Journal of African Earth Sciences最新文献

{"title":"Hydrochemical study of groundwater in Tazerbo, Libya, using statistical analysis and geochemical modeling","authors":"Hend S. Abu Salem ,&nbsp;Osama A. El Fallah ,&nbsp;Mohamed M. El Kammar","doi":"10.1016/j.jafrearsci.2024.105362","DOIUrl":"10.1016/j.jafrearsci.2024.105362","url":null,"abstract":"<div><p>The hydrochemical assessment of groundwater is vital in order to constrain the sources of solutes for groundwater management and sustainability. This work uses integrated multivariate statistical analysis and hydrogeochemical modeling to define the controls on the groundwater chemistry in Tazerbo wellfield in Libya. Thirty-five water samples were analyzed where two main types of waters were distinguished: Ca–HCO₃ and Mg–HCO₃. Two main clusters differentiated the study area into two distinct zones, C1 in the west and C2 in the east. Four principal components were obtained from factor analysis showing the effect of water-rock interaction. Pearson correlation and cross plots of major ions revealed that the main controls on water chemistry in the west are weathering of iron rich clays, silicate weathering, and ion exchange, while the controls on the east are sulfate reduction, ion exchange, silicate weathering, and possible mixing with geothermal water rich in CO₂. Temporal changes in the ionic compositions of groundwater were recorded between 2004 and that of the current study. These changes could be attributed to the change in the production and pumping strategy due to the induced land subsidence and water level decline in 2006. Moreover, several wells were abandoned during the past few years due to lack of maintenance that resulted from the political instability of the country. Therefore, they should be maintained to avoid local compositional changes due to localized pumping. Besides, water quality assessment was applied and evaluated the suitability of the groundwater for drinking and irrigation. However, higher Fe should be removed before supply.</p></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"218 ","pages":"Article 105362"},"PeriodicalIF":2.2,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141964369","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Provenance, organic geochemistry and sequence stratigraphy of foredeep sediments (Gurpi and Pabdeh formations) in the Zagros pro-foreland sedimentary system, North Dezful embayment, SW Iran","authors":"Abolfazl Jamshidipour ,&nbsp;Mohammad Khanehbad ,&nbsp;Maryam Mirshahani ,&nbsp;Ali Opera","doi":"10.1016/j.jafrearsci.2024.105367","DOIUrl":"10.1016/j.jafrearsci.2024.105367","url":null,"abstract":"<div><p>The Zagros pro-foreland sedimentary system originated in the Upper Cretaceous and is ongoing. The Pabdeh and Gurpi formations were deposited in the foredeep of the pro-foreland in the northern Dezful embayment. On average, the Gurpi Formation has a thickness of 134 m, whereas the Pabdeh Formation has a thickness of 164 m. The two formations consist mainly of calcareous shales and limestone. Various analytical techniques such as X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscope (SEM), petrophysical logs, Rock-Eval pyrolysis, gas chromatography (GC), and thin sections were used to study the origin of sediments and sedimentary sequences. The predominant minerals found in the shales of these formations include calcite, quartz, dolomite, albite, anorthite, halite, iron minerals, and clay minerals. The highest values of major oxides found in the samples are calcium oxide (CaO), silicon dioxide (SiO₂), aluminum oxide (Al₂O₃), and iron oxide (Fe₂O₃). The source rock of the shales is determined by the quantities of the major oxides present in felsic to intermediate igneous rocks. These sediments are located in a passive continental margin tectonic setting. Clay minerals such as illite, montmorillonite, palygorskite, and sepiolite indicated considerable weathering due to semi-arid to semi-humid conditions, as shown by the CIA index. The average total organic carbon (TOC) content in the samples from the Gurpi Formation is 0.96 wt%, whereas it is 1.27 wt% for the Pabdeh Formation. Both formations include type II kerogen capable of generating oil and gas. The Gurpi and Pabdeh formations have four sedimentary cycles created in a semi-deep to deep environment.</p></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"218 ","pages":"Article 105367"},"PeriodicalIF":2.2,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141932462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Estimation of porosity distribution from formation image logs and comparing the results with NMR log analysis: Implications for the heterogeneity analysis of carbonate reservoirs with an example from the Asmari reservoir, southwest Iran","authors":"Milad Moradi ,&nbsp;Ali Kadkhodaie ,&nbsp;Mohammad Reza Taheri ,&nbsp;Abbas Chenani","doi":"10.1016/j.jafrearsci.2024.105366","DOIUrl":"10.1016/j.jafrearsci.2024.105366","url":null,"abstract":"<div><p>Estimating heterogeneity in carbonate rocks is the most important parameter in identifying reservoir and non-reservoir areas. Diagenetic and sedimentary processes directly control reservoir heterogeneity. In this regard, the high hydrocarbon production rate and the reduction of the complexity of the carbonate reservoirs require the evaluation of a new architecture of the reservoir, in which the simultaneous impact of the diagenetic-sedimentary processes on the petrophysical logs is investigated. The current study studies the Oligocene-Miocene Asmari Formation Iran's giant carbonate reservoir. Based on petrographic studies, sedimentary facies, depositional environment and diagenetic processes were characterized. Formation evaluation was conducted to determine lithology, water saturation, fluid volume, and effective porosity. The estimated porosity from the evaluation of the conventional logs (full suite) was compared with the results of estimating the porosity from the NMR T2 distribution curve and the porosity histogram of the image logs. Lorenz's coefficient of heterogeneity was used to understand the heterogeneity of the reservoir. Diagenetic-sedimentary processes and petrophysical logs were used to investigate the pore type and their distribution. The results of petrographic studies, NMR T2 distribution curve, and porosity histogram show that the diagenetic-sedimentary process is the most important factor enhancing the reservoir heterogeneity. Diagenetic and sedimentary processes were traced by evaluating NMR and Image logs. Based on the results, the porosity distribution using the T2 curve and Image show a good agreement. Diagenetic processes mainly dissolution and dolomitization increased the heterogeneity of the main production zones (zones 3 and 4) of the Asmari reservoir that was confirmed using NMR and Image logs.</p></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"218 ","pages":"Article 105366"},"PeriodicalIF":2.2,"publicationDate":"2024-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141932475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Felsic xenoliths in Triassic quartz-monzodiorite dykes from the central Jebilet (Morocco): Detailed petrography and geochemistry, with a critical assessment of the so-called “granulitic” samples","authors":"Jacky Bouloton ,&nbsp;Dominique Gasquet ,&nbsp;Christian Pin ,&nbsp;Aimeryc Schumacher","doi":"10.1016/j.jafrearsci.2024.105349","DOIUrl":"10.1016/j.jafrearsci.2024.105349","url":null,"abstract":"<div><p>Felsic xenoliths occur locally in the Early Triassic quartz-monzodiorite dykes that crosscut the Sarhlef basin in Central Jebilet, Morocco. Irrespective of the secondary features linked to entrapment, three types of xenoliths are distinguished on the basis of textural evidence: 1) isotropic rocks of broad granitic appearance; 2) foliated samples whose planar fabric undoubtedly corresponds to a ghost foliation, 3) a specific xenolith with a blastomylonitic structure.</p><p>Geochemically, samples with Na &gt; K and moderately negative εNd values (-1.5 to - 3.8), reflecting a hybrid origin, depart from samples with K &gt; Na and strongly negative εNd values (-9.1 to - 11.7), pointing to a stronger or even pure crustal derivation. The blastomylonitic sample differs drastically from the rest by its plagiogranitic composition and elevated Nb content, associated with a highly radiogenic Nd isotope signature (εNd₂₄₀ = + 6.3). Altogether, these features and available radiometric data suggest a connection of the xenoliths with the Variscan igneous bodies that crop out in the central Jebilet. The potassic xenoliths with unradiogenic Nd are broadly similar to the granodiorite plutons. The xenoliths with Na &gt; K and mildly negative εNd and the blastomylonitic plagiogranite are reminiscent of the bimodal association of microgranites and gabbros of the Sarhlef basin.</p><p>From a structural point of view, samples with a gneissic fabric may reflect the possible occurrence of a metamorphic, migmatitic complex at somewhat deeper crustal level. However, based on detailed mineralogical and geochemical data, the samples previously known as “mid-crustal granulites” turn out to be highly differentiated, aplo-pegmatitic rocks, interpreted as early, incipient partial melts. The presence of high-grade metamorphic rocks at depth is only documented by one small, HT garnet-biotite xenolith, while peraluminous lenses (fibrolite + spinel ± corundum) dispersed in the quartz-monzodiorite dykes suggest that a metapelitic component was involved in the melting process generating these lavas. In summary, this set of felsic xenoliths does not provide much information on the crustal composition under the Jebilet, apart from fairly superficial levels.</p></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"219 ","pages":"Article 105349"},"PeriodicalIF":2.2,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142041135","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Forward numerical modelling of pleistocene marine strata, North-West of Morocco","authors":"Soufiane Tichli ,&nbsp;Peter Burgess ,&nbsp;James Lovell-Kennedy ,&nbsp;Mohamed Outiskt ,&nbsp;Khadija Aboumaria","doi":"10.1016/j.jafrearsci.2024.105364","DOIUrl":"10.1016/j.jafrearsci.2024.105364","url":null,"abstract":"<div><p>Numerical stratigraphic forward modelling is useful to understand and reconstruct the relative sea-level and sediment supply history responsible for particular strata. This analysis uses BARSIM, a simple 2D forward stratigraphic process-response model that simulates wave and storm processes, applied with an inverse modelling optimisation method to better understand the history of Pleistocene strata in the Achakkar basin of the Tangier region, Morocco. Observations of grain size and bed thickness in four outcrop vertical sections are matched with BARSIM model output to estimate the lowest-error best-fit relative sea level and sediment supply histories that may have controlled deposition of the observed strata assuming deposition over a 10 ky period, consistent with available dating from outcrop sections. The best-fit relative sea level history drops from 4.88 to −2.82 m with two lower-amplitude highstands in between, most likely representing interglacial eustatic and tectonic event. The best-fit sediment supply is variable through time and different for each vertical section, with greatest variation from 11.7 to 2.11 m²y^-1 over the 10 ky interval in the north-east vertical section. The spatial and temporal variation of sediment supply in the four vertical sections represents typically dynamic depositional conditions in shallow marine nearshore areas. On the other hand, it can indicate high stratigraphic incompleteness caused by periods of non-deposition or erosion with temporal variations in sediment supply. The optimum way for the simple model to reproduce short intervals of high sedimentation rate separated by longer periods of hiatus and deposition followed by erosion results in a discontinuous stratigraphic record.</p></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"218 ","pages":"Article 105364"},"PeriodicalIF":2.2,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141886567","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tectonic and climate changes influences on distribution and morphology of Quaternary travertine, Kurkur oasis, Egypt","authors":"Kamal Abou Elmagd ,&nbsp;Al-Hussein Mohamed Fathy ,&nbsp;Wael Abdelwahab ,&nbsp;Mohammed Hassan Younis","doi":"10.1016/j.jafrearsci.2024.105365","DOIUrl":"10.1016/j.jafrearsci.2024.105365","url":null,"abstract":"<div><p>The present study aims to investigate the relationship between tectonic activity, climate changes and Quaternary travertine deposition around Kurkur Oasis in the southern Western Desert of Egypt. Our findings, based on field observations and structural investigations, revealed that extensional tectonics played a significant role in the formation and the distribution of travertine deposits in the study area. Three main travertine morphotypes are documented: fissure ridge, spring mound, and terrace mound along with four lithotypes: crystalline crust, fine-grained lithoclast, paper-thin raft, and reed. The spatial distribution of these travertine occurrences indicates that travertines located closest to the springs exhibit crystalline crust and paper-thin raft lithotypes. While, the reed and the fine-grained lithoclastic types are situated farther from the water sources. Terraces mounds are related to pluvial episodes, which led to travertine deposition in the suitable tectonically created depressions. A two-stage hypothesis for travertine deposition are proposed herein, involving tectonic fissuring and the circulation of carbonated water. These results may enhance our understanding of travertine formation and have broader implications for geological research in similar tectonic environments.</p></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"218 ","pages":"Article 105365"},"PeriodicalIF":2.2,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141886566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessing landslide susceptibility in northern Morocco: A geostatistical mapping approach in Al Hoceima-Ajdir","authors":"Ayyoub Sbihi ,&nbsp;Mohamed Mastere ,&nbsp;Brahim Benzougagh ,&nbsp;Velibor Spalevic ,&nbsp;Paul Sestras ,&nbsp;Mirjana Radovic ,&nbsp;Slobodan B. Marković ,&nbsp;Lizny Jaufer ,&nbsp;Shuraik Kader","doi":"10.1016/j.jafrearsci.2024.105361","DOIUrl":"10.1016/j.jafrearsci.2024.105361","url":null,"abstract":"<div><p>Landslides are a significant global risk due to their impact on nature, society, and the economy. The Al Hoceima-Ajdir region is highly susceptible to geohazards such as earthquakes and ground instabilities caused by local tectonic movements and specific climatic and geomorphological conditions. This study aims to assess landslide susceptibility in Al Hoceima-Ajdir using a digital mapping approach that integrates the geostatistical Frequency Ratio tool, geomatic tools, and field observations. The frequency ratio method, a widely used technique in geospatial analysis, evaluates the relative frequency of landslides based on the spatial distribution of conditioning factors such as slope, lithology and land use – land cover. This method calculates the ratio of the frequency of landslides within specific classes of these factors to their respective frequencies in the entire study area. This research introduces a novel susceptibility map highlighting major threats to several natural and touristic sites crucial to the region's socio-economic activities. The susceptibility map was developed by analyzing 40 historical landslides along various predisposing factors, including topographic, geo-hydrological, and anthropogenic parameters. The results identify areas prone to landslides and classify their susceptibility into five levels ranging from very high to very low, with each level indicating a different degree of risk and requiring a specific set of preventive measures. The reliability of this map was evaluated using the Receiver Operating Characteristics (ROC) method, demonstrating a high accuracy of 89%, further validated by field visits. This high-precision susceptibility map is significant for pre- and post-risk management, enhancing prevention and mitigation strategies. It also protects society, the economy, and the environment by providing a reliable regional planning and hazard management tool. The findings of this study offer a significant advancement in the methodology for landslide susceptibility assessment and present a model that can be adapted to other regions facing similar geohazards. The research underscores the importance of integrating geostatistical tools with field data to produce accurate and actionable susceptibility maps, benefitting the global scientific community by improving hazard prediction and management strategies.</p></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"218 ","pages":"Article 105361"},"PeriodicalIF":2.2,"publicationDate":"2024-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1464343X24001948/pdfft?md5=7dfda11aa2b397a8486e6d1e92b828c0&pid=1-s2.0-S1464343X24001948-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141839054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhanced classification of pyrite generations based on mineral chemistry using uniform manifold approximation and projection (UMAP)","authors":"Yann Waku Mpaka ,&nbsp;Bjorn P. von der Heyden","doi":"10.1016/j.jafrearsci.2024.105363","DOIUrl":"10.1016/j.jafrearsci.2024.105363","url":null,"abstract":"<div><p>Trace element signatures are tracked to unravel the genetic history of ore deposits in several mineral systems. This is particularly true for pyrite, a ubiquitous component of many ore-forming systems, including orogenic gold deposits. Here, we critically compare the efficacy of utilizing Uniform Manifold Approximation and Projection (UMAP) versus Principal Component Analysis (PCA) as dimensionality reduction tools applied to a 31 element dataset collected using Laser Ablation Inductively Coupled Mass Spectrometry of pyrite grains from the Kibali gold district (Democratic Republic of Congo). Because of the non-linearity inherent to mineral chemistry and because of its superior preservation of local (distances within clusters) and global (separation between clusters) data relationships, the UMAP approach outperforms dimensionality reduction by PCA. We further present a workflow in which UMAP dimensionality reduction is followed by k-means clustering to guide the classification of pyrite generations in the Kibali case study. Validating this approach with trace elements and UMAP + k-means on a seed-by-seed petrography basis shows that the workflow significantly enhances the original pyrite classification, previously based on texture. This study thus emphasizes the utility of employing advanced statistical analysis methods to capture the intricate nature of pyrite formation. These findings will shape best practices for handling large multi-element datasets in pyrite mineral chemistry studies and are extrapolatable to other mineral systems in which trace element signatures are used to infer the conditions of ore deposit genesis.</p></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"218 ","pages":"Article 105363"},"PeriodicalIF":2.2,"publicationDate":"2024-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1464343X24001961/pdfft?md5=d470e79cceb063e632678f9c71309aed&pid=1-s2.0-S1464343X24001961-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141850217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multiproxy faunal analysis of the middle – upper Eocene deposits in the Fayum area, Egypt: Insights into sequence stratigraphy, trophic conditions, and oxygenation","authors":"Abdel Galil A. Hewaidy,&nbsp;Youssef S. Bazeen,&nbsp;Ahmed Samir,&nbsp;El Sayed M. Moneer,&nbsp;Arafa F. El-Balkiemy,&nbsp;Haitham M. Ayyad","doi":"10.1016/j.jafrearsci.2024.105352","DOIUrl":"10.1016/j.jafrearsci.2024.105352","url":null,"abstract":"<div><p>The Eocene epoch experienced significant fluctuations in climate, ranging from intense greenhouse warming to icehouse cooling, which profoundly impacted the global depositional systems. The middle – upper Eocene deposits in Garet Gehannam, Fayum area, Egypt, present an exciting opportunity to explore paleoenvironmental dynamics using a multiproxy dataset of calcareous nannofossils, benthic foraminifera, ostracods, and molluscan assemblages. Calcareous nannofossil biostratigraphy constrained the studied sequence to the NP17 and NP-19-20 zones. Furthermore, three 3^rd-order depositional sequences, BAR.SQ.1, BAR.SQ.2, and PR.SQ.3 were identified. The BAR.SQ.1 sequence encompasses the Gehannam Formation, with a transgressive systems tract (TST) and a highstand systems tract (HST). The BAR.SQ.2 sequence corresponds to the lower Birket Qarun Formation and exhibits a TST/HST pattern. The PR.SQ.3 sequence, however, consists solely of a TST spanning the upper Birket Qarun and Qasr El Sagha formations. The main trend of our multiproxy-based sea level curve shows an overall stepped Tethyan sea level regression within the 2^nd-order cycle. This regression is characterized by a transition from outer neritic to inner settings, interrupted by two minor 3^rd-order transgressive pulses. This sea level trend was likely driven by global eustatic changes and regional tectonic uplift related to the final collisional phase between Africa/Arabia and Eurasia, which led to the closure of the Neotethys Ocean. Multiproxy faunal analysis reveals a pronounced upsection shift from low-oxic and mesotrophic conditions to well-ventilated, oligotrophic settings tracking long-term sea level fall. The lowering of the sea level may have expanded aerobic ventilation windows on the continental shelf while potentially reducing nutrient influx. Our multiproxy sequence stratigraphic and paleoenvironmental analysis provides insights into the complex interplay of tectonic, eustatic, and climatic influences on the region during the middle – late Eocene episode along the southern Tethyan margin.</p></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"218 ","pages":"Article 105352"},"PeriodicalIF":2.2,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141769629","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structural assessment and petrophysical evaluation of the pre-Cenomanian Nubian sandstone in the October Oil Field, central Gulf of Suez, Egypt","authors":"A.A. Azab ,&nbsp;Bassem S. Nabawy ,&nbsp;Saad Mogren ,&nbsp;Kh Saqr ,&nbsp;Elkhedr Ibrahim ,&nbsp;S.M. Talha Qadri ,&nbsp;M. Kh Barakat","doi":"10.1016/j.jafrearsci.2024.105351","DOIUrl":"10.1016/j.jafrearsci.2024.105351","url":null,"abstract":"<div><p>The low quality of the seismic resolution of the studied Cambrian Pre-Cenomanian formations, which rest directly on the basement in the October Field in the Gulf of Suez, requires study, and the structure pattern controlling these formations is uncertain. The poor quality of the seismic data resolution in the Gulf of Suez is due to the presence of thick sequences of evaporites represented by the South Gharib and Zeit formations. Therefore, the current study used seismic reflection data integrated with well-log data to define the structural-stratigraphic setting of the pre-Cretaceous Nubian reservoir sequence. The study aims at locating and delineating zones having excellent reservoir potential within the Nubian sequence horizons (Nubian Transition, main Nubian, Nubian marker-1, and Nubia marker-2, referred to as NT, MN, M1 and M2, respectively) through the integration of the 3D static modelling and the petrophysical parameters deduced from the well-log data processing. A detailed petrophysical analysis, based on the wireline logs of some wells, was performed to determine the lithological units using two types of cross plots (Neutron-Density and M-N plots), and the different petrophysical parameters that characterize the various Nubian horizons were also computed. 3D modelling was used to visualise the lateral and vertical changes of the reservoir characteristics. The seismic mapping reveals that the Nubian structure is controlled by an NW-SE trending (Clysmic trend) of an NE-plunging asymmetrical anticlinal feature unconformably resting on a basement horst. The main structure is affected by two major normal faults, which trend NW, andis cut by two smaller sub-parallel faults that disturb the core of the structure, which is unaffected by the easterly oriented faults of the Aqaba trend. The petrophysical analyses indicate that the Nubian sandstones have intervals of good reservoir quality, with a total net-pay thickness of about 500 m, net sand ratios (60–90 %), effective porosity (10–25 %), and hydrocarbon saturation (85%), which may encourage further drilling, especially in the southeast portion. The result of this study can be extended to the other Nubia sandstones resting on the basement complex in the Gulf of Suez.</p></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"218 ","pages":"Article 105351"},"PeriodicalIF":2.2,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141769630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}