1,720,962 research outputs found
The sedimentological characterisation of labyrinthian reservoir analogues
No full textCivil Engineering and Geoscience
Process stratigraphy: from numerical simulation to lithology prediction
No full textProcess-based stratigraphic models provide attractive tools to simulate sedimentary system dynamics spanning a wide range of spatial and temporal scales and segments of the sediment routing system while allowing full access to the model responses, i.e. the spatial distribution of lithologies as a function of the intervening processes and environmental conditions at the time of deposition. Apart from improving our understanding regarding the evolution of sedimentary systems under pre-specified allogenic forcing mechanisms and intrinsic dynamics, process-based stratigraphic models can be used to improve basin-fill history reconstructions and increase the geological credibility of static reservoir models by integrating regional information to local-scale heterogeneities. The realism and predictive power of the model responses and geological model realizations may be quantitatively assessed by comparison with the geophysical/geological data available.Hydraulic Structures and Flood RiskApplied Geolog
Depositional environments and sediment partitioning during early stage foreland basin thrusting: The Late Ilerdian-Early Cuisian Roda Sequence, South Pyrenean Foreland Basin (Spain).
No full textThe Late Ilerdian-Early Cuisian Roda Sequence spans approximately 3 Ma and formed in the South Pyrenean Foreland Basin (Spain). It is mapped in detail across the present-day Tremp-Graus, Ager and Ainsa sub-basins, and across the Boltaña Anticline into the Jaca sub-basin. The South Pyrenean Foreland Basin basin formed during the early stage of oblique collision of the Iberian Plate with the Eurasian Plate, and was bounded to the north by the Pyrenean chain and to the south by the Sierras Marginales. Within the basin, a time-sequenced series of curved thrusts developed (controlled by the location of inverted Mesozoic extensional faults) of which the Montsec thrust was decisive for the development of the Roda Sequence. This thrust sheet was displaced in a mostly southward direction and has an E-W orientation; it carried the Ilerdian-Cuisian sediments of the present-day Tremp-Graus and Ainsa sub-basins. It is well-expressed at the surface as well as partly buried by younger sediments. The Montsec thrust sheet is bounded east and west by the corresponding lateral ramps oriented SW-NW (Segre line), and SE-NW (La Fueba thrust system). Beyond the SE-NW oriented lateral ramp, the present-day Ainsa and Jaca sub-basins are located. The thrust had a significant influence on sediment dispersal patterns and the nature and location of depositional environments during the development of the Roda Sequence.Applied Geolog
Alluvial Stratigraphic Response to Astronomical Climate Change: Numerical modelling and outcrop study in the Bighorn Basin, Wyoming, USA
No full textAlluvial stratigraphy is influenced by both allogenic and autogenic factors, which are difficult to be distinguished from each other because they operate at overlapping spatial and temporal scales. Moreover, it remains uncertain whether autogenic dynamics can result in sedimentary cyclicity that resembles allogenically-driven stratigraphic products. In order to undertake this challenge and address the uncertainty, we first test what sedimentary processes can produce the alluvial cyclicity observed in outcrops by designing comparable scenarios in the process-based numerical modelling. In the meantime, we systematically characterize floodplain aggradation cycles by tracing them in a UAV-based photogrammetric model. Moreover, we comprehensively describe channelized sandstone bodies in the field and the model to reconstruct the paleogeography. Lastly, we configure the relationships between floodplain aggradation cycles and sandstone bodies of different river styles, based on which we identify the link between orbital forcing and alluvial stratigraphic response.Applied Geolog
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Reservoir Heterogeneity Effect on CO2 Storage: Investigate the effect of carbonate-cemented layers in the Roda Sandstone on the migration of the CO2 plume at a short-term timescale using RRM and DARTS
No full textThe storage of carbon dioxide is now regarded as a critical industrial application aimed at mitigating its accumulation in the atmosphere. Reservoirs and aquifers have been identified as viable alternative locations. This report seeks to examine the impact of sedimentological heterogeneity on the development and migration of CO2 plumes over time. The study uses the Roda Sandstone Formation as a case study, primarily due to the presence of carbonate-cemented layers within the Gilbert-delta lobes, which contribute to reservoir heterogeneity commonly observed in subsurface formations. The utilization of a sketch-based modeling approach was employed in constructing the geo-models represented by Rapid Reservoir Modeling (RRM) software since the Roda Sandstone is an exposed section in Isabena Valley in Spain. Furthermore, various realizations are constructed using different parameters of the cemented layers to comprehensively comprehend all potential scenarios. The aforementioned observations pertain to variations in the thickness and lateral continuity of the cemented layers. Additionally, dynamic modeling is also performed by injecting CO2 into the reservoir for 50 years. The simulator utilized for dynamic modeling is the Delft Advanced Research Terra Simulator (DARTS). The findings demonstrate that reservoirs with moderate sedimentological heterogeneity are actually better sites to store CO2 due to the capacity and effectiveness of the storage.Geo-Energy Engineerin
Using Machine Learning to Predict Facies Associations from Wireline Logs for the Carboniferous in the Southern North Sea
No full textThe use of wireline facies associations can alleviate core data shortage during facies prediction by providing a more extensive input dataset. Wintershall has assigned wireline facies associations directly on cored and un-cored wells in the Carboniferous of the Sothern North Sea. Conducting facies prediction using these wireline facies associations as an input can help with tapping into the remaining exploration and development potential of the area. However, the accuracy of this input must be evaluated using core data before machine learning algorithms are applied. This was quantified as 71% for 9 cored wells, where the background floodplain and braided channel facies had the highest accuracies of 88% and 81% respectively, and the mouth bars and marine shales facies could not be adequately validated due to their insufficient core sampling. Consequently, when using wireline facies associations for training facies prediction algorithms, this input’s intrinsic uncertainty should be accounted for while examining the outputs, especially for facies that are not sufficiently validated by cores. Applying facies prediction with Support Vector Machine (SVM), Multilayer Perceptron Neural Network (MLP) and Recurrent Neural Network (RNN), showed that RNN can achieve the highest overall accuracy of 80.9%, due to the highest F1 scores for braided channel (0.88), point bars (0.60) and coal (0.53). The class imbalance problem is apparent for this dataset where the majority classes of background floodplain, braided channel, point bar and coal, are more predicted than the minority classes of crevasse splay sands, mouth bars, and marine shale. Applying RNN on the Westphalian A, B and C separately served as a form of imbalance correcting technique that increased the F1 scores of underrepresented facies. Future work can further refine the results by exploring imbalance correcting techniques through under-sampling the background floodplain and over-sampling the crevasse splay, mouth bar and marine shale facies.Applied Earth Science
Koekoekspolder geothermal field development with long-term sustainability (100 years)
No full textRevealing an optimal geothermal development strategy attempt with long-term sustainability (upcoming 100 years) based on a real 3D model derived from seismic data is considered one of the main contributions of this research study. The heat extraction and thermal recharge of the reservoir must be in balance to extend the productive lifetime of the Koekoekspolder field system. Based on the best results obtained among different unconventional thermal development approaches, the best locations for the new production wells or extra geothermal doublets as well as the timing, injection temperatures, and rate at which the doublets operate are determined. The best strategy to develop the Koekoekspolder field can be achieved by several steps such as understanding the reservoir properties such as the sedimentary facies, porosity, and permeability distribution by analyzing the literature studies and the static model that simulates the Slochteren formation using Petrel software based on the seismic and log data available followed by a dynamic model that mimics the flow of the hot aquifer inside the reservoir using Eclipse 300 software. Both static and dynamic models must be calibrated by the accessible production data to decrease inaccuracy. The thermal boundaries that are taken into consideration for the koekoekspolder field are not mere confining layers. The workflow of this research study ensures a high degree of realism in terms of the input data and output information of the thermal model of the Koekoekspolder field. The best locations for the new production wells or extra geothermal doublets are determined based on the best simulation results obtained from this research study which fulfill the future energy demand increment. The procedures used in this research study give clear guidance on how the Koekoekspolder field or any other geothermal field can be sustainably developed using a robust history-matched model that has reliable predictions. The low-enthalpy deep geothermal system of the koekoekspolder field is optimized and developed using different types and scenarios of operational strategies for doublets which allow adequate periods for operational thermal recharge. This study takes into consideration different thermal parameters that are not common to achieve enhanced predictions. Moreover, it illustrates the importance and benefits of considering reservoir boundary conditions. Finding suitable sustainable geothermal field development for the Koekoekspolder field can be achieved by new well-studied techniques that can ensure adequate thermal recharge periods. The results of this research study show that the energy demand can be fulfilled with low investment costs to increase the profit of the field owner. Long-term (around 1 century) sustainable development of geothermal fields such as Koekoekspolder and the new technology in this research study can partially contribute to achieving the geothermal master plan objectives in the Netherlands as well as enhancing low and high-enthalpy geothermal field development worldwide.Koekoekspolder geothermal field development with long-term sustainabilityGeo-Energy Engineerin
Macrofauna associations and formation of shell concentrations in the Early Eocene Roda Formation (southern Pyrenees, Spain)
No full textThe invertebrate macrofauna (mainly molluscs) of the Early Eocene Roda Formation (southern Pyrenees, Spain) is reported and classified in seven biofacies associations, representing ecologically related groups of macro-invertebrates of shallow marine fan-delta environments ranging in depth from intertidal mudflat to shallow carbonate shelf settings (maximum water depth c. 60 m). The most common association is indicative of mixed siliciclastic-carbonate substrates with the characteristics of an abandonment surface in shallow subtidal settings above wave base. The second most frequent biofacies association is found in subtidal normal marine outer-bay carbonate environments with a relatively low sedimentation rate. However, the most prominent associations, although seldomly occurring, are a (par)autochtonous polytypic coral-mollusc hardground association on top of the last major fandelta sandstone body, an autochtonous monotypic oyster association adapted to soft muddy bottoms representing a time span of c. 500 years, and a parautochtonous (probably) brackish water, intertidal mudflat association dominated by Potamididae. The occurrence of the associations is related to the autocyclic shifting of depocentres, waterdepth, and the palaeotopography of the seafloor as evident from lateral transitions between biofacies associations. This facilitated the formation of calcareous horizons of restricted spatial extent. These are explained as a response to local starvation of clastic sediment supply rather than being a manifestation of relative sea-level changes
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