Alvar Braathen

• Dahlin, Anders; Lecomte, Isabelle; Senger, Kim; Smyrak-Sikora, Aleksandra Anna; Braathen, Alvar & Stemmerik, Lars (2025). Analysing lithological complexity in outcrop-scale seismic models of interbedded siliciclastics and carbonates from Svalbard. Marine and Petroleum Geology. ISSN 0264-8172. 181, p. 1–25. doi: 10.1016/j.marpetgeo.2025.107494. Full text in Research Archive Show summary

  Thin sedimentary units typically constitute a large part of the volume of reservoirs targeted for hydrocarbons, CO2 storage, or groundwater but are considered to be below resolution thresholds of conventional seismic reflection data. Nonetheless, they affect seismic imaging through interference, and where lithology varies significantly over short distances, reflection characteristics may change laterally. This is especially valid for interbedded siliciclastic-carbonate systems characterised by lateral and vertical changes in lithology. We use high-resolution digital outcrop models of two interbedded siliciclastic-carbonate outcrops from Svalbard as input for seismic modelling using a 2D point-spread-function based convolution. The digital outcrop models show Carboniferous to Triassic strata, from southern Spitsbergen and Bjørnøya. We investigate detection thresholds (bed thickness, layer geometry, lithologic variability) and discuss their implications for resolvability on seismic data. Our base-case seismic models illustrate that units below the vertical resolution can be detected, even at high velocities (5–5.5 km/s). We present 6 scenarios to test the influence of thin (metre-scale) beds, lithological variability, faults, karstification, and imaging parameters on the seismic models. They illustrate that in mixed successions variations in reflection amplitudes, dimming and tuning effects become important for recognising thin units. Additionally, thin interfingering units can create artefacts such as apparent “faults”, thus leading to misinterpretation of seismic sections in this type of depositional setting. Varying seismic imaging parameters, such as adding random noise or reducing dominant frequency decrease the detectability of thin units.

• Maher, Harmon; Johnson, Ashley; Braathen, Alvar & Osmundsen, Per Terje (2025). Cataclastic Strain in the Footwall Rocks of the Mormon Point Turtleback, Death Valley. Lithosphere. ISSN 1941-8264. 2024(Special 15). doi: 10.2113/2024/lithosphere_2024_206. Full text in Research Archive Show summary

  We explore an example of distributed brittle deformation in a core complex exposed in the Black Mountains of Death Valley in California, USA, and distinguish between cataclastic flow, common within fault zones, and a more general and inclusive phenomenon of cataclastic strain. In canyon traverses that cut hundreds of meters into footwall rocks within the Mormon Point turtleback slip surfaces are pervasive at the outcrop scale. Several relationships indicate most of the slip surfaces formed during and after turtleback formation. With slip surface densities typically greater than 1 per meter traverse and offsets from centimeters to meters, crude minimum estimates of bulk shear strain angle components range from ~10 to 60°, indicating a non-rigid footwall. While the kinematics are generally consistent with the established dextral transtensional environment, they vary considerably spatially. Local preferred orientations vary from shallowly to steeply dipping surfaces with the entire range of dip- to strike-slip movement. The variation suggests a domainal character to the cataclastic strain at outcrop and cliff-side scales. Internal strain within larger blocks bounded by larger-magnitude slip surfaces may be accommodated by distributed lower-magnitude slip. Earlier ductile fabrics in syn-kinematic intrusive rocks indicate a ductile to brittle transition in footwall deformation consistent with the known exhumation history. In Sheep Canyon, a marble tectonite zone separates footwall rocks of the Copper Canyon turtleback to the northeast with significantly less cataclastic strain from those of the Mormon Point turtleback to the southwest which have an abundance. Such spatial variation of footwall cataclastic strain as a function of core complex geometry and lithology may be an important phenomenon in some core complexes and in other settings and is worth further investigation.

• 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. Full text in Research Archive Show summary

  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. Full text in Research Archive Show summary

  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.

• Senger, Kim; Betlem, Peter; Braathen, Alvar; Olaussen, Snorre & Sand, Gunnar (2025). Longyearbyen CO2 lab project — from a vision of a CO2-neutral Svalbard to a geoscience data eldorado. Arctic Science. ISSN 2368-7460. 11, p. 1–26. doi: 10.1139/as-2024-0019. Full text in Research Archive Show summary

  The Longyearbyen CO2 lab project was initiated in 2006 by the University Centre in Svalbard (UNIS) to establish whether subsurface storage of locally produced CO2 is feasible. Over a decade of drilling operations and geoscientific research concluded that the subsurface was suitable for storing the CO2 generated from the local power plant. The geological ingredients for successful CO2 storage are in place, comprising a ca. 300 m thick, sandstone-dominated reservoir rock capped by an impermeable mudstone-dominated succession. No CO2 was ever injected for storage in Svalbard for economic and political reasons. However, the project generated a wealth of new data, some of which proved critical for studies related to CO2 storage elsewhere. The data were also key to the characterization of fluid flow and geothermal potential in Svalbard, deciphering past climatic changes, unravelling past tectonic events, some of relevance for understanding the plate tectonic evolution of the Arctic, as well as updating the global geological timescale. In this contribution, we briefly outline the history and main achievements of the Longyearbyen CO2 lab project, before describing, categorizing and openly sharing the publicly available data from the project, including peer-reviewed publications (123 so far) and theses (18 PhD and 34 MSc).

• 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. Full text in Research Archive Show summary

  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.

• Dahlin, Anders; Blinkenberg, Kasper Høj; Braathen, Alvar; Olaussen, Snorre; Senger, Kim & Smyrak-Sikora, Aleksandra Anna [Show all 7 contributors for this article] (2024). Late syn-rift to early post-rift basin fill dynamics of a mixed siliciclastic-carbonate succession banked to a basement high, Hornsund, southwestern Spitsbergen, Arctic Norway. Basin Research. ISSN 0950-091X. 36(4). doi: 10.1111/bre.12880. Full text in Research Archive Show summary

  The transition from syn-rift to post-rift sedimentation in rift basins is difficult to characterize in terms of stratigraphic architecture and dominating control on sedimentation, due to decreasing tectonic activity interplaying with regional subsidence, eustatic sea level changes, and differential compaction of underlying syn-rift sediments. Our case study of the Late Palaeozoic Inner Hornsund Fault Zone targets late syn-rift strata recorded in the (?Pennsylvanian – ?lower Permian) Treskelodden Formation in Hornsund, southern Spitsbergen, representing a mixed siliciclastic-carbonate succession, with siliciclastics primarily sourced from the adjacent Sørkapp-Hornsund High. We document local scale (<10 km) facies variability, sequence stratigraphy, and evolution of a succession deposited along a flank of the structural high during the late syn-rift stage. We observe that during the transition towards rift termination (glacio-)eustatic sea level changes and overall regional flooding became a more prominent forcing factor controlling sedimentation. Our dataset includes sedimentary logs, microfacies analysis, and high-resolution digital outcrop models. We identify four progressively backstepping stratigraphic sequences, reflecting an evolution from (1) terrestrial siliciclastics through (2–3) nearshore mixed siliciclastic–carbonates, to (4) carbonate ramp deposits. On the small scale (<5 m) the internal sediment cyclicity of the succession was formed by autogenic processes, particularly the changing rate of sediment input from the southwestern source area (the uplifted Sørkapp-Hornsund basement high). On the larger scale (10s of m), the importance of glacio-eustatic sea-level changes, driven by waxing and waning of ice caps in the southern hemisphere (Gondwana), increased as the rift-related tectonics decreased. The interdisciplinary methods used in this study provide new knowledge of the Middle Pennsylvanian to Permian depositional evolution in southern Spitsbergen, besides a novel framework for comparison to adjacent basins in the region and similar basins elsewhere.

• Bauck, Marit Stokke; Faleide, Jan Inge; Fossen, Haakon; Hassaan, Muhammad & Braathen, Alvar (2024). Late Palaeozoic structural evolution of the Patch Bank Ridge and Utsira High, northern North Sea. Basin Research. ISSN 0950-091X. 36(5). doi: 10.1111/bre.12890. Full text in Research Archive Show summary

  This study focuses on the Late Palaeozoic development of the area east of Utsira High in the North Sea, where the stratigraphic section below the late Permian Rotliegend Group is undrilled. We use regional 3D seismic data to study structuring, sediment distribution and geomorphology across the Patch Bank Ridge and Utsira High in the North Sea. The results show that the Stord Basin and the bounding Utsira East fault initially developed during the Late Palaeozoic extension, probably during the Devonian, and that the Utsira Shear Zone controlled the location of Late Palaeozoic depocentres. The Patch Bank Ridge is an uplifted part of the Stord Basin where we identify Late Palaeozoic growth strata along the southern and northern flanks, indicating a similar timing of the structural evolution in this area. Two key wells, in the Sele High and Ling Depression, are used to relate a Late Palaeozoic isopach map with regional structuring, surface tilt and basement morphology to the enigmatic parts of the Late Palaeozoic basin system. Our results supplement regional models for the Late Palaeozoic basin development, we suggest that the deeply eroded Devonian half-grabens preserved on the Utsira High formed parts of an extensive basin system that show stratigraphic expansion towards their bounding faults. The Top Basement surface at these highs offers several distinct geomorphologies that evolved during three periods of exposure, expressed as (i) a tilted and rugose landscape, (ii) distinct drainage networks and (iii) peneplain surfaces. Cover sediments place these landscapes to the (i) Devonian, (ii) Carboniferous/Permian/Triassic and (iii) Late Triassic periods.

• 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. Full text in Research Archive Show summary

  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.

• 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. Full text in Research Archive Show summary

  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.

• Braathen, Alvar; Midtkandal, Ivar & Osmundsen, Per Terje (2024). Geomorphological traits of landscapes in continental rifts—From fault-elastic rebound to sedimentary sinks. Basin Research. ISSN 0950-091X. 36(4). doi: 10.1111/bre.12881. Full text in Research Archive
• Maher, Harmon; Braathen, Alvar; Ganerød, Morgan; Myhre, Per Inge; Osmundsen, Per Terje & Redfield, Thomas Fitzmaurice (2023). Discussion on ‘Paleozoic sedimentation and Caledonian terrane architecture in NW Svalbard: indications from U–Pb geochronology and structural analysis’ by Koglin et al. 2022 (JGS, 179, jgs2021-053). Journal of the Geological Society. ISSN 0016-7649. 180(4). doi: 10.1144/jgs2022-179. Full text in Research Archive
• Haines, Emma Michie & Braathen, Alvar (2023). How displacement analysis may aid fault risking strategies for CO<inf>2</inf> storage. Basin Research. ISSN 0950-091X. 36(1). doi: 10.1111/bre.12807. Full text in Research Archive Show summary

  Abstract Developing an accurate understanding of the ways in which faults have grown within a particular region and stratigraphy can aid risk management for CO 2 storage sites. Areas of fault interaction lead to differences in the stress field, resulting in an increased strain, which is often accommodated by a high intensity of deformation bands and/or fracturing, dependent on host rock properties. These structures alter the permeability surrounding faults. Hence, detecting areas of interaction of structures throughout the fault growth history allows the identification of locations where high risk may occur in terms of the hydraulic properties of a fault zone. The Vette Fault Zone (VFZ), bounding the Alpha prospect within the potential CO 2 Smeaheia storage site, Northern Horda Platform, is shown to have grown from a minimum of seven fault segments. By utilising a comparison with the adjacent Tusse Fault Zone (TFZ), we can identify potential areas of high risk, where fluids may have the ability to flow across or along the VFZ. The high seal strength of the TFZ holding back a large gas column is likely to be created by shale juxtaposition and smearing with cataclastic processes. The same could be assumed for the VFZ, associated with similar tectonics and displaced stratigraphy. However, rather than membrane breaching causing fluids to flow across the fault, potential areas of high risk have been identified at locations of relict breached relay zones, where the initial displacement of the intersecting faults and area of overlap was high. These areas appear to correspond with the location of hydrocarbon contact depth (spill point) along the TFZ. Using the same assumptions for the VFZ, we can observe one potential area of high risk, which lies within the area of suggested CO 2 accumulation.

• Osmundsen, Per Terje; Svendby, Anne Kathrine; Braathen, Alvar; Bakke, Beate & Andersen, Torgeir Bjørge (2023). Fault growth and orthogonal shortening in transtensional supradetachment basins: Insights from the `Old Red´ of western Norway. Basin Research. ISSN 0950-091X. 35(4), p. 1407–1432. doi: 10.1111/bre.12759. Full text in Research Archive Show summary

  For basins that evolve adjacent to large-magnitude normal faults, tectonic controls on sedimentation involve isostatic back rotation of an exhuming footwall and, commonly, the evolution of kilometre-scale extension-parallel folds. Based on observations from classic localities in western Norway, we propose a three-stage evolution scenario for transtensional supradetachment basins where the basins become progressively re-arranged because of core complex exhumation and subsequent orthogonal shortening. Extension-parallel transverse synclines initially form due to a normal displacement gradient, but when displacements accumulate beyond a certain magnitude, the hanging wall increasingly responds to core complex exhumation and the original depocentre, formed close to the original area of maximum displacement, will become inverted and dismembered above the core complex. Two new synclinal depocentres will develop along the flanks. Because these synclines form by extensional fault growth rather than by shortening, they will be associated with widening of the basin and onlap onto basement at high angles to the maximum elongation trend with overall grain-size decrease and retrogradational stacking patterns. Further, because these synclines grow away from the evolving core complex, sedimentary units will become asymmetrically distributed inside each syncline in such a way that the oldest deposits in the syncline will be preserved on the flank most proximal to the core complex. In transtensional environments, a third evolutionary stage may involve constrictional strain where extension-parallel folds and reverse faults produced by orthogonal shortening enhance or interact with other structures. Ultimately, initial extensional sub-basins may become warped across extension-parallel folds. Hanging wall deformation will be manifested in shifting accommodation patterns, with depocentres that generally migrate in the direction of the detachment fault. Accommodation patterns initially related to megafault growth may conceptually evolve into depocentres controlled by orthogonal shortening.

• Horota, Rafael Kenji; Senger, Kim; Rodes, Nil; Betlem, Peter; Smyrak-Sikora, Aleksandra & Jonassen, Marius Opsanger [Show all 8 contributors for this article] (2023). West Spitsbergen fold and thrust belt: A digital educational data package for teaching structural geology. Journal of Structural Geology. ISSN 0191-8141. 167. doi: 10.1016/j.jsg.2022.104781. Full text in Research Archive Show summary

  The discipline of structural geology is taking an advantage of compiling observations from multiple field sites to comprehend the bigger picture and constrain the region's geological evolution. In this study we demonstrate how integration of a range of geospatial digital data sets that relate to the Paleogene fault and thrust belt exposed in the high Arctic Archipelago of Svalbard, is used in teaching in bachelor-level courses at the University Centre in Svalbard. This event led to the formation of the West Spitsbergen Fold and Thrust Belt and its associated foreland basin, the Central Spitsbergen Basin. Our digital educational data package builds on published literature from the past four decades augmented with recently acquired high-resolution digital outcrop models, and 360° imagery. All data are available as georeferenced data containers and included in a single geodatabase, freely available for educators and geoscientists around the world to complement their research and fieldwork with course components from Svalbard.

• Olaussen, Snorre; Grundvåg, Sten-Andreas; Senger, Kim; Anell, Ingrid; Betlem, Peter & Birchall, Thomas [Show all 15 contributors for this article] (2023). Svalbard Composite Tectono-Sedimentary Element, Barents Sea”. Geological Society of London Memoirs. ISSN 0435-4052. 57. doi: 10.1144/M57-2021-36. Full text in Research Archive Show summary

  The Svalbard Composite Tectono-Sedimentary Element (SCTSE) is located on the northwestern corner of the Barents Shelf and comprises a Carboniferous–Pleistocene sedimentary succession. Due to Cenozoic uplift, the succession is subaerially exposed in the Svalbard archipelago. The oldest parts of the succession consist of Carboniferous–Permian mixed siliciclastic, carbonate and evaporite, and spiculitic sediments that developed during multiple phases of extension. The majority of the Mesozoic succession is composed of siliciclastic deposits formed in sag basins and continental platforms. Episodes of Late Jurassic and Early Cretaceous contraction are evident in the eastern part of thearchipelago and in nearby offshore areas. Differential uplift related to the opening of the Amerasian Basin and the Cretaceous emplacement of the High Arctic Large Igneous Province created a major hiatus spanning from the Late Cretaceous and early Danian throughout the SvalbardCTSE. The West Spitsbergen Fold and Thrust Belt and the associated foreland basin in central Spitsbergen (Central Tertiary Basin) formed as a response to the Eurekan Orogeny and the progressive northward opening of the North Atlantic during the Paleogene. This event was followed by the formation of yet another major hiatus spanning the Oligocene–Pliocene. Multiple reservoir and source-rock units exposed in Svalbardprovide analogues to the prolific offshore acreages in the SW Barents Sea, and are important for the de-risking of plays and prospects. However, the archipelago itself is regarded as a high-risk acreage for petroleum exploration. This is due to Paleogene contraction and late Neogene uplift of the western and central parts in particular. There is an absence of mature source rocks in the east, and the entire region is subjected to strict environmental protection

• Würtzen, Camilla Louise; Braathen, Alvar; Poyatos-Moré, Miquel; Mulrooney, Mark Joseph; Line, Lina Hedvig & Midtkandal, Ivar (2022). Impact of faulting in depocentres development, facies assemblages, drainage patterns, and provenance in continental half-graben basins: An example from the Fanja Basin of Oman. Basin Research. ISSN 0950-091X. 00, p. 1–39. doi: 10.1111/bre.12731. Full text in Research Archive Show summary

  Fault throw gradients create transverse folding, and this can influence accommodation creation and sedimentary routing and infill patterns in extensional half-graben basin. The Fanja half-graben basin (Oman) offers an excellent outcrop of an alluvial fan succession displaying cyclical stacking and basin-scale growth-fold patterns. These unique conditions allow for an investigation of fault-timing and accommodation development related to fault-transverse folding. Our study combines geological mapping, structural analysis, sedimentary logging and correlation, and bulk mineralogical compositions. Mapping reveals that the basin is bounded by a regional-scale fault, with local depocentres changing position in response to transverse syncline and anticline development ascribed to fault-displacement gradients. The alluvial Qahlah Formation (Late Cretaceous) is unconformably overlying the Semail Ophiolite, and is in turn overlain by the marine Jafnayn Formation (Late Palaeocene). Facies and stratigraphic analysis allows for subdivision of the Qahlah Formation into four informal units, from base to top: (i) laterite in topographic depressions of the ophiolite, (ii) greenish pebbly sandstones, deriving from axially draining braided streams deposited in the low-relief half-graben basin. This green Qahlah grades vertically into the red Qahlah, formed by alluvial fanglomerates and floodplain mudstones, with drainage patterns changing from fault-transverse to fault-parallel with increasing distance to the main fault. The red Qahlah can be divided into (iii) the Wadi al Theepa member, found in a western basin depocentre, with higher immaturity and sand: mud ratio, suggesting a more proximal source, and (iv) the Al Batah member, located in the eastern part of the basin. The latter shows better sorting, a lower sand: mud ratio, and more prominent graded sub-units. It also shows eastward expansion from an orthogonal monocline, ascribed to accommodation developed in a relay ramp. Changes in sedimentary facies and depositional patterns are consistent with differential mineralogical composition. The Green Qahlah is composed of quartz and lithic mafic rock fragments, sourced from the ophiolite and schists of the metamorphic basement. The Red Qahlah is composed of chert and kaolinite sourced from the Hawasina Nappe succession in the footwall of the master fault. These changes in source area are linked to unroofing of fault-footwalls and domal structures during the extensional collapse of the Semail Ophiolite. The novelty of this study resides in linking sedimentology and fault-displacement events controlling fault-perpendicular folding, and its influence on depocentre generation and stratigraphic architecture. This is an approach seldom considered in seismic analysis, and rarely analysed in outcrop studies, thus placing the results from this study among the key outcrop-based contributions to the field.

• Serck, Christopher Sæbø; Braathen, Alvar; Hassaan, Muhammad; Faleide, Jan Inge; Riber, Lars & Messager, Grégoire [Show all 7 contributors for this article] (2022). From metamorphic core complex to crustal scale rollover: Post-Caledonian tectonic development of the Utsira High, North Sea. Tectonophysics. ISSN 0040-1951. 836. doi: 10.1016/j.tecto.2022.229416. Full text in Research Archive
• 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. Full text in Research Archive Show summary

  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.

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• Hansen, Torsten Hundebøl; Blondel, Simon; Evans, Sian Lianne; Bruhn, Rikke & Braathen, Alvar (2025). Salt structures along the Hummer Fault Zone, offshore S. Norway – a CO2-storage perspective. Full text in Research Archive
• Anell, Ingrid & Braathen, Alvar (2025). The confounding clinoform: Recognizing compound clinoforms in the Triassic prograding stratigraphy on Svalbard and implications for reservoir properties. Full text in Research Archive
• Smyrak-Sikora, Aleksandra Anna; Senger, Kim; Osmundsen, Per Terje; Janocha, Julian; Mosociova, Tereza & Ammerlaan, Fenna [Show all 9 contributors for this article] (2025). Surface to subsurface expression of a long-lived structural element: the Billefjorden Fault Zone in Svalbard. 10th International Conference on Arctic Margins (ICAM-X) - Abstract Volume. 2025, p. 59–59. doi: https:/zenodo.org/records/16810950. Full text in Research Archive
• 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. Full text in Research Archive
• Blondel, Simon; Evans, Sian Lianne; Hansen, Torsten Hundebøl; Bruhn, Rikke & Braathen, Alvar (2024). Tectono-Stratigraphy Of The Norwegian-Danish Basin: Halokinetic Controls On The Plays For underground CO2 Storage. Full text in Research Archive
• Blondel, Simon; Evans, Sian Lianne; Hansen, Torsten Hundebøl; Bruhn, Rikke & Braathen, Alvar (2024). Tectono-Stratigraphy Of The Norwegian-Danish Basin: Halokinetic Controls On The Plays For underground CO2 Storage. Full text in Research Archive
• Blondel, Simon; Evans, Sian Lianne; Hansen, Torsten Hundebøl; Bruhn, Rikke & Braathen, Alvar (2024). Revitalizing under-explored salt basins for the energy transition: Geological storage in the Central North Sea. Full text in Research Archive
• Holden, Nora; Alaei, Behzad; Skurtveit, Elin; Braathen, Alvar; Midtkandal, Ivar & Osmond, Johnathon L. [Show all 8 contributors for this article] (2024). CO2 storage on the Horda Platform - Assessing structural complexities and fault-seal integrity. Full text in Research Archive
• Holden, Nora; Skurtveit, Elin; Braathen, Alvar; Alaei, Behzad; Midtkandal, Ivar & Osmond, Johnathon L. [Show all 8 contributors for this article] (2024). CO2 storage on the Horda Platform. Full text in Research Archive
• Holden, Nora; Alaei, Behzad; Skurtveit, Elin; Braathen, Alvar; Midtkandal, Ivar & Osmond, Johnathon L. [Show all 8 contributors for this article] (2024). Structural de-risking of CO2 storage sites on the Horda Platform. Full text in Research Archive
• Hansen, Torsten Hundebøl; Blondel, Simon; Evans, Sian Lianne; Bruhn, Rikke & Braathen, Alvar (2024). Salt structures along the Hummer Fault Zone, offshore Southern Norway. Full text in Research Archive
• Hansen, Torsten Hundebøl; Blondel, Simon; Evans, Sian Lianne; Bruhn, Rikke & Braathen, Alvar (2024). Salt structures along the Hummer Fault Zone, offshore Southern Norway. Full text in Research Archive
• Osmond, Johnathon; Faleide, Jan Inge & Braathen, Alvar (2024). Beyond trap and seal in the northern Horda Platform: when a structural geologist decided to map the Quaternary seismostratigraphy and pockmarks too. Full text in Research Archive
• Osmond, Johnathon; Faleide, Jan Inge & Braathen, Alvar (2024). Quaternary seismostratigraphic framework and pockmarks within the Norwegian Channel, northern North Sea. Full text in Research Archive Show summary

  https://doi.org/10.3997/2214-4609.2024101728 Summary: The Norwegian Channel is host to a tremendous amount of activity related to the petroleum industry in the northern North Sea, but the area is now receiving new attention related to the ongoing energy transition. Previous workers developed a seismostratigraphic framework for sediments above the Upper Regional Unconformity (URU) based on legacy 2D seismic data and core from the BH8903 geotechnical wellbore located above the Troll East field, but regional horizon surface maps remain absent from the literature. Additionally, sediments within the channel preserve both seafloor and buried pockmarks. While previous studies provided maps of pockmark areal densities and explored a wide range of possible controls over pockmark distributions within the Norwegian Channel, work can be improved by using data with greater coverage and quality. For this work, we have utilised a large, modern 3D seismic survey, wellbore data, and the legacy seismostratigraphic framework in order to produce novel Quaternary seismic horizons surface maps and updated pockmark distribution maps within the Norwegian Channel. Overall, our results have utility for basin studies and hydrocarbon exploration within the region, but also supports work for local CO2 storage and offshore wind developments, which require the mapping of overburden stratigraphy and potential geohazards

• 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. Full text in Research Archive Show summary

  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 [Show all 7 contributors for this article] (2024). Containment derisking of a potential CO2 storage hub in the Horda Platform, Norwegian North Sea. Full text in Research Archive
• Osmond, Johnathon; Holden, Nora; Würtzen, Camilla Louise; Cruz, Erika H de La; Skurtveit, Elin & Faleide, Jan Inge [Show all 7 contributors for this article] (2024). Distribution of Upper Jurassic–Upper Cretaceous seals in the northern Horda Platform: considerations for CO2 storage within the Smeaheia area (EL002). Full text in Research Archive Show summary

  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.

• Hansen, Torsten Hundebøl; Blondel, Simon; Evans, Sian Lianne; Bruhn, Rikke & Braathen, Alvar (2024). CCNS - Evaluating CO2-storage potential offshore Southern Norway. Full text in Research Archive
• Skurtveit, Elin; Midtkandal, Ivar & Braathen, Alvar (2023). A naturally occurring CO2 laboratory in Utah. Full text in Research Archive
• Evans, Sian Lianne; Blondel, Simon; Braathen, Alvar & Bruhn, Rikke (2023). CO2 storage in salt basins: Influence of salt tectonics on seal integrity and containment risk. Full text in Research Archive
• 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. Full text in Research Archive
• Evans, Sian Lianne; Blondel, Simon; Braathen, Alvar & Bruhn, Rikke (2023). Optimising Site Selection for CO2 Storage in Salt Basins: the Norwegian-Danish Basin, a future European energy hub. Full text in Research Archive
• Evans, Sian Lianne; Blondel, Simon; Braathen, Alvar & Bruhn, Rikke (2023). CO2 storage in salt basins: Influence of salt tectonics on seal integrity and containment risk. Full text in Research Archive
• Skurtveit, Elin; Petrie, Elizabeth S.; Smith, Scott Adam; Faleide, Thea Sveva; Sundal, Anja & Choi, Jung Chan [Show all 10 contributors for this article] (2023). Core analysis from Little Grand Wash fault, Utah, and application for fault risk assessment for co2 storage in the Norwegian North Sea. Full text in Research Archive Show summary

  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.

• Blondel, Simon; Evans, Sian Lianne; Bruhn, Rikke & Braathen, Alvar (2023). CO2 storage research and Cross-border synergies in the southern Norwegian North Sea. Full text in Research Archive
• Blondel, Simon; Evans, Sian Lianne; Hansen, Torsten Hundebøl; Bruhn, Rikke & Braathen, Alvar (2023). CO2 storage research and cross-border synergies: Underground CO2 storage potential assessment in the western Norwegian-Danish basin. Full text in Research Archive
• Blondel, Simon; Evans, Sian Lianne; Bruhn, Rikke & Braathen, Alvar (2023). CO2 storage research and cross-border synergies: Underground CO2 storage potential assessment in the western Norwegian-Danish basin. Full text in Research Archive
• 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. Full text in Research Archive
• 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. Full text in Research Archive
• 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. Full text in Research Archive
• Braathen, Alvar (2023). Impact of fault-elastic rebound for sediment characteristics in hanging wall basins: observations and cases. Full text in Research Archive
• Blinkenberg, Kasper & Braathen, Alvar (2023). Zechstein carbonates of the Utsira High region. Full text in Research Archive
• Osmundsen, P.T. & Braathen, Alvar (2023). From rift-fault to mega-fault: fault throw and rollback impacting basin geometries. Full text in Research Archive
• Osmundsen, P.T. & Braathen, Alvar (2023). Setting of the Frøya High and its northwards continuation to the Norland Ridge. Full text in Research Archive
• Peron-Pinvidic, Gwen & Braathen, Alvar (2023). Evolution of the mid-Norwegian margin – from rift to breakup. Full text in Research Archive
• Parcher, J. & Braathen, Alvar (2023). Basement-top plays and Jurassic deposits off the Utsira High (Johan Sverdrup Field). Full text in Research Archive
• Braathen, Alvar (2023). Plans for a Suprabasins-II proposal (to Petromaks2: 15/2 or 15/9-23?). Full text in Research Archive
• 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. Full text in Research Archive
• Braathen, Alvar (2023). Isostatic rollback of faults and perched basins – some observations. Full text in Research Archive
• Braathen, Alvar & Midtkandal, Ivar (2023). Plans for a Suprabasins-II proposal. Full text in Research Archive
• Braathen, Alvar (2023). Plans for a Suprabasins-II proposal. Full text in Research Archive
• Braathen, Alvar (2023). Introduction to Suprabasins. Full text in Research Archive
• Braathen, Alvar (2023). Introduction to Utsira High proper. Full text in Research Archive
• Braathen, Alvar (2023). Status on Suprabasins. Full text in Research Archive
• Evans, Sian Lianne; Blondel, Simon; Braathen, Alvar & Bruhn, Rikke (2023). Evolution of salt diapirs in the Norwegian NDB. Full text in Research Archive
• 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. Full text in Research Archive
• Osmond, Johnathon; Mulrooney, Mark Joseph; Würtzen, Camilla Louise; Cruz, E. De La; Skurtveit, Elin & Faleide, Jan Inge [Show all 7 contributors for this article] (2022). Upper Jurassic through Lower Cretaceous seal characterization in the northern Horda Platform. Full text in Research Archive
• Midtkandal, I; Braathen, Alvar & Osmundsen, Per Terje (2022). Rift footwall range geomorphology as a function of fault length and throw. Full text in Research Archive
• Smyrak-Sikora, Aleksandra; Augland, Amund; Betlem, Peter & Braathen, Alvar (2022). Deep-time paleoclimate events preserved in Svalbard’s rock record – a review. 35th IAS Meeting of Sedimentology. Full text in Research Archive
• Vicedo, v; Robles-Salcedo, R; Poyatos-Moré, Miquel; Braathen, Alvar & Midtkandal, Ivar (2022). Evolution of a Paleogene shallow-marine platform in the northern sector of the Ibra Basin (NE Oman). Full text in Research Archive
• Hassan, Muhammad & Braathen, Alvar (2022). Tectonic evolution of the Utsira High region. Full text in Research Archive
• Haines, Emma Michie & Braathen, Alvar (2022). Strategies to De-Risk Faults in the Subsurface for CO2 Storage: A Case Study from Smeaheia. Full text in Research Archive
• Holden, Nora; Osmond, Johnathon; Mulrooney, Mark Joseph; Skurtveit, Elin; Braathen, Alvar & Sundal, Anja (2022). Influence of faults on Co2 migration. Full text in Research Archive
• 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. Full text in Research Archive
• Anell, Ingrid; Braathen, Alvar; Midtkandal, Ivar; Olsen, Stine Grimsrud; Haugen, Maria & Wallace, Malcolm W (2022). Geometric controls on clinoforms, the building blocks of sedimentary basins – from ripple to shelf-edge. Full text in Research Archive
• Blinkenberg, Kasper Høj; Braathen, Alvar; Stemmerik, Lars; Gianotten, Ingrid Piene & Polonio, Israel (2022). Permian carbonates of the Utsira High - new learnings. Full text in Research Archive
• Puig, Jose Maria; Braathen, Alvar & Howel, John (2022). Shallow marine sedimentary architecture of Jurassic growth-basin proximal to exhumed basement – the Johan Sverdrup case. Full text in Research Archive
• Osmond, Johnathon L.; Mulrooney, Mark Joseph; Holden, Nora; Leon, Elias H.; Cruz, Erika H. de La & Würtzen, Camilla Louise [Show all 9 contributors for this article] (2022). Containment derisking of a potential CO2 storage hub in the Horda Platform, Norwegian North Sea. Full text in Research Archive
• 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. Full text in Research Archive Show summary

  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 [Show all 9 contributors for this article] (2022). Containment Risk Assessment and Management of CO2 Storage on the Horda Platform. Full text in Research Archive
• 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. Full text in Research Archive Show summary

  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.

• Würtzen, Camilla Louise; More, M.P; Midtkandal, Ivar & Braathen, Alvar (2022). The impact of faulting in depocentre development, facies assemblages, drainage patterns, and provenance in continental half‐graben basins: an example from the Fanja Basin of Oman. Basin Research. Full text in Research Archive
• Braathen, Alvar; Skurtveit, Elin; Mulrooney, Mark Joseph; Haines, Emma Michie; Faleide, Thea Sveva & Osmond, Johnathon [Show all 10 contributors for this article] (2022). Understanding faults and their influence on fluid flow. Full text in Research Archive
• Haines, Emma Michie; Braathen, Alvar & Alaei, Behzad (2022). How Fault Interpretation Method May Influence the Assessment of a Fault-bound CO2 Storage Site. Full text in Research Archive
• Haines, Emma Michie & Braathen, Alvar (2022). Strategies to De-Risk Faults in the Subsurface for CO2 Storage: A Case Study from Smeaheia. Full text in Research Archive
• Skurtveit, Elin; Bjørnarå, Tore Ingvald; Michie, Emma; Gasda, Sarah Eileen; Keilegavlen, Eirik & Sandve, Tor Harald [Show all 10 contributors for this article] (2022). Updated workflow for fault risk assessment and application to Vette Fault Zone, Horda Platform, offshore Norway. Full text in Research Archive
• Smyrak-Sikora, Aleksandra Anna; Blinkenberg, Kasper H.; Braathen, Alvar; Janocha, Julian; Johannessen, Erik Petter & Mosociova, Tereza [Show all 11 contributors for this article] (2022). Carboniferous - Permian rift systems in Svalbard. Full text in Research Archive
• Osmundsen, Per Terje; Peron, Gwenn; Gresseth, Julie Linnea Sehested & Braathen, Alvar (2022). 3D evolution of exensional detachment faults and their effect on the architecture of rifts and rifted margins. Full text in Research Archive
• Osmundsen, Per Terje; Peron, Gwenn; Gresseth, Julie Linnea Sehested & Braathen, Alvar (2022). 3D evolution of large-magnitude extensional faults and their effects on the architecture of rifts and rifted margins. Full text in Research Archive
• Blinkenberg, Kasper; polonio, israel & Braathen, Alvar (2022). Follow-up meeting. Full text in Research Archive
• Smyrak-Sikora, Aleksandra; Blinkenberg, Kasper; Braathen, Alvar & Dahlin, Anders (2022). Carboniferous–Permian rift systems in Svalbard. Full text in Research Archive
• Blinkenberg, Kasper; polonio, israel & Braathen, Alvar (2022). Zechstein collaboration work. Full text in Research Archive
• Blinkenberg, Kasper; Hodgkins, Malcolm & Braathen, Alvar (2022). U/Pb geochronology status meeting. Full text in Research Archive
• Blinkenberg, Kasper; polonio, israel; Rameil, Niels & Braathen, Alvar (2022). Lundin carbonates. Full text in Research Archive
• Blinkenberg, Kasper; polonio, israel & Braathen, Alvar (2022). Zechstein meeting. Full text in Research Archive
• Blinkenberg, Kasper; Rameil, Niels & Braathen, Alvar (2022). Core workshop and core viewing of Zechstein material. Full text in Research Archive
• Braathen, Alvar & Eliassen, Gard (2023). Sele Ridge tectonics. Universitetet i Oslo. Full text in Research Archive
• Betlem, Peter; Senger, Kim; Braathen, Alvar; Skurtveit, Elin; Park, Joonsang & Lecomte, Isabelle Christine [Show all 7 contributors for this article] (2023). De-risking top seal integrity - Imaging heterogeneity across shale-dominated cap rock sequences. Universitetet i Oslo. Full text in Research Archive Show summary

  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.

• Braathen, Alvar & Johansen, Sindre Ekrene (2022). Tectono-sedimentary evolution of NW parts of the Devonian Hornelen Basin, West Norway. Universitetet i Oslo. Full text in Research Archive
• Jarl, Espelund & Braathen, Alvar (2022). Extensional fault growth in high-resolution seismic data. Universitetet i Oslo. Full text in Research Archive
• Bondevik, Lars H. & Braathen, Alvar (2022). Extensional fault growth in high-resolution seismic data. Universitetet i Oslo. Full text in Research Archive

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