Western Desert Of Egypt Research Articles

Detection of shallow and deep conductive zones using direct current resistivity and time-domain electromagnetic methods, west El-Minia, Egypt

Direct current (DC) resistivity and time-domain electromagnetic (TEM) methods were used to distinguish between saturated and dry zones and in an evaluation of groundwater resources in the western desert of Egypt. DC-resistivity method was used to evaluate the shallow section while TEM method was used for the shallow and deep aquifer sections. In the decay (voltage) curves, the last parts of the early stage and the intermediate stage refer to the shallow aquifer while the late stage indicates the deep aquifer. The effect of ramp-off time was studied. The shallow unrecorded depths of the high current diffusion speed and first and last diffusion depths were determined. The resistivity and thickness of surface deposits and loop side length are the prime influences on diffusion, investigation, and shallow unrecorded depths. By combining the two methods, the subsurface layers were classified into eight conductive and resistive zones. The third (15-75.5 O m), sixth (55-124 O m), and seventh (35-54 O m) are high conductively zones that corresponds to the shallow and deep aquifers, respectively. The TEM method delineated the sedimentary basin and the maximum penetration depth was ∼1300 m. The complementary of two methods confirmed that the resistivity method is sensitive to shallow conductive and resistive zones while the TEM method is sensitive to shallow and deep conductive and resistive zones. The TEM method assisted in identifying the shallow unrecorded depths, the effect of ramp-off time, diffusion depths, and the effect of shallow resistive depths on diffusion depths.

Influences of Well Test Techniques and Uncertainty in Petrophysics on Well Test Results

In the present study, well logs and well test data of both conventional build-up tests and Mini-DST from different oil and gas fields are utilized to evaluate the effects of uncertainty in petrophysics and test techniques on well test results. This includes producing wells from the Nile Delta and Western Desert-Egypt together with published results from West Qurna oil field-Iraq. Results indicated that permeability is strongly dependent on petrophysics interpretation, particularly pay thickness, while the radius of investigation is significantly dependent on fluid properties, especially compressibility. The skin factor calculations showed great sensitivity towards the pressure measurements with medium influences on porosity and oil viscosity. The calculations of Mini DST and Build-up test are compared within the uncertainty context for effective permeability, radius of investigation, and skin factor, and the findings are discussed in detail. In all cases, error analysis indicated that well test results and interpretation of conventional build up data are largely stable and may reduce overall uncertainty to 30% of the corresponding Mini-DST results/interpretation. The results of this study not only characterize each input parameter involved in the interpretation of well test data but also confirms the superiority of conventional build-up on Mini-DST techniques.

The provenance and history of Abu Muharak barchan sands (Kharga Depression) inferred from textural, mineralogical, and geochemical perspectives

The current study deals with textural, mineralogical, and geochemical characteristics of the barchan dune sands of Abu Muharak dune belts in the Kharga Depression. Abu Muharak is the longest dune belt in the Western Desert of Egypt. Sand samples from 37 sites were texturally, petrologically, and chemically analyzed. Our goals were to interpret the provenance of the sands in terms of grain size, petrology, and geochemistry and correlate these data with the proposed source such as Nubian sandstone, Pleistocene alluvial, and Holocene lacustrine sediments as well as ancient aeolian deposits exposed at the Kharga Depression. The present study concludes that the Moghra sandstone is the main source of the Abu Muharak dune belt with local contributions from Pleistocene alluvial and dune deposits as well as weathered Nubian sandstone in the Kharga Depression.

Potential aquifer mapping for cost-effective groundwater reverse osmosis desalination in arid regions using integration of hydrochemistry, environmental isotopes and GIS techniques

In arid regions, water resources are scarce; therefore, sea and brackish groundwater desalination using reverse osmosis (RO) techniques is commonly used to provide freshwater for potable purposes. El-Moghra Oasis, a case study of an inland depression, represents an arid region in the Western Desert of Egypt. The oasis relies mainly on the brackish groundwater in El-Moghra Aquifer for salt-tolerant crop irrigation and feeding desalination plants. The RO brackish groundwater desalination conserves about 75% of the total cost compared to seawater as feed water. Accordingly, the main target of the present work is to allocate cost-effective sites for constructing desalination plants to solve freshwater shortages. The hydrogeochemical and isotopic techniques have been applied to understand the aquifer recharge mechanism and the main factors that deteriorate the groundwater quality. Additionally, an Analytical Hierarchy Process (AHP) relying on the geographic information systems (GIS) utilized to delineate the promising desalination sites. Four main criteria linked with the cost of RO groundwater desalination were investigated, including aquifer hydraulic parameters, hydrogeochemical characteristics, recharge indicators based on isotopic tracers, and other miscellaneous parameters related to the site accessibility and environmental issues. These four main criteria include fourteen sub-criteria; depth to water (DTW), aquifer saturated thickness (ST), transmissivity (T), total dissolved solids (TDS), iron (Fe), total groundwater hardness (TH), calcium sulfate (CaSO4), silica (SiO2), strontium (Sr), oxygen-18 (δ18O), global solar radiation (GSR), land slope (LS) and distance to roads (D). The final suitability map identifies the most favorable locations for constructing a desalination plant is in the northeast, which comprises 64.5% of the study area. The locations with low appropriateness are concentrated in the west and southwest and account for 35.5% of the area.

Hydrogeochemical and geophysical investigations to delineate underground water aquifer in arid regions: A case study, Gara oasis, Egypt

The goal of the present study is to investigate, delineate, and evaluate the shallow Miocene groundwater aquifer with vertical and lateral facies variations in the Gara oasis, western desert of Egypt. This oasis represents a typical arid region in North Africa. Through grid texture analysis, lineament detection, edge detection, thresholding, and identifying areas of structural complexity from the filtered residual reduced-to-pole magnetic anomaly map, it is possible to outline the fracture zones that principally control the groundwater aquifers and water flow in the area. The groundwater quality and quantity are examined hydro-geochemically through nine groundwater samples that were gathered from wells and springs distributed throughout the area around Gara Lake. Measurements of physio-chemical parameters (TDS, pH, and EC) are carried out and its spatial distribution is critically studied. The results reveal that the ion-exchange process caused by water-rock interaction is the dominant process. Furthermore, the main ions in the groundwater in the study areas were Na and Cl. This might be due to evaporation or halite dissolution with the upward flow of waters through the fractures from the deep aquifer of the Nubian sandstone to the shallow aquifer of the fractured Miocene limestone.

Genetic variation and molecular characterization of Zygophyllum coccineum L. ecotypes of the iron mining area of El-Wahat El-Bahariya in Egypt

Remediation and mitigation processes can recover the ecosystems affected by mining operations. Zygophyllum coccineum L. is a native indigenous xerophyte that grows in Egypt's Western Desert, particularly around the iron mining ore deposits, and accumulates high rates of potentially toxic elements (PTEs) in its succulent leaves. The present study evaluated the genetic variation and molecular responses of Z. coccineum to heavy metal stressful conditions in three sites. Results revealed that Z. coccineum bioaccumulation capacity was greater than unity and varied amongst the three locations. In response to heavy metal toxicity, Z. coccineum plants boosted their antioxidative enzymes activity and glutathione levels as a tolerance strategy. Anatomically, a compact epidermis, a thick spongy mesophyll with water storage cells, and a thicker vascular system were observed. Protein electrophoretic analysis yielded 20 fragments with a polymorphism rate of 85%. The antioxidant genes (CAT: catalase, POD: peroxidase and GST: polyphenol oxidase) showed greater levels of expression. In addition, DNA-based molecular genetic diversity analyses using Start Codon Targeted (SCoT) and Inter Simple Sequence Repeat (ISSR) markers yielded 54 amplified fragments (i.e. 24 monomorphic and 30 polymorphic), with 12 unique fragments and a polymorphism rate of 55.5%. The greatest PIC values were recorded for SCoT-6 (0.36) and for both of the 14 A and 44 B ISSR primers (0.25). Diversity index (DI) of all SCoT and ISSR amplified primers was 0.23. The present findings reveal the distinct heavy metal's adaption attributes of Z. coccineum, indicating its improved survival in severely arid mining environments.

Impacts of land-use changes and landholding fragmentation on crop water demand and drought in Wadi El-Farigh, New Delta project, Egypt

Despite Egypt’s limited water resources, more lands in the western desert of the Nile Delta are currently being reclaimed to increase the agricultural area to feed its fast-growing population and provide jobs for new generations. These reclaimed lands are prone to drought since they are located in arid regions with limited water resources for irrigation. Moreover, a high rate of landholdings fragmentation was observed with the migration of large numbers of new farmers to the newly reclaimed areas. Hence, the current work uses remote sensing data to investigate the impacts of landholdings fragmentation and land-use changes on irrigation water demand and drought propagation in two selected sites in Wadi El-Farigh area, one of the newly reclaimed valleys in the western desert of Egypt. To achieve that goal, high-resolution satellite images were used to quantify the land-use changes and patterns. The Surface Energy Balance System (SEBS) was used to estimate the actual evapotranspiration (ETa) from 2010 to 2020. Standardized Precipitation Index (SPI) and Evaporative Stress Index (ESI) were used to monitor drought. Results indicated a large transformation of seasonal herbaceous crops to tree-fruit crops in the two study sites. However, landholding fragmentation caused a reduction in the total cultivated area and thus the accumulated water consumption over one study site. Although the accumulated ETa decreased following the decline in the total cultivated area, the ETa rate per hectare increased by 18.4% and 19.6% for trees and herbaceous crops, respectively, reflecting the negative impact of climate change. ESI and SPI time series confirms that the area became extremely dry, particularly after 2017. In conclusion, land use and climate change increased crop water demand, while landholding fragmentation led to cropland loss. Hence, more policies for land protection and adaptation strategies to climate change are essentially needed.

Artificial Neural Network Model to Predict Production Rate of Electrical Submersible Pump Wells

Summary Production data are essential for designing and operating electrical submersible pump (ESP) systems. This study aims to develop artificial neural network (ANN) models to predict flow rates of ESP artificially lifted wells. The ANN models were developed using 31,652 data points randomly split into 80% (25,744 data points) for training and 20% (5,625 data points) for testing. Each data set included measurements for wellhead parameters, fluid properties, ESP downhole sensor measurements, and variable speed drive (VSD) sensors parameters. The models consisted of four separate neural networks to predict oil, water, gas, and liquid flow rates. Sensitivity analyses were performed to determine the optimum number of input parameters that can be used in the model. The best performance was achieved with ANN models of 16 input parameters that are readily available in ESP wells. The results of the best ANN configuration indicate that the mean absolute percent error (MAPE) between the predicted flow rates and the actual measurements for the testing data points of the oil, water, gas, and liquid networks is 3.7, 5.2, 6.4, and 4.1%, respectively. In addition, the correlation coefficients (R2) are 0.991, 0.992, 0.983, and 0.979 for the estimated oil, water, gas, and liquid flow rates for the testing data points, respectively. The performance of the ANN models was compared against performance of published physics-based models and the results were comparable. Unlike the physics-based methods, the ANN models have the advantage that they do not require periodic calibration. The ANN models were used to predict the flow rate curves of an oilwell in the Western Desert of Egypt. The results were compared to the actual separator test data. It was clear that the model results matched the actual test data. The ANN model is useful for predicting individual well production rates within wide variety of pumping conditions and completion configurations. This should allow for continuous monitoring, optimization, and performance analysis of ESP wells as well as quicker response to operational issues. In comparison to traditional separators and multiphase flowmeters (MPFMs), the use of the developed ANN models is simple, quick, and inexpensive.

An Improved Capillary Pressure Model for Fractal Porous Media: Application to Low-Permeability Sandstone

Capillary pressure is a crucial input in reservoir simulation models. Generally, capillary pressure measurements are expensive and time-consuming; therefore, there is a limitation on the number of cores tested in the laboratory. Accordingly, numerous capillary pressure models have been suggested to match capillary pressure curves and overcome this limitation. This study developed a new fractal capillary pressure model by depicting the porous system as a bundle of tortuous triangular tubes. The model imitates the pores’ angularity, providing a more accurate representation of the pore system than smooth circular openings. Moreover, triangular tubes allow the wetting phase to be retained in the tube’s corners. A genetic algorithm was employed to match the capillary pressure curves and obtain the proposed model’s parameters. Capillary pressure data of eight low-permeability sandstone samples from the Khatatba formation in the Western Desert of Egypt were utilized to test the proposed model. The results revealed that the developed model reasonably matched the laboratory-measured data.

Reuse of Abandoned oil and gas wells for Power generation in Western Dessert and Gulf of Suez fields of Egypt

This study investigates the capable outcome of using existing abandoned oil and gas wells as a geothermal energy source in Egypt. Geothermal resources of Egypt are mainly located along the Gulf of Suez and Red Sea in addition to some additional spots with lower potential in the Western Desert of Egypt. In Gulf of Suez the geothermal potential identified data and parameters dignified from oil and gas wells under the regulation of the Egyptian General Petroleum Corporation. Using abandoned oil and gas well which already lost their economic value would save drilling time and cost which would decrease the ROR of the investment. In this paper a simulation model cycle has been made by ASPEN HYSYS software to show the reliability of using the abandoned oil and gas wells outlet fluid as a source geothermal energy in Egypt by mapping the geothermal favorability locations with the oil and gas field area. Mapping shows that in Egypt there is potential of extracting low, medium and high temperature extractions from wells according to the location. Results demonstrates that the output power for the simulation geothermal power plant in different locations of Egypt and at various temperatures. Showing that in western desert the maximum output power that can be generated from the modified binary cycle is 3.063 MW at output temperature of 125 °C. Whereas in the Gulf of Suez proposed maximum output is 44.6 MW that can be produced from modified Flash steam cycle at an output temperature of 300 °C.

Novel Correlation for Calculating Water Saturation in Shaly Sandstone Reservoirs Using Artificial Intelligence: Case Study from Egyptian Oil Fields

The accurate determination of water saturation in shaly sandstone reservoirs has a significant impact on hydrocarbons in place estimation and selection of possible hydrocarbon zones. The available numerical equations for water saturation estimation are unreliable and depend on laboratory core analysis. Therefore, this paper attempts to use artificial intelligence methods in developing an artificial neural network model (ANN) for water saturation (Sw) prediction. The ANN model is developed and validated by using 2700 core measured points from the fields located in the Gulf of Suez, Nile Delta, and Western Desert of Egypt, with inputs including the formation depth, the caliper size, the sonic time, gamma rays (GRs), shallow resistivity (Rxo), neutron porosity (NPHI), the photoelectric effect (PEF), bulk density, and deep resistivity (Rt). The study results show that the optimization process for the ANN model is achieved by distributing the collected data as follows: 80% for training and 20% for testing processes, with an R2 of 0.973 and a mean square error (MSE) of 0.048. In addition, a mathematical equation is extracted out of the ANN model that is used to estimate the formation water saturation in a simple and direct approach. The developed equation can be used incorporating with the existing well logs commercial software to increase the accuracy of water saturation prediction. A comparison study is executed using published correlations (Waxman and Smits, dual water, and effective models) to show the robustness of the presented ANN model and the extracted equation. The results show that the proposed correlation and the ANN model achieved outstanding performance and better accuracy than the existing empirical models for calculating the formation water saturation with a high correlation coefficient (R2) of 0.973, lowest mean-square error (MSE) of 0.048, lowest average absolute percent relative error (AAPRE) of 0.042, and standard deviation (SD) of 0.24. To the best of our knowledge, the current study and the proposed ANN model establish a novel base in the estimation of formation water saturation.

The Provenance of Ancient Cotton and Wool Textiles from Nubia: Insights from Technical Textile Analysis and Strontium Isotopes

Abstract Late antique and medieval cotton and wool textiles found in the middle Nile Valley (Nubia, northern Sudan) were analysed for their technical characteristics and strontium (Sr) isotope composition. All wool textiles exhibit Sr isotope signatures consistent with the isotopic background of the region studied and are considered to be of local origin. However, a medieval wool kilim from Meinarti shows technical and aesthetic features suggesting its foreign Maghreb provenance. As this fabric dates back to the occupation of Meinarti by the Beni Ikrima tribe, it is suggested that the kilim was woven by the Beni Ikrima people from local Nubian raw material. The cotton samples tested come from abroad and document trade with the oases of the Egyptian Western Desert, the west coast of India, and perhaps also with the Arabian Peninsula or Pakistan.

Subsurface geology and geochemical evaluation of the Middle Jurassic-Lower Cretaceous organic-rich intervals, West Kalabsha area, Western Desert, Egypt

The West Kalabsha (WKAL) area is a western extreme exploratory area of the Faghur Basin in the Western Desert of Egypt. The study of four wells (WKAL; A-1 X, K-1 X, P-1X, and C-1 X), interpreted with twenty seismic lines, shows that the area is dissected by a series of normal faults with an irregular, E–W strike direction. The general trend of the throw is toward the south–southeast. The most prospective area for hydrocarbon (HC) migration is toward the north (upthrown side) of an E-W striking normal fault north of the WKAl-K-1 X and A-1 X wells. The WKAL-P-1 X and WKAL-K-1 X wells in the Faghur Basin were selected for both geochemical evaluation of possible source rock intervals and burial history modelling within the basin. Integration of the wire-line logs with geochemical analysis identified six organic matter-rich intervals (OMRIs) within the Middle Jurassic-Lower Cretaceous sequence. Four intervals are in the Alam El-Bueib-3C (AEB-3C) member with a cumulative vertical thickness of 530ft. The other OMRIs are 110ft in thickness recorded within the AEB-6 (10ft) and Upper Safa (100ft) members. The studied organic matter (OM) reveals type III, IIIC, and IV kerogens (mainly gas-prone) with a terrestrial origin. They have reached a maturity level consistent with the late oil window. The expulsion threshold depth detected in the WKAL-P-1 X well is 12000ft in the AEB-3C member, whereas the active source depth limit (ASDL) is 15000ft in the Safa Member. The present study suggests a paleo-geothermal gradient range between 1.13oF/100ft and 1.39oF/100ft with an estimated regional erosion of 5500 to 7000ft of strata mainly between the Paleozoic-Jurassic and Cretaceous-Tertiary boundaries. The present-day geothermal gradient based on bottom-hole temperatures shows a geothermal gradient of 1.4oF/100ft (WKAL-P-1 X), that increases to the north to 1.65oF/100ft (WKAL-K-1 X). Burial history modelling reveals that sedimentary strata entered the mature oil zone in the Early Cretaceous (110–115Ma) at depths of 7500–8000ft in the deepest part of WKAL-P-1 X and WKAL-K-1 X wells (Paleozoic strata). Maturation continued to present, resulting in Jurassic and Lower Cretaceous strata currently falling into the late oil window.

Eco-biochemical responses, phytoremediation potential and molecular genetic analysis of Alhagi maurorum grown in metal-contaminated soils

BackgroundAlhagi maurorum Medik. (camelthorn) is a dominant desert plant indigenous in various habitats, including the Western Desert of Egypt. The plant is especially prevalent in and around economic iron ore deposits. Nutrient and heavy metal levels in A. maurorum tissues and soil samples were assessed to identify associations between heavy metal levels in plants and soil. The objective was to evaluate this species as an indicator of heavy metal pollution. Photosynthetic pigments, protein, proline, alkaloids, flavonoids, 2,2-diphenyl-1-picrylhydrazylscavenging, reduced glutathione, malondialdehyde, antioxidant enzymes, and stress-related gene expression were assessed to determine their functional roles in metal stress adaptation in ultra- and molecular structure. Additionally, the molecular genetic variation in A. maurorum samples was assessed using co-dominant sequence-related amplified polymorphism (SRAP) and inter simple sequence repeats (ISSR).ResultsA substantial difference in enzymatic and non-enzymatic antioxidants of A. maurorum was observed in samples collected from three sites. A. maurorum is suited to the climate in mineralized regions. Morphologically, the stem shows spines, narrow leaves, and a reduced shoot system. Anatomically, modifications included a cuticle coating on leaves and stems, sunken stomata, a compact epidermis, and a thick cortex. Significant anatomical-physiological differences were observed with varying heavy metal soil content, antioxidative enzyme activities increased as a tolerance strategy, and glutathione levels decreased in response to heavy metal toxicity. Heavy metal accumulation also affected the expression of stress-related genes. The highest levels of expression of GST, G6PDH, 6PGD, nitrate reductase 1, and sulfate transporter genes were found in plants collected from site A1. However, auxin-induced protein exhibited its highest expression in plants collected from A2. Six SRAP combinations yielded 25 scoreable markers with a polymorphism rate of 64%, and 5 ISSR markers produced 11 bands with a polymorphism rate of 36.36% for three A. maurorum genotypes. The ME1xEM7 primer combinations provided the most polymorphic information content and resolving power, making it the most useful primer for differentiating A. maurorum genotypes. SRAP markers exhibited a higher diversity index (0.24) than ISSR markers (0.16).ConclusionsA. maurorum displayed adaptive characteristics for heavy metal sequestration from mining site soils and is proposed as a strong candidate for phytoremediation.

Short-Term Sea-Level Changes and Sequence Stratigraphy of the Mid-Cretaceous Kharita Formation Reservoirs in Egypt: Insights from Geochemical and Palynological Data.

Widespread deposition of siliciclastic sediments with consequent alternations between fine-grained siltstones and shales versus coarse-grained sandstones in the north Western Desert of Egypt provides an archive for mid-Cretaceous sea-level oscillations. This study presents elemental geochemical data as well as palynofacies and palynomorph components of upper Albian reservoirs in the Abu Gharadig Basin, north Western Desert. During the mid-Cretaceous, the studied area is located in the transition zone between the fluvio-deltaic and shallow marine settings at the southern margin of the Tethys Ocean. Thirty rock cutting samples were collected from the Kharita Formation and analyzed for major and trace elements, total organic carbon, and palynological composition. These data, together with geophysical gamma ray log values and lithological composition, allowed us to reconstruct the changes in relative sea level at this time in the framework of a third-order transgressive–regressive (T–R) sequence stratigraphic model. Palynomorph composition, represented by a fairly diverse assemblage of terrestrial plant spores and pollen grains versus marine dinoflagellate cysts and other microplankton, was employed along with the variation in the particulate organic matter composition. Chemical proxies, including Si, Ti, and often K and Fe, and their ratios normalized to Al, as well as the carbonate content and the Sr/Ca ratio, provided significant stratigraphic variations with respect to sea-level changes. The above proxies allowed for the subdivision of the studied reservoir intervals into three T–R sequences.

Mantle-derived fluids in the continental-scale Nubian aquifer

The Nubian aquifer of northeastern Africa is one of the largest confined fossil-water aquifer systems in the world. It is central for ongoing water needs and future development goals of Egypt, Libya, Sudan and Chad. Groundwater extraction and consumptive use over the past 40 years have led to a continuous decline of water level and to the reduction and/or cessation of natural flow in artesian wells and springs. This study introduces new noble gas and stable isotope geochemical data from deep groundwater supply wells of the main oases of the Western Desert of Egypt (Bahariya, Farafra, Dahkla, and Kharga) and places these data in the context of a regional compilation of published hydrological and hydrochemical data. Helium isotopes, stable isotope compositions for water (δ2H; δ18O) and dissolved inorganic carbon (δ13C), salt compositions, and [CO2] suggest deeply derived fluid inputs. Highly variable groundwater temperatures (20–56 °C) also suggest the presence of geothermal inputs that mix with aquifer water. Nubian water displays high PCO2 (up to three orders of magnitude higher than atmosphere) and hydrochemical analysis using δ13C suggests up to ~30% of the CO2 is derived from deep geologic sources. Helium isotope (3He/4He) ratios of samples obtained from the Nubian aquifer range from crustal values of 0.02RA (where RA reflects the 3He/4He in air or 1.384 × 10−6) to values of up to 0.36RA (2.5% mantle helium) in Dahkla Oasis of Egypt and up to 1.4RA (17% mantle helium) in Libya. Correlations among excess heat, increases in [CO2], δ13C, and 3He/4He indicate that small volumes of deeply sourced fluids carrying mantle-derived volatiles are leaking into the Nubian aquifer. Geothermal water apparently ascend along faults and shear zone conduits and mix with regional groundwater. The origin of these volatiles may be partial melts in low velocity upper mantle beneath the aquifer and young magmatism surrounding the Nubian aquifer. Fluid-rock interactions along flowpaths can explain variable associations and correlations among the tracers. Variability of composition and temperature suggest complex fluid mixing within the Nubian aquifer, the existence of fault-bounded hydrologic sub-basins, and a connection between tectonics and water quality. Better understanding of the sources and admixtures of deep geothermal fluid inputs is needed for informed water management.

Oil biomarker signature and hydrocarbon prospectivity of Paleozoic versus Mesozoic source rocks in the Faghur–Sallum basins, Egypt's Western Desert

Exploration campaigns focusing on Paleozoic plays in the Egyptian north Western Desert Sallum and Faghur basins have been limited to date, and little has been done to investigate their hydrocarbon generation potential. A total of 284 shale, calcareous shale, coaly shale and siltstone side-wall core and cuttings samples, covering the rock succession that ranges from the Silurian Kohla Formation to the Turonian Abu Roash Formation were analyzed for source rock potential. In addition, eight reservoired Paleozoic–Mesozoic oil samples were geochemically analyzed. This paper systematically investigates (1) organic enrichment, hydrocarbon generation potential, and thermal maturity of Mesozoic as well as possible Paleozoic source rocks, and (2) composition and biomarker characteristics of crude oil samples in the study area from the far north Western Desert basins of Egypt.The Silurian Kohla and Basur and the Carboniferous Desouqy and Dhiffah siltstone and shale rock samples show overall poor and fair to good source rock potential for the Lower and Upper Cretaceous rock units, respectively. In contrast, high TOC (up to 4.83 wt%) and Rock-Eval S2 (up to 6.57 mg HC/g rock) for the Devonian Zeitoun Formation samples indicates fair to very good source potential. The Middle Jurassic Khatatba Formation samples, compared with the Devonian Zeitoun Formation or other rock units in the stratigraphic column of the study area, have the highest TOC (30.1 wt%) and the highest S2 (26.9 mg HC/g rock), indicating fair to excellent source rock potential. These high values of the Khatatba Formation are locally related to organic-rich coaly shales and calcareous shale intervals. The Rock-Eval results indicate an overall dominance of Type-III kerogen with strongly varying OI values. This highly gas-prone character for most samples was confirmed petrographically by abundant vitrinite phytoclasts and recycled organic matter. Coals and coaly shale facies from the Alam El Bueib and Khatatba formations that contain liptinitic materials may represent Type-III kerogens that are capable of generating gas with minor oil. Based on Rock-Eval Tmax and HI results, the Zeitoun and Khatatba samples range from early to peak oil window. This is consistent with the Ro measurements of the Paleozoic Zeitoun samples (0.65–1.02%) and the Middle Jurassic Khatatba samples (0.59–1.01%).The Faghur oils are light (35°–46° API gravity), belong to a single genetic family and are non-biodegraded based on wide-ranging n-alkanes. Abundant tricyclic diterpanes, C24 tetracyclic terpane, C27 Ts trisnorneohopane, diahopane, cyclohexanes, C29 steranes and rearranged steranes and low to very low gammacerane and extended hopanes are common molecular signatures of the analyzed light oil and condensate samples. These findings indicate a relatively oxic fluvio-deltaic environment for the corresponding clay-rich coaly shale and calcareous shale source rocks that contain predominantly higher land-plants with negligible algal/bacterial organic materials. Based on saturated- and aromatic-maturity parameters, the analyzed oils were inherited from peak–late mature source rock.

Decoding of seismic data for complex stratigraphic traps revealing by seismic attributes analogy in Yidma/Alamein concession area Western Desert, Egypt

Sandstone channels are one of the best stratigraphic traps for hydrocarbon accumulation, and their depositional and composition make them difficult to detect on ordinary seismic data, especially in structurally affected onshore areas like the Western Desert of Egypt. The Western Desert of Egypt has many hydrocarbon-bearing reservoirs of various compositions like carbonates and sandstones with high production rates, and thus the Western Desert of Egypt is recognized as a hot spot for oil and gas exploration. One of the important reservoirs in the Lower Cretaceous “the Aptian sand” produced around 285 MBBLS cumulative oil of 22° API and still produces 102 BOPD. This reservoir has a channel-type depositional environment, and the dimensions of this channel could be resolved by good quality 3D seismic data in the moderately deep basins as the basins become deeper, the detection of the channel becomes increasingly challenging. This study aims to delineate the geometry of this reservoir and reveal the exposure from the Aptian sand channel in the Alamein area using the seismic attributes analogy on the re-processed 3D seismic data to determine the best drilling location for increasing the production from this reservoir. In this context, the relative acoustic impedance (RAI), iso-frequency components, and sweetness stratigraphic attribute analyses were conducted on the optimized seismic data and attested as important as they resolved the stratigraphic geological mystery in the structurally affected study area. These attribute analyses revealed the exposure from the distinctive meander channel of the Aptian sand for the first time in the study area nearby the producing Alamein field, where this channel was hard to be distinguished by the ordinary seismic interpretation methods and there is no drilled well penetrated the detected channel’s body. Upon the results, the conclusion and recommendation summaries to intensify the efforts to test the productivity of the detected channel to increase the production from this motivating reservoir by drilling a new well targeting the best structural locations of the channel body.

Living in a fringe environment: three Late Roman settlements in the Kharga Oasis (Egypt's Western Desert)

AbstractThis article presents a comparative analysis of three Late Roman sites located at the northern outskirts of the Kharga Oasis in Egypt's Western Desert: Umm al-Dabadib, Ayn al-Labakha, and the Gib/Sumayra Complex. These were part of the district of the Oasis Magna, which included the oases of Dakhla and Kharga. An analysis of their layout, including both shape and extent, is followed by an evaluation of their absolute and relative positions. These data are then compared to the administrative and historical contexts within which the three sites flourished. Both administrative and economic aspects are considered, as well as the presence of the army. The complex picture that emerges suggests that these three sites played several roles at the same time and were part of a large-scale strategic design that encompassed not only the Kharga Oasis but the entire Western Desert.

Facies and early diagenesis of rainwater-fed paleospring calcareous tufas in the Kurkur oasis area (southern Egypt)

The Quaternary calcareous tufas precipitated in the Kurkur Oasis area in the southern Western Desert of Egypt were analyzed to determine their implications for the construction of environmental conditions during their formation. X-ray diffraction analysis showed that the tufas consist of low-Mg calcite, whereas macroscopic and microscopic analyses showed the presence of both allochthonous (clastic) and autochthonous components consisting predominantly of pisoliths, oncoids, intraclasts, lithoclasts, stromatolites and encrusted plant materials. These tufas form four facies associations that represent pisolitic intraclastic/lithoclastic oncoidal rudstones, phytohermal /bryophyte framestones, stromatolite-algal boundstones, and speleothem-like flowstones. These tufa associations were formed within a karstified carbonate terrain by a rainwater-fed paleospring system comprising waterfalls, slopes, dammed areas, lacustrines-paludal, and fluvial channel margin environments. Early diagenetic features are cementation, neomorphism and subaerial dissolution. Isotope-geochemical analysis indicated that the negative δ18O values (between – 13.26 and – 8.89‰ V-PDB) and the negative δ13C values (between – 3.16 and – 1.62‰ V-PDB) of the studied tufas are consistent with carbonates deposited from meteoric water in regions with much precipitation.