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Evidence for active generation and seepage of sub-salt natural gas/condensate blend in the east offshore Nile Delta, Egypt: Integrated geochemical, petrophysical and seismic attribute approaches

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Petroleum Science 2025年第1期22卷 130-150页

作者： Mahmoud Leila Ahmed A.Radwan Amir Ismail Emad A.Eysa geology department Faculty of Science Mansoura University School of Mining and Geosciences Nazarbayev University department of geology Faculty of Science Al-Azhar UniversityAssiut Branch department of geology Faculty of Science Helwan University department of Physical and Environmental Sciences Texas A&M University—Corpus Christi geology department Faculty of Science Zagazig University

Offshore Nile Delta in Egypt represents an enormous hydrocarbon province with recent projected gas and condensate discoveries of more than 50 trillion cubic feet “TCF”. Most of these occur in the post-salt hydrocarbon plays where biogenic gases are dominant. This study integrates organic geochemistry,seismic geomorphology and petrophysics in order to decipher the origin, and accumulation conditions of the wet gas/condensate blend in the Upper Miocene sub-salt Wakar Formation sandstones in Port Fouad Marine “PFM” Field, offshore Nile Delta. Hydrocarbon pay zones are scattered thin（ 1 w.t.%, hydrogen index“HI” > 200 mg HC/g TOC） and mature(Tmax> 430°C, vitrinite reflectance “VR” > 0.6 %R_o), source rocks are restricted to Upper Miocene Wakar and Oligo-Miocene Tineh formations. The latter contains more mature organofacies（up to 1.2 %R_o） and type II/III kerogen, thereby demonstrating a good capability to generate wet gases. The studied gas is wet and has thermogenic origin with signs of secondary microbial alteration, whereas the condensate contains a mixture of marine and terrestrial input. Molecular biomarkers of the condensate, isotopic and molecular composition of the gas reveals a generation of condensate prior to gas expulsion from the source. The Wakar sandstones have a heterogeneous pore system where three reservoir rock types（RRTI, RRTII and RRTIII）. RRTI rocks present the bulk composition of the Wakar pay zones. Spatial distribution of RRTI facies likely control the accumulation of the sub-salt hydrocarbons. Our results provide a new evidence on an active petroleum system in the sub-salt Paleogene successions in the offshore Nile Delta where concomitant generation of ga

关键词： Petrophysical evaluation Source rock Hydrocarbon geochemistry Biomarkers Gas chimneys Rock-typing

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Responses of non-marine deposits to fluctuating base level and their implications in the Precambrian sequence building:Late Neoproterozoic Girbhakar Sandstone,Rajasthan,India

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Journal of Palaeogeography 2025年第01期14卷 66-90页

作者： Pradip Samanta Soumik Mukhopadhyay Arunava Sen Madhurya Roy department of geology University of North Bengal department of Geological Sciences Jadavpur University

The distinctive sedimentation patterns of the late Neoproterozoic Girbhakar Sandstone were investigated within the context of a Precambrian sedimentation system devoid of vegetation. This comprehensive study utilized an integrated approach, incorporating facies analysis, fluvial architectural elements analysis, and palaeocurrent analysis, to offer detailed insights into the controlling factors of sedimentology and depositional settings within the studied interval. Process-based facies analysis revealed thirteen distinct facies types organized into five associations, uncovering a diverse range of depositional palaeoenvironments —from alluvial fan and braided fluvial to transitional marine settings. An alluvial fan, dominated by debris flow and multiple ephemeral channels at the basin margin, emerged initially. The stratigraphic architecture of this alluvial fan and the associated ephemeral fluvial system was primarily influenced by water table fluctuations in arid to semiarid climatic conditions. A transition to a semi-perennial to perennial braided fluvial system occurred as the depositional slope decreased. However, the stratigraphic architecture of these fluvial systems exhibited distinctive variations in response to fluctuating base level rise. Notably, the basal segment, characterized by an unconformity below and a granular lag succeeded by wave-agitated sandstone above, represented the lowstand systems tract(LST). During the early LST, channel belts prograded at the northern distal end of upstream aggradational semi-perennial braided systems in response to the transgression of Girbhakar Sea from the north, aligning with the late Neoproterozoic Indian plate configuration. The coarsening upward deposits suggest a potential classification as a braid-delta, formed by a gradual rise in base level, low epeiric gradient, and episodic flashy discharges, which facilitate the downstream development of this deposit. During the late LST, the evolution of perennial fluvial

关键词： Late Neoproterozoic Marwar Basin Girbhakar Sandstone Alluvial fan Braid-delta Braid-plain Allogenic and autogenic control Lowstand systems tract Fluvial sequence stratigraphy

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Basin inversion controls on diagenetic evolution of Lower Cretaceous non-marine succession:the English Wealden sandstones

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Journal of Palaeogeography 2025年第01期14卷 15-39页

作者： Oladapo O.Akinlotan Sunday E.Okunuwadje Stuart J.Hatter Anglia Ruskin university department of Geography University of Sussex department of geology and Petroleum geology University of Aberdeen Badley Ashton & Associates Ltd Winceby House Winceby

Modelling the diagenetic history of a tectonically active basin is crucial for understanding the depositional and post-depositional processes including the evolution and development of porosity and permeability. This study describes the diagenetic imprints of the inverted Lower Cretaceous Weald Basin and examines the depositional and tectonic controls on the diagenetic, porosity and permeability evolution of its ***-two representative sandstone samples from the Weald Basin were subjected to detailed microscopic(optical and scanning electron) analyses. The dominant early diagenetic fabrics include grain-coating detrital clays, degraded and dissolved detrital grains, and vermiform kaolinite pore-filling cement while uplift-related or telogenetic characteristics are mainly post-compactional pore-filling goethite and hematite cement. This work is significant because it presents the first diagenetic model of the Lower Cretaceous Wealden sandstones which can be very useful for understanding basins with similar depositional and tectonic settings.

关键词： Diagenesis Diagenetic evolution Basin inversion Lower Cretaceous English Wealden Weald Basin

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Evaluating the hydrocarbon generation potential of the Paleocene–Eocene carbonaceous rocks in the Barmer and Bikaner-Nagaur Basins, western Rajasthan, India

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China geology 2025年第1期8卷 77-91页

作者： Alok Kumar Khairul Azlan Mustapha Alok K.Singh Mohammed Hail Hakimi Ali Y.Kahal Waqas Naseem Hijaz Kamal Hasnan department of geology Faculty of ScienceUniversiti MalayaKuala Lumpur 50603Malaysia department of geology Institute of ScienceBanaras Hindu UniversityVaranasi 221005India department of Petroleum Engineering and GeoEngineering Rajiv Gandhi Institute of Petroleum TechnologyJais 229304India Institute of geology and Petroleum Technologies Kazan Federal UniversityKazan 420008Russia geology and Geophysics department King Saud UniversityRiyadh 11451Saudi Arabia department of geology University of PoonchRawalakot 12350Pakistan

The Bikaner-Nagaur and Barmer Basins(Rajasthan)are the most important petroliferous sedimentary basins in *** over a decade,the exploration and extraction of hydrocarbons in these ***-Eocene age rocks bear organic-rich sediments in these basins,including lignite and carbonaceous shale *** present research investigates the source rock properties,petroleum potential and thermal maturity of the carbonaceous shale partings from the lignite mines of Gurha(Bikaner-Nagaur Basin)and Kapurdi(Barmer Basin)using petrographical and geochemical *** carbonaceous shales have high organic matter(OM),with considerable total organic carbon(TOC)contents ranging from 13%to 39%.Furthermore,they contain hydrogen-rich kerogen,including types II and II/III,as evidenced by the Rock-Eval and elemental analysis *** existence of these kerogen types indicates the abundance of reactive(vitrinite and liptinite)***,the carbonaceous shales from the Bikaner–Nagaur Basin have oil generation potentials,with a high hydrogen index(up to 516 mg HC/g TOC)and a H/C ratio(up to 1.5)along with a significant presence of oil-prone liptinitic *** from the geochemical and petrological results,the studied shales have low huminite reflectance(0.31%–0.48%),maximum temperature(S_(2) peak;Tmax)between 419℃ and 429℃,and low production index values(PI:0.01–0.03).These results indicate that these carbonaceous shales contain immature OM,and thereby,they cannot yet release commercial amount of *** immaturity level in the studied outcrop section is due to the shallow burial *** proxies further indicate the presence of both oil and gas-prone source rocks.

关键词： Carbonaceous shale Petroliferous Bikaner-Nagaur Basin Barmer Basin High hydrogen index Hydrogen-rich kerogen Western Rajasthan Geochemistry Petrology

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Spatial distribution of landslides in response to the geomorphometric constraints in Darma Valley,kumaun Himalaya

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山地科学学报（英文） 2025年第1期22卷 48-70页

作者： Mohd SHAWEZ Vikram GUPTA Anand Kumar GUPTA Gautam RAWAT Geomorphology Environmental and Engineering GeologyWadia Institute of Himalayan GeologyDehradun 248001India Academy of Scientific and Innovative Research Ghaziabad 201002India Geomorphology Environmental and Engineering GeologyWadia Institute of Himalayan GeologyDehradun 248001India Academy of Scientific and Innovative Research Ghaziabad 201002India department of geology Sikkim UniversityGangtok 737102India

The kumaun Himalaya is well-known as a geologically and tectonically complex region that amplifies mass wasting processes,particularly *** study attempts to investigate the interplay between landslide distribution and the litho-tectonic regime of Darma Valley,kumaun Himalaya.A landslide inventory comprising 295 landslides in the area has been prepared and several morphotectonic proxies such as valley floor width to height ratio(Vf),stream length gradient index(SL),and hypsometric integral(HI)have been used to infer tectonic *** analysis,including basic,linear,aerial,and relief aspects,of 59 fourth-order sub-basins,has been carried out to estimate erosion potential in the study *** result demonstrates that 46.77％of the landslides lie in very high,20.32％in high,21.29％in medium,and 11.61％in low erosion potential zones *** order to determine the key parameters controlling erosion potential,two multivariate statistical methods namely Principal Component Analysis(PCA)and Agglomerative Hierarchical Clustering(AHC)were *** reveals that the Higher Himalayan Zone(HHZ)has the highest erosion potential due to the presence of elongated sub-basins characterized by steep slopes and high *** clusters created through AHC exhibit positive PCA values,indicating a robust correlation between PCA and ***,the landslide density map shows two major landslide *** of these hotspots lies in the vicinity of highly active Munsiyari Thrust(MT),while the other is in the Pandukeshwar formation within the MT's hanging wall,characterized by a high exhumation *** SL and low Vf values along these hotspots further corroborate that the occurrence of landslides in the study area is influenced by tectonic *** study,by identifying erosion-prone areas and elucidating the implications of tectonic activity on landslide distribution,empowers policymakers and government agencies to develop strategies for hazard asse

关键词： Landslides Geomorphometric analysis Multivariate statistical analysis Darma valley kumaun Himalaya

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Geochemistry and petrogenesis of Mesoproterozoic mafic granulite and amphibolite dykes from Saltora, Bankura district, Chhotanagpur Gneissic Complex, eastern India: Implications for their emplacement in within-plate setting

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China geology 2025年第1期8卷 159-186页

作者： Poulami Roy Bapi Goswami Ankita Basak Anwesa Sen Chittaranjan Bhattacharyya department of geology University of Calcutta35 Ballygunge Circular RoadKolkata 700019India

Distinguishing high-grade mafic-ultramafic rocks originally crystallized from within-plate basaltic magmatism is challenging and crucial because the chemical composition of the igneous rocks has been modified during high-grade metamorphism,causing misidentification of the characters of the parental *** metamorphosed mafic dykes occur throughout the Chhotanagpur Gneissic Complex(CGC)of eastern Indian *** E-W trending mafic dykes from the Saltora area in the southeastern CGC underwent metamorphism in two episodes:M1(650 MPa;770℃)and M2(300 MPa;744℃).The metamafics are enriched in LILE,depleted in HFSE,and display strong fractionation of LREE,nearly flat HREE patterns in a chondrite-normalized REE diagram,and show tholeiitic differentiation *** geochemical affinity is towards rift-related,continental within-plate *** 7%–10%melting of the carbonated spinel-peridotite sub-continental lithospheric mantle(SCLM)produced the parental mafic *** pre-existing SCLM was metasomatized by slab-derived fluid during the previous *** upwelling of the asthenosphere in a post-collisional tectonic setting caused E-W trending fractures,lithospheric thinning,and gravitational *** dykes were emplaced during crustal extension around 1070 *** remarkable geochemical similarity between the mafic dykes of Saltora and Dhanbad,the ca.1096 Ma Mahoba(Bundelkhand craton),and the ca.1070 Ma Alcurra mafic dykes in Australia supports a genetic link.

关键词： Metamorphosed mafic dykes Within-plate basaltic magmatism Carbonated spinel-peridotite Chhotanapgpur Gneissic Complex Mesoproterozoic Continental rift Crustal extension SCLM Petrogenesis India

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Molecular dynamics simulation:The key to reveal the enrichment mechanisms of helium

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Science China Earth Sciences 2025年第2期68卷 643-645页

作者： Wenhui LIU department of geology Northwest UniversityXi’an 710069China Petroleum Exploration and Production Research Institute SINOPECBeijing 102206China

In recent years,helium and its enrichment mechanisms have been the frontier and attractive research in the field of geological resources(Liu et al.,2024).In the earliest geosciences,noble gases and their isotopes,including helium,were used as tracers for geochronology and geological processes due to their chemical inertness and *** attention has been paid to the isotope composition in geological bodies.

关键词： attractive frontier gases

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Macrofaunal Paleocommunities and Microfacies Analysis from the Upper Cretaceous in North Eastern Desert of Egypt

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Acta Geologica Sinica(English Edition) 2025年第1期99卷 15-37页

作者： Saeed FAREED Yasser SALAMA Abdelaziz MAHMOUD Helwan university Faculty of SciencesGeology DepartmentHelwanCairo 11Egypt Beni-Suef university Faculty of SciencesGeology DepartmentBeni Suef 62511Egypt

The Upper Cretaceous successions of Wadi Umm-Khayshar,southern Galala Plateau,North Eastern Desert,Egypt,are composed of highly diversified faunas and subdivided from base to top into the Galala(Middle-Late Cenomanian),Maghra El Hadida(Latest Cenomanian-Late Turonian),Matulla(Coniacian-Santonian),and Sudr(Campanian-Maastrichtian)*** ammonite biozones are recorded in the studied section:Neolobites vibrayeanus,Vascoceras cauvini(late Cenomanian),Vascoceras proprium,Choffaticeras segne,and Coilopoceras requienianum(Turonian)*** paleoenvironments of the Upper Cretaceous succession are interpreted based on detailed study and microfacies analysis that reflect a deposition in a homoclinal ramp platform ranging from intertidal to deep *** paleoecology of the Cenomanian-Turonian succession in the studied section is explained based on a detailed study of macrofaunal associations and sedimentary *** analysis(Q-mode cluster analysis,using the Raup-Crick Paired group method)of 1029 macrobenthic specimens,including 45 species of mollusks and echinoids yielded five macrofaunal associations(A-E)that are described and interpreted as remnants of *** nektonic elements are represented by 235 cephalopod specimens of 20 species;heatmap cluster analyses show the distribution of these specimens during the Upper Cenomanian-Turonian *** parameters(substrate consistency,rate of sedimentation,water energy,surface-water productivity,and oxygen availability)controlled the distribution of the studied *** five associations are divided into two major groups:low-stress associations(A,B,C,and D),and a highstress association(E).The low stress associations are recorded from two different habitats:(1)a high-energy,firm substrate habitat,dominated by epifaunal bivalves,large epifaunal gastropods and a regular echinoid;(2)a low-energy,soft substrate habitat dominated by infaunal bivalves and *** high stress associ

关键词： invertebrate paleontology ammonites Upper Cretaceous microfacies Southern Galala NE Egypt

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Sr-Nd isotopic characteristics and their significance in provenance tracing of detrital sediment in major rivers and marginal seas of eastern China

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Science China Earth Sciences 2025年第2期68卷 523-537页

作者： Xiaobao GAO Chao LI Zhifei DUAN Yulong GUO Shouye YANG State Key Laboratory of Marine geology Tongji UniversityShanghai 200092China

Sr-Nd isotopes are widely utilized as reliable tracers in sediment provenance *** this study,we compiled 304 Sr and 335 Nd isotope data of fine-grained surface sediments collected from major rivers in eastern China,including the Huanghe River,Changjiang River,southeastern coastal rivers,and rivers in Taiwan Island,as well as from marginal seas(Yellow Sea and East China Sea)and the Okinawa *** comprehensive dataset allowed us to examine the spatial distribution patterns of these isotopes and their implications for provenance *** variations ofεNd values in the sediments in Changjiang and Huanghe Basins primarily reflect the diversity of sediment sources,whereas the^(87)Sr/^(86)Sr ratios are influenced by both grain size and source ***,the reduction in^(87)Sr/^(86)Sr ratios observed in the middle and lower Changjiang River is attributed to the inputs of sources characterized by distinct^(87)Sr/^(86)Sr signatures beyond mere grain size *** the southeastern coastal and Taiwan rivers,sediments in the tidal reaches of the Jiao River exhibit hybrid characteristics,a mix of Changjiang-derived sediment and those originating from local ***,the Min River and Jiulong River sediments predominantly reflect local sources,with minimal influence from the Changjiang *** significant isotopic variation of Sr-Nd isotopic characteristics observed between riverine sediments on the eastern and western sides of Taiwan Island underscores the diverse provenance heterogeneity of source rocks in the *** the marginal seas,our data indicates that the surface sediments in the central mud area of the South Yellow Sea and the southern Yellow Sea are predominantly sourced from the Changjiang River catchment,potentially augmented by inputs from Korean *** inner shelf sediments of the East China Sea are primarily influenced by Changjiang River inputs,whereas rivers in eastern Taiwan Island contribute to the sediments on

关键词： Sr-Nd isotope Provenance tracing Detrital sediments Eastern China rivers Marginal seas

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Geochemistry and petrogenesis of magnesian high-K granitoids from Bundelkhand Craton,Central India:New insights into crustal evolution

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Acta Geochimica 2025年第1期44卷 36-58页

作者： Shailendra K.Prajapati Meraj Alam Parashar Mishra Hemant Kumar Geological Survey of India Northern RegionLucknowUP 226024India department of geology Indira Gandhi National Tribal UniversityAmarkantakMP 484887India

Background The Bundelkhand Craton is significant for preserving the multiphase granitoids magmatism from Paleoarchean to Neoarchean *** consists of a variety of granite rocks,including TTGs,sanukitoids,and high-K *** study presents geochemical characteristics of high-silica(68.97 wt.%–73.99 wt.%),low-silica(58.73wt.%–69.94 wt.%),and high K_(2)O(2.77 wt.%–6.16 wt.%)contents of *** The data on Bundelkhand Craton’s granitic magmatism and geodynamics is not sufficiently *** data from this study will be used to further understand the origin,source,and petrogenesis of granitoid rocks and their implications for the evolution of *** Twenty-one samples were collected and analyzed for major,trace,and REE *** elements were measured using X-ray fluorescence spectrometry(XRF),and trace and REE elements were analyzed by *** procedures from the Geological Survey of India were *** The geochemical analysis presents high-silica(68.97-73.99 wt.%),low-silica(58.73-69.94 wt.%),and high K_(2)O(2.77-6.16 wt.%)contents in granitoids,classified as *** rocks are calcic to calcalkalic,magnesian,and range from peraluminous to metaluminous *** patterns showed strong LREE enrichment relative to HREEs,with prominent negative Eu anomalies corresponding to earlier plagioclase ***-element patterns revealed negative anomalies in Nb,Sr,P,and Ti and positive anomalies in *** The geochemical signatures attributed to the post-collisional magma generation and continental crustal *** studied rocks show A-type and A2-type lineage,suggesting they originated from the melting of continental crust during transitional/post-collisional tectonic *** formation of hybrid granitoids in the Bundelkhand Craton is connected to the fractionation of hybrid magmas in shallow-seated magma chambers during these tectonic processes.

关键词： Geochemistry Petrogenesis A-type granites Crustal evolution Bundelkhand craton

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