Norwegian Geotechnical Institute (NGI) Digital Archive
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Early-stage assessment of structural damage caused by braced excavations: Uncertainty quantification and a probabilistic analysis approach
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Application of a fuzzy verification framework for the evaluation of a regional-scale landslide early warning system during the January 2020 Gloria storm in Catalonia (NE Spain)
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The new museum of the Viking Age – Assessment of vibration from groundworks to avoid damage to artefacts
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Deliverable 4.1 Report on initial assessments of rock-failure risks for case studies
Get PDFThis report provides an initial assessment of the state of stress and the estimated conditions for rock failure at the study sites being considered in the ACT SHARP Project. The multinational SHARP consortium has the overall objective to improve understanding on:
“Stress history and reservoir pressure for improved quantification of CO2 storage containment risks”
SHARP Storage is a research project funded under the ERA-NET ACT programme for accelerating Carbon Capture and Storage (CCS). The overall aim is to improve the accuracy of subsurface CO2 storage containment risk management through the improvement and integration of subsurface stress models, rock mechanical failure and seismicity observations.
In this report we present a preliminary assessment of the state of stress at several case study sites and make initial estimates for tensile and shear failure of reservoirs and caprocks. The intention is to provide an early assessment using currently available data to support research in the SHARP project, and with a view to improving these assessments in future. We refer to this initial work as a ‘round 1’ rock failure assessment. After we have developed novel ways to assess the many aspects of stress and strain in rock systems, we expect to develop updated and improved ‘round 2’ rock failure assessments.
The case studies considered in the ‘Round 1’ rock-failure risks assessment are as follows:
• Norway – Horda/Smeaheia region (mainly released datasets);
• UK Southern North Sea – Bunter storage play (mainly published data, White Rose dataset);
• Netherlands – Aramis site, Rotliegend pre-salt (relatively mature dataset);
• Denmark – Lisa Structure (few wells, more of a ‘greenfield’ site);
• India Rajasthan – Bhagewala Heavy Oil Field (mature field with no CCS assessment).
Before reporting the case study assessments, we present an overview of the scientific and technical challenges involved in making rock failure assessments, which can also act as a general guide for future CO2 storage studies and site assessments.
The portfolio of case studies described in the report includes a range of potential storage sites with a wide variation in the degree of storage development maturity. While detailed site characterisation and rock failure studies have been conducted for the Horda/Smeaheia region and parts of the UK Southern North Sea (SNS) Bunter storage play, rock failure characterisation studies at the Aramis site and Lisa Structure are limited to regional studies. The Bhagewala Heavy Oil Field in India is the least mature of the case studies considered in the SHARP project. While the field operator has developed extensive understanding of the field throughout its productive history, detailed studies of its CO2 storage potential are not available in the public domain. As a result, no pre-existing evaluations of the in situ stress state, seismicity, rock mechanical properties or rock failure risk are currently available to the SHARP consortium. Where detailed studies are not available, publicly available sources have been used to develop an initial understanding of in situ stress and regional seismicity.
One aim of the SHARP project will be to further develop on the initial understanding of rock failure risks outlined in this report.European CommissionpublishedVersio
Recreational Fishing Impacts in an Offshore and Deep-Water Marine Park: Examining Patterns in Fished Species Using Hybrid Frequentist Model Selection and Bayesian Inference
Get PDFNo-take marine reserves are often located in remote locations far away from human activity, limiting perceived impact on extractive users but also reducing their use for investigating impacts of fishing. This study aimed to establish a benchmark in the distribution of fished species across the Ningaloo Marine Park – Commonwealth (NMP-Commonwealth), and adjacent comparable habitats within the Ningaloo Marine Park - State (NMP-State), in Western Australia to test if there was evidence of an effect of recreational fishing, as no commercial fishing is allowed within either marine park. We also examined whether the remote location of the newly established (2018) No-take Zone (NTZ), in NMP-Commonwealth, limits its use for studying the effects of fishing. Throughout the NMP-Commonwealth and NMP-State, where recreational fishing is permitted, we expected the abundance of recreationally fished fish species to increase with increasing distance to the nearest boat ramp, as a proxy of recreational fishing effort. Conversely, we did not expect the abundance of non-fished species and overall species richness to vary in response to the proxy for human activity. Distance to the nearest boat ramp was found to be a strong predictor of fished species abundance, indicating that the effect of recreational fishing can be detected across the NMP-Commonwealth. The effect of the NTZ on fished species abundance was weakly positive, but this difference across the NTZ is expected to increase over time. Habitat composition predictors were only found to influence species richness and non-fished species abundance. This study suggests a clear footprint of recreational fishing across the NMP-Commonwealth and as a result the new NTZ, despite its remote location, can act as a control in future studies of recreational fishing effects.publishedVersio
Shaking and splashing—A case study of far-field effects of the Mjølnir asteroid impact on depositional environments in the Barents Sea
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Utfordringer med svarte leirskifere; mellomlagring og naturlige blandmasser
Get PDFDet er planlagt flere store byggeprosjekt i Oslo-regionen de neste årene. Dette vil resultere i utgraving av potensielt syredannende svart leirskifer i volumer som er større enn kapasiteten til godkjente deponier. NGI har et internt forskningsprosjekt «Under Oslo» som fokuserer på innovasjon, bærekraft og økonomi knyttet til underjordiske byggearbeider. Delprosjekt 1 omhandler svarte leirskifere. Svarte leirskifre er sedimentære bergarter med høyt innhold av sulfider, organisk materiale, tungmetaller og naturlig forekommende radionuklider. Riktig håndtering under prosjektgjennomføring og korrekt varig lagring av utgravde masser er avgjørende for å unngå forvitring og sur avrenning, som kan føre til skader på konstruksjoner og miljø. Mellomlagring kan være nødvendig for logistiske formål og for å gi mulighet for forsvarlig karakterisering av utgravde masser, mens langvarig midlertidig lagring kan gi negative effekter på miljøet. For å få bedre forståelse av tidsforløpet i forvitring og syredanning, er det samlet inn historiske data og startet opp utlekkingseksperimenter i konteinere. Tilgjengelige data fra storskala forsøk så langt indikerer at det går mer enn ett år før forvitring av frisk (uforvitret) skifer gir sur utlekking. Basert på disse dataene anbefales maksimum 6 måneder mellomlagring av uforvitret skifer – fordelt på byggeplass og deponi. Ved sprengning og utgraving kan det å skille svartskifer fra omkringliggende steinmasser være vanskelig, noe som resulterer i store mengder masser med en mindre andel svartskifer. De syredannende egenskapene til slike blandede masser er vanskelig å fastslå, og som følge av dette havner store mengder potensielt trygge masser på deponi. Konteiner- og kolonneforsøk med opptil 20 % innhold av alunskifer har etter 2 år ingen pH senkning, men det kan ikke utelukkes at dette vil komme på et senere tidspunkt. Ledningsevne og metallinnhold i avrenningen øker med økende skiferinnhold og tyder på høyere reaktivitet. Den aller beste håndteringen av svartskifer er å la den ligge uforstyrret i bakken. Kan man planlegge prosjekter slik at man tar ut minst mulig potensielt syredannende berg
