Elin Skurtveit

• Betlem, Peter; Rosenqvist, Marija Plahter; Millett, John; Griffiths, Luke; Filina, Irina & Park, Joonsang [Vis alle 9 forfattere av denne artikkelen] (2025). Fluid flow behaviour in vesicular basalt samples from the Skoll High, Vøring Margin. Geomechanics and Geophysics for Geo-Energy and Geo-Resources. ISSN 2363-8419. 12(1). doi: 10.1007/s40948-025-01080-9. Fulltekst i vitenarkiv Vis sammendrag

  Abstract This study presents the fluid flow testing results of 32 lava flow samples recovered from IODP Sites U1571/U1572 (145–315 mbsf) on the Skoll High, Vøring Margin. Few past studies have investigated the mid-Norwegian margin’s basalt reservoir and flow properties. Even fewer implement subsurface-like conditions to explore in-situ fluid flow and the possible response to changing pore fluids during injection. These aspects are critical for large-scale carbon sequestration. In this study, hydraulic properties including porosity and permeability were measured at ambient conditions for all samples along with multi-stress, multi-fluid core flooding experiments on a representative sample enclosed in an X-ray µCT scanner. Petrographic observations reveal varying degrees of alteration with secondary clays, including smectite, commonly lining pores and vesicles. He-porosities (4.2–45.6%) fall mostly below the theoretical percolation threshold of ~ 30% for randomly distributed spherical pores. Klinkenberg-corrected nitrogen-gas permeability (0.0038–361.9 mD) shows weak correlation to porosity and no apparent depth dependence. Further, brine permeability is four orders of magnitude lower than gas permeability, with no notable flow reduction during injection of CO 2 . Rather than being stress-dependent, we argue that brine-induced swelling significantly reduced the accessibility of microstructural elements to fluids. The findings urge caution when using literature-reported, ambient gas measurements for basalts with similar levels of alteration as they may not accurately reflect in-situ fluid flow properties. Low matrix permeability of the moderately to highly altered vesicular basalts and prevalence of swelling clays may, without major contributions from fractures, limit the injectivity potential into the basaltic lava flows on the Skoll High, Vøring Margin.

• Braathen, Alvar & Skurtveit, Elin (2025). Faults in CO2 storage: Anisotropy in flow and irregular displacement gradients informing reactivation. Tectonophysics. ISSN 0040-1951. 918. doi: 10.1016/j.tecto.2025.230999. Fulltekst i vitenarkiv Vis sammendrag

  Current understanding of extensional faults, which are essential for subsurface CO2 storage, reveals that fault risk assessment and modeling are significantly hindered by uncertainty. This underscores the need for insights into the datasets and methodologies used for evaluating fault sealing and reactivation. Data on fault architecture from outcrops, combined with mechanical insights, indicate the presence of hydraulic anisotropy and varying strength relationships within faults that influence their potential for reactivation. We propose that large portions of faults may yield through minor slip events or creep, while sticky spots are responsible for larger fault slip events. Enhancing our detection and understanding of these sticky spots – primarily characterized by abrupt displacement gradients that require further investigation - could improve risk assessment, monitoring, and mitigation strategies related to fault reactivation and inform seismic activity in CO2 storage initiatives.

• Holden, Nora; Skurtveit, Elin; Alaei, Behzad; Midtkandal, Ivar & Braathen, Alvar (2025). Influence of growth fault complexities on fault seal assessments in the Smeaheia CO2 storage site, northern North Sea. Journal of Structural Geology. ISSN 0191-8141. 200. doi: 10.1016/j.jsg.2025.105501. Fulltekst i vitenarkiv Vis sammendrag

  Growth faults exhibit great variability in their structural and sedimentological architecture. While these faults create structural traps that are critical for effective CO2 storage, their complexities are often overlooked in the integrity assessment of storage sites. This study focuses on the Vette Fault Zone in the Smeaheia CO2 storage site, northern North Sea. Here, the intended Upper Jurassic storage complex in the footwall juxtaposes predominately Lower Cretaceous syn-rift strata in the hanging wall. The primary seal in the footwall shows signs of degradation, with increased erosion occurring in the fault zone's eastward concave sections. The hanging wall features transverse folding of pre-rift units, overlain by thick syn-rift strata sourced from the immediate fault scarp and catchments beyond the fault block crest. These structures and deposits are not captured in nearby wells and therefore insufficiently considered when assessing fault rock composition and sealing potential. Incorporating these features, we find that the level of detail used to define the syn-rift layering has the most significant influence, whereas restoring the footwall to its pre-erosional state has only a minor effect. Not considering these structural complexities likely leads to underestimating the Vette Fault Zone's sealing potential. For fault seal assessments in settings with complex growth faults, we stress the importance of a detailed understanding of the structural development, defining confidence in host rock composition, utilizing a scenario-based approach for fault seal assessment, and presenting related uncertainties.

• Griffiths, Luke; Thompson, Nicholas; Smith, Halvard; Skurtveit, Elin & Grande, Lars (2025). Rock mechanical testing of core from the Eos Northern Lights CCS confirmation well and implications for the Geomechanics of North Sea CO2 storage. International Journal of Greenhouse Gas Control. ISSN 1750-5836. 144. doi: 10.1016/j.ijggc.2025.104371. Fulltekst i vitenarkiv Vis sammendrag

  This study presents and analyses the results of rock mechanical testing of sandstone and shale samples from the CO2 storage confirmation well 31/5–7 (Eos) in EL 001 in the North Sea. Although detailed experimental laboratory programs are performed for many hydrocarbon development projects in the North Sea, only a limited number of site-specific experimentally-derived mechanical data are available in the literature. The tested samples included sandstone from the Cook (2680.25–2680.5 m) and Johansen (2761.00–2761.25 m and 2725–2725.25 m) formations, and shale from the Intra-Drake Formation (2592.00–2595.18 m). For each of the sandstones, Brazilian tests, three drained isotropically-consolidated (CID) triaxial tests, one hydrostatic test, and one anisotropically-consolidated uniaxial strain test (CAUST) were performed. For the shale, the testing comprised four permeability tests conducted on both vertical and horizontal plugs, five undrained isotropically-consolidated triaxial tests (CIU; three on vertical plugs and two on horizontal plugs), seven Brazilian tests (on four horizontal and three vertical plugs), and a uniaxial strain test (CAUST). The tests were designed to characterize the mechanical behaviour of the reservoir and cap rocks within stress and strain regimes relevant to CO2 injection scenarios. Measurements of the elastic and poroelastic properties, strength, failure criteria, and permeability are provided, including an assessment of the mechanical and hydraulic anisotropy in the case of the shale samples. The data, accessible through CO2Datashare (Northern Lights JV, 2023), significantly enhance the understanding of North Sea lithologies and supply critical parameters for accurately modeling the geomechanical response of the reservoir and overburden in response to CO2 injection.

• Soldal, Magnus; Choi, Jung Chan & Skurtveit, Elin (2025). Experimental Evaluation of Predicted Undrained Pore Pressure Generation as a Function of Stress Path and Material Orientation in the Draupne Shale. Rock Mechanics and Rock Engineering. ISSN 0723-2632. 58, s. 6043–6058. doi: 10.1007/s00603-025-04452-5. Fulltekst i vitenarkiv Vis sammendrag

  This study experimentally investigates the effects of various stress paths and orientations on induced undrained pore pressure in the Draupne shale and their predictability using experimentally determined pore pressure parameters and elements of anisotropic poroelasticity. A test procedure considering multiple cycles of various stress paths in a triaxial test on a sample of known orientation is suggested to measure the anisotropic pore pressure parameters needed to predict pore pressure generation. Furthermore, a definition of principal stress increments which detaches them from the principal stress directions is used for consistency and to enable easier access to stress paths rarely examined experimentally. The undrained pore pressure from the multi-cycle stress path triaxial tests showed a significant stress-path dependency in which the normalized pore pressure was linearly correlated with the total stress path. The calculated tensorial pore pressure parameters (Bv and Bh) were used to predict undrained pore pressure as a function of sample axis orientation relative to material symmetry. The predicted changes in pore pressure were found to be very similar to those measured in triaxial tests on samples with various orientations. The experimental results from a multi-cycle stress path triaxial test on a sample with a different orientation demonstrated that also the combined effects of variations in stress orientation and stress path could be successfully predicted. These findings confirm that the tensorial pore pressure parameters can be efficiently used to forecast pore pressure changes in samples of various orientations, even when subjected to stress changes along any stress path. The observations herein suggest that measurements from a single triaxial test can be combined with the proposed definition of principal stress increments to predict undrained pore pressure generation in a North Sea shale subjected to complex changes in stress path and orientation. This approach, therefore, contributes significantly to the understanding of induced pore pressure in low-permeable materials and provides valuable input to geomechanical modelling of various field operations.

• Kettlety, Tom; Martuganova, Evgeniia; Kühn, Daniela; Schweitzer, Johannes; Weemstra, Cornelis & Baptie, Brian [Vis alle 11 forfattere av denne artikkelen] (2024). A unified earthquake catalogue for the North Sea to derisk European CCS operations. First Break. ISSN 0263-5046. 42(5), s. 31–36. doi: 10.3997/1365-2397.fb2024036. Fulltekst i vitenarkiv
• Huang, C.; Carlton, Brian David; Kettlety, T; Larsen, T.; Kendall, J.M. & Skurtveit, Elin (2024). Preliminary Earthquake Ground Motion Database for the North Sea, 85th EAGE Annual Conference & Exhibition. European Association of Geoscientists and Engineers (EAGE). ISSN 9789462824980. Fulltekst i vitenarkiv
• Grande, Lars; Griffiths, Luke; Park, Joonsang; Skurtveit, Elin & Thompson, Nicholas (2024). Cooling-induced geomechanical response of North Sea reservoirs, and relevance for CO<inf>2</inf> storage monitoring. International Journal of Greenhouse Gas Control. ISSN 1750-5836. 138. doi: 10.1016/j.ijggc.2024.104228. Fulltekst i vitenarkiv Vis sammendrag

  Many studies on CO2 injection monitoring focus on fault stability risks due to increased pore pressure. However, the temperature of the injected fluid can also significantly impact the near-wellbore region through cooling-induced strain, stress changes, and fracturing, necessitating tailored monitoring strategies. This study evaluates the potential for near-well monitoring by examining the magnitude of strain and associated failure scenarios in reservoir formations down to approximately 2.6 km, where injected CO2 may cause temperature decreases of around 80 °C. The combined effects of pore pressure and cooling on stress path and elastic-inelastic strain are assessed using laboratory triaxial test data and selected well logs. The impact of cooling was simulated directly via uniaxial strain tests or indirectly through multistage tests with Acoustic Emission (AE) monitoring. An analytical approach based on the Mohr-Coulomb failure criterion is employed to evaluate the stress path relative to the failure criteria. Results indicate that shallow, uncemented sands and weakly cemented sandstones predominantly exhibit elastic expansion in response to injection. In contrast, deep, stiff sandstones can experience cooling-induced contraction, inelastic damage, and even fracturing. The findings are further discussed in relation to well-based monitoring techniques, including fibre optics and other methods.

• Silva, Diana; Skurtveit, Elin; Soldal, Magnus & Braathen, Alvar (2024). Frictional strength of siliciclastic sediment mixtures in fault stability assessment. Journal of Structural Geology. ISSN 0191-8141. 187. doi: 10.1016/j.jsg.2024.105232. Fulltekst i vitenarkiv Vis sammendrag

  Frictional strength of fault zones is a key parameter for evaluation of fault stability and reactivation. We measure friction using the direct shear test (DST) for (i) sand-clay mixes mimicking fault gouges, and (ii) strength of fault zone interfaces. The sand-clay mixing ratio is linked to the established Shale Gouge Ratio (SGR) used in fault seal analysis, suggesting an approach for linking the measured frictional properties to the established subsurface fault characterization methods and risk assessment. We use powdered caprock material from the Draupne Formation mixed with sand to prepare the fault gouge and discuss application of results for fault zones on the Horda Platform, Norwegian North Sea. Shearing of fault gouge show a systematic decrease in residual friction coefficient with increasing clay content from 0.6 (φ = 31°) in pure sand (SGR 0%) to 0.4 (φ = 22°) for clay rich mixtures (SGR 100%). Interface testing mimicking fault gouge on sand surface is less systematic and shows residual friction coefficients ranging from 0.53 to 0.6 (φ = 28–31°) for SGR 0–50%. Detailed interpretation of the shear testing results shows changes in drainage properties, volumetric changes during shearing and shear responses to normal stresses indicating threshold values for sand versus clay dominated material behaviour. However, the results are non-conclusive on the question if a linear variation of friction with clay content or a threshold between sand dominated versus clay dominated friction provides the best approach for linking friction to fault clay content.

• Holden, Nora; Alaei, Behzad; Skurtveit, Elin & Braathen, Alvar (2024). Implications of depth conversion on fault geometries and fault-risk assessment in the Smeaheia CO2 storage site, northern North Sea. Geoenergy. 2(1). doi: 10.1144/geoenergy2024-006. Fulltekst i vitenarkiv Vis sammendrag

  Assessments of fault geometries and fault-risk parameters are crucial when evaluating the integrity of a structurally controlled CO2 storage site. To perform these assessments, seismic data, recorded in time, must be converted to depth. The velocity models used for this time to depth conversion influence the final depth image and, consequently, the geometry of the interpreted faults. Against this background, we created four velocity models for depth conversion, assessed the impact on fault throw, dip and thickness of the primary seal, and, subsequently, a fault-risk assessment of the Vette Fault Zone in the Smeaheia CO2 storage site. We found that depth conversion had a larger influence on fault throw and thickness of the primary seal than on fault dip. In contrast, the overall assessment of the presence of a membrane seal and geomechanical integrity showed less sensitivity to the depth conversion process. Consequently, we suggest that a relatively robust fault-risk assessment can be made with a variety of velocity model designs and data input. Nevertheless, we found a mean difference of 2% in the shale gouge ratio, 4% in the slip tendency and 9% in the dilation tendency for the Vette Fault Zone, emphasizing the importance of accounting for the influence of depth conversion in optimizing structural assessments in potential CO2 storage sites.

• Petrie, Elizabeth S.; Skurtveit, Elin; Faleide, Thea Sveva; Halvorsen, Kristine; Smith, Scott Adam & Arvesen, Brock C. (2024). Development of fluid pathways and associated diagenetic variations in a natural CO2 leaking fault zone. Lithosphere. ISSN 1941-8264. 2023(14). doi: 10.2113/2023/lithosphere_2023_335. Fulltekst i vitenarkiv Vis sammendrag

  Permeability within fault zones can vary through time due to repeated deformation events and rock–fluid interactions. Understanding the history of fault zone alteration is critical when building hydrogeologic models and evaluating the risk of mechanical rock failure during subsurface storage. Newly acquired drill core recovered within the fault damage zone and fault core of the Little Grand Wash fault (LGWF) is combined with observations from outcrop, optical petrography, computerized tomography image analysis, and ultrasonic velocity measurements to characterize the rock types and preserved structural deformation features within this fault zone. These data are used to understand the history of mechanical rock failure and mineralization associated with this fluid-charged fault system. We identify multiple structural features and use their cross-cutting relationships to understand the history of deformation and their association with changes in fault zone permeability and rock mechanical properties. At the LGWF zone, structural deformation features vary temporally and are used to recognize a decoupling between fault slip and fluid flow. The formation of most open-mode veins occurred after shear failure within the LGWF zone. Early-developed shear bands are cut by carbonate veins, that are in turn cut by shear fractures, followed by a second phase of vein formation and ultimately by folding in the fault core. This sequence of formation reflects changes in mechanical rock properties due to subsurface rock–fluid interactions and indicates that the alteration of rock matrix by secondary carbonate cement results in increased unconfined compressive strength, decreased permeability, and increased ultrasonic velocity. In this fault zone, and possibly other fault zones, the changes in rock properties associated with deformation can be detected through their geophysical response.

• Grande, Lars; Skurtveit, Elin; Choi, Jung Chan; Mondol, Md Nazmul Haque & Thompson, N. (2024). Consolidation Behaviors of Clays, Mudstones and Shales -CO2 Storage Sites in Horda Platform, Offshore Norway, 58th U.S. Rock Mechanics/Geomechanics Symposium. American Rock Mechanics Association (ARMA). ISSN 9780979497599. doi: 10.56952/ARMA-2024-0457. Fulltekst i vitenarkiv
• Choi, Jung Chan & Skurtveit, Elin (2024). Optimizing Resource Allocation in Fault Stability Assessment: Sobol Sensitivity Analysis for Smeaheia Area, Norway, 85th EAGE Annual Conference & Exhibition. European Association of Geoscientists and Engineers (EAGE). ISSN 9789462824980. doi: 10.3997/2214-4609.2024101379. Fulltekst i vitenarkiv Vis sammendrag

  This study introduces a variance-based Sobol sensitivity analysis for fault stability assessment, with a focus on the Smeaheia area in Norway. It addresses the challenges of determining accurate input ranges for fault stability in early field development due to limited data availability. The analysis aims to understand the relative importance and interaction of various input parameters and how they vary with conditions such as depth. Key findings include significant interaction effects of directional stress and geometry parameters and depth-dependent variation in influential factors, offering insights into complex fault dynamics. This study highlights that the suggested approach can enhance resource prioritization and strategic decision-making in early field development by providing a deeper understanding of fault mechanics through advanced sensitivity analysis.

• Haines, Emma Michie; Braathen, Alvar & Skurtveit, Elin (2024). Can Detailed Displacement Analysis Improve Risking Strategies of Faults Bounding CO2 Storage Sites? 85th EAGE Annual Conference & Exhibition. European Association of Geoscientists and Engineers (EAGE). ISSN 9789462824980. doi: 10.3997/2214-4609.202410387. Fulltekst i vitenarkiv Vis sammendrag

  Developing an accurate understanding of the ways in which faults have grown can aid risk management for CO2 storage sites. Areas of fault interaction increase strain, accommodated by high intensity of deformation bands and/or fracturing, altering the permeability. Hence, detecting areas of breached fault intersections helps identify areas of high risk in terms of hydraulic properties. The Vette Fault Zone (VFZ), bounding the potential CO2 storage site Smeaheia, is interpreted to have grown from at least seven segments. By utilising a comparison with the adjacent Tusse Fault Zone (TFZ), we can identify which segment(s) may be considered high risk. The high seal strength of the TFZ holding back a large gas column is likely created by shale juxtaposition and smearing with cataclastic processes. The same could be assumed for the VFZ, associated with similar tectonics and displaced stratigraphy. Instead, potential areas of high risk are identified at locations of relict breached relays, where the initial displacement of the intersecting faults and area of overlap was high. These areas correspond with the Troll East contact depth. Using the same assumptions for the VFZ, we can observe one potential area of high risk, which lies within the area of suggested CO2 accumulation.

• Choi, Jung Chan; Skurtveit, Elin; Huynh, Khoa D.V. & Grande, Lars (2023). Uncertainty of stress path in fault stability assessment during CO<inf>2</inf> injection: Comparing smeaheia 3D geomechanics model with analytical approaches. International Journal of Greenhouse Gas Control. ISSN 1750-5836. 125. doi: 10.1016/j.ijggc.2023.103881. Fulltekst i vitenarkiv Vis sammendrag

  This study investigates the limitation of simplified stress path assumptions, particularly uniaxial strain conditions, in fault stability assessments for CO2 injection sites. We conducted a 3D geomechanics simulation for the Smeaheia fault block in the Norwegian North Sea and compared the results with simplified stress path assumptions. Our results indicate that the uniaxial strain assumption underestimates the change in effective horizontal stress, particularly for bounding faults subjected to a significant change in pore pressure gradient with soft surroundings. Rotations of maximum horizontal stresses parallel to soft surroundings are also observed along the bounding faults due to the directional difference in stiffness contrast along faults. This underestimation results in overestimation of fault stability by up to 60% for an extreme case. Our study thus highlights that the uniaxial strain assumption, which limits to account for lateral deformation on the fault/reservoir boundary, overlooks critical changes in the effective horizontal stress and associated critical scenarios for fault stability assessments. When bounding faults are juxtaposed with low-stiffness shale formation under a normal stress regime, calibrating the fault stability assessment by 30% for a base case and 60% for a conservative assessment can provide a practical way to correct the uncertainties caused by using uniaxial strain assumption.

• Bjørnarå, Tore Ingvald; Skurtveit, Elin; Haines, Emma Michie & Smith, Scott Adam (2023). Characterizing along-and across-fault fluid-flow properties for assessing flow rates and overburden fluid migration along faults: a case study from the North Sea. Petroleum Geoscience. ISSN 1354-0793. 29(3). doi: 10.1144/petgeo2023-033. Fulltekst i vitenarkiv Vis sammendrag

  Assessing fault zones as fluid-migration pathways requires the characterization of permeability both across and along faults, as well as the adjacent volume. The hydraulic properties of the Vette Fault Zone, North Sea, are described by modelling the mixing of host-rock lithologies into the fault zone, and the fault width is derived from empirical relationships as a function of throw and clay content. To better understand the sensitivity related to the uncertainties in overburden lithologies and fault-width correlations, a parametric study with 1125 model realizations were solved in a 2D steady-state, single-phase, subsurface flow model. The fault zone, included as a discrete permeable structure, significantly alters the flow field compared to a model that only considers lithological juxtaposition. The most prominent hydraulic communication in the Vette Fault Zone is downwards from the storage reservoir where sand is mixed into the fault zone. Increasing the host-rock permeability in the overburden also increases the fault permeability and shifts the inflection point for down-fault flow, causing the pressurized reservoir to drain towards the overburden and the top surface. For CO2 storage application, the models highlighted the potential for downward communication along the fault for brine, and the CO2 capillary sealing towards the overburden.

• Betlem, Peter; Birchall, T; Lord, G; Skurtveit, Elin; Løvlie, Karoline Helen & Oldfield, S. [Vis alle 11 forfattere av denne artikkelen] (2022). Integrated Characterization of the Faulted Caprock Shales of the Longyearbyen CO2 Lab, 83rd EAGE Annual Conference & Exhibition 2022. European Association of Geoscientists and Engineers (EAGE). ISSN 9789073834125. doi: 10.3997/2214-4609.202210905. Fulltekst i vitenarkiv
• Skurtveit, Elin; Roberts, Daniel; Kühn, Daniela; Hindriks, Kees K.; Ringrose, Philip & Larsen, Tine [Vis alle 18 forfattere av denne artikkelen] (2022). Improved quantification of CO2 storage containment risks - an overview of the SHARP Storage project. 16th Greenhouse Gas Control Technologies Conference 2022 (GHGT-16). Fulltekst i vitenarkiv Vis sammendrag

  Carbon Capture and Storage (CCS) is now maturing in Europe and worldwide with several Net Zero projects emerging. Hence, the need for safe and reliable CO2 storage sites is accelerating and the accurate assessment of large-scale storage options at the gigatonne-per-year is critical. The SHARP project addresses the main priority areas required to improve current technologies to deliver CO2 storage volumes at the scale needed to meet demands for large scale storage. Research needs identified in the industry has provided the base for this well-integrated project with the ambitions to reduce the uncertainty in the geomechanical response to CO2 injection. Six case studies from sites in the North Sea and India will be matured during the projects. Ongoing work includes review of existing stress data, updating and integration of seismic catalogues and planning of new experimental data for improved constitutive models and rock failure attributes. Improved data analysis, compiling data from different sources, and new data generated in the project is expected to provide a base for updated failure risk assessment and more targeted monitoring. An initial assessment of rock failure risk in in progress and will be updated with a "Round 2" failure assessment incorporating new learnings and more mature data. The improved failure risk assessment includes the use of Bayesian statistical approach for quantification of uncertainties in geomechanical properties. Methods to quantify geological containment risk will be developed by reading across event tree techniques from other industries (e.g. nuclear). A set of generic release diagrams have been derived in a series of interdisciplinary workshops as a starting point for risk modelling

• Grande, Lars; Mondol, Md Nazmul Haque; Skurtveit, Elin & Thompson, Nicholas (2022). Stress Estimation from Clay Content and Mineralogy-Eos Well in the Aurora CO2 Storage Site, Offshore Norway. 16th Greenhouse Gas Control Technologies Conference 2022 (GHGT-16). doi: 10.2139/ssrn.4286343. Fulltekst i vitenarkiv Vis sammendrag

  Determination of in-situ stress is vital for many engineering applications, including Carbon Capture and Storage (CCS). A reliable estimation of minimum horizontal stress (σh) in a top seal is crucial for quantifying risk related to safe CO2 injection/storage. In this study, an alternative method is used to estimate the ratio between effective horizontal stress to vertical stress (K0, which directly relates to σh) from clay volume as indicated by gamma ray and spectra gamma ray logs. The method is based on correlations from laboratory uniaxial strain tests on natural and synthetic mixtures of clay with known mineralogy. The alternative method is predicting stress from volume clay (Vcl method) assuming uniaxial strain conditions; in addition, corrections accounting for smectite-rich high plasticity clays and uplift have been introduced. The method has been demonstrated for 5 wells and one geotechnical well in Aurora, Smeaheia, and Troll East, in the Horda Platform area. It is found that the sonic log method and the Vcl method are comparable within the Dunlin Group. For organic-rich shales like the Draupne Formation, the Thorium values from the spectral gamma log should be used for Vcl rather than the regular total gamma log. When other mineralogy data are present, this can be used for more precise quantification of Vcl and smectite and better estimation of K0. The Vcl method is a good alternative when sonic logs are unavailable to fill in the gaps in between field stress data, to understand the local lithological impact on stress, and reduce uncertainty. After correcting for uplift and high smectite content, the Vcl method were found to reproduce high K0 values as indicated from field stress tests in shallower units (Nordland, Hordaland, Shetland). For deeper main sealing units Draupne and Drake, the diagenetic impact may resulted in low K0 values although extensivly uplifted. The method presented improves quantification and reduces the uncertainty of σh which is one key input in all integrity evaluations

• Liberty, Lee M.; Yelton, Jonathan; Skurtveit, Elin; Braathen, Alvar; Midtkandal, Ivar & Evans, James P. (2022). Regolith and host rock influences on CO<inf>2</inf> leakage: Active source seismic profiling across the Little Grand Wash fault, Utah. International Journal of Greenhouse Gas Control. ISSN 1750-5836. 119. doi: 10.1016/j.ijggc.2022.103742. Fulltekst i vitenarkiv Vis sammendrag

  Understanding carbon dioxide (CO2) reservoir to surface migration is crucial to successful carbon capture and sequestration approaches; especially fault/reservoir interactions under injection pressure. Through seismic imaging, we explore regolith and shallow stratigraphy across the Little Grand Wash fault. The presence of natural CO2 seeps, travertine and tufa deposits confirm modern and ancient fault-controlled CO2 leakage. We consider this an analogue for a long-failed sequestration site. We estimate bulk porosity and fracture density for host rock, regolith, and fault zone from petrophysical relationships. When combined with existing geochemical and geological data, we characterize a 60 m wide damage zone that represents the primary surface delivery channel for CO2 originating from reservoir depths. Within this damage zone, low seismic velocities suggest sediments have formed through host rock chemical dissolution or mechanical weathering. In contrast, velocities within the adjacent host rock are consistent with low fracture density clastic rocks. We measure anomalously high seismic velocities within the fault zone along one profile that best represents a sealed (cemented/plugged) low permeability, relic flow channel. This suggests that shallow fault zone permeability varies along strike. While regional stress changes may account for decadal- to millennial-scale changes in CO2 pathways, we speculate that the total fluid pressure has locally reduced the fault's minimum horizontal effective stress; thereby producing both low- and high-permeability fault segments that either block or promote fluid migration. Studying CO2 migration in this system can inform potential risks to future sequestration projects and guide monitoring efforts.

• Osmond, Johnathon; Mulrooney, Mark Joseph; Holden, Nora; Skurtveit, Elin; Faleide, Jan Inge & Braathen, Alvar (2022). Structural traps and seals for expanding CO<inf>2</inf> storage in the northern Horda platform, North Sea. American Association of Petroleum Geologists Bulletin. ISSN 0149-1423. 106(9), s. 1711–1752. doi: 10.1306/03222221110. Fulltekst i vitenarkiv Vis sammendrag

  Development and maturation of geological carbon dioxide (CO2) storage projects along the Norwegian Continental shelf is ongoing, but even more storage locations are needed to reach climate mitigation goals by 2050. To augment the future Aurora injection site and expand CO2 storage in the northern Horda platform of the North Sea, the region’s potential must be assessed. Here, we leverage the latest wellbore and seismic data to map storage aquifers, identify structural traps, and assess possible top and fault seals associated with Lower and Upper Jurassic storage complexes in four major fault blocks. Our results indicate that both storage complex aquifers are preserved throughout the study area. From our minimum size criteria, we have identified a total of 95 Lower and 64 Upper Jurassic traps representing approximately 2.37 × 1010 and 5.80 × 1010 m3 in gross rock volume, respectively. Mapping, modeling, and formation pressure analyses suggest that top seals are sufficiently thick over the majority of structural traps and provide vertical pressure barriers between storage aquifers. Across-fault juxtaposition seals are abundant but dominate the Upper Jurassic storage complexes. Lower Jurassic aquifers, however, are often upthrown against Upper Jurassic aquifers, but apparent across-fault pressure differentials and shale gouge ratio values >0.15 correlate, suggesting fault rock membrane seal presence. Aquifer self-juxtapositions, however, are likely areas with poor fault seal. Overall, our work provides added support that the northern Horda platform represents a promising location for CO2 storage expansion, carrying the potential to become a future storage hub in the North Sea.

• Holden, Nora; Osmond, Johnathon L.; Mulrooney, Mark Joseph; Braathen, Alvar; Skurtveit, Elin & Sundal, Anja (2022). Structural characterization and across-fault seal assessment of the Aurora CO<inf>2</inf> storage site, northern North Sea. Petroleum Geoscience. ISSN 1354-0793. 28(4). doi: 10.1144/petgeo2022-036. Fulltekst i vitenarkiv Vis sammendrag

  Faults play an essential role at many potential CO2 storage sites because they can act as conduits or barriers to fluid flow. To contribute to the evaluation of the Aurora storage site in the northern North Sea, we perform a structural characterization and assessment of across-fault seals that displace the Lower Jurassic storage complex. We find that first-order faults are predominately north–south striking and west dipping, with throws greater than the thickness of the primary seal (>85 m). In contrast, second-order faults have lower throws (15–50 m), and variable strike and dip directions. Due to the dip of the storage complex, injected CO2 is likely to migrate northwards before encountering the first-order Svartalv Fault Zone on its footwall side, which juxtaposes the storage units against younger sand-rich units. However, shale gouge ratio values exceed 0.30 at the depth of the storage complex, suggesting that a fault membrane seal may be present. Furthermore, second-order NE-dipping faults create juxtaposition seals and, in places, small-scale structural traps (24–48 m) along the Svartalv Fault Zone. Overall, we suggest that faults within the Aurora storage site could provide barriers to plume migration, allowing more CO2 to become trapped and thereby increasing the storage capacity.

Se alle arbeider i NVA

• Munoz, Jhon-Meyer; Torabi, Anita; Basa, Abhisek; Hansen, Torsten Hundebøl & Skurtveit, Elin (2026). Fault-core in overburden section: geomechanical and geo chemical characterisation of the Baza fault core, southern Spain. I Ziegler, Martin; Nicol, Romain; Jaeggi, David & Nussbaum, Christophe (Red.), Caprock Integrity & Gas Storage Symposium 2026. Swiss Federal Office of Topography. s. 41–45. doi: https:/www.swisstopo.admin.ch/dam/en/sd-web/jwHxgZfGm5AB/Conference%20Proceedings%20CIGSS%202026.pdf. Fulltekst i vitenarkiv
• Choi, Jung Chan; Soldal, Magnus & Skurtveit, Elin (2026). Factors controlling fault stability: contrasting drained and un-drained stress paths during CO₂ injection. I Ziegler, Martin; Nicol, Romain; Jaeggi, David & Nussbaum, Christophe (Red.), Caprock Integrity & Gas Storage Symposium 2026. Swiss Federal Office of Topography. s. 37–40. doi: https:/www.swisstopo.admin.ch/dam/en/sd-web/jwHxgZfGm5AB/Conference%20Proceedings%20CIGSS%202026.pdf. Fulltekst i vitenarkiv
• Skurtveit, Elin & Soldal, Magnus (2026). Experimental characterization of fault rock in laboratory. I Ziegler, Martin; Nicol, Romain; Jaeggi, David & Nussbaum, Christophe (Red.), Caprock Integrity & Gas Storage Symposium 2026. Swiss Federal Office of Topography. s. 24–27. doi: https:/www.swisstopo.admin.ch/dam/en/sd-web/jwHxgZfGm5AB/Conference%20Proceedings%20CIGSS%202026.pdf. Fulltekst i vitenarkiv
• Høe, M.; Senger, Kim; Skurtveit, Elin; Choi, Jung Chan; Hellevang, H. & Betlem, Peter [Vis alle 7 forfattere av denne artikkelen] (2025). Seal Integrity of the Agardhfjellet Formation, Svalbard: Influence of Mineralogical and Depositional Environment on Geomechanical Properties. I Seals, International Conference on Fault and Top (Red.), Seventh International Conference on Fault and Top Seals. European Association of Geoscientists and Engineers (EAGE). doi: 10.3997/2214-4609.202532026. Fulltekst i vitenarkiv Vis sammendrag

  The Agardhfjellet Formation (Fm) in Svalbard, a middle Jurassic to lowermost Cretaceous mudstone-dominated unit, is investigated for its geomechanical properties critical for CO2 storage seal integrity. This study focuses on how mineralogy and depositional environment influence the formation’s geomechanical behavior, using borehole data from fully cored drill cores in central Spitsbergen. The Agardhfjellet Fm, partially equivalent to the Fuglen and Hekkingen formations in the Barents Sea, is analyzed for its lithology, grain size, and redox conditions through XRF-derived trace element ratios (Zr/Rb, U/Th, V/(V+Ni)). These indicate an oxic to anoxic depositional environment, with the coarser-grained Oppdalssåta Member contrasting the finer-grained Slottsmøya and Lardyfjellet Members. Geomechanical properties, assessed via log-derived Young’s modulus (E) and Poisson’s ratio (ν), reveal that the Oppdalssåta Member is more brittle, while Slottsmøya and Lardyfjellet Members are more ductile, indicating a correlating between Zr/Rb ratio and elastic response. Further, higher gamma ray values suggest more ductile behavior, however no clear trends between organic content (resistivity) and elastic properties are observed. Initial interpretation of these findings suggest that grain size and mineralogy significantly influence failure mode and fracture potential, with Zr/Rb ratios potentially serving as a useful proxy for assessing seal integrity in a CO2 storage context.

• Skurtveit, Elin; Soldal, Magnus; Høe, M.J.; Betlem, Peter & Petrie, E.S. (2025). Fault Gouge Permeability Characterization and Implications for Fluid Migration During Fault Reactivation. I Seals, International Conference on Fault and Top (Red.), Seventh International Conference on Fault and Top Seals. European Association of Geoscientists and Engineers (EAGE). doi: 10.3997/2214-4609.202532021. Fulltekst i vitenarkiv Vis sammendrag

  Fault zone permeability remains a challenging parameter to address both in outcrop and subsurface. Limited experimental data providing permeability measurements on natural fault rock samples from sealing parts of the fault are available. More data is needed to improve our understanding of fluid migration in faults and dynamic changes related to subsurface injection and the risk of fault reactivation and alteration of the seal capacity. In this work we measure permeability for a natural fault gouge sample from Little Grand Wash Fault zone in Utah using a novel direct shear device. The low permeability measured is in line with a sealing fault core and supports field observations of the damage zone as the main pathway for CO2 migration. The shear loading phase of the experiment suggest a reduction in permeability during shearing and provides key data for improving our understanding of fault reactivation and effects on fluid migration.

• Choi, Jung Chan; Aadland, T.; Skurtveit, Elin & Norborg, A.K. (2025). FracStress+: An Integrated Workflow for Fault Stability Screening in CO2 Storage. I Conference, World CCUS (Red.), World CCUS Conference 2025. European Association of Geoscientists and Engineers (EAGE). doi: 10.3997/2214-4609.202522083. Fulltekst i vitenarkiv Vis sammendrag

  As the scale of CO₂ storage projects increases, the potential for injected CO2 to interact with faults also increases. Field screening needs, therefore, to incorporate robust stability assessments to ensure long-term containment integrity. The study introduces FracStress+, an integrated workflow that automates fault stability screening by seamlessly connecting geologic model in Petrel with the Python-based fault stability analyzer, FracStress, via the Cegal Prizm platform. A proof-of-concept application to a hypothetical CO₂ storage site demonstrates how the workflow enables fault stability assessment directly within Petrel. The results indicate that this approach improves efficiency and consistency by reducing manual data handling and streamlining stress analysis.

• Holden, Nora; Alaei, Behzad; Skurtveit, Elin & Braathen, Alvar (2024). The impact of depth conversion on fault geometry and its influence on fault-risk assessment in the Smeaheia storage site. Fulltekst i vitenarkiv
• Holden, Nora; Alaei, Behzad; Skurtveit, Elin; Braathen, Alvar; Midtkandal, Ivar & Osmond, Johnathon L. [Vis alle 8 forfattere av denne artikkelen] (2024). CO2 storage on the Horda Platform - Assessing structural complexities and fault-seal integrity. Fulltekst i vitenarkiv
• Holden, Nora; Skurtveit, Elin; Braathen, Alvar; Alaei, Behzad; Midtkandal, Ivar & Osmond, Johnathon L. [Vis alle 8 forfattere av denne artikkelen] (2024). CO2 storage on the Horda Platform. Fulltekst i vitenarkiv
• Goertz-Allmann, Bettina & Skurtveit, Elin (2024). Public perception of CCUS –Findings from the ENSURE and SHARP projects. Fulltekst i vitenarkiv
• Holden, Nora; Alaei, Behzad; Skurtveit, Elin; Braathen, Alvar; Midtkandal, Ivar & Osmond, Johnathon L. [Vis alle 8 forfattere av denne artikkelen] (2024). Structural de-risking of CO2 storage sites on the Horda Platform. Fulltekst i vitenarkiv
• Osmond, Johnathon L.; Holden, Nora; Mulrooney, Mark Joseph; Skurtveit, Elin; Faleide, Jan Inge & Braathen, Alvar (2024). Beyond Aurora and Smeaheia; structural traps and seals for additional CO2 storage within Jurassic Horda Platform aquifers. Fulltekst i vitenarkiv Vis sammendrag

  Summary: Geological carbon dioxide sequestration (CCS) is a relatively small, yet viable solution for reducing CO2 emissions as we approach the year 2050. This is particularly true for emissions resulting from industrial operations that likely cannot be rendered into emissionless processes, such as cement production. The Aurora CO2 storage site located in the northern Horda Platform of the Norwegian North Sea is part of the Longship project, one of the world’s first to demonstrate the full CCS value chain. Injection and containment of CO2 is scheduled take place by 2024 within the Lower Jurassic storage complex comprised of Dunlin Gp siliciclastic saline aquifers capped by mudrocks and shales. While current well tests at Aurora suggest favorable conditions for injection rates of 5 megatons per year, more storage sites are required and under development. Roughly 40 km east of Aurora, a second CO2 storage exploitation license has recently been awarded in the Smeaheia area. In contrast to Aurora, injection is likely to transpire within an Upper Jurassic storage complex, with aquifers of the Viking Gp overlain by fine-grained rocks of the Viking Gp and Lower Cretaceous Cromer Knoll Gp, similar to parts of the nearby Troll field. While storage complexes in both areas are fairly well-established, less is certain about whether or not the same concepts could be utilized throughout greater northern Horda Platform, and what other areas have potential. In order to address the possibility of expanding the northern Horda Platform into a larger CO2 storage hub, we utilized 3D seismic reflection and wellbore data to study the Lower and Upper Jurassic storage complexes with a regional structural trap and seal approach. Here, we show Lower and Upper Jurassic storage aquifers presence, and highlight the array of fault-bound structural traps. We also present top seal thickness variations and evidence of their effectiveness, where we consider fine-grained Cretaceous Shetland Gp and Paleocene Rogaland Gp rock as additional seals of the Upper Jurassic storage complex. Furthermore, because faults have generally been observed to provide barriers or conduits to across-fault fluid migration, we have assessed the lateral fault seals critical for containing injected CO2 within the mapped traps. While across-fault juxtaposition seals are of high confidence and are critical for the Upper Jurassic storage complex, we go on to illustrate that membrane seals are also necessary for success in the Lower Jurassic storage complex, but both pressure data and empirical modeling imply their seal effectiveness. Finally, as the Aurora and Smeaheia storage sites develop and technical work continues to be carried out, the results from this study suggest that the Upper and Lower Jurassic storage complexes could be utilized to develop northern Horda Platform CO2 into a larger storage hub.

• Osmond, Johnathon; Holden, Nora; Cruz, Erika H de La; Würtzen, Camilla Louise; Skurtveit, Elin & Faleide, Jan Inge [Vis alle 7 forfattere av denne artikkelen] (2024). Containment derisking of a potential CO2 storage hub in the Horda Platform, Norwegian North Sea. Fulltekst i vitenarkiv
• Osmond, Johnathon; Holden, Nora; Würtzen, Camilla Louise; Cruz, Erika H de La; Skurtveit, Elin & Faleide, Jan Inge [Vis alle 7 forfattere av denne artikkelen] (2024). Distribution of Upper Jurassic–Upper Cretaceous seals in the northern Horda Platform: considerations for CO2 storage within the Smeaheia area (EL002). Fulltekst i vitenarkiv Vis sammendrag

  Summary: On the road towards achieving climate mitigation goals by 2050, geological carbon dioxide sequestration (CCS) will play a key role in reaching net-zero greenhouse gas emissions globally. In the northern Horda Platform of the Norwegian North Sea, the developing Aurora CO2 storage site will be an early contributor to the solution. There, injection of 1.5 megatonnes of CO2 per year or more into a Lower Jurassic storage complex (Dunlin Group) will commence in 2024. However, other storage locations in the northern Horda Platform appear to be on the rise. Of note is the EL002 storage exploitation license in the Smeaheia fault block, which offers an attractive Upper Jurassic storage complex comprised of Viking Group sandstone storage formations (saline aquifer) and younger seals. The Alpha 3-way closure bounded by the Vette fault zone is one of several prospects that could be employed for injected CO2 containment. However, the heterolithic the Draupne Formation, Cromer Knoll Group, and Shetland Group (Upper Jurassic through Upper Cretaceous) must serve as top and lateral (fault) seals, which have not been well studied until recently. In this contribution, we show the distribution of these seals utilizing the latest 3D seismic and wellbore data for detailed interpretation and modeling, while also comparing our observations to the Troll East field along the Tusse fault zone, whose trap and seal provides an excellent analog with respect to CO2 storage within the Alpha prospect. Moreover, we preview new cuttings XRD data coupled with corresponding wireline logs in order to help correlate regional facies changes, particularly their relation to key Alpha trap contacts give that quartz-, carbonate-, and clay-rich facies vary vertically and horizontally. Overall, this study highlights considerations for EL002, as well as the continued development of the northern Horda Platform into a future CO2 storage hub in the North Sea.

• Larsen, Tine B.; Skurtveit, Elin; Pearson, Steve; Kettlety, Tom; Choi, Jung Chan & Huang, Chen [Vis alle 15 forfattere av denne artikkelen] (2024). SHARP project – an integrated approach for assessing CO2 storage containment risks. Fulltekst i vitenarkiv Vis sammendrag

  SHARP is an interdisciplinary project with the overall aim to develop improved methods for quantitative assessment of subsurface CO2 storage containment risks. The project combines subsurface stress models, rock mechanical failure experiments, and seismicity observations with probabilistic modelling of fault stability, seismic hazard, and containment risk. This presentation will summarise and give a status update on risk quantification work of the SHARP project. Uncertainties and parameter ranges are included for the failure data, and independent and dependent failures of geological barriers are treated probabilistically. A new catalogue of natural seismicity in the North Sea form the basis for constructing offshore ground motion prediction equations (GMPEs) and an updated regional probabilistic seismic hazard analysis (PSHA). Natural seismicity, pressure, and pressure induced seismicity are identified as potential root causes of leakage (triggers) and a catalogue of generic release diagrams are built for realistic geological settings. The generic release diagrams are mapped onto test cases from the North Sea. The geological containment risk with uncertainties will be evaluated though event tree analysis and Monte Carlo runs, where the inputs are the quantified contributions from release diagrams, probabilistic fault stability analysis and the seismic hazard curve.

• Kühn, Daniela; Kettlety, Tom; Martuganova, Evgeniia; Jerkins, Annie Elisabeth; Asplet, Joseph & Goertz-Allmann, Bettina [Vis alle 17 forfattere av denne artikkelen] (2024). Understanding North Sea seismicity to gain stress field information and de-risk large-scale CO2 injections. Fulltekst i vitenarkiv Vis sammendrag

  Carbon capture and storage technologies are an essential part of EU’s decarbonisation efforts. Combined with sustainable energy resources, they are necessary to move Europe towards a net zero carbon emissions economy. Currently, several Mt-scale CO2 storage projects are being developed in the North Sea. Containment risk evaluation includes analysing tectonic earthquake patterns to potentially map faults, reveal their orientation and failure style, invert for stress directions and at later stages, enable the discrimination of natural and induced seismicity. In addition, seismological information may contribute to the geomechanical understanding of the reservoir and caprock response to large-scale CO2 injection over time. A wealth of data exists from various European seismological agencies, but much of it has not been analysed collectively. Within the framework of the ACT project SHARP Storage, an extensive unique earthquake bulletin was compiled using seismicity data from all relevant data centres. Preliminary processing included duplicate removal and explosion identification. The magnitude of completeness of this data set varies both spatially and temporally. The most seismically active regions in the study area are the Viking and Central grabens. Coastal areas are populated with more events than the central part of the North Sea due to the denser distribution of seismic stations onshore allowing for the detection of smaller (M<3) magnitude events. Data sets are planned to being made public after finalising the project. For events occurring after 1990 and possessing magnitudes larger than M > 3.5, waveforms are currently being collected as a basis for further analysis, including event relocation and magnitude homogenisation. Inverted moment tensors, shear-wave splitting measurements, and stress drop analysis will be compared to and complement a review of borehole stress measurements to better gauge the present-day stress field and enhance seismic hazard assessments. Ground motion prediction equations (GMPEs) are being derived for the onshore regions nearest the development CO2 storage projects, and an updated probabilistic seismic hazard analysis is being carried out on a regional scale.

• Kettlety, Tom; Voss, Peter; Martuganova, Evgeniia; Schweitzer, Johannes; Dahl-Jensen, Trine & Jerkins, Annie Elisabeth [Vis alle 7 forfattere av denne artikkelen] (2024). Improving the accuracy of earthquake magnitudes for North Sea seismicity. Fulltekst i vitenarkiv Vis sammendrag

  To effectively design and operate the many CO2 storage projects that are being developed in the North Sea, seismicity needs to be accurately characterised. Measuring seismicity can provide insights into the stress state in the region, fault density and faulting style, as well as fracturing in the overburden. Understanding background seismicity rates is also key to discriminating, determining the risk of, and mitigation against induced seismicity that could result from injection. Communicating earthquake risk is a key challenge in this field, and central to that is the reporting of earthquake sizes or magnitudes. These magnitudes are reported to the public, and thus their integrity needs to be ensured and their uncertainties thoroughly characterised. Magnitudes also are key input into seismic hazard analysis, a necessary step in the site characterisation of CO2 storage projects and other offshore infrastructure. This study compares and re-evaluates the magnitude estimates from a large database of North Sea seismicity compiled by the ACT3 project SHARP Storage. Magnitudes and their associated uncertainties are computed in a consistent manner and compared to the recordings reported by the regional agencies. Systematic differences are explored, and key sensitives are identified. These results will aid in the monitoring of seismicity in the North Sea, risk assessment for CO2 storage and other infrastructure, and the communication of seismic hazard.

• Huang, Chen; Carlton, Brian David; Kettlety, Tom; Larsen, Tine; Kendall, Michael & Skurtveit, Elin (2024). Reevaluating seismic hazard and ground-motions for North Sea CO2 storage projects. Fulltekst i vitenarkiv Vis sammendrag

  The North Sea plays a strategic role in the transition towards the green economy, as it hosts many offshore wind farms and carbon capture and storage (CCS) sites. The North Sea is characterized by moderate seismicity. For example, the 2023 Mw 5.1 North Sea earthquake was the largest earthquake in the region in 33 years, and led to a temporary shutdown of production of Equinor’s oil platform Snorre B. This study presents the preliminary results of the North Sea ground-motion model and highlights the challenges in conducting PSHA for the North Sea region. These results improve the assessment of seismic hazard and risks to CO2 storage security in the North Sea.

• Feng, Yu; Grande, Lars; Skurtveit, Elin; Choi, Jung Chan & Thompson, Nicholas (2023). Reducing Uncertainty in Site-specific Stress Prediction for CO2 Storage in the North Sea, Norway. Fulltekst i vitenarkiv
• Skurtveit, Elin (2023). Hvordan lagrer vi CO2 og er det trygt? Fulltekst i vitenarkiv
• Grande, Lars; Forsberg, Carl Fredrik; Mondol, Md Nazmul Haque; Skurtveit, Elin; Singh, Rao Martand & Amiri, Seyed Ali Ghoreishian [Vis alle 10 forfattere av denne artikkelen] (2023). Impact of sediment composition, glacial loading and uplift on ground stresses in the Horda-Platform area. Fulltekst i vitenarkiv
• Skurtveit, Elin (2023). SHARP Storage - Stress history and reservoir pressure for improved quantification of CO2 storage containment risks. Fulltekst i vitenarkiv
• Skurtveit, Elin (2023). SHARP Storage - Stress history and reservoir pressure for improved quantification of CO2 storage containment risks. Fulltekst i vitenarkiv
• Skurtveit, Elin; Midtkandal, Ivar & Braathen, Alvar (2023). A naturally occurring CO2 laboratory in Utah. Fulltekst i vitenarkiv
• Skurtveit, Elin (2023). Improved workflow for fault risk assessment in faulted CO2 storage sites. Fulltekst i vitenarkiv
• Skurtveit, Elin (2023). In-situ stress and failure prediction. Fulltekst i vitenarkiv
• Soldal, Magnus & Skurtveit, Elin (2023). Measurements of capillary breakthrough pressures and permeabilities in traditional seals and application for CO2 storage. Fulltekst i vitenarkiv
• Osmond, J.L.; Holden, Nora; Mulrooney, Mark Joseph; Skurtveit, Elin; Faleide, Jan Inge & Braathen, Alvar (2023). Beyond Aurora and Smeaheia; structural traps and seals for additional CO2 storage within Jurassic Horda Platform aquifers. Fulltekst i vitenarkiv
• Skurtveit, Elin; Petrie, Elizabeth S.; Smith, Scott Adam; Faleide, Thea Sveva; Sundal, Anja & Choi, Jung Chan [Vis alle 10 forfattere av denne artikkelen] (2023). Core analysis from Little Grand Wash fault, Utah, and application for fault risk assessment for co2 storage in the Norwegian North Sea. Fulltekst i vitenarkiv Vis sammendrag

  Fault zones contain a mixture of lithologies, various fault structures, and evidence for fluid-rock interaction events, representing a record of multiple deformation events during the faulting history. The resulting complex and highly variable mixture of properties makes faults challenging structures to model, and specifically assessing the fault zone permeability and probability of reactivation is difficult. The ability of fault zones to transport fluids has received renewed attention during the last 10 years of developing subsurface, geological storage reservoirs for CO2. The North Sea sedimentary basin offshore Norway has an enormous potential for storing CO2. However, to qualify fault traps in saline aquifers for storage, improved workflows for fault risk assessment focusing on fault zone flow properties and mechanical stability is needed. An improved approach for fault modelling is under development: we quantify the uncertainties in fault rock properties to address the probability of failure and subsequent changes in permeability. To support our understanding of subsurface faults in the North Sea, we utilize knowledge from the Little Grand Wash (LGW) fault, located in Emery County, Utah. The LGW fault zone provides a natural laboratory to study fault zone development in geological analogues, failure mechanisms, and fluid migration. As a supplement to already published well data and core descriptions from this area, three new cores were retrieved from the fault in 2019. In total 16.5 meters of core, covering both the hanging wall (Jurassic Brushy Basin Member of the Morrison Formation) and footwall (Jurassic Summerville Formation) damage zone, have been logged and sampled for petrophysical analysis and mechanical testing. The current work presents new data on variation of permeability, porosity, strength, and sonic velocity inside the fault damage zone, including measurements on different lithologies, various types of cementation and selected deformation bands, fractures, and veins. Petrophysical and chemical analysis combined with visual identification of oil stains and bleaching provide the possibility for a holistic understanding of the system and we derive valuable knowledge for improving fault risk workflows applicable for CO2 storage projects in the Norwegian North Sea.

• Goertz-Allmann, Bettina & Skurtveit, Elin (2023). Public acceptance and communication of CCS . Fulltekst i vitenarkiv
• Skurtveit, Elin (2023). SHARP Storage - Stress history and reservoir pressure for improved quantification of CO2 storage containment risks. Fulltekst i vitenarkiv
• Skurtveit, Elin; Griffiths, Luke & Thompson, Nicholas (2023). Northern Lights core test data to be shared. Fulltekst i vitenarkiv
• Skurtveit, Elin (2023). Supporting industrial needs - Applied research for CO2 storage. Fulltekst i vitenarkiv
• Skurtveit, Elin (2023). What happens to CO2in faults? Fulltekst i vitenarkiv
• Skurtveit, Elin (2023). The Northern Lights and Longship project – a research perspective. Fulltekst i vitenarkiv
• Skurtveit, Elin (2023). Fault assessment. Fulltekst i vitenarkiv
• Bjørnarå, Tore Ingvald; Skurtveit, Elin; Haines, Emma Michie & Smith, Scott Adam (2023). Overburden fluid migration along faults using different permeability models – Example from the North Sea (Vette Fault). Fulltekst i vitenarkiv
• Roberts, Dan; Phillips, Dan; Grande, Lars; Forsberg, Carl Fredrik; Mondol, Md Nazmul Haque & Choi, Jung Chan [Vis alle 8 forfattere av denne artikkelen] (2023). Accounting for Stress History and Lithology in Geomechanical Models: Implications for Subsurface CO2 Storage Integrity on the Horda Platform. Fulltekst i vitenarkiv
• Holden, Nora; Alaei, Behzad; Skurtveit, Elin & Braathen, Alvar (2023). Uncertainty in fault-risk assessment - implications of depth-conversion on fault-risk assessment in the Smeaheia CO2 storage site, northern North Sea. Fulltekst i vitenarkiv
• Holden, Nora; Osmond, Johnathon L.; Mulrooney, Mark Joseph; Skurtveit, Elin; Sundal, Anja & Braathen, Alvar (2023). Structural characterization and across-fault seal assessment of the Aurora CO2 storage site. Fulltekst i vitenarkiv
• Holden, Nora; Alaei, Behzad; Skurtveit, Elin & Braathen, Alvar (2023). Implications of depth-conversion on fault geometries and fault-risk assessment in the Smeaheia CO2 storage site, northern North Sea. Fulltekst i vitenarkiv
• Skurtveit, Elin (2023). Fault analysis in CO2 storage projects. Fulltekst i vitenarkiv
• Holden, Nora; Alaei, Behzad; Skurtveit, Elin & Braathen, Alvar (2023). Uncertainty in fault-risking. Influence of depth-conversion on fault-geometry and fault-risk assessment in the Smeaheia CO2 storage site. Fulltekst i vitenarkiv
• William, John; Ringrose, Philip Sefton; Thompson, Nicholas D.; Zarifi, Zoya; Bisdom, Kevin & Kettlety, Tom [Vis alle 9 forfattere av denne artikkelen] (2023). Comparison of initial stress state and rock-failure risks for five prospective CO2 storage sites. Fulltekst i vitenarkiv
• Griffiths, Luke; Thompson, Nicholas; Smith, Halvard; Grande, Lars & Skurtveit, Elin (2023). Rock mechanical testing of core from Eos CCS validation well. Fulltekst i vitenarkiv
• Choi, Jung Chan; Skurtveit, Elin; Soldal, Magnus & Grande, Lars (2023). Effect of undrained creep on the long-term mechanical stability of North Sea mudstones and shales. Fulltekst i vitenarkiv
• Bohloli, Bahman; Sparrevik, Per & Skurtveit, Elin (2022). Fiberoptisk teknologi sikrer lagring av klimagasser under Nordsjøen. geoforskning.no. Fulltekst i vitenarkiv
• Osmond, Johnathon; Mulrooney, Mark Joseph; Holden, Nora; Skurtveit, Elin; Faleide, Jan Inge & Braathen, Alvar (2022). Quaternary stratigraphy and pockmark mapping in the Norwegian Channel, northern North Sea. Fulltekst i vitenarkiv
• Osmond, Johnathon; Mulrooney, Mark Joseph; Würtzen, Camilla Louise; Cruz, E. De La; Skurtveit, Elin & Faleide, Jan Inge [Vis alle 7 forfattere av denne artikkelen] (2022). Upper Jurassic through Lower Cretaceous seal characterization in the northern Horda Platform. Fulltekst i vitenarkiv
• Bjørnarå, Tore Ingvald; Skurtveit, Elin; Haines, Emma Michie & Smith, Scott Adam (2022). Leakage rate calculations - Smeaheia. Fulltekst i vitenarkiv
• Skurtveit, Elin & Bjørnarå, Tore Ingvald (2022). FRISK and NCCS innovation sprint. Fulltekst i vitenarkiv
• Skurtveit, Elin; Grande, Lars & Smith, Scott Adam (2022). Permeability data & application for faults. Fulltekst i vitenarkiv
• Holden, Nora; Osmond, Johnathon; Mulrooney, Mark Joseph; Skurtveit, Elin; Braathen, Alvar & Sundal, Anja (2022). Influence of faults on Co2 migration. Fulltekst i vitenarkiv
• Osmond, Johnathon; Mulrooney, Mark Joseph; Holden, Nora; Skurtveit, Elin; Faleide, Jan Inge & Braathen, Alvar (2022). Past fluid containment and present applications toward future CO2 storage in the northern Horda Platform, offshore Norway. Fulltekst i vitenarkiv
• Smith, Scott Adam; Faleide, Thea Sveva; Petrie, Elizabeth S. & Skurtveit, Elin (2022). Velocity variations due to lithology and fractures in a fault zone with CO2 seepage, Utah, USA. EarthDoc. doi: 10.3997/2214-4609.202243030. Fulltekst i vitenarkiv
• Osmond, Johnathon L.; Mulrooney, Mark Joseph; Holden, Nora; Leon, Elias H.; Cruz, Erika H. de La & Würtzen, Camilla Louise [Vis alle 9 forfattere av denne artikkelen] (2022). Containment derisking of a potential CO2 storage hub in the Horda Platform, Norwegian North Sea. Fulltekst i vitenarkiv
• Bohloli, Bahman & Skurtveit, Elin (2022). Development of CCS projects in Norway. Fulltekst i vitenarkiv
• Osmond, Johnathon; Mulrooney, Mark Joseph; Holden, Nora; Skurtveit, Elin; Faleide, Jan Inge & Braathen, Alvar (2022). Distribution of faulted Mesozoic and Tertiary seals for CO2 storage in the northern Horda Platform, Norwegian North Sea. Fulltekst i vitenarkiv Vis sammendrag

  This lecture summarizes a recent case study involving the derisking of geological seals for a potential offshore CO2 storage site. In the northern Horda Platform of the northern North Sea, the structural and stratigraphic architecture of the producing Troll East hydrocarbon field is directly analogous to the Alpha CO2 storage prospect in the Smeaheia fault block just to the east of the field. Building on this observation, we have mapped the proven regional seal units of Troll East in order to extrapolate and understand their distribution throughout the northern Horda Platform. Here, we utilize our results to compare Alpha with Troll East, and discuss top and fault seal presence in the context of derisking Alpha’s CO2 storage prospectivity.

• Wu, Long; Skurtveit, Elin; Thompson, Nicholas D.; Michie, Emma; Fossen, Haakon & Braathen, Alvar [Vis alle 9 forfattere av denne artikkelen] (2022). Containment Risk Assessment and Management of CO2 Storage on the Horda Platform. Fulltekst i vitenarkiv
• Petrie, Elizabeth S.; Skurtveit, Elin; Faleide, Thea Sveva & Halvorsen, Kristine (2022). Fracture Systems and Development in an Active Fault Zone. Geological Society of America Abstracts with Programs. doi: 10.1130/abs/2022PR-376078. Fulltekst i vitenarkiv
• Osmond, Johnathon; Mulrooney, Mark Joseph; Holden, Nora; Skurtveit, Elin; Faleide, Jan Inge & Braathen, Alvar (2022). Screening traps and seals for CO2 storage expansion in the northern Horda Platform, Norwegian North Sea. Fulltekst i vitenarkiv Vis sammendrag

  Evaluation and development of new and exciting CO2 storage opportunities on the Norwegian Continental Shelf is on the rise. Of note is the Aurora site located in northern Horda Platform of the Norwegian North Sea, where injection is scheduled to commence in 2024 under project Longship. While the planned injection volumes at Aurora are over 1.5 megatonnes per year, many more storage locations are required in order to meet international climate mitigation targets by 2050. Other parts of the northern Horda Platform show CO2 storage potential, but additional subsurface characterization is required. As a contribution towards this effort, I present two possible Jurassic storage complexes (Lower and Upper), where I discuss the presence of available storage aquifers, structural traps, as well as top and fault seals. Overall, our work supports the notion that the northern Horda Platform may be capable of hosting a future CO2 storage hub for northern Europe.

• Braathen, Alvar; Skurtveit, Elin; Mulrooney, Mark Joseph; Haines, Emma Michie; Faleide, Thea Sveva & Osmond, Johnathon [Vis alle 10 forfattere av denne artikkelen] (2022). Understanding faults and their influence on fluid flow. Fulltekst i vitenarkiv
• Bjørnarå, Tore Ingvald; Skurtveit, Elin; Haines, Emma Michie & Smith, Scott Adam (2022). Fault modelling approaches. Fulltekst i vitenarkiv
• Skurtveit, Elin; Bjørnarå, Tore Ingvald; Michie, Emma; Gasda, Sarah Eileen; Keilegavlen, Eirik & Sandve, Tor Harald [Vis alle 10 forfattere av denne artikkelen] (2022). Updated workflow for fault risk assessment and application to Vette Fault Zone, Horda Platform, offshore Norway. Fulltekst i vitenarkiv
• Saqab, Muhammad Mudasar; Riera, Rosine; Paumard, V.; Lane, Andrew & Skurtveit, Elin (2022). Neogene Faulting and Evidence of Fluid Flow in the Caswell Sub-Basin (Browse Basin): Implications for CO2 Sequestration. EarthDoc. doi: 10.3997/2214-4609.202275009. Fulltekst i vitenarkiv
• Bjørnarå, Tore Ingvald; Smith, Scott Adam; Michie, Emma & Skurtveit, Elin (2022). Fault leakage analysis addressing vertical migration rates along faults. Fulltekst i vitenarkiv
• Bjørnarå, Tore Ingvald; Skurtveit, Elin; Michie, Emma & Smith, Scott Adam (2022). Overburden Fluid Migration along the Vette Fault Zone, North Sea, Using Different Fault Permeability Models. EarthDoc. doi: 10.3997/2214-4609.202243033. Fulltekst i vitenarkiv
• Skurtveit, Elin & Bjergene, Liv Røhnebæk (2022). Hvordan sikrer vi trygg lagring av CO2 under havbunnen? [Internet]. NGI Podkast: Med blikket mot bakken. Fulltekst i vitenarkiv
• Skurtveit, Elin; Bjørnarå, Tore Ingvald; Haines, Emma Michie; Gasda, Sarah Eileen; Eidsvig, Unni & Braathen, Alvar (2022). Updated workflow for fault risk assessment and application to Vette Fault Zone, Horda Platform, offshore Norway. Fulltekst i vitenarkiv
• Choi, Jung Chan; Skurtveit, Elin; Soldal, Magnus & Grande, Lars (2022). Can the creep stabilize a fault? : Undrained stress path of the shale creep. Fulltekst i vitenarkiv
• Osmond, Johnathon L.; Mulrooney, Mark Joseph; Holden, Nora; Skurtveit, Elin; Faleide, Jan Inge & Braathen, Alvar (2022). Structural traps and seals for expanding CO2 storage in the northern Horda Platform, North Sea. Fulltekst i vitenarkiv Vis sammendrag

  Full-scale CO2 storage within the Norwegian Continental Shelf is scheduled to commence in 2024 at the Aurora site under project Longship and the Northern Lights JV. While tens of megatons of injected CO2 are anticipated over the coming years, many more storage locations are required in order to meet international climate mitigation targets by 2050. In the event of success at Aurora, the northern Horda Platform region could be further developed into a North Sea CO2 storage hub, but more subsurface evaluation is needed to identify prospective sites. Here, I present two possible Jurassic storage complexes (Lower and Upper), and discuss the presence of available storage aquifers, structural traps, as well as top and fault seals based on the latest 3D seismic and wellbore data. Our results indicate that both storage complex aquifers are preserved throughout the study area, and we have identified a total of 95 Lower and 64 Upper Jurassic fault-bound traps. Mapping, modeling, and formation pressure analyses suggest that top seals are sufficiently thick over the majority of identified traps, and provide vertical pressure barriers between storage aquifers. While across-fault juxtaposition seals appear to dominate the Upper Jurassic storage complexes, Lower Jurassic aquifers are often up-thrown against Middle and Upper Jurassic aquifers, posing a potential risk to CO2 containment for many Lower Jurassic footwall traps. However, I go on to show that apparent across fault pressure differentials and shale gouge ratio values >0.15 correlate at such juxtapositions, suggesting fault rock membrane seal presence. Moreover, I illustrate that aquifer self-juxtapositions are likely zones of poor fault seal within the study area. Overall, our work provides added support that the northern Horda Platform represents a promising location for CO2 storage expansion, carrying the potential to become a future storage hub for northern Europe.

• Skurtveit, Elin (2022). Fracture flow experiments, Little Grand Wash fault. Fulltekst i vitenarkiv
• Faleide, Thea Sveva; Smith, Scott Adam; Petrie, E. S.; Halvorsen, Kristine & Skurtveit, Elin (2022). Core characterization: CT scans, mini-perm, uniaxial compressional strength (UCS) test, P&S velocity. Fulltekst i vitenarkiv
• Skurtveit, Elin (2022). Hvordan sikrer vi trygg fangst og lagring av CO2? : Hvor mye CO2 kan vi lagre på norsk sokkel, og hvordan gjør vi det? Fulltekst i vitenarkiv
• Holden, Nora; Osmond, Johnathon L.; Mulrooney, Mark Joseph; Skurtveit, Elin; Braathen, Alvar & Sundal, Anja (2022). Structural characterization and across-fault seal assessment of the Aurora CO2 storage site, northern North Sea. Fulltekst i vitenarkiv
• Larsen, Tine B.; Skurtveit, Elin; Ringrose, Philip; Hindriks, Kees K.; Kühn, Daniela & Roberts, Dan [Vis alle 10 forfattere av denne artikkelen] (2022). Stress history and reservoir pressure for improved quantification of CO2 storage containment risks (SHARP Storage). EGU General Assembly. doi: 10.5194/egusphere-egu22-1787. Fulltekst i vitenarkiv
• Noort, Reinier Van; Choi, J.C.; Skurtveit, Elin; Fowler, T & Phillips, Chris (2024). Industry Guidelines for Setting the CO2 Specification in CCUS Chains Work Package WP10: Geological Storage. Wood PLC. Fulltekst i vitenarkiv
• Betlem, Peter; Senger, Kim; Braathen, Alvar; Skurtveit, Elin; Park, Joonsang & Lecomte, Isabelle Christine [Vis alle 7 forfattere av denne artikkelen] (2023). De-risking top seal integrity - Imaging heterogeneity across shale-dominated cap rock sequences. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  The below-ground geological storage of CO2 is seen as an important component to the long-term reduction of global greenhouse gas emissions. One of the difficult tasks is to find large storage locations with good seals (“roofs”) that prevent any stored CO2 from leaking back to the atmosphere. Leaking fluids typically follow fractures, cracks and more permeable (“open”) routes as they bypass rocks that are tighter. Such local variations contribute to geological complexity, and their study is important to geological CO2 storage. This doctoral work revolved around the use of emerging digital technologies, computer models, and drones to investigate the impact of geological complexities on fluid flow in Svalbard. Studies in Svalbard benefit from the archipelago’s unique outdoor laboratory that makes it exceptionally for analogue studies; Little vegetation makes for excellent outcrops, and a wealth of existing data can be integrated to solve complicated questions. Surface features are frequently used as analogues for “invisible” processes underground as they can more easily be catalogued and interpreted. This doctoral work did precisely that and used detailed surface information to investigate the potential impact of geological complexity on the fluid flow below ground. The resulting findings were then used to assess the current state of fluid leakage in central Svalbard, aided by dedicated studies of gas leakage and gas hydrate occurrence in the fjords. As Svalbard has a shared geological history with large parts of the Norwegian continental shelf, these findings are of regional importance.

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