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This study examines the factors that controlled the formation of Quaternary calcareous tufa deposits along the valley of the Inglares River (Álava, north Spain), currently fed by a karst-carbonate aquifer. It is based on stratigraphic, chronological (Amino Acid Racemisation, AAR), sedimentological, and δ13C and δ18O analyses, complemented by palaeontology (molluscs, ostracods and charophytes). The examined deposits occur as isolated bodies in the uppermost and downmost stretches of the valley, reaching 45 and 25m in thickness, respectively. AAR dating classified them into two groups: Middle Late Pleistocene (MIS 5e) and Middle and Late Holocene (MIS 1). The former only occurred in the downstream stretch. Up to eleven carbonate facies and minor allochthonous coarse detrital facies have been characterised and arranged into four distinct facies associations. Their features and bedding geometries suggested two main depositional settings: a low- to moderate-slope stepped stretch with small barrage cascades, dammed areas, and abundant palustrine zones (downstream system) and a high-slope stretch with steep stepped cascades and pools (upstream system). These settings respond to bedrock lithology and structural changes throughout the valley, which appear to be the principal factors controlling the tufa depositional architecture. Based on δ13C, an increase in aridity was inferred from the Middle–Late Pleistocene to Holocene. The isotopic differences between the upstream and downstream Holocene tufa might reflect the spatial evolution of δ13C and δ18O in stream water through the approximately 8km long surveyed transect. Erosion due to sudden changes in water discharge may have caused the stratigraphic gap between the two tufa groups.

This paper investigates the genesis of the Productive Series sediments within the uplift zone of Pirallahi Island, focusing on the distribution conditions and lithofacies characteristics of different origins. For this purpose, the lithofacies characteristics and conditions of the Lower Pliocene Productive Series sediments in the Pirallahi Island structure have been analyzed, particularly based on geophysical well logging (GWL) data. Using a significant number of well logging diagrams, the distribution of sand and shale lithologies for the productive horizons were determined, systematically classified, and correlation schemes were established. The research includes a detailed analysis of the sedimentary environments to interpret depositional patterns, integrating GWL data with lithological core analyses where available. The facies analysis on Pirallahi Island has included nearly all the boreholes drilled in the field, with the distribution of facies considered from top to bottom across the study area. In addition, the study includes a quantitative assessment of porosity, permeability and clay content to comprehensively evaluate the reservoir potential. Well log analysis allowed interpretation of the effective porosity of the rocks and their shale content, providing a clearer understanding of reservoir heterogeneity. The main objective of the study reported in this paper is to demonstrate lithofacies variability in both horizontal and vertical directions using cross section and lithofacies modeling techniques. The developed facies model is thus demonstrated on a number of surfaces, providing a predictive framework for identifying favorable reservoir zones. The resulting regularities are discussed, highlighting the implications of facies variability for hydrocarbon exploration and production strategies.

Ensemble smoothers are among the most successful and efficient techniques currently available for history matching. However, because these methods rely on Gaussian assumptions, their performance is severely degraded when the prior geology is described in terms of complex facies distributions. Inspired by the impressive results obtained by deep generative networks in areas such as image and video generation, we started an investigation focused on the use of autoencoders to construct a continuous parameterization for facies models. In our previous publication, we combined a convolutional variational autoencoder (VAE) with the ensemble smoother with multiple data assimilation (ES-MDA) for history matching production data in models generated with multiple-point geostatistics. Despite the good results reported in our previous publication, a major limitation of the designed parameterization is the fact that it does not allow applying distance-based localization during the ensemble smoother update, which limits its application in large-scale problems. The present work is a continuation of this research project focusing on two aspects: firstly, we benchmark nine different formulations, including VAE, generative adversarial network (GAN), Wasserstein GAN (WGAN), WGAN with gradient penalty, WGAN with spectral normalization, variational auto-encoding GAN, principal component analysis (PCA) with cycle GAN, PCA with transfer style network, and VAE with style loss. These formulations are tested in a synthetic history matching problem with channelized facies. Secondly, we propose two strategies to allow the use of distance-based localization with the deep learning parameterizations.

Sedimentary facies modeling is a critical approach for understanding geological phenomena, yet the strong heterogeneity of reservoir systems poses a serious challenge for their refined characterization. In this study, we innovatively propose an interpretable attention-guided generative adversarial network framework with dual-domain learning, which achieves precise sedimentary facies modeling under the constraints of well facies and soft probability data. Specifically, we first effectively extract and preserve prior information of sedimentary facies models from both spatial and frequency domain perspectives. Then, during simulation, to enhance the capability of the network model for finely characterizing complex heterogeneous models, cross-spatial attention mechanisms are designed to effectively capture short-range and long-range dependencies between multi-scale pattern features. Additionally, through systematic feature map visualization analysis, we elucidate the processes of conditional fitting and complex sedimentary facies model reconstruction, intuitively demonstrating the functional mechanisms of each module. Finally, systematic experiments are conducted on multiple datasets to validate the effectiveness of the proposed method. The results demonstrate that the generated sedimentary facies models exhibit high consistency with training datasets in terms of visual realism and statistical indicators. Quantitative comparisons reveal remarkable performance of the method, achieving low Wasserstein distance (0.09), Kernel Inception Distance (0.0017) and Kernel Maximum Mean Discrepancy (0.21). These findings further confirm the high realism of the generated realizations regarding pattern features. This study offers a reliable and practical method for geological reservoir modeling, thereby advancing quantitative, precise geological research with broad application prospects.

The difficulty of correlating continental deposits hinders predicting lacustrine and palustrine carbonate facies variations in time and space. This study aims to understand better the factors governing these facies heterogeneities by measuring carbonate isotopes and conducting facies, petrographic and sequence stratigraphic analyses of the Lutetian–Aquitanian deposits of the Paris Basin, that record the transition from marine to lacustrine environments. Large‐scale correlations enabled the definition of two lacustrine–palustrine carbonate facies models. (1) The coastal lacustrine system (Bartonian to Rupelian), consists of fine‐grained brackish carbonate exhibiting episodic marine inputs during short‐term relative sea‐level maxima and evaporite sedimentation during relative sea‐level minima. Lacustrine sediments differ notably from marine ones with more negative δ13C and δ18O compositions that co‐vary and a biota adapted to low salinity conditions. In the associated palustrine environment, depositional sequences evolve upwards from micritic lacustrine deposits to nodular and then laminar calcretes. Microbial‐coated grains and rhizoliths indicate biological processes during repeated subaerial exposure phases in sub‐tropical to arid climates. (2) The inland lacustrine system (Rupelian and Aquitanian) was disconnected from the marine domain and showed evidence of microbial activity with microbial crusts and oncoidal rudstones. Facies rich in micritic intraclasts composed of palustrine and lacustrine facies indicate the reworking of already lithified sediments along the margins. In the palustrine domain, the calcrete facies are less abundant than breccias formed in‐situ by desiccation, limestones with root traces, or organic‐rich wackestones and marls. This system reflects a more temperate climate with more developed microbial structures and less exposed carbonates than the coastal lacustrine system. The southward migration of the depocentre and the transition from marine environments to (1) coastal and then (2) inland systems are controlled by uplift phases induced by Pyrenean and Alpine orogenesis. Third‐order relative sea‐level variations appear to control only short‐term cycles in coastal systems. In this work focussing on the Cenozoic continental carbonates of the Paris Basin, new information is brought to light on the spatialisation of continental carbonates facies thanks to correlations between coastal and palustrine environments. It presents arguments for distinguishing between marine (lagoon‐type) and continental (lake‐type) deposits based on facies, microfacies, large‐scale correlation, palaeontology and isotope data. By providing two new facies models for lacustrine and palustrine carbonates, this manuscript illustrates the coupled impact of tectonics, climate and episodic connections to the marine domain on facies distribution and type.

Based on drilling, core and seismic data, combined with the regional tectonic sedimentary evolution background, the sedimentary environment of the Triassic carbonate rocks in the Mangeshlak Basin was studied. A sedimentary facies model of this set of carbonate rocks was established. Research has shown that the Mangeshlak Basin underwent a complete large-scale marine transgression–regression sedimentary evolution process during the Triassic. During the early to middle Triassic, seawater gradually invaded the northwest region of the basin from northwest to southeast and gradually regressed in the late Middle Triassic. In the lower part of the Triassic carbonate rocks, the primary components are developed granular limestone or dolomite with oolitic structures, interspersed with a small amount of thin mudstone, which is a good reservoir; the upper part of the Triassic is mainly composed of sedimentary mudstone and mudstone, which can form good sealings. The hill-shaped reflections of the platform edge facies, along with the high-frequency, strong-amplitude, and moderately continuous reflections within the restricted platform interior, are clearly visible on the seismic profile. These features are consistent with the sedimentary environment and lithofacies characteristics revealed by drilling data along the profile. Drilling and seismic data revealed that the sedimentary environment of the early and middle Triassic in the basin is mainly composed of shallow water platform edges and restricted platforms, as well as carbonate rock slopes and open non-marine shelves in deep water areas. A sedimentary facies model of the Triassic carbonate rock segment in the basin was established, comprising restricted platforms, platform edges, carbonate rock slopes, and non-marine shelves. Unlike the modified Wilson marginal carbonate rock platform model, the carbonate rock platform edge in the Mangeshlak Basin does not develop reef facies. Instead, it is mainly composed of oolitic beach (dam) sediments, making it the most favorable sedimentary facies zone for the Triassic reservoir development in the basin.

Abstract The prolific Oligocene-Miocene Asmari Formation is the primary reservoir rock hosting important hydrocarbon resources in Iran and consists of fluvial/deltaic siliciclastic and shallow marine carbonate rocks in the Hendijan Field. Due to the significant facies variability of the formation, the presence and quality of the reservoir pose a significant uncertainty in the characterization of the reservoir. This study compares two facies models, one based on well logs only and the second based on estimated facies volumes as a secondary variable in facies modelling. The petrophysical evaluation with microscopic thin sections and electrofacies analysis were used to classify the facies and determine the reservoir quality. As a result, the Ghar Member was identified as a highly porous interval, while the lower part of the Asmari Formation is characterized by tight facies. A sequential Gaussian simulation (SIS) algorithm was used to build the 3D facies model on the basis of the well logs. Acoustic impedance, shear impedance and density (derived from pre-stack inversion) were used as inputs to an artificial neural network to generate acoustic and density log volumes. Using electrofacies cut-offs, facies volume was constructed and used as a secondary variable to improve the initial facies model. The final facies model was compared with the blind well to check the validity of the prediction and satisfactory results were obtained. Since the values are present in all the cells of the reservoir (the traditional facies model only has values for the well location), the estimated facies volume is an accurate variable in the prediction of the facies model for the Asmari reservoir and for this reason the secondary facies model is more reliable than the primary one.

The morphology, internal architecture, and emplacement mechanisms of the Central Atlantic Magmatic Province (CAMP) lava flows of the Hartford and Deerfield basins (USA) are presented. The Talcott, Holyoke, and Hampden formations within the Hartford basin constitute distinct basaltic units, each exhibiting chemical, mineralogical, and structural differences corresponding to flow fields. Each flow field was the result of several sustained eruptions that produced both inflated pahoehoe flows and subaquatic extrusions: 1–5 eruptions in the Talcott formation and 1–2 in Holyoke and Hampden basalts, where simple flows are dominant. The Deerfield basin displays the Deerfield basalt unit, characterized by pillow lavas and sheet lobes, aligning chemically and mineralogically with the Holyoke basalt unit. Overall, the studied flow fields are composed of thick, simple pahoehoe flows that display the entire range of pahoehoe morphology, including inflated lobes. The three-partite structure of sheet lobes, vertical distribution of vesicles, and segregation structures are typical. The characteristics of the volcanic pile suggest slow emplacement during sustained eruptive episodes and are compatible with a continental basaltic succession facies model. The studied CAMP basalts of the eastern United States are correlated with the well-exposed examples on both sides of the Atlantic Ocean (Canada, Portugal, and Morocco).

Integrating well log and core samples data were applied to interpret paleoenvironment of deposition of Miocene succession for understanding of reservoir facies model from a well Bakhrabad (BK)-10 of Bengal Basin. Miocene succession was subdivided into two depositional sequences/models which contain 9 para sequence sets and 35 para sequences. Detailed examination of well log data, based on considering GR (gamma ray) log shapes, size, lithologic variations permit a subdivision into five electrofacies models, e.g., bell, funnel, cylindrical, egg/bow and linear shape models. The succession consists of alternating shales, shaly sand, silts and sandstones, with minor mudstones. The study revealed eight distinct lithofacies models namely, shale dominated facies, heterolithic sandstone facies, cross bedding facies, parallel laminated shale with alternate sand/silt facies, ripple-lamination facies, bioturbation facies, wavy bedded facies and laminated shale facies. The depositional models for the Miocene sediments encountered in the studied well BK-10 inferred to be that of delta-front setting and fluvio-deltaic to shallow marine environments. Based on lithofacies and electrofacies models associations, Miocene succession interpreted as a coarsening upward deltaic progradation; although more repetitive marine transgression and regression sedimentary processes might have an impact on the architecture of reservoir facies model.

The Permian succession of the Paraná Basin records the progressive disconnection from the Panthalassic Ocean that bathed the southwestern Gondwana Supercontinent from the Ordovician to the early Permian. The development of the Gondwanides Belt in the southwestern part of the continent acted as an orographic barrier, restricting marine connections and trapping marine waters in a megalake. In this study, we present a detailed analysis of the transition from marine to continental environments in the Serra Alta and Corumbataí formations, documenting high‐resolution stratigraphic sequences with significant hydrological and salinity changes. Our data illustrate how sedimentation and accommodation dynamics shaped the evolution of this continental‐scale lake system, which was greatly influenced by meteorological phenomena, including storms and seiches. The megalake experienced transitions between overfilled, brackish to freshwater balanced‐fill and saline underfilled stages, associated with distinct fourth‐order transgressive and regressive stratigraphic sequences. These changes in water balance and salinity fostered the development of a unique, endemic bivalve‐dominated fauna derived from marine ancestors, highlighting the basin's response to changing environmental conditions. Notably, this study identifies tectonic events and climate shifts as primary allogenic forces controlling deposition. Meanwhile, local sediment dynamics and episodic events such as storms and seiches originated key autogenic changes in the resulting stacking patterns. Such meteorological phenomena generated an intriguing heterolithic pattern in the fine‐grained lake deposits, which would otherwise be confused with astronomical tides. Our results provide insights into the understanding of sedimentological processes in large lacustrine systems, with implications for paleoclimatic and paleoenvironmental reconstructions in megalakes from the geological record. During the Late Permian, the rise of the Gondwanides Belt trapped marine waters, giving birth to a vast megalake. This lake shifted between overfilled, balanced‐fill and underfilled stages that are recorded by high‐frequency accommodation changes, while meteorological seiches shaped the sedimentary dynamic and produced heterolithic beds.