Search Results (5)

The Transylvanian Basin is an intra-Carpathian sedimentary unit displaying complex tectonic and sedimentary evolution that started in the Late Cretaceous. This study presents a geotechnical characterization of three Paleogene lithostratigraphic units located in the northwestern part of the basin, i.e., Brebi, Mera, and Moigrad. These formations record the transition from marine carbonate facies to brackish and subsequently fluvial environments, controlled by tectonic uplifts, marine regressions, and fluctuations in sediment supply. A total of 583 soil samples were collected through geotechnical boreholes and analyzed in the laboratory according to EN ISO standards, assessing natural moisture content, bulk density, grain size distribution, Atterberg limits, carbonate content, unconfined compressive strength, and shear strength parameters. Characteristic values of these properties were determined based on probabilistic distributions. The analyzed formations exhibit well-differentiated lithological and geotechnical characteristics, primarily governed by the degree of plasticity and the presence of calcium carbonate. The Brebi Formation predominantly consists of medium-plasticity clays with highly to very highly carbonate content, indicating a partially cemented microstructure. The Mera Formation is mainly composed of high-plasticity clays having a variable content of carbonates, with frequent sandy intercalations, resulting in significant variability in mechanical properties. The Moigrad Formation consists of two distinct lithological complexes: a clay-rich complex composed of variably plastic calcareous clays spanning all four plasticity classes and a sandy unit made up of weakly cohesive sediments with a granular structure and locally developed carbonate microcementation. Full article

Fluvio-lacustrine systems are highly dynamic continental environments, often developing in tectonically controlled, endorheic basins where sedimentation reflects the interplay of fluvial processes, lake-level fluctuations, climate, and subsidence. The main aim of this paper is to reconstruct the depositional architecture and paleogeographic evolution of the Ludwikowice Formation (Intra-Sudetic Basin, NE Bohemian Massif), which preserves a high-resolution record of a late Carboniferous (late Gzhelian) fluvio-lacustrine system. The formation developed as a fining-upward megacyclothem documenting the transition from proximal alluvial and fluvial fan deposits to distal, organic-rich lacustrine facies referred to as the Lower Anthracosia Shale (LAS). This study integrates lithological data from 92 archival boreholes with high-resolution sedimentological, geochemical, petrological, palynological, and magnetic susceptibility analyses from two fully cored reference sections (Ścinawka Średnia PIG-1 and Rybnica Leśna PIG-1) and selected exposures. Nine facies associations (FA1–FA9) have been identified within the formation, including fluvial, sandy to muddy floodplain, aeolian, playa lake margin/coastal mudflat, nearshore, delta plain, subaqueous delta front and subaqueous fan, prodelta, and open lake. The succession shows progressive thickening into narrow, NW–SE-trending depocenters associated with possible strike-slip faulting. Geochemical and isotopic data indicate alternating hydrologically open and closed lake conditions, while magnetic susceptibility reflects climatically driven variations in detrital influx and microbial activity. Organic petrography and palynofacies analyses reveal redox-controlled maceral associations. The Ludwikowice Formation constitutes a detailed archive of Late Paleozoic environmental change and provides new insights into sedimentation and organic matter preservation in intramontane endorheic basins. Our results highlight the response of fluvio-lacustrine systems to climatic and tectonic factors and provide a framework for interpreting analogous successions throughout the stratigraphic record. Full article

Natural gas power generation has the advantages of flexible operation, short start–stop times, and fast ramp rates. It has a strong peaking capacity and speed compared to coal power generation, and can greatly reduce emissions of harmful substances such as sulphur dioxide. However, in practice, the accurate identification of borehole fluvial facies in the exploration area is one of the most important conditions affecting the success of gas field exploration. An insufficient number of drilling points in the exploration area and the accurate identification of lithological data features are key to the correct identification of borehole fluvial facies, and understanding how to achieve accurate identification of borehole fluvial facies when there are insufficient training data is the focus and challenge of research within the field of natural gas energy exploration. This paper proposes a borehole fluvial facies identification method applicable to the sparse sample size of drilling points, using the Sulige gas field in the Ordos Basin of China as the research object, with the drilling lithology data in the field as the sample data and the data augmentation and classification of the images through generative adversarial networks. The trained model was then validated on the Hangjinqi gas field with the same geological properties. Finally, this paper compares the recognition accuracy of borehole fluvial facies with that of other deep learning algorithms. It was verified that this research method can be applied to oil and gas exploration areas where the number of wells drilled is small and there are limited data, and that this method achieves accurate identification of borehole fluvial facies in the exploration area, which can help to improve the efficiency of oil and gas resources drilling identification to ensure the healthy development of the power and energy industry. Full article

The hydrocarbon-bearing formation of Miano gas field belongs to the Early Cretaceous and it is bounded by two shale intervals, which are considered as maximum flooding surfaces (MFS). The hydrocarbon-bearing interval includes two reservoir units: a tight gas reservoir and its overlying conventional reservoir. Core samples, borehole logs, and well production performance revealed that the two reservoirs present reversed trends in reservoir quality through the gas field without obvious barriers. The average shale volume of the tight gas reservoir changes from 24.3% to 12.2% and the average permeability changes from 32.65 mD to 0.02 mD from the south to north. However, the average effective porosity of the overlaying conventional reservoir increases from 20% to 26% and the average permeability increases from 10 mD to 300 mD. The reversed trends in the two reservoirs lead to challenges in production forecast and development well proposals in the tight gas reservoir. Therefore, reservoir characterization and a predictive reservoir model are essential for further exploitation of Miano gas field. The geological genesis analysis integrating cores, borehole logs, and three-dimensional (3D) seismic data reveals that the producing interval of the tight gas reservoir is tidal-influenced shore facies deposition with intergranular pore space reduced by mineral cementation during burial diagenesis, while the overlaying conventional reservoir is fluvial-influenced deltaic deposition with abundant, well-connected intergranular macropores, which leads to a better reservoir quality. A reservoir model containing both the tight gas reservoir and the conventional reservoir is constructed considering the reservoir nature understanding, and the accuracy of the model is confirmed by reservoir surveillance activities with the simulation model. The study will be critical to the further reservoir development and hydrocarbon production in Miano gas field. Full article

Urban geomorphology is a theme of increasing interest over the last decades. The present research about the Turin geomorphology (NW Italy) was carried out based on the drilling of 40 boreholes, of which 34 were designed for the construction of a new sewer collector by SMAT-Società Metropolitana Acque Torino, while other 6 were in the Valentino Park. These investigations allow us to evaluate the detailed morphology of the proglacial plain of the Rivoli-Avigliana end-moraine system (RAES) and facies, thickness and petrographic composition of fluvial sandy gravel forming this plain (Turin Unit). The local discovery of a truncated palaeosol suggests that this unit lies on a significant erosional surface shaped on more ancient fluvial sediments. New radiocarbon dating of woody macrorest above the palaeosol proves the Last Glacial Maximum (LGM) age of the Turin Unit. The same investigations suggest the presence of erosional terraces (Molinette T1 and Murazzi T2), shaped by the Po River in the proglacial sediments, and depositional terraces (Vallere T3 and Parco Stura T4), which are essentially formed by sand. Dating of woody macrorest confirms the widespread presence of RAES Late Pleistocene proglacial sediments and the subsequent entrenched Po fluvial terraces due to a significant Holocene fluvial deviation. Full article