis. There is a rapid increase in the water salinity of the TCA from 1998 to 2022 due to evaporation, rock weathering, mixing with old trapped sea water, and seepage of saline water from salt lakes. The significant variations in the water salinity of the TCA aquifer are due to the mixing between fresh water of NSSA (dilution) and salt water from Zeituna and Siwa lakes through downward flow in some locations, where over-extraction of water for irrigation purposes has decreased the water pressure in the TCA. The mixing model confirmed salt lakes' contribution in increasing the TCA salinity by 2%–4%. Mixing water from TCA and NSSA could be the best management of the water resources in Siwa Oasis, as well as the application of subsurface drip irrigation.
Display omitted
•Approach integrates stable isotopes, PCA, K-Means cluster analysis with geochemical and mixing modelling.•Successful characterization of TCA, NSSA, drains, springs and lakes recharge sources and controlling factors.•Mixing, evaporation, water-rock interaction, control surface water and groundwater chemistry.•Water resources management through application of subsurface drip irrigation, mixing water of TCA and NSSA, and artificial lake.
Digital elevation models produced from COSMO-SkyMed imagery were used to delineate palaeo-drainage in a wide area surrounding the Siwa and Al-Jaghbub oases of the western Sahara Desert (Egypt and ...Libya).
This new generation of synthetic aperture radar imagery is suitable for this purpose because of its high spatial resolution and capacity to penetrate dry surface sediments. Different techniques such as radar interferometry and radargrammetry were used to produce digital elevation models. These were assessed for accuracy and then combined to produce a single elevation model of the area.
The resulting elevation model was used to support the geological study and palaeo-environmental interpretation of the area. It revealed buried features of the landscape, including inactive palaeo-drainage systems. Drainage features were extracted from the elevation model using geographical information systems; results were combined and assessed with respect to geological field data, as well as data from the literature. Previous studies in the area suggest that a wide river, probably the old Nile River, flowed into the Libyan palaeo-Sirte before the Late Messinian drawdown of the Mediterranean Sea. During the Late Messinian lowering of the sea the fluvial system changed shape and carved deep canyons throughout north-eastern Africa.
The reported findings on the key Siwa area were used to precisely delineate the physiography of the modern drainage network and to confirm findings from our previous geological research in the area.
•DEM creation from COSMO-SkyMed images through SAR interferometry and radargrammetry•Accuracy assessment and DEM fusion through statistical analysis and GIS Map Algebra•Automatic extraction and palaeo-environmental interpretation of drainage networks•Path of the Nile River before the Late Messinian drawdown of the Mediterranean Sea
Egyptian Oases are still the most varied in the world, each one has a special character. Siwa Oasis is a place of magic and quietness with a unique ecology. This research tends to show the problems ...associated with the traditional construction technique in Siwa oasis due to the weakness of the available building materials such as Karshif particles and silt mortar which do not have an appropriate strength and rain resistance. On the other hand the modern building technique which is used in the building nowadays is not only unsuitable with the oasis unique architectural character but also has a negative impact on environment and cultural heritage. This research paper discusses the environmental impact of construction and the preservation of vernacular techniques of construction as the heritage of Siwa oasis. So, it presents a proposed construction technique using a durable structure system with enhanced local materials to be able to survive a long period of time and conserve the unique character of Siwa Oasis. In addition, the proposed architectural design of affordable residential building is compared with the traditional and modern building techniques through their strength, thermal insulation and cost. The comparison outcome shows the advantages of the proposed architectural design and its reinforced concrete structural system which using Karshif particles as exterior walls to be an eco-friendly enclosure with the surrounding environment and create a pleasant indoor environmental quality for inhabitants.
Crop diversity is shaped by biological and social processes interacting at different spatiotemporal scales. Here, we combined population genetics and ethnobotany to investigate date palm (Phoenix ...dactylifera L.) diversity in Siwa Oasis, Egypt. Based on interviews with farmers and observation of practices in the field, we collected 149 date palms from Siwa Oasis and 27 uncultivated date palms from abandoned oases in the surrounding desert. Using genotyping data from 18 nuclear and plastid microsatellite loci, we confirmed that some named types each constitute a clonal line, that is, a true‐to‐type cultivar. We also found that others are collections of clonal lines, that is, ethnovarieties, or even unrelated samples, that is, local categories. This alters current assessments of agrobiodiversity, which are visibly underestimated, and uncovers the impact of low‐intensity, but highly effective, farming practices on biodiversity. These hardly observable practices, hypothesized by ethnographic survey and confirmed by genetic analysis, are enabled by the way Isiwans conceive and classify living beings in their oasis, which do not quite match the way biologists do: a classic disparity of etic versus. emic categorizations. In addition, we established that Siwa date palms represent a unique and highly diverse genetic cluster, rather than a subset of North African and Middle Eastern palm diversity. As previously shown, North African date palms display evidence of introgression by the wild relative Phoenix theophrasti, and we found that the uncultivated date palms from the abandoned oases share even more alleles with this species than cultivated palms in this region. The study of Siwa date palms could hence be a key to the understanding of date palm diversification in North Africa. Integration of ethnography and population genetics promoted the understanding of the interplay between diversity management in the oasis (short‐time scale), and the origins and dynamic of diversity through domestication and diversification (long‐time scale).
Thirty soil samples were collected from different locations in Siwa Oasis, Egypt. The activity was measured with a γ-ray spectrometer using a scintillation detector with a NaI(Tl) crystal, 3 × 3 ...inch. The average activity concentrations of
226
Ra,
232
Th, and
40
K in the soil are 22 ± 2, 12 ± 0.6, and 158 ± 8 Bq kg
–1
, respectively. In addition, the radiological hazards were calculated for the investigated samples. The average values of radiological hazards affecting the population were 60 Bq kg
–1
, 27.5 nGy h
–1
, 33.7 mSv year
–1
, 0.16, 0.22, 0.44, and 1.18 × 10
–4
for the radium equivalent activity, absorbed γ-dose, effective dose, external and internal hazard indices, gamma index, and excess lifetime cancer risk (ELCR), respectively. According to the results obtained, all samples would not present significant radiological hazards.
Microfacies studies were carried out on the Middle Miocene Marmarica Formation exposed at the Gabal Western Bahi El-Din and Gabal El-Najdeen, the Siwa Oasis, northwestern Desert (Egypt). It was ...distinguished into the lower, middle, and upper members. Eleven microfacies types were recognized, which include skeletal lime-mudstone, dolomitic lime-mudstone, intraclastic wackestone, bryozoan wackestone, foraminiferal wackestone, foraminiferal bryozoan packstone, glauconitic molluscan packstone, molluscan intraclastic packstone, pelletal peloidal skeletal packstone, dolostones, and claystone microfacies. This formation includes several types of emergence- meter-scale cycles (shallowing-upward). Field observations and petrographic analyses revealed that these cycles consist of pure carbonates and mixed siliciclastic carbonates. These cycles consist of four types of gradual cycles and six types of non-gradual cycles. The gradual emergence cycles indicate a balance between the rate of subsidence, sea level oscillations, and sedimentation rate. The non-gradual cycles indicate an irregular balance between sedimentation rate and subsidence rate. The non-gradual cycles denote high-frequency sea level variation and/or short-term sea level oscillations, which are associated with high carbonate formation. The depositional environments of the Marmarica Formation are restricted to lagoonal at the base, followed upward to open marine conditions. Both environments most probably characterize the platform setting.
Fracture zones on the Earth’s surface are important elements in the understanding of plate motion forces, the dynamics of the subsurface fluid flow, and earthquake distributions. However, good ...exposures of these features are always lacking in arid regions, characterized by flat topography and where sand dunes extensively cover the terrain. During field surveys these conditions, in many cases, hinder the proper characterization of such features. Therefore, an approach that identifies the regional fractures as lineaments on remotely-sensed images or shaded digital terrain models, with its large scale synoptic coverage, could be promising.
In the present work, a segment tracing algorithm (STA), for lineament detection from Landsat-7 Enhanced Thematic Mapper Plus (ETM+) imagery, and the data from the Shuttle Radar Topographic Mission (SRTM) 30
m digital elevation model (DEM), has been applied in the Siwa region, located in the northwest of the Western Desert of Egypt. The objectives are to analyze the spatial variation in orientation of the detected linear features and its relation to the hydrogeologic setting in the area and the underlying geology, and to evaluate the performance of the algorithm applied to the ETM+ and the DEM data.
Detailed structural analysis and better understanding of the tectonic evolution of the area could provide useful tools for hydrologists for reliable groundwater management and development planning. The results obtained have been evaluated by the structural analysis of the area and field observations. Four major vertical fracture zones were detected corresponding to two conjugate sets of strike-slip faults that governed the surface, and subsurface environments of the lakes in the region, and these correlate well with the regional tectonics.
PDF
