Journal articles on the topic 'Facies (Geology) Analysis'
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1
Anderton, R. "Clastic facies models and facies analysis." Geological Society, London, Special Publications 18, no. 1 (1985): 31–47. http://dx.doi.org/10.1144/gsl.sp.1985.018.01.03.
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Postma, George. "The geology of fluvial deposits, sedimentary facies, basin analysis and petroleum geology." Sedimentary Geology 110, no. 1-2 (May 1997): 149–50. http://dx.doi.org/10.1016/s0037-0738(96)00081-4.
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Pendrel, John, and Henk Schouten. "Facies — The drivers for modern inversions." Leading Edge 39, no. 2 (February 2020): 102–9. http://dx.doi.org/10.1190/tle39020102.1.
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It is common practice to make facies estimations from the outcomes of seismic inversions and their derivatives. Bayesian analysis methods are a popular approach to this. Facies are important indicators of hydrocarbon deposition and geologic processes. They are critical to geoscientists and engineers. The application of Bayes’ rule maps prior probabilities to posterior probabilities when given new evidence from observations. Per-facies elastic probability density functions (ePDFs) are constructed from elastic-log and rock-physics model crossplots, over which inversion results are superimposed. The ePDFs are templates for Bayesian analysis. In the context of reservoir characterization, the new information comes from seismic inversions. The results are volumes of the probabilities of occurrences of each of the facies at all points in 3D space. The concepts of Bayesian inference have been applied to the task of building low-frequency models for seismic inversions without well-log interpolation. Both a constant structurally compliant elastic trend approach and a facies-driven method, where models are constructed from per-facies trends and initial facies estimates, have been tested. The workflows make use of complete 3D prior information and measure and account for biases and uncertainties in the inversions and prior information. Proper accounting for these types of effects ensures that rock-physics models and inversion data prepared for reservoir property analysis are consistent. The effectiveness of these workflows has been demonstrated by using a Gulf of Mexico data set. We have shown how facies estimates can be effectively used to build reasonable low-frequency models for inversion, which obviate the need for well-log interpolation and provide full 3D variability. The results are more accurate probability-based net-pay estimates that correspond better to geology. We evaluate the workflows by using several measures including precision, confidence, and probabilistic net pay.
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Saraswat, Puneet, and Mrinal K. Sen. "Artificial immune-based self-organizing maps for seismic-facies analysis." GEOPHYSICS 77, no. 4 (July 1, 2012): O45—O53. http://dx.doi.org/10.1190/geo2011-0203.1.
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Seismic facies, combined with well-log data and other seismic attributes such as coherency, curvature, and AVO, play an important role in subsurface geological studies, especially for identification of depositional structures. The effectiveness of any seismic facies analysis algorithm depends on whether or not it is driven by local geologic factors, the absence of which may lead to unrealistic information about subsurface geology, depositional environment, and lithology. This includes proper identification of number of classes or facies existing in the data set. We developed a hybrid waveform classification algorithm based on an artificial immune system and self-organizing maps (AI-SOM), that forms the class of unsupervised classification or automatic facies identification followed by facies map generation. The advantage of AI-SOM is that, unlike, a stand-alone SOM, it is more robust in the presence of noise in seismic data. Artificial immune system (AIS) is an excellent data reduction technique providing a compact representation of the training data; this is followed by clustering and identification of number of clusters in the data set. The reduced data set from AIS processing serves as an excellent input to SOM processing. Thus, facies maps generated from AI-SOM are less affected by noise and redundancy in the data set. We tested the effectiveness of our algorithm with application to an offshore 3D seismic volume from F3 block in the Netherlands. The results confirmed that we can better interpret an appropriate number of facies in the seismic data using the AI-SOM approach than with a conventional SOM. We also examined the powerful data-reduction capabilities of AIS and advantages the of AI-SOM over SOM when data under consideration were noisy and redundant.
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Coletti, Giovanni, Giulia Bosio, Alberto Collareta, John Buckeridge, Sirio Consani, and Akram El Kateb. "Palaeoenvironmental analysis of the Miocene barnacle facies: case studies from Europe and South America." Geologica Carpathica 69, no. 6 (December 1, 2018): 573–92. http://dx.doi.org/10.1515/geoca-2018-0034.
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Abstract Acorn barnacles are sessile crustaceans common in shallow-water settings, both in modern oceans and in the Miocene geological record. Barnacle-rich facies occur from polar to equatorial latitudes, generally associated with shallow-water, high-energy, hard substrates. The aim of this work is to investigate this type of facies by analysing, from the palaeontological, sedimentological and petrographical points of view, early Miocene examples from Northern Italy, Southern France and South-western Peru. Our results are then compared with the existing information on both modern and fossil barnacle-rich deposits. The studied facies can be divided into two groups. The first one consists of very shallow, nearshore assemblages where barnacles are associated with an abundant hard-substrate biota (e.g., barnamol). The second one includes a barnacle-coralline algae association, here named “barnalgal” (= barnacle / red algal dominated), related to a deeper setting. The same pattern occurs in the distribution of both fossil and recent barnacle facies. The majority of them are related to very shallow, high-energy, hard-substrate, a setting that represents the environmental optimum for the development of barnacle facies, but exceptions do occur. These atypical facies can be identified through a complete analysis of both the skeletal assemblage and the barnacle association, showing that barnacle palaeontology can be a powerful tool for palaeoenvironmental reconstruction.
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Staňová, Sidónia, Ján Soták, and Norbert Hudec. "Markov Chain analysis of turbiditic facies and flow dynamics (Magura Zone, Outer Western Carpathians, NW Slovakia)." Geologica Carpathica 60, no. 4 (August 1, 2009): 295–305. http://dx.doi.org/10.2478/v10096-009-0021-4.
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Markov Chain analysis of turbiditic facies and flow dynamics (Magura Zone, Outer Western Carpathians, NW Slovakia)Methods based on the Markov Chains can be easily applied in the evaluation of order in sedimentary sequences. In this contribution Markov Chain analysis was applied to analysis of turbiditic formation of the Outer Western Carpathians in NW Slovakia, although it also has broader utilization in the interpretation of sedimentary sequences from other depositional environments. Non-random facies transitions were determined in the investigated strata and compared to the standard deep-water facies models to provide statistical evidence for the sedimentological interpretation of depositional processes. As a result, six genetic facies types, interpreted in terms of depositional processes, were identified. They comprise deposits of density flows, turbidity flows, suspension fallout as well as units which resulted from syn- or post-depositional deformation.
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Gao, Dengliang. "Latest developments in seismic texture analysis for subsurface structure, facies, and reservoir characterization: A review." GEOPHYSICS 76, no. 2 (March 2011): W1—W13. http://dx.doi.org/10.1190/1.3553479.
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In exploration geology and geophysics, seismic texture is still a developing concept that has not been sufficiently known, although quite a number of different algorithms have been published in the literature. This paper provides a review of the seismic texture concepts and methodologies, focusing on latest developments in seismic amplitude texture analysis, with particular reference to the gray level co-occurrence matrix (GLCM) and the texture model regression (TMR) methods. The GLCM method evaluates spatial arrangements of amplitude samples within an analysis window using a matrix (a two-dimensional histogram) of amplitude co-occurrence. The matrix is then transformed into a suite of texture attributes, such as homogeneity, contrast, and randomness, which provide the basis for seismic facies classification. The TMR method uses a texture model as reference to discriminate among seismic features based on a linear, least-squares regression analysis between the model and the data within an analysis window. By implementing customized texture model schemes, the TMR algorithm has the flexibility to characterize subsurface geology for different purposes. A texture model with a constant phase is effective at enhancing the visibility of seismic structural fabrics, a texture model with a variable phase is helpful for visualizing seismic facies, and a texture model with variable amplitude, frequency, and size is instrumental in calibrating seismic to reservoir properties. Preliminary test case studies in the very recent past have indicated that the latest developments in seismic texture analysis have added to the existing amplitude interpretation theories and methodologies. These and future developments in seismic texture theory and methodologies will hopefully lead to a better understanding of the geologic implications of the seismic texture concept and to an improved geologic interpretation of reflection seismic amplitude.
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He, Qing Kun, and Chang Ying Shi. "Application of Electron Probe Microanalyzer (EPMA) to Depositional Environment Identification of Sedimentary Rock." Advanced Materials Research 881-883 (January 2014): 1795–98. http://dx.doi.org/10.4028/www.scientific.net/amr.881-883.1795.
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s: Electron microprobe technology is widely used to component analysis of metals, minerals and geology. Elements of sedimentary rock including B, Ga, Ba, Sr, Co, V, Cr, Mn, Fe, Ni were analyzed by EPMA respectively. It was discussed that marine faces and continental facies, oxidation environment and reducing environment, the depth of water and salinity influence on sedimentary rock, respectively. Then the influence of marine faces, continental faces, oxidation environment, reducing environment and the depth of water and salinity on sedimentary rock was discussed respectively. The results show that EPMA is a useful instrument to analyze the components of sedimentary rock.
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Verdiansyah, Okki. "A Desktop Study to Determine Mineralization Using Lineament Density Analysis at Kulon Progo Mountains, Yogyakarta and Central Java Province, Indonesia." Indonesian Journal of Geography 51, no. 1 (April 30, 2019): 31. http://dx.doi.org/10.22146/ijg.37442.
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A geological study was conducted in Kulon Progo and its surrounding areas (Kulon Progo and Purworejo Regency). It focused on regional geology, tectonic configuration, geodynamics and magmatism, lithology and volcanology, and mineralization. Although there has been considerable research of mineralization in the area—particularly in Kokap (Kulon Progo Regency), Bagelen (Purworejo Regency) and Gupit (Magelang Regency), the potential of precious metals has not been determined due to data limitations. The study combined qualitative and semi-quantitative methods using a desktop geologic analysis, which facilitates lithology interpretation, volcanic boundary system, and lineament density assessment. The geology of the region is composed of an ancient volcanic complex of the Old Andesite Formation formed during the Late Oligocene-Miocene, and the mineralization in Kokap, Bagelen, and Gupit is epithermal. Based on the analysis results, the mineralization occurs in the central to proximal facies of the paleo-volcano, and the system ranges from 2.2 to 3.8 km in diameter. The manual analysis of the lineament density showed that the main direction of the lineaments was SE-NW with a maximum density of 2025.9 m/km2 and an anomaly limit of >1800 m/km2. In the combined semi-automatic analysis, the maximum density was 8.3 km/km2. The target area of mineralization included four anomalous areas, namely Bagelen-Kokap, Salaman, Kaligesing, and Loano, associated with the central and proximal facies of each small paleo-volcano.
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Fukuda, Sojiro, and Hajime Naruse. "Shape difference of mud clasts depending on depositional facies: application of newly modified elliptic Fourier analysis to hybrid event beds." Journal of Sedimentary Research 90, no. 10 (October 1, 2020): 1410–35. http://dx.doi.org/10.2110/jsr.2020.67.
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ABSTRACT Hybrid event beds are the deposits from sediment gravity flows that change their rheological behavior through their passage, entraining muddy sediments and damping turbulence. Muddy facies of hybrid event beds are often associated with abundant mud clasts which show a wide variety of size and shape. The variation of clast occurrence in hybrid event beds is expected to preserve the information of entrainment and transport processes of muddy sediments in submarine density currents. However, previous analyses of hybrid event beds have focused on describing the overall clast occurrence rather than the statistical size and shape analyses because traditional shape parameters are incapable of characterizing the complex shape of mud clasts. Here, a new quantitative grain-shape analysis of mud clasts is conducted and allows visualization of the spatial variation of clast size and shape, which suggests the wide variety of origin and transport systems of entrained mud clasts. This new method revises the traditional elliptic Fourier analysis, substituting Fourier power spectra (FPS) for traditional elliptic Fourier descriptors to overcome the mirror-wise shape problem. Further, principal-component analysis is shown to capture significant shape attributes more effectively than traditional shape parameters. The proposed method is applied to mud clasts in sediment-gravity-flow deposits in the lower Pleistocene Otadai Formation, central Japan. Results imply that there are distinctive shape and size differences of mud clasts that are strongly associated with depositional facies rather than the distance from the source. The clasts have a higher angularity than other facies in the debrite intervals in hybrid event beds. It is also shown that clasts in sandy, structureless facies have different characteristics in shapes based on elongation and convexity compared to laminated facies. Comparison between different shape-analysis methods demonstrates that none of the traditional methods are able to visualize these trends as effectively as the method presented herein. These results highlight the importance of the quantitative shape analysis of sediment grains and the effectiveness of FPS-based elliptic Fourier analysis.
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Kirk, M. "Westphalian alluvial plain sedimentation, Isle of Arran, Scotland." Geological Magazine 126, no. 4 (July 1989): 407–21. http://dx.doi.org/10.1017/s0016756800006592.
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AbstractFacies analysis suggests that Westphalian (Upper Carboniferous) Coal Measure sequences on the Isle of Arran, Scotland, were deposited in a proximal alluvial plain environment close to the basin margin. Detailed examination of well exposed coastal sections has revealed the existence of six laterally and vertically interrelated sedimentary facies. Facies 1 to 3 are interpreted as fluvial channel deposits. Low sinuosity multistorey (facies 1), low sinuosity vertically accreted (facies 2), and rare high sinuosity laterally accreted channel deposits (facies 3) are developed. Associated overbank sediments comprise the deposits of crevasse splays (facies 4), flood plains (facies 5) and shallow lakes (facies 6). In terms of the spatial distribution of facies, a relatively high proportion of fluvial channel and floodplain deposits (facies 2 and 5) occur in the more proximal sequence at Laggan compared with the more distally located sequence occurring at Corrie. Palaeocurrent measurements from fluvial channel sandstones indicate that sediment source areas and the Westphalian basin margin lay to the north and northwest. Down palaeoslope towards the southeast, normal coal-bearing Westphalian sediments formed penecontemporaneously on the Scottish mainland in Ayrshire.A sedimentological model is presented for the proximal non-coal-bearing Westphalian sequences of Arran. This model can explain the differences observed between the Arran sediments, and contemporaneous normal coal-bearing Westphalian sediments of the Scottish mainland.
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Duperron, María, and Roberto Adrián Scasso. "Paleoenvironmental significance of microbial mat-related structures and ichnofaunas in an Ordovician mixed-energy estuary, Áspero Formation of Santa Victoria Group, northwestern Argentina." Journal of Sedimentary Research 90, no. 4 (April 8, 2020): 364–88. http://dx.doi.org/10.2110/jsr.2020.17.
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ABSTRACT The study on a unique set of outstandingly preserved sedimentary surface textures (SSTs) found in the late Tremadocian Áspero Formation of northwestern Argentina, coupled with the sedimentological and ichnological analysis, indicate that they were formed in the intertidal to supratidal setting of a mixed-energy estuary recording storm and tide sedimentation. We recognize seven types of SSTs: probably biotic microbial mat-related SSTs (Kinneyia, elephant skin, exfoliating sandy laminae), abiotic SSTs (elliptical scours and convex parallel ridges type I “wrinkle marks” sensuAllen 1985), and problematic (convex parallel ridges type II and dot matrix texture). Elliptical scours and convex parallel ridges type I show features which indicate reworking of a cohesive sandy substrate in an intertidal or supratidal setting. Abundance of biotic SSTs with specific associated trace fossils reflect matground development and mat-grazing ichnofaunas, indicating the suppression of intense, penetrative bioturbation due to intense physicochemical stress. The “dot matrix” texture, described here for the first time, consists of a regular horizontal network of millimeter-scale pits; it appears associated with exfoliating sandy laminae, probably reflecting a mat-related origin. Three facies associations are defined through paleoenvironmental analysis. Facies association 1 is dominated by high-energy sandy and bioclastic storm deposits with tidal flat facies, and corresponds to the outer bay of a mixed-energy estuary; highly impoverished Cruziana assemblages and distal expressions of the Skolithos Ichnofacies reflect high energy and sedimentation rate. Facies association 2 shows tidal-channel and tidal-flat facies with subordinated storm deposits, representing the middle bay; impoverished Cruziana assemblages dominated by simple facies-crossing structures, with high-density monogeneric opportunistic suites, evidence physicochemical stress associated with subaerial exposure, frequent episodic deposition, high water turbidity, and/or brackish water conditions in these relatively sheltered tidal flats. Facies association 3 is formed by interdistributary-bay deposits with intercalation of channel-fill deposits in the upper part, and represents the river-dominated bay-head delta; low degrees of bioturbation in fine-grained facies indicate brackish- to fresh-water conditions. SSTs are found in tidal flat facies of facies association 2; they indicate an intertidal to supratidal environment subject to localized conditions of intense physicochemical stress. The paleoenvironmental interpretation of SSTs converges with the one performed through sedimentological and ichnological analysis, producing a robust and more detailed paleoenvironmental model for the Áspero Formation. Our study highlights the use of SSTs as a tool for supporting and refining paleoenvironmental analysis.
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Elisheva, O. V., and K. A. Sosnovskikh. "Experience in applying the method of fractal analysis to clarify the boundaries of facies zones when introducing digital technologies in the exploration process." Oil and Gas Studies, no. 5 (October 31, 2021): 36–50. http://dx.doi.org/10.31660/0445-0108-2021-5-36-50.
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In order to improve the efficiency of exploration drilling at various greenfield license areas owned by Rosneft Oil Company, Tyumen Petroleum Scientific Center LLC has been actively developing and implementing various innovative technologies in recent years that allow increasing the probability of discovering new hydrocarbon deposits. One of such approaches is the use of different methods based on the principles of fractality of geological objects. The article presents the results of using the fractal analysis method to solve one of the applied problems of oil and gas geology, namely, the correction of the boundaries of facies zones on facies maps, which are the basis for constructing risk maps for the "reservoir". It is shown that the boundaries of the facies zones on facies maps, built mainly on seismic data and a limited amount of materials from exploration drilling, have a large variability. The found statistical relationship between the distribution of the total reservoir thicknesses in different facies zones and the fractal dimension of the traps made it possible to correct facies and risk maps.
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Permana, Aang Panji, Subagyo Pramumijoyo, and Sunarty Suly Eraku. "MICROFACIES AND DEPOSITIONAL ENVIRONMENT OF TERTIARY LIMESTONE, GORONTALO PROVINCE, INDONESIA." Series of Geology and Technical Sciences 2, no. 446 (April 15, 2021): 15–21. http://dx.doi.org/10.32014/2021.2518-170x.29.
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The research area is located in northern Limboto Lake in Gorontalo Province, which has complex geological characteristics. The geological complexities include stratigraphy and tectonics which influence the formation of the Limboto Basin. Limestone research in the Late Tertiary Limboto Basin is very intriguing to be done because of the lack of research in limestone. Gorontalo limestone outcrops, which become the focus of the research, have a total thickness of 30 meters. The research objective is to analyze facies, microfacies, and depositional environment of tertiary limestone. These two research objectives are attained by using two research methods, namely measurd section and petrography analysis. The research result exhibits that there are four Gorontalo limestones facies, including coralline rudstone intercalated with thin mudstone facies, sandy micrite intercession facies, coralline rudstone intercession facies and sandy allochem limestone intercession facies. According to the limestone micro- facies standard, the depositional environment of Gorontalo limestone is platform interior restricted (facies zone 8).
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Breckenridge, Jake, Angelos G. Maravelis, Octavian Catuneanu, Kevin Ruming, Erin Holmes, and William J. Collins. "Outcrop analysis and facies model of an Upper Permian tidally influenced fluvio-deltaic system: Northern Sydney Basin, SE Australia." Geological Magazine 156, no. 10 (March 7, 2019): 1715–41. http://dx.doi.org/10.1017/s0016756818000973.
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AbstractAn integrated study of sedimentological, sequence-stratigraphic and palaeodispersal analysis was applied to the Upper-Permian clastic sedimentary succession in the Northern Sydney Basin, Australia. The succession is subdivided into fifteen facies and three facies associations. The facies associations are further subdivided into eight sub-facies associations. The sedimentary evolution involves progradation from delta-front to delta-plain to fluvial depositional environments, with a significant increase in sediment grain size across the unconformable contact that separates the deltaic from the overlying fluvial system. In contrast to the delta front that is wave/storm- and/or river-influenced, the delta plain is significantly affected by tides, with the impact of tidal currents decreasing up-sequence in the delta plain. The general lack of wave-influenced sedimentary structures suggests low wave energy in the delta plain. The abrupt termination of the tidal impact in the fluvial realm relates to the steep topographic gradients and high sediment supply, which accompanied the uplift of the New England Orogen. The sequence-stratigraphic framework includes highstand (deltaic forest and topset) and lowstand (fluvial topset) systems tracts, separated by a subaerial unconformity. In contrast to most of the mud-rich modern counterparts, this is an example of a sand-rich tidally influenced deltaic system, developed adjacent to the source region. This investigation presents a depositional model for tidal successions in regions of tectonic uplift and confinement.
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Moore, Shawn A., Lauren P. Birgenheier, Matthias D. Greb, Daniel Minisini, Maísa Tunik, and Julieta Omarini. "Facies heterogeneity and source potential of carbonate-mudstone-dominated distal ramp deposits, Agrio Formation, Neuquén Basin, Argentina." Journal of Sedimentary Research 90, no. 5 (May 7, 2020): 533–70. http://dx.doi.org/10.2110/jsr.2020.25.
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ABSTRACT The carbonate-mudstone-dominated Lower Cretaceous Agrio Formation is the youngest marine source rock of the hydrocarbon-prolific Neuquén Basin in Argentina, yet its facies variability and unconventional hydrocarbon potential remains relatively understudied. Detailed studies of mudstone facies variability in thick, carbonate mudstone successions deposited largely below storm wave base (i.e., chalk–marl, black shale, limestone), like the Agrio Formation, are rare and instead commonly focus on biostratigraphy or organic geochemistry alone. A continuous northern section of the Agrio Formation and a southern composite section of the lower Pilmatué and middle Avilé members, totaling ∼ 1,200 m of outcrop, were measured. From these measured sections, programmed pyrolysis (n = 339 samples), X-ray diffraction (XRD; n = 69), and thin sections (n = 69) were used to develop a high-resolution integrated macrofacies and microfacies scheme. The four most volumetrically abundant facies include detrital-quartz-silt-bearing fine mudstone (facies 1), radiolarian-bearing calcareous fine mudstone (facies 2), detrital-quartz-silt- and shell-bearing calcareous fine mudstone (facies 3), and calcareous wackestone (facies 4). All four facies are volumetrically dominated by carbonate mud matrix (i.e., micrite) that represents either 1) original pelagic coccolithophore deposition modified by diagenesis, 2) transported carbonate mud (i.e., bottom currents like contour currents or sediment gravity flows), or 3) a combination of both. Outcrop observations, XRD mineralogic trends, and petrographic variations in grain composition between detrital quartz silt, radiolarian and microfossil to macrofossil content (mainly benthic foraminifera and bivalves) distinguish the four mudstone facies. The facies scheme indicates distinctly more heterogeneous and current-influenced sedimentation in the downdip sub-storm wave base than previously described in the Agrio and in carbonate-dominated basinal settings in general. A depositional model is proposed for further testing that may prove valuable towards re-evaluating basinal carbonate mudstone successions worldwide. Utilizing TOC, S2, and HI value cutoffs, this study defines five discrete stratigraphic packages in the Agrio Formation that have the highest source potential, collectively totaling ∼ 140 m thick. The novel integration of macrofacies and microfacies analysis, stratigraphy, and a geochemical analysis allow both depositional insights and the assessment of a potential source rock. The study adds to a growing body of literature on 1) carbonate ramp (or slope) to basinal processes and 2) facies models for organic-rich, carbonate-dominated mudstone successions that are unconventional hydrocarbon systems.
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Liu, Shiqi, and Yuyang Liu. "Sedimentary Characteristics Analysis and Sedimentary Facies Prediction of Jurassic Strata in the Northwest Margin of Junggar Basin—Covering the W105 Well Region in the Wuerhe Area." Minerals 12, no. 1 (January 5, 2022): 68. http://dx.doi.org/10.3390/min12010068.
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As the northwestern area of the Junggar Basin is a key area for oil and gas exploration, the sedimentary facies of the Jurassic formations in the Wuerhe area has long been a focus of research. The target strata are Jurassic strata, including five formations: the Lower Jurassic Badaowan and Sangonghe, the Middle Jurassic Xishanyao and Toutunhe and the Upper Jurassic Qigu. Disputes over the are sedimentary facies division exist in this area. Considering the W105 well region in this area as an example, the overall sedimentary facies of single-well logging facies is analyzed and then expanded to two cross-sections and characterized. Based on previous studies, a detailed overview of the regional stratigraphy is obtained by well logs and other data. Then, two cross-sections are selected and analyzed. The single-well and continuous-well facies of 10 wells in the sections are analyzed to grasp the sand bodies’ spatial distribution. Finally, a planar contour map of the net to gross ratio is mapped to analyze the sources and the distribution of the sand bodies in each period. The sedimentary facies map is also mapped to predict the sedimentary evolution. The results show that the sedimentary facies of the Badaowan Formation in the study area was an underwater distributary channel of the fan-delta front, and the sand body spread continuously from northwest to southeast. The Sangonghe Formation entered a lake transgression period with a rising water level, at which time shore–shallow lacustrine deposits were widespread throughout the region. The period of the Xishanyao Formation entered a regression period, the northwest region was tectonically uplifted, and the central and southeastern regions facies were dominated by the fan-delta front and shallow lacustrine. During the Toutunhe Formation period, the northwest region continued to uplift and was dominated by delta plain facies. During the period of the Qigu Formation, the thickness of stratigraphic erosion reached its maximum, and the non-erosion area of the study area was mainly deposited by the fan-delta plain. Overall, the Jurassic system in the W105 well area is a fan delta–lacustrine–fan delta sedimentary system.
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Zhao, Tao, Fangyu Li, and Kurt J. Marfurt. "Constraining self-organizing map facies analysis with stratigraphy: An approach to increase the credibility in automatic seismic facies classification." Interpretation 5, no. 2 (May 31, 2017): T163—T171. http://dx.doi.org/10.1190/int-2016-0132.1.
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Pattern recognition-based seismic facies analysis techniques are commonly used in modern quantitative seismic interpretation. However, interpreters often treat techniques such as artificial neural networks and self-organizing maps (SOMs) as a “black box” that somehow correlates a suite of attributes to a desired geomorphological or geomechanical facies. Even when the statistical correlations are good, the inability to explain such correlations through principles of geology or physics results in suspicion of the results. The most common multiattribute facies analysis begins by correlating a suite of candidate attributes to a desired output, keeping those that correlate best for subsequent analysis. The analysis then takes place in attribute space rather than ([Formula: see text], [Formula: see text], and [Formula: see text]) space, removing spatial trends often observed by interpreters. We add a stratigraphy layering component to a SOM model that attempts to preserve the intersample relation along the vertical axis. Specifically, we use a mode decomposition algorithm to capture the sedimentary cycle pattern as an “attribute.” If we correlate this attribute to the training data, it will favor SOM facies maps that follow stratigraphy. We apply this workflow to a Barnett Shale data set and find that the constrained SOM facies map shows layers that are easily overlooked on traditional unconstrained SOM facies map.
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Łoziński, Maciej, Piotr Ziółkowski, and Anna Wysocka. "Tectono-sedimentary analysis using the anisotropy of magnetic susceptibility: a study of the terrestrial and freshwater Neogene of the Orava Basin." Geologica Carpathica 68, no. 5 (October 26, 2017): 479–500. http://dx.doi.org/10.1515/geoca-2017-0031.
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Abstract The Orava Basin is an intramontane depression filled with presumably fine-grained sediments deposited in river, floodplain, swamp and lake settings. The basin infilling constitutes a crucial record of the neoalpine evolution of the Inner/Outer Carpathian boundary area since the Neogene, when the Jurassic-Paleogene basement became consolidated, uplifted and eroded. The combination of sedimentological and structural studies with anisotropy of magnetic susceptibility (AMS) measurements provided an effective tool for recognition of terrestrial environments and deformations of the basin infilling. The lithofacies-oriented sampling and statistical approach to the large dataset of AMS specimens were utilized to define 12 AMS facies based on anisotropy degree (P) and shape (T). The AMS facies allowed a distinction of sedimentary facies ambiguous for classical methods, especially floodplain and lacustrine sediments, as well as revealing their various vulnerabilities to tectonic modification of AMS. A spatial analysis of facies showed that tuffites along with lacustrine and swamp deposits were generally restricted to marginal and southern parts of the basin. Significant deformations were noticed at basin margins and within two intrabasinal tectonic zones, which indicated the tectonic activity of the Pieniny Klippen Belt after the Middle Miocene. The large southern area of the basin recorded consistent N-NE trending compression during basin inversion. This regional tectonic rearrangement resulted in a partial removal of the southernmost basin deposits and shaped the basin’s present-day extent.
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Haas, János, Kinga Hips, Pál Pelikán, Norbert Zajzon, Annette E. Götz, and Edit Tardi-Filácz. "Facies analysis of marine Permian/Triassic boundary sections in Hungary." Acta Geologica Hungarica 47, no. 4 (December 2004): 297–340. http://dx.doi.org/10.1556/ageol.47.2004.4.1.
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BRISTOW, CHARLIE. "Facies analysis in the Lower Greensand using ground-penetrating radar." Journal of the Geological Society 152, no. 4 (July 1995): 591–98. http://dx.doi.org/10.1144/gsjgs.152.4.0591.
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Rigueti, Ariely L., Patrick Führ Dal' Bó, Leonardo Borghi, and Marcelo Mendes. "Bioclastic accumulation in a lake rift basin: The Early Cretaceous coquinas of the Sergipe–Alagoas Basin, Brazil." Journal of Sedimentary Research 90, no. 2 (February 27, 2020): 228–49. http://dx.doi.org/10.2110/jsr.2020.11.
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ABSTRACT Coquinas constitute widespread deposits in lacustrine, estuarine, and shallow marine settings, where they are a valuable source of information on environmental conditions. Thick coquina successions were deposited in a series of lacustrine rift basins that formed along the Brazilian Continental Margin during the early stages of the opening of the South Atlantic Ocean, in the Early Cretaceous. In the Sergipe–Alagoas Basin, the coquina sequence, equivalent to the Morro do Chaves Formation, crops out in the Atol Quarry, and is considered a relevant analog for the economically important hydrocarbon reservoirs in the Pre-salt strata (Barremian to Aptian) of the Campos Basin (Pampo, Badejo, and Linguado oil fields), which occur only in the subsurface. The aim of this study is to generate a depositional and stratigraphic model through facies and stratigraphic analyses of a well core. These analyses allowed the geological characterization of the Morro do Chaves Formation and of its transition to the adjacent stratigraphic units, the Coqueiro Seco Formation above and the Penedo Formation below, contributing to the growing knowledge of sedimentation in rift basins and exploratory models in hydrocarbon-producing reservoirs. Facies analysis consists of sedimentological, taphonomic, and stratigraphic features of the rocks. Fourteen depositional facies were recognized, stacked into low-frequency and high-frequency, deepening-upward and shallowing-upward cycles driven by the interaction between climate and tectonism. A depositional model is presented, based on the correlation between well-core and outcrop data described in previous studies, providing insights into the spatial distribution of facies. The detailed analysis of facies and stacking patterns sheds light on depositional processes, paleoenvironmental conditions, and the evolution of the system through time, so we may better understand analogous deposits in the geological record.
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Yan, Bai Quan, Er Shuang Gao, Dan Dan Peng, Xiao Lei Tian, and Guang Wang. "Sedimentary Microfacies Analysis of S II Reservoir Group in the Block X of Daqing Oil Field." Advanced Materials Research 616-618 (December 2012): 170–73. http://dx.doi.org/10.4028/www.scientific.net/amr.616-618.170.
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With the continuous and deepening development of oil field, reseach of sedimentary microfacies is more and more important on the basis of energy facies. The study area is the thin oil thermal recovery experimental zone of Daqing Oilfield. A variety of microfacies boundary has strong resistant and limiting effect for the filterring flow characteristics of underground fluid. This study is based on the fine contrast to reservoir, establish high resolution sequence stratigraphic framework, set up the logging facies mode of different levels of the energy levels on the basis, make the logging facies identification and combination of space for 17 sedimentary time units of SⅡ reservoir group by well to well and layer to layer, portray fine 17 sedimentary time units of the spatial distribution characteristics of sedimentary microfacies, and provid the scient geology-orientation for subsequent thermal recovery program and development effectiveness evaluation.
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Steklain, André F., Francisco Ganacim, Marcio R. Adames, João L. Gonçalves, and Danian S. Oliveira. "Structure-oriented filtering in unsupervised multiattribute seismic facies analysis." Leading Edge 41, no. 6 (June 2022): 411–4171. http://dx.doi.org/10.1190/tle41060411.1.
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The growing use of automated methods in seismic interpretation highlights the importance of data treatment. We analyze the effect of structure-oriented filtering seismic data on machine learning techniques and apply the filter to the data before calculating seismic attributes. We apply this methodology to a migrated section of Buzios Field from the Brazilian presalt in Santos Basin. The analysis is restricted to the case of unsupervised methods, namely self-organized maps and generative topographic mapping. We use four different seismic attributes that are known to be good salt indicators. Two are based on texture, and two are based on coherence. The use of filtering can improve salt identification in clustering when more attributes are considered.
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Al-ghafour, Raafat, Manal Al-Kubaisi, and Ali Al-Musawy. "Microfacies and Diageneses Associated Mishrif Formation in X Oilfield Southeast Iraq." Iraqi Geological Journal 55, no. 2D (October 31, 2022): 127–39. http://dx.doi.org/10.46717/igj.55.2d.11ms-2022-10-27.
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The fractal fifteen thin section showed that the deposition of the Mishrif Formation is gradual upwards. It was deposited in a period that suffered from several marine fluctuations. It began as a cycle of marine retreat that led to the sedimentation of reefs, followed by a short-term marine advance, and then a widespread marine retreat that led to the emergence of sedimentary facies and various Rudist assemblies. Through scrutiny and analysis of the slides, the presence of five main facies (basin facies, slope facies, shallow open marine, shoal, and rudist biostrom environment) was observed. Theresults showed that the morphological processes re-crystallization, decomposition and dolomitization have the greatest role in improving the porosity, in addition to that the Rudist biostrom and shoal facies environment have good reservoir properties in units MA, MB2 and MB2.The modulation processes affecting the development of the reservoir properties of the different units were identified, with an indication of the severity of their impact and their role in the growth and destruction of porous systems. These processes are micritization, dissolution, dolomitization, cementation, recrystallization, stylolitization, and compaction.
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Singh, Sagar, Ilya Tsvankin, and Ehsan Zabihi Naeini. "Facies prediction with Bayesian inference: Application of supervised and semisupervised deep learning." Interpretation 10, no. 2 (March 3, 2022): T279—T290. http://dx.doi.org/10.1190/int-2021-0104.1.
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Accurate delineation of geologic facies and determination of live fluids from seismic reflection data is crucial for reservoir characterization during petroleum exploration. Facies classification or fluid identification is often done manually by an experienced interpreter, which makes this process subjective, laborious, and time-consuming. Several machine-learning models have been proposed to automate multiclass facies segmentation, but significant practical challenges (e.g., limited scope of labels for training purposes, skewed data distribution, inefficient performance evaluation metrics, etc) still remain. We present supervised and semisupervised Bayesian deep-learning methodologies to improve analysis of seismic facies depending on the scope of the labeled data. The developed networks reliably predict facies distribution using seismic reflection data and estimate the corresponding uncertainty. Therefore, they provide more consistent and meaningful information for seismic interpretation than commonly used deterministic approaches. We apply the proposed deep-learning models to field data from the North Sea to demonstrate the generalized-prediction capabilities of our methodology. In the case of sufficient availability of manually interpreted labels (or facies), the supervised learning model accurately recovers the facies distribution. When the amount of the interpreted labels is limited, we efficiently apply the semisupervised algorithm to avoid overfitting.
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Liu, Di, Changchun Zou, Yihang Chang, Ping Yang, Zhonghong Wan, and Weiguang Liu. "Seismic facies discrimination incorporating relative rock physics." Leading Edge 40, no. 10 (October 2021): 734–41. http://dx.doi.org/10.1190/tle40100734.1.
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Seismic facies discrimination is usually performed based on a rock-physics-driven quantitative interpretation approach. The accuracy of the study of rock physics largely impacts the reservoir and fluid recognition. However, the study is commonly conducted with absolute well logs without removing the trend effect. Such an approach may introduce inappropriate low-frequency information and bias further analysis of seismic data (crossplotting, facies probability density function generation, and projection angle determination). By contrast, relative rock physics with the trend decomposed reflects the rock-property variation of the overburden and underlying formation. The relative portions are more consistent with the seismic reflectivity, providing an alternative tool to facies interpretation through a seismic inversion scheme. A workflow for seismic facies discrimination has been investigated that incorporates relative rock physics, long short-term memory-based nonlinear seismic inversion, and Bayesian classification. This workflow is employed in a case study from Songliao Basin in northeast China, through which the results of relative and absolute approaches in key steps are analyzed and compared. The consistency of facies, determined through relative and absolute methods with petrophysical interpretation, is calculated. The relative analysis exhibits improved agreement with petrophysical interpretation in overall facies and reservoir sand discrimination of the blind wells. This indicates the potential to minimize the trend bias by integrating relative rock physics in quantitative interpretation.
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Chen, C., G. Gao, B. A. Ramirez, J. C. Vink, and A. M. Girardi. "Assisted History Matching of Channelized Models by Use of Pluri-Principal-Component Analysis." SPE Journal 21, no. 05 (April 20, 2016): 1793–812. http://dx.doi.org/10.2118/173192-pa.
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Summary Assisted history matching (AHM) of a channelized reservoir is still a very-challenging task because it is very difficult to gradually deform the discrete facies in an automated fashion, while preserving geological realism. In this paper, a pluri-principal-component-analysis (PCA) method, which supports PCA with a pluri-Gaussian model, is proposed to reconstruct geological and reservoir models with multiple facies. PCA extracts the major geological features from a large collection of training channelized models and generates gridblock-based properties and real-valued (i.e., noninteger-valued) facies. The real-valued facies are mapped to discrete facies indicators according to rock-type rules (RTRs) that determine the fraction of each facies and neighboring connections between different facies. Pluri-PCA preserves the main (or principal) features of both geological and geostatistical characteristics of the prior models. A new method is also proposed to automatically build the RTRs with an ensemble of training realizations. An AHM work flow is developed by integrating pluri-PCA with a derivative-free optimization algorithm. This work flow is validated on a synthetic model with four facies types and a real-field channelized model with three facies types, and it is applied to update both the facies model and the reservoir model by conditioning to production data and/or hard data. The models generated by pluri-PCA preserve the major geological/geostatistical descriptions of the original training models. This has great potential for practical applications in large-scale history matching and uncertainty quantification.
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Donselaar, M. E., and C. R. Geel. "Facies architecture of heterolithic tidal deposits: the Holocene Holland Tidal Basin." Netherlands Journal of Geosciences - Geologie en Mijnbouw 86, no. 4 (December 2007): 389–402. http://dx.doi.org/10.1017/s001677460002360x.
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AbstractThe size, shape and spatial position of lithofacies types (or facies architecture) in a tidal estuarine basin are complex and therefore difficult to model. The tidal currents in the basin concentrate sand-sized sediment in a branching pattern of tidal channels and fringing tidal flats. Away from the sandy tidal flats the sediment gradually changes to mud-dominated heterolithic deposits and clay. In this paper the facies analysis of a tidal estuarine basin, the Holocene Holland Tidal Basin (HHTB) is presented based on core data and Cone Penetration Tests (CPT). Four lithofacies associations are recognized: (1) tidal channel sand, (2) sand-dominated heterolithic inter-tidal flat, (3) mud-dominated heterolithic inter-channel and (4) fresh-water peat. The high data density allowed for the construction of a detailed facies architecture model in which the size, shape and spatial position of the tidal estuarine facies elements were established. The results can be used to improve the reservoir modelling in highly heterogeneous estuarine reservoir settings.
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Török, Ákos. "Facies analysis and genetic interpretation of travertine, Buda Vár-hegy, Hungary." Acta Geologica Hungarica 46, no. 2 (October 2003): 177–93. http://dx.doi.org/10.1556/ageol.46.2003.2.5.
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Komkov, Ivan K., Alina V. Mordasova, Marina V. Dakhnova, Maria A. Bolshakova, Svetlana V. Mozhegova, and Natalia V. Pronina. "Conditions of sedimentation and distribution of organic matter in the Lower-Middle Jurassic complex of the South-Western part of the West Siberian oil and gas basin." Georesursy 24, no. 2 (May 16, 2022): 150–71. http://dx.doi.org/10.18599/grs.2022.2.15.
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The article is devoted to the variation of generation potential of the Lower-Middle Jurassic organic matter in the Karabash area (South-Western part of the West Siberian basin) depending on facies and sedimentary cyclisity. Based on geochemical and lithological core studies, specific geochemical features of organic matter established for main facies groups of Early-Middle Jurassic in the study area. The best generation potential inherent in deposits of swamps, swampy floodplains and tidal plains. These facies groups characterized by predominance of the continental organic matter and considered to gas source rocks. However, macerals composition, kinetic spectra and biomarker analysis show the presence also of marine organic matter. Some facies groups, such as flooded swamps and swampy floodplains has potential to generate hydrocarbons due to preservation of liptinites with high hydrogen index. Cyclic analysis with basics of sequence stratigraphy of the continental deposits allow tracing the correlation between generation potential and relative sea level changes.
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Muzaal, Zahraa A., Fahad M. Al-Najm, Wasan S. Al-Qurnawi, and Maher J. Ismail. "Rock Type and Pore Throat Radius of Zubair Formation in the W Oil Field: Analysis Utilizing Core and Log Data." Iraqi Geological Journal 55, no. 1D (April 30, 2022): 118–29. http://dx.doi.org/10.46717/igj.55.1d.8ms-2022-04-24.
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The Zubair Formation is a prolific oil reservoir in several southeastern Iraq oil fields. The formation comprises thick sandstones with interbedded shales and siltstones of Lower Cretaceous age (Hauterivian to lower Aptian). The environment of the Zubair Formation consists of fluviodeltaic, deltaic, and marine sandstones. In southern Iraq, the area is subdivided into informal members (oldest to youngest). The Lower Shale, lower sand, middle shale, main pay upper sand, and the upper shale. At the W oilfield, the main pay member is an oil producer. The thickness is of the main reservoir about 100 meters thick. A recent study focused on the Main Pay upper sand, which is divided into three informal units. The upper unit H and lower unit L reservoir units are connected by shale intervals (K unit) that extend throughout the field area laterally. There exist four depositional lithofacies of Zubair Formation fluvial, channel, mouth bar, and prodelta depositional lithofacies. Four Facies were defined according to gamma-ray sandstone, shaly sand, sandy shale, and shale Facies. The Zubair formation has four types of rocks (RRT1, RRT2, RRT3, and RRT4) due to heterogeneity. The RRT1 is characterized by 10%-25% porosities and 10-1000 mD permeability. The RRT2 has a similar porosity range to RRT1, 15%–25%, but an order ofmagnitude lower permeability range from 10-100 mD. RRT3 is considered to have high porosity and low permeability is thought to have great storage but poor flow potential. RRT 3 is characterized by 6%-15% porosities and <10 mD permeability. Meanwhile, RRT4 is considered to have low porosity and low permeability. Various rock types showed in the H unit due to heterogeneity, which composed this unit. The K unit unveiled RRT4 due to shale Facies. The rocks types common of unit L are RRT1 and RRT2 where the L unit mostly ranged from sandstone to shaly sand Facies.
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Patzke, Mollie, J. Wilder Greenman, Galen P. Halverson, and Alessandro Ielpi. "The initiation of the Mesoproterozoic Bylot basins (Nunavut, Arctic Canada) as recorded in the Nyeboe Formation, Fury and Hecla Group." Journal of Sedimentary Research 91, no. 11 (November 12, 2021): 1166–87. http://dx.doi.org/10.2110/jsr.2020.185.
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ABSTRACT Reconstructing Precambrian sedimentary environments over broad cratonic regions often relies on a combination of facies, structural, and provenance analyses. The Mesoproterozoic (ca. 1270–1090 Ma) Fury and Hecla Group, exposed on the Melville Peninsula and northern Baffin Island (Nunavut, Canada), is considered broadly correlative with strata of the Borden, Hunting–Aston, and Thule basins (together referred to as the Bylot basins). We present the results of updated mapping and the first high-resolution sedimentologic and stratigraphic analysis of the lowermost unit in the Fury and Hecla Group, the Nyeboe Formation. The Nyeboe Formation comprises five distinct facies associations: alluvial to fluvial, eolian-backshore, marine-intertidal, marine foreshore to shoreface, and marine-offshore. Thin mafic units are interbedded within the marine shoreface facies and are interpreted to represent volcanic flows. Lateral relationships between facies associations are complex, but generally, facies associations transition from a terrestrial environment at the base to a nearshore marine environment at the top, indicating a transgression. Considering both the along-strike and -dip thickness trends, the presence of mafic volcanic rock units, and possible syndepositional fault orientations crosscutting the deposits, we infer that the Fury and Hecla Group was deposited in a regime of crustal thinning in a half-graben setting. Our results from the Nyeboe Formation suggest a lithostratigraphic correlation to the Nauyat and Adams Sound formations of the Borden Basin. Therefore, this study establishes a geodynamic link between the opening of the Fury and Hecla Basin to the other Bylot basins and contributes to the understanding of a large late Mesoproterozoic intracontinental-basin system.
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Alhalbaasi, Jassim M., Abdulhameed A. Alhadaithy, and Kamal B. Al-Paruany. "Investigation the Origins of Groundwater Salinity in Baghdad City by Using Environmental Isotopes and Hydrochemical Techniques." Iraqi Geological Journal 55, no. 2C (September 30, 2022): 209–20. http://dx.doi.org/10.46717/igj.55.2c.16ms-2022-08-29.
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The hydrochemical and isotopic techniques have become one of the most popular and successful methods for determining the hydrogeochemical features of groundwater in recent years. A total of 15 samples were collected during wet (March, 2021) and dry (August, 2021) seasons. An approach with major elements (Cl-, Na+, Mg2+, Ca2+, and SO4 2=) and multi-isotope (2H, 18O) are used in this study to solve the geochemical variation of salinity in groundwater in Baghdad. The results of the analysis of groundwater samples in the study area showed that the major cations were Ca2+ and Na+, while the major anion was SO4, Cl, and HCO3. The Ca-SO4 and Ca-Na-Cl-SO4. hydrochemical facies are the dominant hydrochemical facies of groundwater on the Al-Karakh and Al-Russafa sides, respectively. Ca-HCO3 was found to be the dominant hydrochemical facies of the Tigris River. Human activities and geochemical processes may have caused differences in hydrochemical Facies. According to isotope analysis, the study area has multiple sources of salinity. This can be attributed to the effects of natural dissolution of the salt compounds, mixing with sewage, and industrial water sink. The results and data from this work can be used to research groundwater recharge and interaction, as well as to protect groundwater quality.
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Galli, Gianni. "Facies analysis of a Devonian carbonate shoreline system (northern Italy)." Sedimentary Geology 46, no. 1-2 (January 1986): 91–110. http://dx.doi.org/10.1016/0037-0738(86)90008-4.
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Humphrey, Elliot, Enrique Gomez-Rivas, Joyce Neilson, Juan Diego Martín-Martín, David Healy, Shuqing Yao, and Paul D. Bons. "Quantitative analysis of stylolite networks in different platform carbonate facies." Marine and Petroleum Geology 114 (April 2020): 104203. http://dx.doi.org/10.1016/j.marpetgeo.2019.104203.
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Wójcik, Ewa, Magdalena Zielińska, Ryszard Chybiorz, and Jerzy Żaba. "Depositional architecture of marginal multiple-source ramp of the Magura Basin (Eocene Flysch formation, Outer Western Carpathians)." Geologica Carpathica 69, no. 4 (August 1, 2018): 347–64. http://dx.doi.org/10.1515/geoca-2018-0021.
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Abstract The Zembrzyce Beds were studied to interpret the environments and facies in the western part of the Siary Subunit. New sedimentological data were obtained for the reconstruction of the depositional architecture of the Zembrzyce Beds. Based on detailed facies analysis, 9 facies and 4 facies associations were recognized. The facies associations represent different architectural elements of a submarine fan, such as: termination of distributary channel with transition to depositional lobe (distal part of mid-fan/outer fan sub-deposystem), lobes and distal lobes (outer fan sub-deposystem). According to the classification of Reading & Richards (1994) the fan deposystem can be classified as mud/sand-rich ramp. This system consists of several elongated lobes that formed synchronously, migrated laterally, and then retreated or decayed. The depositional system was supplied from the north and north-east. The inner-fan sub-deposystem was not detected. The sediments were deposited by high- and low-density turbidity currents and hyper-concentrated density flows sensu Mulder & Alexander (2001) with participation of the depositional background processes (pelagic settling). The sedimentary conditions of the Zembrzyce Beds during the Late Eocene were controlled by tectonic movements, the progress of the subduction and the global sea level changes.
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Chisholm, J. I. "The Upper Band-Better Bed sequence (Lower Coal Measures, Westphalian A) in the central and south Pennine area of England." Geological Magazine 127, no. 1 (January 1990): 55–74. http://dx.doi.org/10.1017/s0016756800014163.
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AbstractAn analysis of outcrop and borehole information relating to the strata between the Upper Band and Better Bed coals of the central and south Pennines shows that two lithological facies can be recognized within a cyclic sequence of mudstones, siltstones and sandstones. In one facies, sandstones and siltstones contain abundant mica, and argillaceous beds are neutral grey in colour. Petrographically the sandstones are feldspathic but contain little lithic material other than multigrain quartz. In the other facies, mica is much less common, argillaceous beds are greenish grey, and sandstones and siltstones contain a notable proportion of chloritic lithoclasts. The sediments of both facies were deposited in lower delta plain/shallow-water delta environments, and palaeocurrent measurements show that the micaceous facies was supplied from the north or east while the green facies came in from the west.Three named divisions of the sequence are based on recognition of the two facies types. They correspond roughly with three upward-coarsening transgressive–regressive sedimentary cycles of presumed eustatic origin. In the lowest part of the succession (Shibden division) the main clastic input was of the micaceous type. Sandstones are found only in the north of the basin, where they form a series of superimposed delta-front bodies. Mudstones were deposited elsewhere, in a large body of open water which, although linked to the sea, was generally of lowered salinity. The restriction of the delta-front sandstones to the same geographical area over a long period of time is attributed to differential subsidence of the basin across deep-seated structures.The sediments of the overlying Brighouse division belong to the green facies, and the source of the elastics lay to the west. After an initial period of mudstone deposition in an extensive, apparently non-marine, body of open water, fluviodeltaic sand and silt spread across the entire area. There is no obvious control of sandstone distribution by basement structures.The succeeding Bradley Wood division includes sediments of both micaceous and green facies. A lobe of medium-grained micaceous sandstone around Sheffield (Thurlstone Channel) represents a fluvial incursion from the east and a linear body of fine-grained green-facies sandstone south of Chesterfield (Bole Hill Channel) represents a similar incursion from the west. Elsewhere, small units of finer-grained elastics are probably deltaic deposits linked to the same sources. The location of the channel sand-bodies suggests control by deep-seated fractures.
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Hess, Aaron M., and Christopher R. Fielding. "Analysis of coastal-plain fluvial architecture and high-frequency stacking patterns in the Upper Cretaceous Masuk Formation, Utah, U.S.A.: Climate-driven cyclicity?" Journal of Sedimentary Research 90, no. 10 (October 1, 2020): 1265–85. http://dx.doi.org/10.2110/jsr.2020.63.
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ABSTRACT Most sequence stratigraphic models are based on the premise that relative changes in sea level (RSL) control stacking patterns in continental-margin settings. An alternative hypothesis, however, is that upstream factors, notably variations in relative water discharge (RQW) or the ratio of water to sediment discharge can influence or control stratal stacking patterns in fluvial systems. Sequence boundaries of RQW-driven systems differ from those driven by base-level fluctuations in that: 1) the depth of incision increases updip, and 2) rates of erosion are spatially uniform, leading to the formation of widespread, planar sequence boundaries. This paper presents an architectural and stratigraphic analysis of the well-exposed Masuk Formation of the Henry Mountains Syncline in southern Utah, an Upper Cretaceous coastal-plain fluvial succession that is interpreted to have been influenced significantly by RQW. Six lithofacies are recognized, three (Facies 1–3) recording floodbasin, mire, and (in one short interval) estuarine environments, and three (Facies 4–6) record different kinds of channel fills on a coastal alluvial plain. Seven major composite channel bodies (Facies 4–6), separated by intervals of non-channel deposits (Facies 1–3), are recognized in the stratigraphic interval. Composite channel bodies display planar, sheet-like geometry and are laterally continuous to a significantly greater extent (> 10 km) than would be expected from purely autogenic channel-belt construction. Together, these intervals record a series of high-frequency sequences, formed along the western margin of the Western Interior Seaway. In each individual sequence is a repetitive facies succession from a basal chaotic sandstone with admixed mudrock and sandstone transitioning upward to a more organized cross-bedded and stratified sandstone. This is interpreted to record cyclical changes from a peaked (flashy) discharge regime to a more normal runoff regime. Paleoflow data indicate a dominance of transverse (eastward-directed) dispersal early in the accumulation of the Masuk Formation, shifting to a pattern of greater axial (northward) dispersal over time. The RQW signal is strong in the lower part of the formation, decreasing upward. This suggests that the relatively short-headed streams draining from the rising Sevier fold–thrust belt were strongly influenced by climatic cyclicity, whereas more distally sourced systems were not. This study provides new insights into the architecture and stacking patterns of coastal-plain fluvial successions, emphasizing the plausible role that climate can play in shaping alluvial architecture in the rock record.
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Xie, Ming, Wei Yang, Mingzhu Zhao, Yingyan Li, Yuan Deng, Yang Gao, Changfu Xu, et al. "Diagenetic Facies Controls on Differential Reservoir-Forming Patterns of Mixed Shale Oil Sequences in the Saline Lacustrine Basin." Minerals 13, no. 2 (January 18, 2023): 143. http://dx.doi.org/10.3390/min13020143.
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The Permian Lucaogou Formation has developed mixed shale reservoirs, but there are few studies on the diagenetic facies, and the control effect of differential diagenesis on the reservoir capacity of shale oil reservoirs in this area is not clear. Therefore, shale samples of the Lucaogou Formation were systematically selected in this study, and through cast thin sections, field emission scanning electron microscopy, XRD mineral analysis, low-temperature nitrogen adsorption and high-pressure mercury injection experiments, the reservoir capacity of the shale oil reservoirs was evaluated from the perspective of diagenetic evolution. The results show that the shale oil reservoir of the Lucaogou Formation in Jimsar Sag is in the middle diagenetic stage A. The diagenetic evolution sequence is compaction—chlorite cementation—silica cementation—first-stage carbonate cementation—first-stage dissolution of authentic albite—illite/smectite mixed layer cementation—second-stage carbonate cementation—second-stage dissolution. The shale reservoirs are divided into five diagenetic facies: tuffaceous–feldspar dissolution facies, mixed cementation dissolution facies, chlorite thin-membrane facies, carbonate cementation facies and mixed cementation compact facies. Among them, the former two diagenetic facies have strong dissolution and weak cementation and are high-quality diagenetic facies, mainly characterized by large pore volume and good pore connectivity, with relatively low D2 values defined as the fractal dimension of mesopores. On the basis of the above research, three different control models of Lucaogou Formation shale oil reservoirs are proposed, including dissolution to increase pores, chlorite cementation to preserve pores, and strong compaction cementation to reduce pores. The quality of reservoirs developed in this model is successively high, medium, and low. This work can provide guidance for the fine characterization and grading evaluation of mixed shale oil reservoirs in saline lake basins and has important theoretical and practical significance for the prediction of shale oil “sweet spot” distribution.
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Gao, Dengliang. "3D seismic volume visualization and interpretation: An integrated workflow with case studies." GEOPHYSICS 74, no. 1 (January 2009): W1—W12. http://dx.doi.org/10.1190/1.3002915.
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One of the major problems in subsurface seismic exploration is the uncertainty (nonuniqueness) in geologic interpretation because of the complexity of subsurface geology and the limited dimension of the data available. Case studies from worldwide exploration projects indicate that an integrated, three-dimensional (3D) seismic volume visualization and interpretation workflow contributes to resolving the problem by mining and exposing critical geologic information from within seismic data volumes. Following 3D seismic data acquisition and processing, the interpretation workflow consists of four integrated phases from data selection and conditioning, to structure and facies characterization, to prospect evaluation and generation, to well-bore planning. In the data selection and conditioning phase, the most favored and frequently used data are the full-angle, limited-angle, and limited-azimuth stack amplitude with significant structure and facies enhancements. Signal-to-noise ratio, color scheme, dynamic range, bit resolution, and visual contrast all affect thevisibility of features of interest. In the structure and facies characterization phase, vertical slicing along arbitrary traverses demonstrates structure styles, stratigraphic architecture, and reservoir geometry in the cross-sectional view. Time/depth slicing defines lateral and vertical variability in the structural trend and areal extent in the map view. Stratal slicing and fault slicing map chronostratigraphic seismic facies and cross-stratal, along-fault seismic signature. Volume flattening and structure restoration aid in unraveling paleostructural framework and stratigraphic architecture and their growth histories. In the prospect evaluation and generation phase, a combination of volume trimming, co-rendering, transparency, attribute analysis, and attribute-body detection is instrumental in delineating volumetric extent and evaluating spatial connectivity of critical seismic features. Finally, in the well-bore planning phase, informed decision-making relies on the integration of all the information and knowledge interrogated from 3D seismic data. Most importantly, interpreters’ geologic insight and play concept are crucial to optimal well-bore planning with high geologic potential and low economic risk.
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Starek, Dušan, Vladimír Šimo, Silvia Antolíková, and Tomáš Fuksi. "Turbidite sedimentology, biostratigraphy and paleoecology: A case study from the Oligocene Zuberec Fm. (Liptov Basin, Central Western Carpathians)." Geologica Carpathica 70, no. 4 (August 1, 2019): 279–97. http://dx.doi.org/10.2478/geoca-2019-0016.
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Abstract Outcrops of a thick turbiditic succession are exposed on the northern bank of the Liptovská Mara reservoir near Liptovská Ondrašová and Ráztoky. The section consists of rhythmic, predominantly thin- to medium-bedded turbidites of the Rupelian age. Their biostratigraphy is based on the calcareous nannofossils. Facies associations of these deposits represent different components of depositional lobe deposits in the turbidity fan system, including mainly the lobe fringe and lobe distal fringe/inter-lobe facies associations and locally the medium bedded deposits of the lobe off-axis facies association. This interpretation is supported by statistical analysis. The deep-sea turbiditic deposits contain trace fossil associations, which include deep-tier fodinichnia and domichnia up to shallow-tier graphoglyptids. Paleocurrent measurements indicate that the majority of sedimentary material was transported from SW and W.
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Hua, Guiyu, Xueqi Yang, Changhai Xu, Shenglan Lei, and Guangfa Zhong. "Log Facies Analysis and Reservoir Properties of Basement Granitic Rocks in the Pearl River Mouth Basin, South China Sea." Petrophysics – The SPWLA Journal of Formation Evaluation and Reservoir Description 63, no. 4 (August 1, 2022): 549–65. http://dx.doi.org/10.30632/pjv63n4-2022a5.
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Basement granitic rocks represent potential hydrocarbon reservoirs; however, our understanding of their reservoir properties remains limited. In the Pearl River Mouth Basin (PRMB) of the northern South China Sea continental margin, granitic rocks account for ~57% of the basement in terms of lithology, which provides an excellent opportunity to investigate the characteristics and distribution of basement granitic reservoirs. Here we report results from a log facies analysis of the basement granitic rocks in the PRMB based on conventional well-logging data of 13 exploration wells. In the analysis, methods of change-point analysis for segmentation and fuzzy c-means clustering for log facies classification were integrated. As a result, five log facies (LF), named LF 1 to 5, were identified. These log facies were interpreted by integrating the analysis of the lithologic significance of different well logs, the analogy with similar cases confirmed in the literature, and the calibration from the limited cutting and sidewall coring data. Reservoir properties of the basement granitic rocks in the PRMB are highly varied, depending on the degree of the development of secondary porosities and fractures. It is suggested that the granitic rocks with developed secondary porosities and fractures, as represented by the low density (DEN), high acoustic transit time (AT), and relatively high neutron porosity (NP) log facies (LF 3), have the best reservoir potential, followed by the high gamma ray (GR), relatively high AT, and low NP (LF 2), and the low NP, moderate DEN, and AT (LF 4) log facies with variable amounts of fractures, respectively. Granitic rocks represented by the remaining LF 1 and 5 are overall tight and of poor reservoir properties. Favorable reservoir log facies, consisting of LF 2 through 4, are heterogeneously distributed. These findings will be beneficial to deepening our understanding of the reservoir properties of basement granitic rocks.
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Cross, Timothy, and Yohan Kusumanegara. "Stratigraphic Controls on Petrophysical Attributes and Fluid-Flow Pathways in an Exhumed Fluvial Reservoir." Mountain Geologist 54, no. 3 (July 2017): 129–45. http://dx.doi.org/10.31582/rmag.mg.54.3.129.
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Fluvial, floodplain and lake strata of the Green River Formation (Eocene) occur within an exhumed oil reservoir exposed in a quarry near Sunnyside, Utah. Strata in the quarry highwalls define three, asymmetrical, 15- to 20-m thick, base-level-rise genetic sequences arranged in a long-term base-level-rise (landward stepping) stacking pattern. Variable intensity of oil stain on rock surfaces is a qualitative measure of pore volumes, as all permeable facies are fully saturated with oil. Visual estimates of oil-stain intensity, combined with petrophysical measurements and petrographic analysis of the different facies, were used to define fluid-flow compartments and their boundaries. Strata and facies that functioned as fluid-flow conduits, retardants and barriers were mapped on photomosaics of the quarry highwall. Three separate fluid-flow compartments coincide with the three genetic sequences. Amalgamated fluvial sandstones at the base of each genetic sequence functioned as flow units of varying permeability and degree of interconnectedness. Laterally continuous floodplain and/or lacustrine mudstones, which cap each genetic sequence, entirely lack oil in matrix porosity and functioned as fluid-flow barriers and compartment boundaries. Petrophysical properties of specific sedimentary facies are sensitive to stratigraphic position at three spatial scales, even though the sedimentary facies appear nearly identical. At the long-term scale, porosity and permeability of the same facies (trough cross-stratified sandstone is the most common) in channel sandstones of the three genetic sequences decrease in stratigraphic succession. Within each genetic sequence, porosity and permeability are highest at the base and decrease quasilinearly to the top. Using oil-stain intensity as a proxy, porosity and permeability generally decrease from base to top of each scour-based channel macroform. Petrophysical variations coincide with subtle variations in grain size and trough cross-stratification set thickness within otherwise indistinguishable sedimentary facies. These results demonstrate that conventional crossplots of porosity/permeability versus sedimentary facies are unnecessarily broad and imprecise. When such petrophysical data are plotted in a stratigraphic context, porosity and permeability values have significantly reduced scatter. Porosity and permeability measurements and predictions of each sedimentary facies should be made from a stratigraphic perspective. From our observations of variations in intensity of oil stain, homogeneity of fluid flow may not be equated directly with facies homogeneity. At one extreme of an apparent continuum, fluid-flow pathways are tortuous and extremely variable within homogeneous, high permeability, amalgamated channel sandstones. Sweep efficiencies may be low in these cases. At an intermediate position in the continuum, increased diversity of sedimentary facies and stratigraphic variability usually cause sufficient stratigraphic separation of permeable and impermeable strata such that fluid-flow pathways are more confined and have a reduced tortuosity. Sweep efficiencies may be high in these cases. At the other extreme of the continuum, where diversity of sedimentary facies and stratigraphic variability is very high, stratigraphic units are discontinuous and restricted in area. In such cases, fluid-flow pathways are not laterally connected, and sweep efficiencies would be low.
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BRÖCKER, MICHAEL, REINER KLEMD, ELLEN KOOIJMAN, JASPER BERNDT, and ALEXANDER LARIONOV. "Zircon geochronology and trace element characteristics of eclogites and granulites from the Orlica-Śnieżnik complex, Bohemian Massif." Geological Magazine 147, no. 3 (November 6, 2009): 339–62. http://dx.doi.org/10.1017/s0016756809990665.
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AbstractU–Pb zircon geochronology and trace element analysis was applied to eclogites and (ultra)high-pressure granulites that occur as volumetrically subordinate rock bodies within orthogneisses of the Orlica-Śnieżnik complex, Bohemian Massif. Under favourable circumstances such data may help to unravel protolith ages and yet-undetermined aspects of the metamorphic evolution, for example, the time span over which eclogite-facies conditions were attained. By means of ion-probe and laser ablation techniques, a comprehensive database was compiled for samples collected from prominent eclogite and granulite occurrences. The 206Pb/238U dates for zircons of all samples show a large variability, and no single age can be calculated. The protolith ages remain unresolved due to the lack of coherent age groups at the upper end of the zircon age spectra. The spread in apparent ages is interpreted to be mainly caused by variable and possibly multi-stage Pb-loss. Further complexities are added by metamorphic zircon growth and re-equilibration processes, the unknown relevance of inherited components and possible mixing of different aged domains during analysis. A reliable interpretation of igneous crystallization ages is not yet possible. Previous studies and the new data document the importance of a Carboniferous metamorphic event at c. 340 Ma. The geological significance of this age group is controversial. Such ages have previously either been related to peak (U)HP conditions, the waning stages of eclogite-facies metamorphism or the amphibolite-facies overprint. This study provides new arguments for this discussion because, in both rock types, metamorphic zircon is characterized by very low total REE abundances, flat HREE patterns and the absence of an Eu anomaly. These features strongly suggest contemporaneous crystallization of zircon and garnet and strengthen interpretations proposing that the Carboniferous ages document late-stage eclogite-facies metamorphism, and not amphibolite-facies overprinting.
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Hong, Zhong, Kunhong Li, Mingjun Su, and Guangmin Hu. "Improved spectral clustering approach — A new tool for unsupervised seismic facies analysis of variable window length." Interpretation 9, no. 2 (April 7, 2021): T407—T420. http://dx.doi.org/10.1190/int-2020-0059.1.
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The traditional constant time window-based waveform classification method is a robust tool for seismic facies analysis. However, when the interval thickness is seismically variable, the fixed time window is not able to contain the complete geologic information of interest. Therefore, the constant time window-based waveform classification method is inapplicable to conduct seismic facies analysis. To expand the application scope of seismic waveform classification in the strata with varying thickness, we have proposed a novel scheme for unsupervised seismic facies analysis of variable window length. The input of the top and bottom horizons can guarantee the comprehensive geologic information of the target interval. Throughout the whole workflow, we use the dynamic time warping (DTW) distance to measure the similarities between seismic waveforms of different lengths. First, we improve the traditional spectral clustering algorithm by replacing the Euclidean distance with the DTW distance. Therefore, it can be applicable in the interval of variable thickness. Second, to solve the problem of large computation when applying the improved spectral clustering approach, we adopt the method of seismic data thinning based on the technology of the superpixel. We combine these two algorithms and perform the integrated workflow of improved spectral clustering. The experiments on synthetic data show that the proposed workflow outperforms the traditional fixed time window-based clustering algorithm in recognizing the boundaries of different lithologies and lithologic associations with varying thickness. The practical application shows great promise for reservoir characterization of interval with varying thickness. The plane map of waveform classification provides convincing reference to delineate reservoir distribution of the data set.
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McMahon, William J., Alexander G. Liu, Benjamin H. Tindal, and Maarten G. Kleinhans. "Ediacaran life close to land: Coastal and shoreface habitats of the Ediacaran macrobiota, the Central Flinders Ranges, South Australia." Journal of Sedimentary Research 90, no. 11 (November 30, 2020): 1463–99. http://dx.doi.org/10.2110/jsr.2020.029.
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ABSTRACT The Rawnsley Quartzite of South Australia hosts some of the world's most diverse Ediacaran macrofossil assemblages, with many of the constituent taxa interpreted as early representatives of metazoan clades. Globally, a link has been recognized between the taxonomic composition of individual Ediacaran bedding-plane assemblages and specific sedimentary facies. Thorough characterization of fossil-bearing facies is thus of fundamental importance for reconstructing the precise environments and ecosystems in which early animals thrived and radiated, and distinguishing between environmental and evolutionary controls on taxon distribution. This study refines the paleoenvironmental interpretations of the Rawnsley Quartzite (Ediacara Member and upper Rawnsley Quartzite). Our analysis suggests that previously inferred water depths for fossil-bearing facies are overestimations. In the central regions of the outcrop belt, rather than shelf and submarine canyon environments below maximum (storm-weather) wave base, and offshore environments between effective (fair-weather) and maximum wave base, the succession is interpreted to reflect the vertical superposition and lateral juxtaposition of unfossiliferous non-marine environments with fossil-bearing coastal and shoreface settings. Facies comprise: 1, 2) amalgamated channelized and cross-bedded sandstone (major and minor tidally influenced river and estuarine channels, respectively), 3) ripple cross-laminated heterolithic sandstone (intertidal mixed-flat), 4) silty-sandstone (possible lagoon), 5) planar-stratified sandstone (lower shoreface), 6) oscillation-ripple facies (middle shoreface), 7) multi-directed trough- and planar-cross-stratified sandstone (upper shoreface), 8) ripple cross-laminated, planar-stratified rippled sandstone (foreshore), 9) adhered sandstone (backshore), and 10) planar-stratified and cross-stratified sandstone with ripple cross-lamination (distributary channels). Surface trace fossils in the foreshore facies represent the earliest known evidence of mobile organisms in intermittently emergent environments. All facies containing fossils of the Ediacaran macrobiota remain definitively marine. Our revised shoreface and coastal framework creates greater overlap between this classic “White Sea” biotic assemblage and those of younger, relatively depauperate “Nama”-type biotic assemblages located in Namibia. Such overlap lends support to the possibility that the apparent biotic turnover between these assemblages may reflect a genuine evolutionary signal, rather than the environmental exclusion of particular taxa.
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Chen, C., G. Gao, P. Gelderblom, and E. Jimenez. "Integration of Cumulative-Distribution-Function Mapping With Principal-Component Analysis for the History Matching of Channelized Reservoirs." SPE Reservoir Evaluation & Engineering 19, no. 02 (March 9, 2016): 278–93. http://dx.doi.org/10.2118/170636-pa.
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Summary Although principal-component analysis (PCA) has been widely applied to effectively reduce the number of parameters characterizing a reservoir, its disadvantages are well-recognized by researchers. First, PCA may distort the probability-distribution function (PDF) of the original model, especially for non-Gaussian properties such as facies indicator or permeability field of a fluvial reservoir. Second, it smears the boundaries between different facies. Therefore, the models reconstructed by traditional PCA are generally unacceptable. In this paper, a work flow is proposed to integrate cumulative-distribution-function (CDF) mapping with PCA (CDF/PCA) for assisted history matching on a two-facies channelized reservoir. The CDF/PCA is developed to reconstruct reservoir models by use of only a few hundred principal components. It inherits the advantage of PCA to capture the main features or trends of spatial correlations among properties, and more importantly, it can properly correct the smoothing effect of PCA. Integer variables such as facies indicators are regenerated by truncating their corresponding PCA results with thresholds that honor the fraction of each facies at first, and then real variables such as permeability and porosity are regenerated by mapping their corresponding PCA results to new values according to the CDF curves of different properties in different facies. Therefore, the models reconstructed by CDF/PCA preserve both geological (facies fraction) and geostatistical (non-Gaussian distribution with multipeaks) characteristics of their original or prior models. The CDF/PCA method is first applied to a real-field case with three facies to quantify the quality of the models reconstructed. Compared with the traditional PCA results, the integration of CDF-based mapping with PCA can significantly improve the quality of the reconstructed reservoir models. Results for the real-field case also reveal some limitations of the proposed CDF/PCA, especially when it is applied to reservoirs with three or more facies. Then, the CDF/PCA together with an effectively parallelized derivative-free optimization method is applied to history matching of a synthetic case with two facies. The geological facies, reservoir properties, and uncertainty characteristics of production forecasts of models reconstructed with CDF/PCA are well-consistent with those of the original models. Our results also demonstrate that the CDF/PCA is applicable for conditioning to both hard data and production data with minimal compromise of geological realism.
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Chesnel, Valentin, and Erick Rodríguez. "Facies analysis of a Bartonian–Aquitanian siliciclastic‑carbonate system, Costa Rica." Sedimentary Geology 417 (May 2021): 105884. http://dx.doi.org/10.1016/j.sedgeo.2021.105884.
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Rodríguez-Tovar, Francisco Javier, Francisco Javier Hernández-Molina, Heiko Hüneke, Estefanía Llave, and Dorrik Stow. "Contourite facies model: Improving contourite characterization based on the ichnological analysis." Sedimentary Geology 384 (April 2019): 60–69. http://dx.doi.org/10.1016/j.sedgeo.2019.03.010.
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