8 research outputs found
Modeling 3D Fracture Network in Carbonate NFR: Contribution from an Analogue Dataset, the Cante Perdrix Quarry, Calvisson, SE France
No full textThe full 3D characterization of fracture networks is a key issue in naturally fractured reservoir modeling. Fracture geometry (e.g., orientation, size, spacing), fracture scale (e.g., bed-confined fractures, fracture corridors), lateral and vertical variations, need to be defined from limited, generally 1D, data. In order to populate a 3D reservoir model, one needs to define, at the field scale, how the fracture network is distributed in between wells and, at the reservoir cell scale, how the fracture properties can be summarized to fully represent the matrix-fracture flow exchange. With well data only, the problem is clearly undersized and we need to define other sources of information, such as relationships between fracturing at well and large-scale drivers, for example, or derive the missing gap from outcrop data, which provide qualitative concepts or quantitative relationships between fracture parameters. The study presented in this article aims at modeling, at the reservoir cell scale, 3D fracture networks from quarry outcrops. An innovative data collection method is used; this allows a full characterization of the fracture network in 2D, which provides the basic inputs required for the construction of DFN models. In turn, the reality of the fracture network can be compared to the simplification that we make while drilling through these networks and ultimately summarizing them as a double porosity reservoir cell, and some basic lessons can be learned.Geoscience & EngineeringCivil Engineering and Geoscience
A Geologically Consistent Permeability Model of Fractured Folded Carbonate Reservoirs: Lessons from Outcropping Analogue
No full textPresently adopted fracture-related permeability models of large folded reservoirs are simplistic and often unrelated to the geological setting and evolution of the considered structure. In order to improve predictions of fluid flow in more complex subsurface fractured reservoirs, we build a 3D fracture network model of an outcropping fold in Tunisia, and populate different structural domains with fracture data, collected from outcrops. Within the studied fold, we find large variations in deformation mechanisms between different formations, with the main mechanisms being Layer Parallel Shortening (LPS), resulting in regional deformation, and the more localized impact of fiber stresses and flexural slip. Within the steep flank of the anticline, we find that in one formation fracturing is mostly controlled by fiber stresses, whereas in the underlying formation flexural slip is the main deformation mechanism. These two formations are separated by a detachment surface. Using stress and strain fields, we aim at reconstructing the conditions at which these fractures have been formed. This can provide a better understanding of the relation between fracture patterns in different structural domains of a fold and the stress evolution that formed these fractures, and the subsequent impact of different fracture patterns on fluid flow in fractured folds.Geoscience & EngineeringCivil Engineering and Geoscience
Quantifying Fracture Heterogeneity in Different Domains of Folded Carbonate Rocks to Improve Fractured Reservoir Analog Fluid Flow Models
No full textFluid flow in carbonate reservoirs is largely controlled by multiscale fracture networks. Significant variations of fracture network porosity and permeability are caused by the 3D heterogeneity of the fracture network characteristics, such as intensity, orientation and size. Characterizing fracture network heterogeneity is therefore essential in order to understand and predict fluid flow in fractured reservoirs, but this cannot be accomplished using only 1D data from wells, which is usually the only type of data available from the subsurface. To extend the 1D data to 3D data we commonly analyze the regional deformation, as different types of fold mechanisms produce different deformation styles and subsequent fracture patterns. 2D outcrop studies of fractures are often used to quantify these multi-scale relations between fracturing and large-scale structures. We build a geometric model, then make a mechanical analysis, followed by populating the fracture domains with outcrop-derived information. We use a novel approach called Digifract, which allows us to collect large amounts of 2D fracture data from outcrops, including fracture size, orientation and spacing measurements. Using this method we accurately quantify the links between multi-scale deformations, from fractures to regional tectonics. We applied the Digifract method in the outermost foothills of the Southern Tunisian Atlas, analysing fractures in different domains of four external folds with simple geometries and deformation histories. The lithology of the outcropping cores of all anticlines consists of the same fractured carbonates. The dimensions of the folds are on the same scale as reservoir analogs and form analogs for reservoirs in the Ghadames/Illizi basin, covering parts of Algeria, Tunisia and Libya. We relate differences in fracture characteristics to different localities (e.g., far or close to fold axes) and different folding stages in order to derive general rules that can be applied to subsurface fold analogs.Geoscience & EngineeringCivil Engineering and Geoscience
Predicting multi-scale deformation and fluid flow patterns in folds using 3D outcrop models and mechanical modelling
No full textNatural fracture patterns in folded carbonates are highly heterogeneous. The present-day fractures are often the result of pre-folding, syn-folding and post-folding related fractures. Furthermore, syn-folding fractures may differ in different domains of the fold. Although there are studies that characterize fracture patterns in outcropping folds, there is still a poor understanding of the relation between large-scale deformation (i.e. folding), and small-scale deformation (i.e. fractures), especially in terms of stresses and process-based predictions of fractures. Our overarching goal is to assess the sensitivity of reservoir-scale flow to different fracture patterns and different fracture properties. Therefore we build multi-scale models of 3D fracture networks in outcropping folds in the foothills of the Tunisian Atlas (central Tunisia). The fracture data is collected from outcrops using efficient methods that collect both fractures and the 3D geometry of the outcrops. We interpret small-scale deformation in terms of stresses and combine this with fold-scale mechanical models to predict the fracture patterns in 3D throughout the fold. The 3D model is used to model fracture fluid flow. This work presents a new approach to outcrop studies, that distinguishes different stages of fracturing and uses stresses to make predictions about fracture patterns in similar structures.Geoscience & EngineeringCivil Engineering and Geoscience
The use of prevalence as a measure of lice burden: a case study of Lepeophtheirus salmonis on Scottish Atlantic salmon, Salmo salar L., farms
No full textThis study investigates the benefits of using prevalence as a summary measure of sea lice infestation on farmed Atlantic salmon, Salmo salar L. Aspects such as sampling effort, the relationship between abundance and prevalence arising from the negative binomial distribution, and how this relationship can be used to indicate the degree of aggregation of lice on a site at a given time point are discussed. As a case study, data were drawn from over 50 commercial Atlantic salmon farms on the west coast of Scotland between 2002 and 2006. Descriptive statistics and formal analysis using a linear modelling technique identified significant variations in sea lice prevalence across year class, region and season. Supporting evidence of a functional relationship between prevalence and abundance of sea lice is provided, which is explained through the negative binomial distribution
The First JWST Spectrum of a GRB Afterglow: No Bright Supernova in Observations of the Brightest GRB of all Time, GRB 221009A
No full textLevan, A. J. et al.--Full list of authors: Levan, A. J.; Lamb, G. P.; Schneider, B.; Hjorth, J.; Zafar, T.; de Ugarte Postigo, A.; Sargent, B.; Mullally, S. E.; Izzo, L.; D'Avanzo, P.; Burns, E.; Fernandez, J. F. Aguei; Barclay, T.; Bernardini, M. G.; Bhirombhakdi, K.; Bremer, M.; Brivio, R.; Campana, S.; Chrimes, A. A.; D'Elia, V.; Valle, M. Della; De Pasquale, M.; Ferro, M.; Fong, W.; Fruchter, A. S.; Fynbo, J. P. U.; Gaspari, N.; Gompertz, B. P.; Hartmann, D. H.; Hedges, C. L.; Heintz, K. E.; Hotokezaka, K.; Jakobsson, P.; Kann, D. A.; Kennea, J. A.; Laskar, T.; Le Floc'h, E.; Malesani, D. B.; Melandri, A.; Metzger, B. D.; Oates, S. R.; Pian, E.; Piranomonte, S.; Pugliese, G.; Racusin, J. L.; Rastinejad, J. C.; Ravasio, M. E.; Rossi, A.; Saccardi, A.; Salvaterra, R.; Sbarufatti, B.; Starling, R. L. C.; Tanvir, N. R.; Thoene, C. C.; van der Horst, A. J.; Vergani, S. D.; Watson, D.; Wiersema, K.; Wijers, R. A. M. J.; Xu, DongWe present James Webb Space Telescope (JWST) and Hubble Space Telescope (HST) observations of the afterglow of GRB 221009A, the brightest gamma-ray burst (GRB) ever observed. This includes the first mid-IR spectra of any GRB, obtained with JWST/Near Infrared Spectrograph (0.6–5.5 micron) and Mid-Infrared Instrument (5–12 micron), 12 days after the burst. Assuming that the intrinsic spectral slope is a single power law, with Fν ∝ ν−β, we obtain β ≈ 0.35, modified by substantial dust extinction with AV = 4.9. This suggests extinction above the notional Galactic value, possibly due to patchy extinction within the Milky Way or dust in the GRB host galaxy. It further implies that the X-ray and optical/IR regimes are not on the same segment of the synchrotron spectrum of the afterglow. If the cooling break lies between the X-ray and optical/IR, then the temporal decay rates would only match a post-jet-break model, with electron index p < 2, and with the jet expanding into a uniform ISM medium. The shape of the JWST spectrum is near-identical in the optical/near-IR to X-SHOOTER spectroscopy obtained at 0.5 days and to later time observations with HST. The lack of spectral evolution suggests that any accompanying supernova (SN) is either substantially fainter or bluer than SN 1998bw, the proto-type GRB-SN. Our HST observations also reveal a disk-like host galaxy, viewed close to edge-on, that further complicates the isolation of any SN component. The host galaxy appears rather typical among long-GRB hosts and suggests that the extreme properties of GRB 221009A are not directly tied to its galaxy-scale environment. © 2023. The Author(s). Published by the American Astronomical Society.A.J.L., D.B.M., and N.R.T. are supported by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement No. 725246). G.P.L. is supported by a Royal Society Dorothy Hodgkin Fellowship (grant Nos. DHF-R1-221175 and DHF-ERE-221005). J.H. and L.I. were supported by a VILLUM FONDEN Investigator grant to JH (project No. 16599). B.D.M. acknowledges support from the National Science Foundation (grant No. AST-2002577). J.P.U.F. acknowledges support from the Carlsberg Foundation. The Cosmic Dawn Center (DAWN) is funded by the Danish National Research Foundation under grant No. 140. D.A.K. acknowledges the support by the State of Hessen within the Research Cluster ELEMENTS (Project ID 500/10.006). R.B., M.G.B., S.C., P.D.A., M.F., A.M., and S.P. acknowledge funding from the Italian Space Agency, contract ASI/INAF No. I/004/11/4. P.D.A. acknowledges support from PRIN-MIUR 2017 (grant 20179ZF5KS). J.F.A.F. acknowledges support from the Spanish Ministerio de Ciencia, Innovación y Universidades through the grant PRE2018-086507.Peer reviewe
Empirical analyses of the length, weight, and condition of adult Atlantic salmon on return to the Scottish coast between 1963 and 2006
No full textSea age, size, and condition of adult Atlantic salmon (Salmo salar) are prime determinants of individual, and hence population, productivity. To elucidate potential mechanisms, 151 000 records of salmon returning to six Scottish coastal sites over 44 years were analysedfor length, weight, and condition, by site, sex, sea age, and river age. After correcting for capture effort biases, all sites showed seasonal increases in length and weight for both 1 sea winter (1SW) and 2SW fish. However, whereas condition increased slightly with season for 2SW, it decreased notably for 1SW. Sites showed common decadal trends in length, weight, and condition. Within years, length and weight residuals from trends were coherent across sites, but residuals from condition trends were not. Rates of seasonal condition change also showed decadal trends, dramatically different between sea ages, but common across sites within sea-age groups. Longer salmon were disproportionately heavy in all seasons. 1SW condition was markedly lower in 2006. Detrended correlations withoceanic environmental variables were generally not significant, and always weak. A published correlation between the condition of 1SW salmon caught at a single site and sea surface temperatures in the Northeast Atlantic could not be substantiated for any of the six fisheries over the wider time-scales examined
Para-infectious brain injury in COVID-19 persists at follow-up despite attenuated cytokine and autoantibody responses
No full textData Availability Statement: The individual-level data from these studies is not publicly available to main confidentiality. Data generated by the ISARIC4C consortium is available for collaborative analysis projects through an independent data and materials access committee at isaric4c.net/sample_access. Data and samples from the COVID-Clinical Neuroscience Study are available through collaborative research by application through the NIHR bioresource at https://bioresource.nihr.ac.uk/using-our-bioresource/apply-for-bioresource-data-access/. Brain injury marker and immune mediator data are present in the paper and in the source data file. Source data are provided with this paper.Supplementary information is available online at: https://www.nature.com/articles/s41467-023-42320-4#Sec20 .Source data are available online at: https://www.nature.com/articles/s41467-023-42320-4#Sec21 .Change history: 04 April 2024. A Correction to this paper has been published: https://doi.org/10.1038/s41467-024-47320-6. The original version of this article omitted three members of the COVID-CNS Consortium. Alex Berry and Obioma Orazulume, who are from the ‘University College London, London, UK’, and Ian Galea, who is from the ‘University of Southampton, Southampton, UK’ were added to the list of COVID-CNS Consortium members. This has been corrected in both the PDF and HTML versions of the article. [The PDF version has been corrected].To understand neurological complications of COVID-19 better both acutely and for recovery, we measured markers of brain injury, inflammatory mediators, and autoantibodies in 203 hospitalised participants; 111 with acute sera (1–11 days post-admission) and 92 convalescent sera (56 with COVID-19-associated neurological diagnoses). Here we show that compared to 60 uninfected controls, tTau, GFAP, NfL, and UCH-L1 are increased with COVID-19 infection at acute timepoints and NfL and GFAP are significantly higher in participants with neurological complications. Inflammatory mediators (IL-6, IL-12p40, HGF, M-CSF, CCL2, and IL-1RA) are associated with both altered consciousness and markers of brain injury. Autoantibodies are more common in COVID-19 than controls and some (including against MYL7, UCH-L1, and GRIN3B) are more frequent with altered consciousness. Additionally, convalescent participants with neurological complications show elevated GFAP and NfL, unrelated to attenuated systemic inflammatory mediators and to autoantibody responses. Overall, neurological complications of COVID-19 are associated with evidence of neuroglial injury in both acute and late disease and these correlate with dysregulated innate and adaptive immune responses acutely.National Institute for Health and Care Research (NIHR) (CO-CIN-01) and jointly by NIHR and UK Research and Innovation (CV220-169, MC_PC_19059). B.D.M. is supported by the UKRI/MRC (MR/V03605X/1), the MRC/UKRI (MR/V007181/1), MRC (MR/T028750/1) and Wellcome (ISSF201902/3). C.D. is supported by MRC (MC_PC_19044). We would like to thank the University of Liverpool GCP laboratory facility team for Luminex assistance and the Liverpool University Biobank team for all their help, especially Dr. Victoria Shaw, Lara Lavelle-Langham, and Sue Holden. We would like to acknowledge the Liverpool Experimental Cancer Medicine Centre for providing infrastructure support for this research (Grant Reference: C18616/A25153). We acknowledge the Liverpool Centre for Cell Imaging (CCI) for provision of imaging equipment (Dragonfly confocal microscope) and excellent technical assistance (BBSRC grant number BB/R01390X/1). Tom Solomon is supported by The Pandemic Institute and the NIHR Health Protection Research Unit (HPRU) in Emerging and Zoonotic Infections at University of Liverpool. D.K.M. and E.N. are supported by the NIHR Cambridge Biomedical Centre and by NIHR funding to the NIHR BioResource (RG94028 and RG85445), and by funding from Brain Research UK 201819-20. We thank NIHR BioResource volunteers for their participation, and gratefully acknowledge NIHR BioResource centres, NHS Trusts and staff for their contribution. We thank the National Institute for Health and Care Research, NHS Blood and Transplant, and Health Data Research UK as part of the Digital Innovation Hub Programme. Support for title page creation and format was provided by AuthorArranger, a tool developed at the National Cancer Institute. The authors would like to acknowledge the eDRIS team (Public Health Scotland) for their support in obtaining approvals, the provisioning and linking of data and facilitating access to the National Safe Haven. The views expressed are those of the author(s) and not necessarily those of the UKRI, NHS, the NIHR or the Department of Health and Social Care
