The Govanda Formation was deposited during the Miocene in the intermontane areas between the Zagros suture and imbricate zones.The Govanda Formation was studied in the Sherwan Mazin area within Mergasor district,Erbil...The Govanda Formation was deposited during the Miocene in the intermontane areas between the Zagros suture and imbricate zones.The Govanda Formation was studied in the Sherwan Mazin area within Mergasor district,Erbil Governorate to identify the lithostratigraphy and microfacies analysis in order to determine the depositional environment of the formation.The formation in the studied section is 116 m thick and mainly consists of reddish-brown,hard,thickbedded,chert-bearing conglomerate,pinkish shale and yellowish-grey,thick-bedded,detrital,fossiliferous limestone.The formation is unconformably underlain by the Upper Cretaceous Tanjero Formation and conformably overlain by the Merga Red Beds series.Four different lithostratigraphic units were identified,based on field observation and petrographic analysis,including a basal conglomerate unit(A),a shale unit(B),a well-bedded limestone unit(C)and a thick and massively-bedded limestone unit(D).The presence of a thick conglomerate bed at the base of the formation indicates a large unconformity that lasted nearly 40 million years.Based on detailed microfacies analysis of carbonate rocks,five main microfacies and 15 submicrofacies are recognized.The main microfacies types include mudstone,wackestone,packstone,grainstone and boundstone microfacies.Based on the microfacies types the depositional environment are defined as open lagoon,reef,fore-reef and back-reef environments of normal to saline,nutrient rich water.展开更多
Seismic texture attributes are closely related to seismic facies and reservoir characteristics and are thus widely used in seismic data interpretation.However,information is mislaid in the stacking process when tradit...Seismic texture attributes are closely related to seismic facies and reservoir characteristics and are thus widely used in seismic data interpretation.However,information is mislaid in the stacking process when traditional texture attributes are extracted from poststack data,which is detrimental to complex reservoir description.In this study,pre-stack texture attributes are introduced,these attributes can not only capable of precisely depicting the lateral continuity of waveforms between different reflection points but also reflect amplitude versus offset,anisotropy,and heterogeneity in the medium.Due to its strong ability to represent stratigraphies,a pre-stack-data-based seismic facies analysis method is proposed using the selforganizing map algorithm.This method is tested on wide azimuth seismic data from China,and the advantages of pre-stack texture attributes in the description of stratum lateral changes are verified,in addition to the method＇s ability to reveal anisotropy and heterogeneity characteristics.The pre-stack texture classification results effectively distinguish different seismic reflection patterns,thereby providing reliable evidence for use in seismic facies analysis.展开更多
Traditional unsupervised seismic facies analysis techniques need to assume that seismic data obey mixed Gaussian distribution.However,fi eld seismic data may not meet this condition,thereby leading to wrong classifi c...Traditional unsupervised seismic facies analysis techniques need to assume that seismic data obey mixed Gaussian distribution.However,fi eld seismic data may not meet this condition,thereby leading to wrong classifi cation in the application of this technology.This paper introduces a spectral clustering technique for unsupervised seismic facies analysis.This algorithm is based on on the idea of a graph to cluster the data.Its kem is that seismic data are regarded as points in space,points can be connected with the edge and construct to graphs.When the graphs are divided,the weights of the edges between the different subgraphs are as low as possible,whereas the weights of the inner edges of the subgraph should be as high as possible.That has high computational complexity and entails large memory consumption for spectral clustering algorithm.To solve the problem this paper introduces the idea of sparse representation into spectral clustering.Through the selection of a small number of local sparse representation points,the spectral clustering matrix of all sample points is approximately represented to reduce the cost of spectral clustering operation.Verifi cation of physical model and fi eld data shows that the proposed approach can obtain more accurate seismic facies classification results without considering the data meet any hypothesis.The computing efficiency of this new method is better than that of the conventional spectral clustering method,thereby meeting the application needs of fi eld seismic data.展开更多
Miocene siliciclastic-carbonate deposits are widely exposed in Cairo-Suez District, Egypt. These deposits are underlain and overlain by continental sediments of Oligocene and post Miocene, respectively. Three stratigr...Miocene siliciclastic-carbonate deposits are widely exposed in Cairo-Suez District, Egypt. These deposits are underlain and overlain by continental sediments of Oligocene and post Miocene, respectively. Three stratigraphic sections were investigated at Gabals Geneife, Homeira and Gharra. Lithostrtigraphically, the Miocene sequence could be differentiated into two main rock units representing shallow deposits with relatively intermittent deep marine incursions. These are from base to top, Gharra Formation and Genefe Formation. Detailed macrofossils investigations led to the recognition of four macrofossil zones, namely Alectryonella plicatula-Crassostrea frondosa Range Zone, Echinolampas amplus-Scutella ammonis Range Zone, Chlamys（Macrochlamys） sardoa-Chlamys（Argopecten） submalvinae Range Zone, and Chlamys gentoni-Pecten（Oppenheimopecten） benedictus-Pecten（P.） ziziniae Assemblage Zone. Microfacies analysis and identified taxa indicated that the Miocene sequence was deposited in transgressive-regressive cycles ranged from near shore, warm shallow inner to middle shelf marine environments with storm influence during the accumulation of the oyster banks.展开更多
Facies characterization of Piacenzian （late Pliocene） carbonate sediments of the Guitar Formation in Car Nicobar Island,India and the subsequent integration of paleoecological data have been applied to interpret the...Facies characterization of Piacenzian （late Pliocene） carbonate sediments of the Guitar Formation in Car Nicobar Island,India and the subsequent integration of paleoecological data have been applied to interpret the paleoenvironment of the coralline algal-reef deposits.Thin-section analysis reveals that Amphiroa,Corallina and Jania are the dominant geniculate corallines,while Lithothamnion,Mesophyllum,Phymatolithon,Lithophyllum,Spongites and Lithoporella are the major non-geniculate corallines contributing to the sedimentary facies.Numerous small and larger benthic foraminifera also dominate the biogenic assemblages.Corals,barnacle shells,echinoid spines,fragments of bryozoans,mollusks and ostracodes are the subordinate constituents.Grainstones dominate the studied facies while packstones and boundstones （with wackestone elements） are the sub lithofacies showing a fair representation.Six carbonate facies presenting a complete reef complex have been distinguished that were deposited in shallow intertidal,back-reef shelf/lagoon,reef and deeper fore-reef shelf settings.Evidences of coralline algal and benthic foraminiferal assemblages,taphonomic signatures of abrasion and fragmentation,grain size,angularity and encrustation indicate a shallow to relatively deeper bathymetric horizon of approximately 10-60 m that corresponds to a regime of high to moderate hydrodynamic conditions.展开更多
Logging facies analysis is a significant aspect of reservoir description.In particular,as a commonly used method for logging facies identification,Multi-Resolution Graph-based Clustering(MRGC)can perform depth analysi...Logging facies analysis is a significant aspect of reservoir description.In particular,as a commonly used method for logging facies identification,Multi-Resolution Graph-based Clustering(MRGC)can perform depth analysis on multidimensional logging curves to predict logging facies.However,this method is very time-consuming and highly dependent on the initial parameters in the propagation process,which limits the practical application effect of the method.In this paper,an Adaptive Multi-Resolution Graph-based Clustering(AMRGC)is proposed,which is capable of both improving the efficiency of calculation process and achieving a stable propagation result.More specifically,the proposed method,1)presents a light kernel representative index(LKRI)algorithm which is proved to need less calculation resource than those kernel selection methods in the literature by exclusively considering those"free attractor"points;2)builds a Multi-Layer Perceptron(MLP)network with back propagation algorithm(BP)so as to avoid the uncertain results brought by uncertain parameter initializations which often happened by only using the K nearest neighbors(KNN)method.Compared with those clustering methods often used in image-based sedimentary phase analysis,such as Self Organizing Map(SOM),Dynamic Clustering(DYN)and Ascendant Hierarchical Clustering(AHC),etc.,the AMRGC performs much better without the prior knowledge of data structure.Eventually,the experimental results illustrate that the proposed method also outperformed the original MRGC method on the task of clustering and propagation prediction,with a higher efficiency and stability.展开更多
In this study, to identify and analyze facies of depositional environment and depositional model of Qom Formation, stratigraphic Saran Section (southwest of Semnan) was selected. Qom Formation in Saran section include...In this study, to identify and analyze facies of depositional environment and depositional model of Qom Formation, stratigraphic Saran Section (southwest of Semnan) was selected. Qom Formation in Saran section includes about 380 meters of conglomerate at the base, chalk, limestone, marl, and shale. Petrographic studies with facies analysis have led to the identification of 12 microfacies, these microfacies have been deposited in four facies groups including tidal flat, lagoon, barrier and open marine. Study of horizontal and vertical facies changes and their comparison with recent and ancient environments reveals that Qom Formation in this section relates to shallow marine environment and its facies were deposited in a shelf carbonate platform and are comparable with contemporary shelf platforms such as Florida and old shelf platforms such as Mozduran. The most important diagenetic processes affecting the studied section include micritization, bioturbation, cementation, dissolution, neomorphism, fracturing, mechanical and chemical compaction, hematitization and dolomitization. These processes have formed in marine, meteoric and burial diagenetic environments.展开更多
Sarvak Formation,a thick carbonate succession with the age of Middle Cretaceous,is one of the most significant hydrocarbon reservoirs in the Zagros basin.The Tang-e Solak section of the Sarvak Formation in the Bangest...Sarvak Formation,a thick carbonate succession with the age of Middle Cretaceous,is one of the most significant hydrocarbon reservoirs in the Zagros basin.The Tang-e Solak section of the Sarvak Formation in the Bangestan anticline with a total thickness of about 850 m has been studied,in order to determinate its microfacies types,depositional setting model and depositional sequences.展开更多
Thin-bedded turbidites are important hydrocarbon-bearing reservoirs in many mature fields throughout the world.The type of turbidite depositional setting strongly influences vertical and horizontal continuity of the r...Thin-bedded turbidites are important hydrocarbon-bearing reservoirs in many mature fields throughout the world.The type of turbidite depositional setting strongly influences vertical and horizontal continuity of the reservoir.However,distinguishing between lobe and levee associated thin-bedded turbidites remains challenging due to their generally similar facies characteristics.This study aims to contribute some insights to this problem by conducting a detailed bed-scale facies analysis on the Early Miocene Temburong Formation exposed at Kampung Bebuloh,Labuan Island,Malaysia,which may uncover features that can help in differentiating between both depositional types.Six facies are recognized in the Temburong Formation,which are interpreted as low density turbidites(F1-F4),hybrid event beds(F5),and sustained turbidites(F6).Detailed facies and ichnology analysis reveal features which are consistent with a lobe fringe deposit rather than leveeassociated environment interpretation,including tabular bed geometries,presence of hybrid event beds,and the absence of thick-bedded channel-fill sandstones.Five facies associations are identified and interpreted as representing sub-environments within an overall lobe depositional setting.A diverse trace fossil assemblage,comprising the Nereites ichnofacies is consistent with a deep marine environment.Further identification of the Paleodictyon and Nereites sub-ichnofacies indicates a distal turbidite system setting,most likely lobe fringe.Based on the thick accumulation of FA2 and FA3 and no distinct observable vertical trend,the Early Miocene Temburong Formation in Labuan is interpreted as turbidites deposited at the fringes of lobe complexes rather than a single lobe fringe.Earlier works into the Temburong Formation in SW Labuan proposed a middle slope to proximal basin floor setting where the thin-bedded intervals were interpreted as potentially representing either levee deposits or the fringes of confined lobe deposits.Conversely,the Temburong Formation at Kampung Bebuloh exhibits characteristics of an unconfined lobe setting,suggesting an evolutionary change in depositional conditions over time.展开更多
The Cretaceous(Albian-Cenomanian) Dalmiapuram Formation is one of the economically significant constituents in the hydrocarbon-producing Cauvery rift basin, SE India that opened up during the Late Jurassic e Early Cre...The Cretaceous(Albian-Cenomanian) Dalmiapuram Formation is one of the economically significant constituents in the hydrocarbon-producing Cauvery rift basin, SE India that opened up during the Late Jurassic e Early Cretaceous Gondwanaland fragmentation. The fossil-rich Dalmiapuram Formation,exposed at Ariyalur within the Pondicherry sub-basin of Cauvery Basin, rests in most places directly on the Archean basement and locally on the Lower Cretaceous(Barremian-Aptian) Basal Siliciclastic Formation. In the Dalmiapuram Formation, a facies association of tectonically-disturbed phase is sandwiched between two drastically quieter phases. The early syn-rift facies association(FA 1), records the first carbonate marine transgression within the basin, comprising a bar-lagoon system with occasionally storms affecting along the shore and a sheet-like non-recurrent biomicritic limestone bed on the shallow shelf that laterally grades into pyrite e glauconite-bearing dark-colored shale in the deeper shelf. Spectacular breccias together with varied kinds of mass-flow products comprise the syn-rift facies association(FA 2). While the breccias occur at the basin margin area, the latter extend in the deeper inland sea. Clast composition of the coarse clastics includes large, even block-sized limestone fragments and small fragments of granite and sandstone from the basement.Marl beds of quieter intervals between tectonic pulses occur in alternation with them. Faulted basal contact of the formation, and small grabens filled by multiple mass-flow packages bear the clear signature of the syntectonic activity localized contortions, slump folds, and pillow beds associated with mega slump/slide planes and joints, which corroborates this contention further. This phase of tectonic intervention is followed by another relatively quieter phase and accommodates the late syn-rift facies association(FA 3). A tidal bar-interbar shelf depositional system allowed a transgressive systems tract motif to grow eventually passing upwards into the Karai Shale Formation, whose contact with the Dalmiapuram Formation is gradational.展开更多
Using seismic attributes as features for classification in feature space, in various aims such as seismic facies analysis, is conventional for the purpose of seismic interpretation. But sometimes seismic data may have...Using seismic attributes as features for classification in feature space, in various aims such as seismic facies analysis, is conventional for the purpose of seismic interpretation. But sometimes seismic data may have no attributes or it is hard to define a small and relevant set of attributes in some applica- tions. Therefore, employing techniques that perform facies modeling without using attributes is neces- sary. In this paper we present a new method for facies modeling of seismic data with missing attributes that called dissimilarity based classification. In this method, classification is based on dissimilarities and facies modeling will be done in dissimilarity space. In this space dissimilarities consider as new features instead of real features. A support vector machine as a powerful classifier was employed in both feature space （feature-based） and dissimilarity space （feature-less） for facies analysis. The proposed feature-less and feature-based classification is applied on a real seismic data from an Iranian oil field. Facies model- ing using seismic attributes provide better results, but the feature-less classification outcome is also satis- factory and the facies correlation is acceptable. Indeed, the power of attributes to discriminate different facies causes to that facies analysis using attributes provide more reliable results comparing to feature- less facies analysis.展开更多
Recent advances in earth science and exploration have made deepwater channel-levee systems a research focus.We collected and analyzed over 10000 km of two-dimensional multichannel seismic data from the offshore Indus ...Recent advances in earth science and exploration have made deepwater channel-levee systems a research focus.We collected and analyzed over 10000 km of two-dimensional multichannel seismic data from the offshore Indus Basin to identify channellevee systems at various hierarchical levels depending on their seismic reflection characteristics.Seismic facies analysis was integrated with well data to map the spatial distribution of channel-levee systems in the offshore Indus Basin across various geological periods,and the factors influencing their development were discussed.These systems within the basin were identified using a developed,refined three-tier classification method.The first-order system consists of multiple spatially stacked complexes,the second-order system continuously developed multistage channel-levee bodies,and the third-order system represents the smallest identifiable sedimentary units on seismic profiles.Our findings demonstrate the evolution of the offshore Indus Basin from a single-stage channel with lateral migration to multistage vertical channel stacking from the Miocene to the Pleistocene.Tectonic activities exert their effect on channel-levee systems through their influence on the relative sea level.They also trigger volcanic or seismic events and affect siliciclastic supply.Warm and humid climate conditions form large river systems,which aid in the transport of terrestrial debris to the basin margin.Most channel-levee systems are assumed to have formed during low sea-level periods.This study offers new insights into the formation and evolution of turbidite sedimentary systems in the offshore Indus Basin and presents a practical classification method for comprehending gravity-flow sedimentary configurations and deepwater hydrocarbon exploration.展开更多
Radar remote sensing can acquire information of sub-surface covered by sand in arid area, detect surface roughness and vegetation coronet's layer and linear feature such as linear structure and channel sensitively...Radar remote sensing can acquire information of sub-surface covered by sand in arid area, detect surface roughness and vegetation coronet's layer and linear feature such as linear structure and channel sensitively. With sediment facies analysis, this paper studies the features of environmental evolution in mid-late Epipleistocene (60 ka BP-20 ka BP) in northeastern Ejin Banner. The conclusions are listed as follows: (1) The evolution of the three lakes, i.e. Gaxunnur, Sugunur and Tian'e lakes, are dominated by faults and regional climate. (2) By analyzing sedimentary section of old Juyanze Lake, the three lakes used to be a large outflow lake before 50 ka BP in northeastern Ejin Banner, and at 50 ka BP, temperature declined rapidly in northwestern China. The event caused the lake's shrinkage. (3) By fault activity uplift in the northern part of old Juyan Lake and depression in the southern part, the lake's water followed from north to south at around 35 ka BP, old Juyanze fluvial fan was formed. At the same time, Juyan Lake separated from Sugunur Lake and Wentugunr old channel was abandoned. (4) In recent 2000 years, Ruoshui River is a wandering river, sometimes it flows into Juyan Lake and sometimes Sugunur and Gaxunnur lakes. Due to human activities and over exploitation, the oasis ecosystem is rapidly degenerated in 15 years (1986-2000).展开更多
This study is focused on sedimentary environments, facies distribution, and sequence stratigraphy. The facies and sequence stratigraphic analyses of the Bahram Formation（middleelate Devonian） in southcentral Iran ar...This study is focused on sedimentary environments, facies distribution, and sequence stratigraphy. The facies and sequence stratigraphic analyses of the Bahram Formation（middleelate Devonian） in southcentral Iran are based on two measured stratigraphic sections in the southern Tabas block. The Bahram Formation overlies red sandstones Padeha Formation in sections Hutk and Sardar and is overlain by Carboniferous carbonate deposits of Hutk Formation paraconformably, with a thickness of 354 and386 m respectively. Mixed siliciclastic and carbonate sediments are present in this succession. The field observations and laboratory studies were used to identify 14 micro/petrofacies, which can be grouped into 5 depositional environments： shore, tidal flat, lagoon, shoal and shallow open marine. A mixed carbonate-detrital shallow shelf is suggested for the depositional environment of the Bahram Formation which deepens to the east（Sardar section） and thins in southern locations（Hutk section）. Three 3rdorder cyclic siliciclastic and carbonate sequences in the Bahram Formation and one sequence shared with the overlying joint with Hutk Formation are identified, on the basis of shallowing upward patterns in the micro/pertofacies.展开更多
Peat forming environment strongly influences the economic value of any coal seam and coal-bearing strata.Hence,pal-aeoenvironmental studies provide important information for coal resource exploration.In this context,d...Peat forming environment strongly influences the economic value of any coal seam and coal-bearing strata.Hence,pal-aeoenvironmental studies provide important information for coal resource exploration.In this context,detailed studies on selected coals from the Parvadeh Area,Iran,were conducted using sedimentology,coal petrology,X-ray diffraction(XRD),scanning electron microscopy-energy dispersive X-ray analyzer(SEM-EDX),and proximate analysis.The sedi-mentary facies above and below the coal seams are mainly marine or marine-influenced facies,supporting that the coal-forming mires in the Parvadeh Area developed in a paralic environment,where the base level must be closely related to sea level.Sulfur contents are moderate to high and mark the influence of brackish/marine water,especially during transgres-sion after peat growth in a lower delta plain environment.The peat-forming mires extended on coastal/delta plain lobes.The lower delta plain/coastal plain coals are characterized by lateral continuity and substantial thickness,whereas few coals possibly representing the upper delta plain are thin and more discontinuous.The detrital nature and composition of the numerous partings and the overall high ash yield in the coal seams indicate an active tectonic area with high rates of creation of accommodation space over peat growth.Coal petrology and coal facies analysis exhibits a permanently high water table within a forest swamp and mostly rheotrophic conditions,sometimes with connection to the seawater.Accord-ing to paleoenvironmental reconstructions,it seems that coal layers may be thicker,with less sulfur(pyrite),but more clastic minerals and partings toward the western part of the area.Although these coal seams presently have low economic potential for the mining operation,partly due to great depth,this humic,high-volatile to medium-volatile bituminous coal may be suitable for exploration of coal bed methane resources.展开更多
Estuarine-systems,developed upon transgressive-phases,feature high-quality reservoir-facies,e.g.tidalbars,that are important stratigraphic-plays critical for hydrocarbon exploration-development.However,capturing their...Estuarine-systems,developed upon transgressive-phases,feature high-quality reservoir-facies,e.g.tidalbars,that are important stratigraphic-plays critical for hydrocarbon exploration-development.However,capturing their intricate architectural elements(heterogeneity and quality)is still challenging due to the complex stacking-nature and limited-examples.Moreover,defining reservoir-boundaries upon staticmodeling of reservoirs cannot be efficient unless it is controlled by stratal-geometries and established depositional-models.To this end,in this study,we performed 3D-static geocellular reservoir-modeling process for the Late-Cenomanian AbuRoash“G”Member(Abu-Gharadig Basin,Egypt)with sequencestratigraphic and geomodel,relative-geological-time(RGT)model and horizon-stacks,constraints.In this investigation,as an effective-workflow,not only facies-analysis,integrating seismic-stratigraphy and GR-log motifs,was applied for paleo-environment reconstruction,but also machine learning-based electrofacies were applied,through self-organized-maps(SOM),to accurately recognize complex facies-assemblages present.Object-based and pixel-based stochastic-simulation processes were applied upon geocellularly modeling rock and fluid properties,utilizing key-information scales of seismic and well-log data.The results show that three third-order depositional sequences dominate the succession,resting on the Late-Cretaceous unconformity,of which sequence-1 encloses the lowstand and transgressive systems-tracts of the fluvio-estuarine Bahariya and Abu Roash“G”units,respectively.The transgressive phase built AbuRoash“G”lithounit features an estuarine depositional-system encompassing four facies-associations,of which tidal-sand-bars represent significant gas-bearing reservoir-quality facies.The tidal-bar facies’efficient reservoir quality calls for attention and testing in future development plans and investigation in similar settings.Furthermore,the facies-constrained workflow established in this study,for reservoir modeling,can effectively help identify the ultimate reservoir-configuration worldwide,as long as the 3D-static modeling process is controlled by the stratal and geomodel restraints.展开更多
This study presents a comprehensive geological modeling approach to understanding the Hartha Formation in the Balad Oilfield.Utilizing Petrel software,a 3D geological model was developed,integrating well data,seismic ...This study presents a comprehensive geological modeling approach to understanding the Hartha Formation in the Balad Oilfield.Utilizing Petrel software,a 3D geological model was developed,integrating well data,seismic contour map,and log analyses to delineate the reservoir’s structural and petrophysical properties.Data preparation involved organizing well headers,tops,and logs from five key wells,followed by the creation of a structural contour map that identified major and minor faults influencing the reservoir.Structural modeling further enhanced the understanding of the Hartha Formation’s geometry,illustrating how tectonic influences and faulting impacted the spatial distribution of reservoir units.Facies modeling identified a predominance of mudstone and wackestone in the upper Hartha Formation,with improved reservoir qualities in the Har.UA and Har.UB units.Petrophysical modeling demonstrated variations in porosity and water saturation,highlighting the impact of structural features on fluid distribution.The findings underscore the complex geological interplay within the Hartha Formation,providing critical insights for future exploration and optimized hydrocarbon recovery strategies.展开更多
In recent years,the Journal of Palaeogeography(Chinese Edition and English Edition)continually received manuscripts,in which some authors are from China and some are from Pakistan,Lithuania,Morocco,South Africa,etc.Th...In recent years,the Journal of Palaeogeography(Chinese Edition and English Edition)continually received manuscripts,in which some authors are from China and some are from Pakistan,Lithuania,Morocco,South Africa,etc.The authors of these manuscripts,according to the viewpoint and method of Miall’s paper(1985),selected rocks from each bed in the clastic sections of their study areas and induced some rock types,such as conglomerates,sandstones and fine-grained stones,and considered them as lithofacies.It does not conform to the definition of lithofacies.I wrote some papers,i.e.,Feng(2018,2019,2020),to point out the problems and hope that the authors worldwide,especially Chinese authors,will not continually cite,spread and follow Miall’s paper(1985)viewpoint and method blindly.Prof.Miall is the first person who considered rocks(in fact,the sediments)as lithofacies and proposed a facies analysis method.His viewpoint and facies analysis method confused the definition of facies and facies analysis method.My current paper is a special article to discuss the principal problems of Miall’s paper(1985),i.e.,he considered the sediments as lithofacies and utilized lithofacies to analyze facies,but not to discuss the contributions and less strictness of architectural elements of his paper.Here,I have to declare that the facies in my current paper is the facies of sedimentary petrology,but not of other geological disciplines,such as igneous petrology,metamorphic petrology,palaeontology,stratigraphy,geophysics,geochemistry.Certainly,the definitions of facies and lithofacies are controversial.My current paper will adhere to the policy of“A hundred flowers blossom and a hundred schools of thought contend”.I hope that through academic discussions,contends and geological practice,these problems will be solved gradually.展开更多
Condensed ammonoid beds of the Hallstatt facies (Anisian-Ladinian) are widespread around the Ancient Theatre of Epidaurus,in the locality Theokafta of the Argolis Peninsula (eastern Peloponnesus).The Hallstatt Formati...Condensed ammonoid beds of the Hallstatt facies (Anisian-Ladinian) are widespread around the Ancient Theatre of Epidaurus,in the locality Theokafta of the Argolis Peninsula (eastern Peloponnesus).The Hallstatt Formation in Argolis appears,generally,in the form of lensoid bodies of variable sizes,inclination and direction and is always found overlying a formation consisting of keratophyric tuffs.In fact,the contact of the keratophyric tuffs with the overlying limestones,specifically evidenced by an in situ brecciated zone,is stratigraphic and constitutes the base of the Hallstatt Limestones.The contact of the Hallstatt Limestones with the overlying radiolarites is stratigraphic as well.Lithofacies and biostratigraphic research has focused on the lowermost horizons of the Hallstatt Limestones of Anisian age (average thickness about 1.30 m),where a dense sampling has been performed,followed by detailed facies analysis.The lowermost horizons of the Hallstatt Limestones of Theokafta represent typical hiatus beds/concretions sensu Wetzel and Allia (2000),characterized by discontinuous sedimentation and erosion.They consist of red ammonoid-bearing hemipelagic limestones with calcium carbonate nodules floating in an enriched Fe-oxides matrix with dispersed lensoid/prismatic calcium carbonate crystals.This part of the section is characterized by condensed sedimentation,due to significant lowering of the rate of sedimentation and includes omission surfaces,firmgrounds and hardgrounds along certain horizons.Nine lithostratigraphic units have been distinguished in the lowermost horizons of the Hallstatt Limestones,including radiolarian packstones,volcaniclastic facies,packstones/floatstones with ammonoids and lag deposits.Tselepidis (2007) defined nine distinct ammonoid biozones from the Anisian to Ladinian,documenting deposition of the Hallstatt facies during a low depositional rate over nearly 5 million years (using the timescale of Gradstein et al.,2004).The biozones:Japonites/Paracrochordiceras,Hollandites,Procladiscites/Leiophyllites,zoldianus,trinidosus,Reitziites/Parakellnerites and the Nevadites (Anisian) and the biozone curionii (Lower Ladinian).Although sedimentation was very condensed,it didn’t reach the level of mixing fauna.Synsedimentary and early burrowing processes differentiated the primary texture characteristics of the deposited sediments.Multiphase diagenesis occurred not very deep below the sediment surface and includes boring and/or encrustation,burial and cementation.The deposition of the studied Hallstatt Limestones is considered to be due to anaerobic oxidation of organic matter,which provided excess alkalinity,inducing carbonate precipitation.Sedi-mentation took place on differentially-subsided deep swells.After drowning,the swells were covered by pelagic carbonate deposits.Further slight rotation of blocks,along listric faults,may have led to additional differential subsidence of the blocks.Shelf bathymetry and thirdorder sea-level changes played a significant role in the formation of the Hallstatt beds.In terms of sequence stratigraphy,the studied hiatus concretions and beds are considered genetically linked to rising or high sea-level,formed at the initiation of transgressions,as well as during the time of maximum rate of transgression,in areas where the sediment input was strongly reduced (’’condensed section’’) .Taking into consideration the present location of the Hallstatt Formation,in the context of the Hellenides,an area suitable for the deposition of the Hallstatt Limestones,should be located between the sub-Pelagonian (western part of the Pelagonian zone) and Pindos geotectonic zones,which during the Triassic corresponded to a platform slope and a deep ocean,respectively.The widespread Middle Triassic Han Bulog Limestones (ammonoid-bearing pelagic limestones) from Triassic successions of the Eastern Alps (Dinarides,Hellenides) may have formed partly in similar slope environments.展开更多
1.Journal of Palaeogeography[JoP]publishes in the general fields of sedimentology and palaeontology that include a distinct and noticeable palaeogeographic aspect or perspective.High-quality original research articles...1.Journal of Palaeogeography[JoP]publishes in the general fields of sedimentology and palaeontology that include a distinct and noticeable palaeogeographic aspect or perspective.High-quality original research articles and authoritative reviews are welcomed.Subdisciplines of interest to JoP include(but not limited to):Facies analysis and sedimentary environments;Palaeobiology(including taxonomy)and palaeoecology;Palaeobiogeography;Stratigraphy;Sequence stratigraphy;Sedimentary geochemistry.展开更多
文摘The Govanda Formation was deposited during the Miocene in the intermontane areas between the Zagros suture and imbricate zones.The Govanda Formation was studied in the Sherwan Mazin area within Mergasor district,Erbil Governorate to identify the lithostratigraphy and microfacies analysis in order to determine the depositional environment of the formation.The formation in the studied section is 116 m thick and mainly consists of reddish-brown,hard,thickbedded,chert-bearing conglomerate,pinkish shale and yellowish-grey,thick-bedded,detrital,fossiliferous limestone.The formation is unconformably underlain by the Upper Cretaceous Tanjero Formation and conformably overlain by the Merga Red Beds series.Four different lithostratigraphic units were identified,based on field observation and petrographic analysis,including a basal conglomerate unit(A),a shale unit(B),a well-bedded limestone unit(C)and a thick and massively-bedded limestone unit(D).The presence of a thick conglomerate bed at the base of the formation indicates a large unconformity that lasted nearly 40 million years.Based on detailed microfacies analysis of carbonate rocks,five main microfacies and 15 submicrofacies are recognized.The main microfacies types include mudstone,wackestone,packstone,grainstone and boundstone microfacies.Based on the microfacies types the depositional environment are defined as open lagoon,reef,fore-reef and back-reef environments of normal to saline,nutrient rich water.
基金supported by the Scientific Research Staring Foundation of University of Electronic Science and Technology of China(No.ZYGX2015KYQD049)
文摘Seismic texture attributes are closely related to seismic facies and reservoir characteristics and are thus widely used in seismic data interpretation.However,information is mislaid in the stacking process when traditional texture attributes are extracted from poststack data,which is detrimental to complex reservoir description.In this study,pre-stack texture attributes are introduced,these attributes can not only capable of precisely depicting the lateral continuity of waveforms between different reflection points but also reflect amplitude versus offset,anisotropy,and heterogeneity in the medium.Due to its strong ability to represent stratigraphies,a pre-stack-data-based seismic facies analysis method is proposed using the selforganizing map algorithm.This method is tested on wide azimuth seismic data from China,and the advantages of pre-stack texture attributes in the description of stratum lateral changes are verified,in addition to the method＇s ability to reveal anisotropy and heterogeneity characteristics.The pre-stack texture classification results effectively distinguish different seismic reflection patterns,thereby providing reliable evidence for use in seismic facies analysis.
基金This work was supported by National Natural Science Foundation of China(Nos.U1562218,41604107,and 41804126).
文摘Traditional unsupervised seismic facies analysis techniques need to assume that seismic data obey mixed Gaussian distribution.However,fi eld seismic data may not meet this condition,thereby leading to wrong classifi cation in the application of this technology.This paper introduces a spectral clustering technique for unsupervised seismic facies analysis.This algorithm is based on on the idea of a graph to cluster the data.Its kem is that seismic data are regarded as points in space,points can be connected with the edge and construct to graphs.When the graphs are divided,the weights of the edges between the different subgraphs are as low as possible,whereas the weights of the inner edges of the subgraph should be as high as possible.That has high computational complexity and entails large memory consumption for spectral clustering algorithm.To solve the problem this paper introduces the idea of sparse representation into spectral clustering.Through the selection of a small number of local sparse representation points,the spectral clustering matrix of all sample points is approximately represented to reduce the cost of spectral clustering operation.Verifi cation of physical model and fi eld data shows that the proposed approach can obtain more accurate seismic facies classification results without considering the data meet any hypothesis.The computing efficiency of this new method is better than that of the conventional spectral clustering method,thereby meeting the application needs of fi eld seismic data.
基金the Deanship of Scientific Research at King Saud University for its funding this research group (No.RG-1436-036)
文摘Miocene siliciclastic-carbonate deposits are widely exposed in Cairo-Suez District, Egypt. These deposits are underlain and overlain by continental sediments of Oligocene and post Miocene, respectively. Three stratigraphic sections were investigated at Gabals Geneife, Homeira and Gharra. Lithostrtigraphically, the Miocene sequence could be differentiated into two main rock units representing shallow deposits with relatively intermittent deep marine incursions. These are from base to top, Gharra Formation and Genefe Formation. Detailed macrofossils investigations led to the recognition of four macrofossil zones, namely Alectryonella plicatula-Crassostrea frondosa Range Zone, Echinolampas amplus-Scutella ammonis Range Zone, Chlamys（Macrochlamys） sardoa-Chlamys（Argopecten） submalvinae Range Zone, and Chlamys gentoni-Pecten（Oppenheimopecten） benedictus-Pecten（P.） ziziniae Assemblage Zone. Microfacies analysis and identified taxa indicated that the Miocene sequence was deposited in transgressive-regressive cycles ranged from near shore, warm shallow inner to middle shelf marine environments with storm influence during the accumulation of the oyster banks.
基金funded by the Council of Scientifc and Industrial Research,India(NET Fellowship,Grant No.09/528/2009-EMR-I)
文摘Facies characterization of Piacenzian （late Pliocene） carbonate sediments of the Guitar Formation in Car Nicobar Island,India and the subsequent integration of paleoecological data have been applied to interpret the paleoenvironment of the coralline algal-reef deposits.Thin-section analysis reveals that Amphiroa,Corallina and Jania are the dominant geniculate corallines,while Lithothamnion,Mesophyllum,Phymatolithon,Lithophyllum,Spongites and Lithoporella are the major non-geniculate corallines contributing to the sedimentary facies.Numerous small and larger benthic foraminifera also dominate the biogenic assemblages.Corals,barnacle shells,echinoid spines,fragments of bryozoans,mollusks and ostracodes are the subordinate constituents.Grainstones dominate the studied facies while packstones and boundstones （with wackestone elements） are the sub lithofacies showing a fair representation.Six carbonate facies presenting a complete reef complex have been distinguished that were deposited in shallow intertidal,back-reef shelf/lagoon,reef and deeper fore-reef shelf settings.Evidences of coralline algal and benthic foraminiferal assemblages,taphonomic signatures of abrasion and fragmentation,grain size,angularity and encrustation indicate a shallow to relatively deeper bathymetric horizon of approximately 10-60 m that corresponds to a regime of high to moderate hydrodynamic conditions.
基金sponsored by the Science and Technology Project of CNPC(No.2018D-5010-16 and 2019D-3808)。
文摘Logging facies analysis is a significant aspect of reservoir description.In particular,as a commonly used method for logging facies identification,Multi-Resolution Graph-based Clustering(MRGC)can perform depth analysis on multidimensional logging curves to predict logging facies.However,this method is very time-consuming and highly dependent on the initial parameters in the propagation process,which limits the practical application effect of the method.In this paper,an Adaptive Multi-Resolution Graph-based Clustering(AMRGC)is proposed,which is capable of both improving the efficiency of calculation process and achieving a stable propagation result.More specifically,the proposed method,1)presents a light kernel representative index(LKRI)algorithm which is proved to need less calculation resource than those kernel selection methods in the literature by exclusively considering those"free attractor"points;2)builds a Multi-Layer Perceptron(MLP)network with back propagation algorithm(BP)so as to avoid the uncertain results brought by uncertain parameter initializations which often happened by only using the K nearest neighbors(KNN)method.Compared with those clustering methods often used in image-based sedimentary phase analysis,such as Self Organizing Map(SOM),Dynamic Clustering(DYN)and Ascendant Hierarchical Clustering(AHC),etc.,the AMRGC performs much better without the prior knowledge of data structure.Eventually,the experimental results illustrate that the proposed method also outperformed the original MRGC method on the task of clustering and propagation prediction,with a higher efficiency and stability.
文摘In this study, to identify and analyze facies of depositional environment and depositional model of Qom Formation, stratigraphic Saran Section (southwest of Semnan) was selected. Qom Formation in Saran section includes about 380 meters of conglomerate at the base, chalk, limestone, marl, and shale. Petrographic studies with facies analysis have led to the identification of 12 microfacies, these microfacies have been deposited in four facies groups including tidal flat, lagoon, barrier and open marine. Study of horizontal and vertical facies changes and their comparison with recent and ancient environments reveals that Qom Formation in this section relates to shallow marine environment and its facies were deposited in a shelf carbonate platform and are comparable with contemporary shelf platforms such as Florida and old shelf platforms such as Mozduran. The most important diagenetic processes affecting the studied section include micritization, bioturbation, cementation, dissolution, neomorphism, fracturing, mechanical and chemical compaction, hematitization and dolomitization. These processes have formed in marine, meteoric and burial diagenetic environments.
基金funded by the department of geology,Islamic Azad University,Science and Research branch,Tehran,Iran.
文摘Sarvak Formation,a thick carbonate succession with the age of Middle Cretaceous,is one of the most significant hydrocarbon reservoirs in the Zagros basin.The Tang-e Solak section of the Sarvak Formation in the Bangestan anticline with a total thickness of about 850 m has been studied,in order to determinate its microfacies types,depositional setting model and depositional sequences.
基金Farah Syafira Burhanuddin reports financial support was provided by ConocoPhillips Company.
文摘Thin-bedded turbidites are important hydrocarbon-bearing reservoirs in many mature fields throughout the world.The type of turbidite depositional setting strongly influences vertical and horizontal continuity of the reservoir.However,distinguishing between lobe and levee associated thin-bedded turbidites remains challenging due to their generally similar facies characteristics.This study aims to contribute some insights to this problem by conducting a detailed bed-scale facies analysis on the Early Miocene Temburong Formation exposed at Kampung Bebuloh,Labuan Island,Malaysia,which may uncover features that can help in differentiating between both depositional types.Six facies are recognized in the Temburong Formation,which are interpreted as low density turbidites(F1-F4),hybrid event beds(F5),and sustained turbidites(F6).Detailed facies and ichnology analysis reveal features which are consistent with a lobe fringe deposit rather than leveeassociated environment interpretation,including tabular bed geometries,presence of hybrid event beds,and the absence of thick-bedded channel-fill sandstones.Five facies associations are identified and interpreted as representing sub-environments within an overall lobe depositional setting.A diverse trace fossil assemblage,comprising the Nereites ichnofacies is consistent with a deep marine environment.Further identification of the Paleodictyon and Nereites sub-ichnofacies indicates a distal turbidite system setting,most likely lobe fringe.Based on the thick accumulation of FA2 and FA3 and no distinct observable vertical trend,the Early Miocene Temburong Formation in Labuan is interpreted as turbidites deposited at the fringes of lobe complexes rather than a single lobe fringe.Earlier works into the Temburong Formation in SW Labuan proposed a middle slope to proximal basin floor setting where the thin-bedded intervals were interpreted as potentially representing either levee deposits or the fringes of confined lobe deposits.Conversely,the Temburong Formation at Kampung Bebuloh exhibits characteristics of an unconfined lobe setting,suggesting an evolutionary change in depositional conditions over time.
文摘The Cretaceous(Albian-Cenomanian) Dalmiapuram Formation is one of the economically significant constituents in the hydrocarbon-producing Cauvery rift basin, SE India that opened up during the Late Jurassic e Early Cretaceous Gondwanaland fragmentation. The fossil-rich Dalmiapuram Formation,exposed at Ariyalur within the Pondicherry sub-basin of Cauvery Basin, rests in most places directly on the Archean basement and locally on the Lower Cretaceous(Barremian-Aptian) Basal Siliciclastic Formation. In the Dalmiapuram Formation, a facies association of tectonically-disturbed phase is sandwiched between two drastically quieter phases. The early syn-rift facies association(FA 1), records the first carbonate marine transgression within the basin, comprising a bar-lagoon system with occasionally storms affecting along the shore and a sheet-like non-recurrent biomicritic limestone bed on the shallow shelf that laterally grades into pyrite e glauconite-bearing dark-colored shale in the deeper shelf. Spectacular breccias together with varied kinds of mass-flow products comprise the syn-rift facies association(FA 2). While the breccias occur at the basin margin area, the latter extend in the deeper inland sea. Clast composition of the coarse clastics includes large, even block-sized limestone fragments and small fragments of granite and sandstone from the basement.Marl beds of quieter intervals between tectonic pulses occur in alternation with them. Faulted basal contact of the formation, and small grabens filled by multiple mass-flow packages bear the clear signature of the syntectonic activity localized contortions, slump folds, and pillow beds associated with mega slump/slide planes and joints, which corroborates this contention further. This phase of tectonic intervention is followed by another relatively quieter phase and accommodates the late syn-rift facies association(FA 3). A tidal bar-interbar shelf depositional system allowed a transgressive systems tract motif to grow eventually passing upwards into the Karai Shale Formation, whose contact with the Dalmiapuram Formation is gradational.
基金the Institute of Geophysics,University of Tehran for its valuable support
文摘Using seismic attributes as features for classification in feature space, in various aims such as seismic facies analysis, is conventional for the purpose of seismic interpretation. But sometimes seismic data may have no attributes or it is hard to define a small and relevant set of attributes in some applica- tions. Therefore, employing techniques that perform facies modeling without using attributes is neces- sary. In this paper we present a new method for facies modeling of seismic data with missing attributes that called dissimilarity based classification. In this method, classification is based on dissimilarities and facies modeling will be done in dissimilarity space. In this space dissimilarities consider as new features instead of real features. A support vector machine as a powerful classifier was employed in both feature space （feature-based） and dissimilarity space （feature-less） for facies analysis. The proposed feature-less and feature-based classification is applied on a real seismic data from an Iranian oil field. Facies model- ing using seismic attributes provide better results, but the feature-less classification outcome is also satis- factory and the facies correlation is acceptable. Indeed, the power of attributes to discriminate different facies causes to that facies analysis using attributes provide more reliable results comparing to feature- less facies analysis.
基金the National Natural Science Foundation of China(Nos.42076220,42206234,42476228)the Laoshan Laboratory Science and Technology Innovation Project(Nos.LSKJ202203404,LSKJ202203401)+2 种基金the Laoshan Laboratory‘14th FiveYear Plan’Major Project(No.2021QNLM020001-1)the Project of China Geological Survey(Nos.DD20230317,DD20230410,DD20190818,DD20191032,DD20160152)the Asia Cooperation Foundation‘China-Pakistan Oil and Gas Resource Potential Assessment and Capacity Training’。
文摘Recent advances in earth science and exploration have made deepwater channel-levee systems a research focus.We collected and analyzed over 10000 km of two-dimensional multichannel seismic data from the offshore Indus Basin to identify channellevee systems at various hierarchical levels depending on their seismic reflection characteristics.Seismic facies analysis was integrated with well data to map the spatial distribution of channel-levee systems in the offshore Indus Basin across various geological periods,and the factors influencing their development were discussed.These systems within the basin were identified using a developed,refined three-tier classification method.The first-order system consists of multiple spatially stacked complexes,the second-order system continuously developed multistage channel-levee bodies,and the third-order system represents the smallest identifiable sedimentary units on seismic profiles.Our findings demonstrate the evolution of the offshore Indus Basin from a single-stage channel with lateral migration to multistage vertical channel stacking from the Miocene to the Pleistocene.Tectonic activities exert their effect on channel-levee systems through their influence on the relative sea level.They also trigger volcanic or seismic events and affect siliciclastic supply.Warm and humid climate conditions form large river systems,which aid in the transport of terrestrial debris to the basin margin.Most channel-levee systems are assumed to have formed during low sea-level periods.This study offers new insights into the formation and evolution of turbidite sedimentary systems in the offshore Indus Basin and presents a practical classification method for comprehending gravity-flow sedimentary configurations and deepwater hydrocarbon exploration.
文摘Radar remote sensing can acquire information of sub-surface covered by sand in arid area, detect surface roughness and vegetation coronet's layer and linear feature such as linear structure and channel sensitively. With sediment facies analysis, this paper studies the features of environmental evolution in mid-late Epipleistocene (60 ka BP-20 ka BP) in northeastern Ejin Banner. The conclusions are listed as follows: (1) The evolution of the three lakes, i.e. Gaxunnur, Sugunur and Tian'e lakes, are dominated by faults and regional climate. (2) By analyzing sedimentary section of old Juyanze Lake, the three lakes used to be a large outflow lake before 50 ka BP in northeastern Ejin Banner, and at 50 ka BP, temperature declined rapidly in northwestern China. The event caused the lake's shrinkage. (3) By fault activity uplift in the northern part of old Juyan Lake and depression in the southern part, the lake's water followed from north to south at around 35 ka BP, old Juyanze fluvial fan was formed. At the same time, Juyan Lake separated from Sugunur Lake and Wentugunr old channel was abandoned. (4) In recent 2000 years, Ruoshui River is a wandering river, sometimes it flows into Juyan Lake and sometimes Sugunur and Gaxunnur lakes. Due to human activities and over exploitation, the oasis ecosystem is rapidly degenerated in 15 years (1986-2000).
基金a part of project of the Hormozgan University and two master theses of the senior author, which is supported by the Department of Geology at Hormozgan University of Bandar Abbas, Iran
文摘This study is focused on sedimentary environments, facies distribution, and sequence stratigraphy. The facies and sequence stratigraphic analyses of the Bahram Formation（middleelate Devonian） in southcentral Iran are based on two measured stratigraphic sections in the southern Tabas block. The Bahram Formation overlies red sandstones Padeha Formation in sections Hutk and Sardar and is overlain by Carboniferous carbonate deposits of Hutk Formation paraconformably, with a thickness of 354 and386 m respectively. Mixed siliciclastic and carbonate sediments are present in this succession. The field observations and laboratory studies were used to identify 14 micro/petrofacies, which can be grouped into 5 depositional environments： shore, tidal flat, lagoon, shoal and shallow open marine. A mixed carbonate-detrital shallow shelf is suggested for the depositional environment of the Bahram Formation which deepens to the east（Sardar section） and thins in southern locations（Hutk section）. Three 3rdorder cyclic siliciclastic and carbonate sequences in the Bahram Formation and one sequence shared with the overlying joint with Hutk Formation are identified, on the basis of shallowing upward patterns in the micro/pertofacies.
文摘Peat forming environment strongly influences the economic value of any coal seam and coal-bearing strata.Hence,pal-aeoenvironmental studies provide important information for coal resource exploration.In this context,detailed studies on selected coals from the Parvadeh Area,Iran,were conducted using sedimentology,coal petrology,X-ray diffraction(XRD),scanning electron microscopy-energy dispersive X-ray analyzer(SEM-EDX),and proximate analysis.The sedi-mentary facies above and below the coal seams are mainly marine or marine-influenced facies,supporting that the coal-forming mires in the Parvadeh Area developed in a paralic environment,where the base level must be closely related to sea level.Sulfur contents are moderate to high and mark the influence of brackish/marine water,especially during transgres-sion after peat growth in a lower delta plain environment.The peat-forming mires extended on coastal/delta plain lobes.The lower delta plain/coastal plain coals are characterized by lateral continuity and substantial thickness,whereas few coals possibly representing the upper delta plain are thin and more discontinuous.The detrital nature and composition of the numerous partings and the overall high ash yield in the coal seams indicate an active tectonic area with high rates of creation of accommodation space over peat growth.Coal petrology and coal facies analysis exhibits a permanently high water table within a forest swamp and mostly rheotrophic conditions,sometimes with connection to the seawater.Accord-ing to paleoenvironmental reconstructions,it seems that coal layers may be thicker,with less sulfur(pyrite),but more clastic minerals and partings toward the western part of the area.Although these coal seams presently have low economic potential for the mining operation,partly due to great depth,this humic,high-volatile to medium-volatile bituminous coal may be suitable for exploration of coal bed methane resources.
文摘Estuarine-systems,developed upon transgressive-phases,feature high-quality reservoir-facies,e.g.tidalbars,that are important stratigraphic-plays critical for hydrocarbon exploration-development.However,capturing their intricate architectural elements(heterogeneity and quality)is still challenging due to the complex stacking-nature and limited-examples.Moreover,defining reservoir-boundaries upon staticmodeling of reservoirs cannot be efficient unless it is controlled by stratal-geometries and established depositional-models.To this end,in this study,we performed 3D-static geocellular reservoir-modeling process for the Late-Cenomanian AbuRoash“G”Member(Abu-Gharadig Basin,Egypt)with sequencestratigraphic and geomodel,relative-geological-time(RGT)model and horizon-stacks,constraints.In this investigation,as an effective-workflow,not only facies-analysis,integrating seismic-stratigraphy and GR-log motifs,was applied for paleo-environment reconstruction,but also machine learning-based electrofacies were applied,through self-organized-maps(SOM),to accurately recognize complex facies-assemblages present.Object-based and pixel-based stochastic-simulation processes were applied upon geocellularly modeling rock and fluid properties,utilizing key-information scales of seismic and well-log data.The results show that three third-order depositional sequences dominate the succession,resting on the Late-Cretaceous unconformity,of which sequence-1 encloses the lowstand and transgressive systems-tracts of the fluvio-estuarine Bahariya and Abu Roash“G”units,respectively.The transgressive phase built AbuRoash“G”lithounit features an estuarine depositional-system encompassing four facies-associations,of which tidal-sand-bars represent significant gas-bearing reservoir-quality facies.The tidal-bar facies’efficient reservoir quality calls for attention and testing in future development plans and investigation in similar settings.Furthermore,the facies-constrained workflow established in this study,for reservoir modeling,can effectively help identify the ultimate reservoir-configuration worldwide,as long as the 3D-static modeling process is controlled by the stratal and geomodel restraints.
文摘This study presents a comprehensive geological modeling approach to understanding the Hartha Formation in the Balad Oilfield.Utilizing Petrel software,a 3D geological model was developed,integrating well data,seismic contour map,and log analyses to delineate the reservoir’s structural and petrophysical properties.Data preparation involved organizing well headers,tops,and logs from five key wells,followed by the creation of a structural contour map that identified major and minor faults influencing the reservoir.Structural modeling further enhanced the understanding of the Hartha Formation’s geometry,illustrating how tectonic influences and faulting impacted the spatial distribution of reservoir units.Facies modeling identified a predominance of mudstone and wackestone in the upper Hartha Formation,with improved reservoir qualities in the Har.UA and Har.UB units.Petrophysical modeling demonstrated variations in porosity and water saturation,highlighting the impact of structural features on fluid distribution.The findings underscore the complex geological interplay within the Hartha Formation,providing critical insights for future exploration and optimized hydrocarbon recovery strategies.
文摘In recent years,the Journal of Palaeogeography(Chinese Edition and English Edition)continually received manuscripts,in which some authors are from China and some are from Pakistan,Lithuania,Morocco,South Africa,etc.The authors of these manuscripts,according to the viewpoint and method of Miall’s paper(1985),selected rocks from each bed in the clastic sections of their study areas and induced some rock types,such as conglomerates,sandstones and fine-grained stones,and considered them as lithofacies.It does not conform to the definition of lithofacies.I wrote some papers,i.e.,Feng(2018,2019,2020),to point out the problems and hope that the authors worldwide,especially Chinese authors,will not continually cite,spread and follow Miall’s paper(1985)viewpoint and method blindly.Prof.Miall is the first person who considered rocks(in fact,the sediments)as lithofacies and proposed a facies analysis method.His viewpoint and facies analysis method confused the definition of facies and facies analysis method.My current paper is a special article to discuss the principal problems of Miall’s paper(1985),i.e.,he considered the sediments as lithofacies and utilized lithofacies to analyze facies,but not to discuss the contributions and less strictness of architectural elements of his paper.Here,I have to declare that the facies in my current paper is the facies of sedimentary petrology,but not of other geological disciplines,such as igneous petrology,metamorphic petrology,palaeontology,stratigraphy,geophysics,geochemistry.Certainly,the definitions of facies and lithofacies are controversial.My current paper will adhere to the policy of“A hundred flowers blossom and a hundred schools of thought contend”.I hope that through academic discussions,contends and geological practice,these problems will be solved gradually.
文摘Condensed ammonoid beds of the Hallstatt facies (Anisian-Ladinian) are widespread around the Ancient Theatre of Epidaurus,in the locality Theokafta of the Argolis Peninsula (eastern Peloponnesus).The Hallstatt Formation in Argolis appears,generally,in the form of lensoid bodies of variable sizes,inclination and direction and is always found overlying a formation consisting of keratophyric tuffs.In fact,the contact of the keratophyric tuffs with the overlying limestones,specifically evidenced by an in situ brecciated zone,is stratigraphic and constitutes the base of the Hallstatt Limestones.The contact of the Hallstatt Limestones with the overlying radiolarites is stratigraphic as well.Lithofacies and biostratigraphic research has focused on the lowermost horizons of the Hallstatt Limestones of Anisian age (average thickness about 1.30 m),where a dense sampling has been performed,followed by detailed facies analysis.The lowermost horizons of the Hallstatt Limestones of Theokafta represent typical hiatus beds/concretions sensu Wetzel and Allia (2000),characterized by discontinuous sedimentation and erosion.They consist of red ammonoid-bearing hemipelagic limestones with calcium carbonate nodules floating in an enriched Fe-oxides matrix with dispersed lensoid/prismatic calcium carbonate crystals.This part of the section is characterized by condensed sedimentation,due to significant lowering of the rate of sedimentation and includes omission surfaces,firmgrounds and hardgrounds along certain horizons.Nine lithostratigraphic units have been distinguished in the lowermost horizons of the Hallstatt Limestones,including radiolarian packstones,volcaniclastic facies,packstones/floatstones with ammonoids and lag deposits.Tselepidis (2007) defined nine distinct ammonoid biozones from the Anisian to Ladinian,documenting deposition of the Hallstatt facies during a low depositional rate over nearly 5 million years (using the timescale of Gradstein et al.,2004).The biozones:Japonites/Paracrochordiceras,Hollandites,Procladiscites/Leiophyllites,zoldianus,trinidosus,Reitziites/Parakellnerites and the Nevadites (Anisian) and the biozone curionii (Lower Ladinian).Although sedimentation was very condensed,it didn’t reach the level of mixing fauna.Synsedimentary and early burrowing processes differentiated the primary texture characteristics of the deposited sediments.Multiphase diagenesis occurred not very deep below the sediment surface and includes boring and/or encrustation,burial and cementation.The deposition of the studied Hallstatt Limestones is considered to be due to anaerobic oxidation of organic matter,which provided excess alkalinity,inducing carbonate precipitation.Sedi-mentation took place on differentially-subsided deep swells.After drowning,the swells were covered by pelagic carbonate deposits.Further slight rotation of blocks,along listric faults,may have led to additional differential subsidence of the blocks.Shelf bathymetry and thirdorder sea-level changes played a significant role in the formation of the Hallstatt beds.In terms of sequence stratigraphy,the studied hiatus concretions and beds are considered genetically linked to rising or high sea-level,formed at the initiation of transgressions,as well as during the time of maximum rate of transgression,in areas where the sediment input was strongly reduced (’’condensed section’’) .Taking into consideration the present location of the Hallstatt Formation,in the context of the Hellenides,an area suitable for the deposition of the Hallstatt Limestones,should be located between the sub-Pelagonian (western part of the Pelagonian zone) and Pindos geotectonic zones,which during the Triassic corresponded to a platform slope and a deep ocean,respectively.The widespread Middle Triassic Han Bulog Limestones (ammonoid-bearing pelagic limestones) from Triassic successions of the Eastern Alps (Dinarides,Hellenides) may have formed partly in similar slope environments.
文摘1.Journal of Palaeogeography[JoP]publishes in the general fields of sedimentology and palaeontology that include a distinct and noticeable palaeogeographic aspect or perspective.High-quality original research articles and authoritative reviews are welcomed.Subdisciplines of interest to JoP include(but not limited to):Facies analysis and sedimentary environments;Palaeobiology(including taxonomy)and palaeoecology;Palaeobiogeography;Stratigraphy;Sequence stratigraphy;Sedimentary geochemistry.
