Norwegian Geotechnical Institute (NGI) Digital Archive
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1356 research outputs found
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Reinforcement learning based process optimization and strategy development in conventional tunneling
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Reactive transport modelling of an intra-basalt sandstone reservoir, Rosebank, UK
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The role of mechanical stratigraphy on CO<inf>2</inf> migration along faults – examples from Entrada Sandstone, Humbug Flats, Utah, USA
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The reuse of excavated soils from construction and demolition projects: Limitations and possibilities
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Multiscale characterisation of chimneys/pipes: Fluid escape structures within sedimentary basins
Get PDFEvaluation of seismic reflection data has identified the presence of fluid escape structures cross-cutting overburden stratigraphy within sedimentary basins globally. Seismically-imaged chimneys/pipes are considered to be possible pathways for fluid flow, which may hydraulically connect deeper strata to the seabed. The properties of fluid migration pathways through the overburden must be constrained to enable secure, long-term subsurface carbon dioxide (CO2) storage. We have investigated a site of natural active fluid escape in the North Sea, the Scanner pockmark complex, to determine the physical characteristics of focused fluid conduits, and how they control fluid flow. Here we show that a multi-scale, multi-disciplinary experimental approach is required for complete characterisation of fluid escape structures. Geophysical techniques are necessary to resolve fracture geometry and subsurface structure (e.g., multi-frequency seismics) and physical parameters of sediments (e.g., controlled source electromagnetics) across a wide range of length scales (m to km). At smaller (mm to cm) scales, sediment cores were sampled directly and their physical and chemical properties assessed using laboratory-based methods. Numerical modelling approaches bridge the resolution gap, though their validity is dependent on calibration and constraint from field and laboratory experimental data. Further, time-lapse seismic and acoustic methods capable of resolving temporal changes are key for determining fluid flux. Future optimisation of experiment resource use may be facilitated by the installation of permanent seabed infrastructure, and replacement of manual data processing with automated workflows. This study can be used to inform measurement, monitoring and verification workflows that will assist policymaking, regulation, and best practice for CO2 subsurface storage operations.publishedVersio
Updated remediation action plan for contaminated sediments outside Elkem Carbon, Kristiansand.
No full textDenne rapporten er en oppdatering av NIVA-rapport 7276-2018 «Tiltaksplan for forurenset sjøbunn utenfor Elkem Carbon, Kristiansand» (Olsen og medarb. 2018). Basert på nye analyser og modellering er det presentert utforming av erosjonsbeskyttelse som del av tildekkingslag og angitt nødvendig tykkelse av dette laget i ulike soner i Elkembukta for hindre spredning som følge av skipsoppvirvling i Elkembukta. Tildekkingslaget og det erosjonsbeskyttende laget må prosjekteres i tråd med gjeldende regelverk og standarder. I den sammenheng bør også geotekniske beregninger gjennomføres for å kontrollere stabilitet og bæreevne i området. I Fiskåbukta, hvor risikoen fra PAH er relativt liten og tilstanden for sedimentlevende dyr god, er det i tiltaksplanen anbefalt overvåket naturlig restitusjon for å følge effekten av utslippsreduksjoner på sedimentkonsentrasjoner og økologisk risiko knyttet til PAH. Anbefalingen endres ikke som følge av denne oppdateringen. Elkem Carbon har i de senere årene hatt fokus på kildekontroll for å redusere utslippene. Det har medført at tilførsler til sjø av PAH med prosessvann i dag er i størrelsesorden 5-10 PAH16 pr. år. Elkem Carbon er i prosess for å redusere PAH med overflatevann. Per i dag er estimerte utslipp av overflatevann i størrelsesorden 25 kg PAH16 pr. år. Det arbeides med ytterligere tiltak for å redusere dette. Dette arbeidet er viktig for å minimalisere rekontaminering av et tildekkingslag og det anbefales at dette arbeidet prioriteres.This report is an update to NIVA report 7276-2018 " Tiltaksplan for forurenset sjøbunn utenfor Elkem Carbon, Kristiansand " (Olsen and medarb. 2018). Based on new analyses and modelling, the design of erosion protection has been presented as part of capping layers of the contaminated sediments in Elkembukta. The erosion protection will prevent resuspension from ship maneuvering. The capping layer and the erosion protection layer must be designed in accordance with applicable regulations and standards. In this context, geotechnical calculations should also be carried out to control stability and carrying capacity in the area. In Fiskåbukta, where the risk from PAH is relatively small and the condition of sediment-living animals is good, it is in the remediation action plan recommended monitored natural recovery to monitor the effect of emission reductions on sediment concentrations and ecological risk associated with PAH. The recommendation does not change as a result of this update. In recent years, Elkem Carbon has focused on source control to reduce emissions. This has meant that inflows to sea of PAH with process water today are in the range of 5-10 PAH16 per year. Elkem Carbon is in the process of reducing PAH with surface water. As of today, estimated discharges of surface water are in the range of 25 kg of PAH16 per year. Further measures are being taken to reduce this. This work is important for minimizing the recontamination of the capping layers and it is recommended that this work be given priority.publishedVersio
Improved seismic monitoring with obs deployment in the arctic: A pilot study from offshore western svalbard
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An Analytical Solution for Pressure-Induced Deformation of Anisotropic Multilayered Subsurface
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