Valentin Zuchuat

• Smyrak-Sikora, Aleksandra; Osmundsen, Per Terje; Braathen, Alvar; Ogata, Kei; Anell, Ingrid Margareta; Mulrooney, Mark Joseph & Zuchuat, Valentin (2019). Architecture of growth basins in a tidally influenced, prodelta to delta-front setting: The Triassic succession of Kvalpynten, East Svalbard. Basin Research.  ISSN 0950-091X. . doi: 10.1111/bre.12410 Full text in Research Archive.
• Zuchuat, Valentin; Midtkandal, Ivar; Poyatos More, Miquel; Da Costa, Sigrid; Brooks, Hannah Louise; Halvorsen, Kristine; Cote, Nathan; Sundal, Anja & Braathen, Alvar (2019). Composite and diachronous stratigraphic surfaces in low-gradient, transitional settings: The J-3 “unconformity” and the Curtis Formation, east-central Utah, U.S.A.. Journal of Sedimentary Research.  ISSN 1527-1404.  89(11), s 1075- 1095 . doi: 10.2110/jsr.2019.56 Show summary

  Unconformities, by definition, correspond to erosional or nondepositional surfaces, which separate older strata below, from younger rocks above, encapsulating significant time gaps. However, recent studies have highlighted the composite nature of some unconformities, as well as their heterochronous and diachronous character, which challenge the use of such a definition in a four-dimensional dynamic environment. The J-3 Unconformity, separating the Middle Jurassic Entrada Sandstone from the Upper Jurassic Curtis Formation (and laterally equivalent units) in east-central Utah (USA), is laterally variable, generated by either erosion-related processes such as eolian deflation, and water-induced erosion, or by deformational processes. The J-3 Unconformity is a composite surface, formed by numerous processes that interacted and overlapped spatially and temporally. This study therefore demonstrates the heterochronous, diachronous, and non-unique nature of this surface interpreted as unconformity, where one process can be represented by varying expressions in the stratigraphic record, and conversely many processes may result in the same stratigraphic expression.

• Zuchuat, Valentin; Sleveland, Arve; Pettigrew, Ross P.; Dodd, Thomas J.H.; Clarke, Stuart M.; Rabbel, Ole; Braathen, Alvar & Midtkandal, Ivar (2019). Overprinted allocyclic processes by tidal resonance in an epicontinental basin: the Upper Jurassic Curtis Formation, east‐central Utah, USA. The Depositional Record.  ISSN 2055-4877.  5(2), s 272- 305 . doi: https://doi.org/10.1002/dep2.69
• Zuchuat, Valentin; Sleveland, Arve Rein Nes; Sprinkel, Douglas A.; Rimkus, Algirdas; Braathen, Alvar & Midtkandal, Ivar (2018). New insights on the impact of tidal currents on a low-gradient, semi-enclosed, epicontinental basin — the Curtis Formation, east-central Utah, USA. Geology of the Intermountain west (GIW).  ISSN 2380-7601.  5, s 131- 165
• Skurtveit, Elin; Braathen, Alvar; Larsen, Eivind Bernhard; Sauvin, Guillaume; Sundal, Anja & Zuchuat, Valentin (2017). Pressure Induced Deformation and Flow Using CO2 Field Analogues, Utah. Energy Procedia.  ISSN 1876-6102.  114, s 3257- 3266 . doi: 10.1016/j.egypro.2017.03.1457 Full text in Research Archive. Show summary

  Exhumed reservoirs providing evidence of CO2 accumulation and transport in geological history offer a unique possibility to supplement our knowledge on leakage processes observed along faults and fractures. A field location and drill core from Central Utah, USA has been used to characterize mechanical properties and fracture distributions in multiple reservoir-caprock couplets where bleaching pattern around fractures provides evidence of fluid flow. Analysis shows that fractures are mainly observed in low porosity units corresponding to layers with high strength and stiffness. Microstructural characterization substantiates evidence of fracture aperture separated by areas with mineral precipitation clogging aperture. Minerals observed filling fractures are calcite, gypsum and pyrite, suggestive of precipitation from reducing fluids. Fracture aperture distribution and identification of mineralogical changes along the fracture surface provides important input for improved, novel analyses of CO2 transport properties of fractures and faults.

• Sundal, Anja; Miri, Rohaldin; Hellevang, Helge; Tveranger, Jan; Midtkandal, Ivar; Zuchuat, Valentin; Aagaard, Per & Braathen, Alvar (2017). Movement of CO 2 charged fluids in low permeability rocks during deformation: migration patterns in the Carmel Formation, Utah. Energy Procedia.  ISSN 1876-6102.  114, s 4537- 4544 . doi: 10.1016/j.egypro.2017.03.1570

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• Anell, Ingrid Margareta; Serck, Christopher Sæbø; Zuchuat, Valentin & Braathen, Alvar (2020). Structural influence on Triassic deposition on the Northern Barents Shelf.
• Zuchuat, Valentin; Hafner, Alison; Osmond, Johnathon L.; Liberty, Lee; Petrie, Elizabeth; Arvesen, Brock; Evans, Jim; Sundal, Anja; Midtkandal, Ivar; Skurtveit, Elin & Braathen, Alvar (2020). CO2 containment and monitoring techniques along Little Grand Wash Fault, east-central Utah, USA. Show summary

  Our current understanding of sub-surface CO2 storage feasibility derives mainly from valuable small-scale projects, which have mostly been working at injection or human time scales. These projects, however, have not been operational long enough to fully assess flow and/or seepage at longer time scales relevant for subsurface CO2 sequestration (e.g. > 10 kY). Many examples of fluid escape have been documented in the offshore subsurface environment (e.g. seismic chimneys), and active or relict natural seeps on land offer informative analogues to subsurface fluid migration. Of note are the natural seeps located in east-central Utah, USA that are easily accessible and represent suitable onshore counterparts to the offshore fluid escape features. These seeps can be studied to improve our understanding of geological and geomechanical factors controlling subsurface CO2 containment and the expression of fluid escape in geophysical images. A critical concern in CCS is how to account for features that are detrimental to subsurface storage containment and are at scales below seismic resolution. This multidisciplinary project aims to address the challenge by collecting surface and subsurface datasets at mesoscopic scales that, through upscaling, will be implemented in seismic investigations and reservoir-seal models. The project builds upon previous studies detailing the complex development of the Jurassic sedimentary basin in question (Zuchuat et al. 2018; 2019a; 2019b) but is also relevant for analogous settings such as the Norwegian Continental Shelf (e.g. Horda Platform region). Overall, this next research phase specifically focuses on the detailed, post-depositional history of the targeted interval in Utah, addressing one fundamental question: what are the thresholds for detecting CO2 seeps in the subsurface? This encompasses more targeted questions: • What does the fault core and the fault damage zone of the leaking Little Grand Wash Fault consist of? • What is the detailed geological footprint of CO2 flow along strata, faults, and fractures? • How did the CO2 flow migrate through a heterogeneous and transitional, faulted reservoir-seal complex? • Can seepage from the storage compartments and fluid saturation be identified by seismic imaging? Zuchuat, V., Sleveland, A. R., Sprinkel, D. A., Rimkus, A., Braathen, A., & Midtkandal, I. (2018). New Insights on the Impact of Tidal Currents on a Low-gradient, Semi-enclosed, Epicontinental Basin—the Curtis Formation, East-central Utah, USA. Geology of the Intermountain West, 5, 131-165. Zuchuat, V., Sleveland, A.R.N., Pettigrew, R.P, Dodd, T.J.H., Clarke, S.M., Braathen, A., & Midtkandal, I. (2019a). Overprinted Allocyclic Processes by Tidal Resonance in an Epicontinental Basin: the Upper Jurassic Curtis Formation, East-Central Utah, USA. The Depositional Record, 5(2), 272-305. Zuchuat, V., Midtkandal, I., Poyatos-Moré, M., Da Costa, S., Brooks, H.L., Halvorsen, K., Cote, N., Sundal, A., & Braathen, A. (2019b). Composite and Diachronous Stratigraphic Surfaces in Low-Gradient, Transitional Settings: the J-3 “Unconformity” and the Curtis Formation, East-Central Utah, U.S.A. Accepted in The Journal of Sedimentary Research.

• Zuchuat, Valentin; Midtkandal, Ivar; Poyatos More, Miquel; Da Costa, Sigrid; Brooks, Hannah L; Halvorsen, Kristine; Sundal, Anja; Cote, Nathan & Braathen, Alvar (2020). Brexit, Megxit, and the J-3 Unconformitexit: how they all lost it.. Show summary

  Unconformities, by definition, correspond to non-depositional or erosive surfaces, separating older strata below, from younger rocks above, and encapsulating significant time gaps. However, recent studies have emphasized the composite nature of some unconformities, as well as their heterochronous and diachronous character, which restricts the use of such a definition to a near one-dimensional setting. This study analyses the nature of the J-3 Unconformity, which separates the Middle Jurassic Entrada Sandstone from the Late Jurassic Curtis Formation (and laterally equivalent units) in east-central Utah (USA). Our detailed mapping and characterization indicates the J-3 “Unconformity” is in fact a composite surface generated by either erosion-related processes such as eolian deflation, and water-induced erosion, or by deformational processes. These multiple mechanisms interacted and overlapped in time and space, which demonstrates the composite and diachronous and non-unique nature of such boundaries. This contact has been historically interpreted as an unconformity, but our results show that this key stratigraphic surface is a time-transgressive flooding-ravinement surface that formed shortly before and during a series of transgressions that flooded the area during the Late Jurassic. Consequently, the regionally extensive, composite, heterochronous, and diachronous J-3 Unconformity does not fit the classic unconformity definition, after which an unconformity universally separates older from younger strata basin-wide. The J3 “Unconformity” case study highlights the fact that one process can be represented by varying expressions in the stratigraphic record, and conversely many processes may result in the same stratigraphic expression. Consequently a revised definition of unconformity is discussed, focusing on processes and associated environmental changes, while abandoning its time-barrier aspect. This investigation also exemplifies some of the implications on subsurface analyses that the inaccurate characterization of the subseismic complex characters of such major stratigraphic bounding surfaces can have. These inaccuracies may lead to imprecise timing and sediment budget predictions, and ultimately have strong implications for basin evolution and reservoir models. Key words: Unconformity, transitional basin, composite surface, ravinement, time-transgressive

• Zuchuat, Valentin; Sleveland, Arve; Sprinkel, Douglas; Pettigrew, Ross P.; Dodd, Thomas J.H.; Clarke, Stuart M.; Braathen, Alvar & Midtkandal, Ivar (2020). When Utah was a blue state: the sedimentology of the tidally-influenced Upper Jurassic Curtis Formation. Show summary

  The sedimentary record of east-central Utah during the Middle/Late Jurassic shows that arid conditions prevailed, punctuated by episodic incursions of the Sundance Sea from the north. It is some of these incursions that terminated the Entrada aeolian system, and deposited the overlying shallow-marine Curtis Formation in a tide-dominated, semi-enclosed basin. The shallow-marine system was neighboured by a coastal aeolian system belonging to the Moab Member of the Curtis Formation, and a fluvially-starved, sporadically-flooded, paralic belt of the Summerville Formation. These paralic deposits progressively blanketed the shallow-marine strata of the Curtis Formation as the sea regressed northward. This study deconstructs and analyses the continental to shallow-marine deposition during one transgressive-regressive cycle. Our analysis sub-divides the Curtis Formation into three informal units: the lower, middle and upper Curtis. Allocyclically-driven, short-lived relative sea-level variations, along with episodes of uplift and deformation, dominated over autocyclic processes of the Curtis Sea as the lower Curtis was deposited. The system entered into tidal resonance following the onset of the major transgression that defines the base of the middle Curtis, as the flooded basin reached an optimal length that corresponded to an odd multiple of one quarter tidal wavelength. This high-energy resonant system overprinted the effects of allocyclic forcing within the middle Curtis. By contrast, the neighbouring coastal systems continued to record allocyclic signals preserved as five stacked aeolian sequences of the Moab Member of the Curtis Formation, and a cyclical pattern recognised within the supratidal Summerville Formation. By documenting a resonant stage in a tide-influenced basin that overprints the otherwise dominant allocyclic processes, this study highlights the importance of assessing coeval depositional systems in order to build complete stratigraphic basin histories. Keywords: allocyclic, autocyclic, Curtis Formation, stratigraphic surfaces, tidal resonance, aeolian sequences, Utah.

• Zuchuat, Valentin (2019). Continental to Shallow Marine Transition in a Tide-Dominated, Low Accommodation basin - Controlling Factors and Depositional Architecture.
• Zuchuat, Valentin; Osmond, Johnathon L.; Sundal, Anja; Midtkandal, Ivar; Skurtveit, Elin; Petrie, Elizabeth; Evans, Jim; Liberty, Lee & Braathen, Alvar (2019). CO2 containment and monitoring techniques along Little Grand Wash Fault, east-central Utah, USA. Show summary

  Our current understanding of sub-surface CO2 sequestration feasibility derives mainly from valuable small-scale projects, which have mostly been working at injection or human time scales. These projects, however, have not been operational long enough to fully assess flow and/or seepage at longer time scales relevant for subsurface CO2 storage (e.g. > 10 kY). Many examples of fluid escape have been documented in the offshore subsurface environment (e.g. seismic chimneys), and natural seeps found on land, both active and relict, offer informative analogues to subsurface fluid migration. Of note are the natural seeps located in east-central Utah, USA that are easily accessible and represent suitable onshore counterparts to the offshore fluid escape features. These seeps can improve our understanding of geological and geomechanical factors controlling subsurface CO2 containment and the expression of fluid escape in geophysical images. A critical concern is how to account for features that are detrimental to subsurface storage containment and are at scales below seismic resolution. This multidisciplinary project aims to address the challenge by collecting surface and subsurface datasets at mesoscopic scales that, through viable upscaling, will be implemented in seismic investigations and reservoir-seal models. Moreover, the project builds upon previous studies detailing the complex development of the Jurassic sedimentary basin in question (Zuchuat et al. 2018; 2019; in press) but is also relevant for the Horda Platform region (Aurora and Smeaheia) or other prospective North Sea CO2 storage sites. Overall, this next research phase specifically focuses on the detailed, post-depositional history of the targeted interval in Utah, addressing one fundamental question: what are the thresholds for detecting CO2 seeps in the subsurface? This encompasses more targeted questions: • What is the detailed geological footprint of CO2 flow along strata, faults, and fractures? • How did the CO2 flow migrate through a heterogeneous and transitional, faulted reservoir-seal complex? • Can seepage from the storage compartment be identified by seismic imaging? • Can detailed geological datasets and related geophysical models verify the existence of – and facilitate quantification of CO2 volumes (saturation) required to create offshore geophysical chimneys, and thereby improve integrity assessment of prospective North Sea CO2 reservoirs? Zuchuat, V., Sleveland, A. R., Sprinkel, D. A., Rimkus, A., Braathen, A., & Midtkandal, I. (2018). New Insights on the Impact of Tidal Currents on a Low-gradient, Semi-enclosed, Epicontinental Basin—the Curtis Formation, East-central Utah, USA. Geology of the Intermountain West, 5, 131-165. Zuchuat, V., Sleveland, A.R.N., Pettigrew, R.P, Dodd, T.J.H., Clarke, S.M., Braathen, A., & Midtkandal, I. (2019). Overprinted Allocyclic Processes by Tidal Resonance in an Epicontinental Basin: the Upper Jurassic Curtis Formation, East-Central Utah, USA. The Depositional Record, 5(2), 272-305. Zuchuat, V., Midtkandal, I., Poyatos-Moré, M., Da Costa, S., Brooks, H.L., Halvorsen, K., Cote, N., Sundal, A., & Braathen, A. (in press.). Composite and Diachronous Stratigraphic Surfaces in Low-Gradient, Transitional Settings: the J-3 “Unconformity” and the Curtis Formation, East-Central Utah, U.S.A. Accepted in The Journal of Sedimentary Research.

• Zuchuat, Valentin; Sleveland, Arve Rein Nes; Pettigrew, Ross P.; Dodd, Thomas J.H.; Clarke, Stuart M.; Braathen, Alvar & Midtkandal, Ivar (2019). Why you should care about neighbouring sedimentary systems: Overprinted allocyclic processes by tidal resonance in the Upper Jurassic Curtis Formation, Utah, USA.
• Bromander, Nikoline; da Costa, Sigrid; Skurtveit, Elin; Evans, Jim; Midtkandal, Ivar; Zuchuat, Valentin; Braathen, Alvar & Sundal, Anja (2018). Regional evaluation of structural collapse in sandstone reservoirs and impact on reservoir quality: a case study from the Entrada Sandstone, Utah, USA.
• daCosta, Sigrid Østmo; Bromander, Nikoline; Zuchuat, Valentin; Braathen, Alvar; Sundal, Anja & Midtkandal, Ivar (2018). Topographic Development as a result of regional incision, faulting, and deposition at the onset of relative sea-level rise; The upper Entrada Sandstone and the lower Curtis Formation, Utah, USA..
• Midtkandal, Ivar; Sundal, Anja; Braathen, Alvar; Petrie, Elizabeth; Evans, James R.; Zuchuat, Valentin; Skurtveit, Elin; Tveranger, Jan; Torabi, Anita & Gutierrez, Marte (2018). Project summary: CO2 seal bypass - a multidisciplinary approach to CO2 migration and storage.
• Zuchuat, Valentin; Midtkandal, Ivar; Miquel, Poyatos-More; Da Costa, Sigrid; Halvorsen, Kristine Årland; Sundal, Anja; Cote, Nathan & Braathen, Alvar (2018). Unconformities matter: The spatial and temporal information contained in the J-3 Unconformity and the Curtis Formation, east-central Utah, USA. Show summary

  Unconformities matter: The spatial and temporal information contained in the J-3 Unconformity and the Curtis Formation, east-central Utah, USA

• Zuchuat, Valentin; Sleveland, Arve Rein Nes; Rabbel, Ole; Braathen, Alvar; Midtkandal, Ivar; Pettigrew, Ross P.; Dodd, Thomas J.H. & Clarke, Stuart M. (2018). Why you should care about neighbouring sedimentary systems: Overprinted allocyclic processes by tidal resonance in the Upper Jurassic Curtis Formation, Utah, USA..
• Midtkandal, Ivar; Zuchuat, Valentin; Braathen, Alvar; Sundal, Anja & Evans, James (2017). Syn-sedimentary subsurface liquefaction and collapse; injectites, pseudo-channels and pseudo-clinoforms in the Jurassic Entrada and Curtis Formations, Utah, USA.
• Skurtveit, Elin; Sundal, Anja; Sauvin, Guillaume; Soldal, Magnus; Zuchuat, Valentin & Braathen, Alvar (2017). Fracture flow experiments addressing CO2 migration in fault zone.
• Sleveland, Arve Rein Nes; Zuchuat, Valentin; Rimkus, Algirdas; Midtkandal, Ivar; Sundal, Anja & Braathen, Alvar (2017). Spatial and temporal distribution of tidally modified sandstone reservoirs – implications for CCS and petroleum exploration.
• Zuchuat, Valentin; Midtkandal, Ivar; Braathen, Alvar; Sundal, Anja; Skurtveit, Elin; Hellevang, Helge; Tveranger, Jan; Evans, James & Petrie, Elizabeth (2017). COPASS - CO2 seal bypass.
• Zuchuat, Valentin; Midtkandal, Ivar; Da Costa, Sigrid; Sundal, Anja & Braathen, Alvar (2017). Schizophrenia in sedimentology: The J-3 Unconformity and the Curtis Formation, Central-Eastern Utah, USA. Show summary

  The tide-dominated, Upper Jurassic Curtis Formation crops out in Eastern-Central Utah, overlying the continental to marginal marine Entrada Sandstone. The contact between the two sedimentary formations is formally identified as the J-3 Unconformity, which can be traced over significant distances. It has since been regarded as a “simple” subaerial unconformity, followed by a third order transgression within an enclosed basin and the resulting deposition of the tide-influenced Curtis Formation. However, careful inspection of the different facies and their sub-regional correlation clearly shows that the essence of the J-3 Unconformity is not merely characterised by a long-lasting phase of subaerial exposure. It instead displays evidence of an intricate poly-erosional history, happening during short-lived syn-depositional transgressive and regressive periods. The initial bounding surface was locally altered by processes associated with development of the Curtis Formation, and the nature of their impact is strongly process-dependent. Pre-Curtis erosional processes mainly involved aeolian deflation and fluvial incision, creating a basinwide gentle relief. Syn-Curtis erosional mechanisms were controlled by the distribution and magnitude of tidal forces within the basin, resulting in a steeper and more localised relief in comparison with pre-Curtis widespread denudation. Furthermore, sedimentary processes alone can’t explain the present-day relief observed with the J-3 Unconformity. Indeed, tectonic played, at various scale, a key role in the funnelling of the various erosional forces and the distribution of the depocentres, with (i) m-scale grabens and horsts structures, and (ii) hydroplastic sand remobilisation, both observed within the uppermost strata of the Entrada Sandstone, as well as (iii) syn-Curtis sub-regional tectonic uplift. This study shows that reducing an unconformity to a single process is insufficient. Instead, careful mapping and understanding of such a schizophrenic surface can provide a non-negligible amount of information regarding the dynamic of a basin and its subsequent infill.

• Zuchuat, Valentin; Sleveland, Arve Rein Nes; Rimkus, Algirdas; Braathen, Alvar & Midtkandal, Ivar (2017). Modelling the Sequence Stratigraphic Development of the Upper Jurassic Curtis Formation along the NE Margin of the San Rafael Swell, Central-Eastern Utah, USA: an Example of a Low-Gradient Tidal Basin.
• Planke, Sverre; Zuchuat, Valentin; Svensen, Henrik; Hammer, Øyvind; Braathen, Alvar; Silkoset, Petter; Midtkandal, Ivar; Nagy, Jenø; Kürschner, Wolfram Michael; van Soelen, Elsbeth Ester; Faleide, Jan Inge; Augland, Lars Eivind; Jones, Morgan Thomas; Jerram, Dougal Alexander; Franeck, Franziska; Sassier, Caroline; Domeier, Mathew; Twitchett, Richard J.; Jochmann, Malte; Zayoncheck, Andrey; Haflidason, Haflidi; Buckley, Simon John; Kurz, Tobias Herbert; Olaussen, Snorre; Mørk, Atle; Løvø, Vigdis & Lie, Jan Erik (2016). Coring and High-Resolution Imaging of the Permian-Triassic Boundary in Deltadalen, Svalbard.
• Sundal, Anja; Miri, Rohaldin; Hellevang, Helge; Tveranger, Jan; Midtkandal, Ivar; Zuchuat, Valentin & Braathen, Alvar (2016). Movement of CO2 charged fluids in low permeability rocks during deformation: migration patterns in the Carmel Formation, Utah.
• Algirdas, Rimkus; Sundal, Anja; Sleveland, Arve Rein Nes; Zuchuat, Valentin & Midtkandal, Ivar (2015). Sedimentology and reservoir quality of a tidally modified marginal marine succession; the Middle Jurassic Curtis Formation, southeastern Utah, USA..
• Planke, Sverre; Twitchett, Richard; Zuchuat, Valentin; Svensen, Henrik; Hammer, Øyvind; Braathen, Alvar; Silkoset, Petter; Midtkandal, Ivar; Nagy, Jenø; Kürschner, Wolfram Michael; van Soelen, Elsbeth Ester; Faleide, Jan Inge; Augland, Lars Eivind; Jochmann, Malte; Zayoncheck, Andrey; Haflidason, Haflidi; Buckley, Simon John; Kurz, Tobias Herbert; Olaussen, Snorre; Mørk, Atle; Løvø, Vigdis & Lie, Jan Erik (2015). Coring the Permian-Triassic Boundary in Deltadalen, Svalbard..
• Rimkus, Algirdas; Sundal, Anja; Sleveland, Arve Rein Nes; Zuchuat, Valentin; Braathen, Alvar & Midtkandal, Ivar (2015). Sedimentology and reservoir quality of a Middle Jurassic marginal marine succession; the Curtis Formation, southeastern Utah, USA. Show summary

  The objective of this study is to investigate the depositional architecture of the Curtis Formation, and evaluate how the observed facies distributions would affect overall reservoir quality. This tidally influenced marginal marine succession is well exposed in southeastern Utah (Humbug Flats, San Rafael Swell) and provides a high-resolution analogue to subsurface reservoirs. In order to constrain the distribution of reservoir-grade sandstone bodies and characterize their heterogeneities, traditional sedimentological field methods were applied and LIDAR-scan data were collected. Permeability, porosity and diagenetic imprint parameters were evaluated from thin sections and used to constrain the model. The Middle Jurassic (Callovian) Curtis and Summerville formations represent a complex set of vertical and lateral facies transitions from tidal shallow marine and supratidal sabkha deposits, respectively. The Curtis Formation developed in a transgressive to regressive, low-gradient epicontinental setting where vertical stacking of sandstone bodies was limited by accommodation. Determining reservoir quality in tidal sediments is extremely challenging due to complex and heterogeneous sand distribution. In this study of the Curtis Formation, sub-seismic scale reservoir heterogeneities are the main focus. Sedimentological characterization is used for classification of significant structures and layers forming potential baffles to fluid flow within genetically related units. Excellent outcrop quality allowed lateral correlation between log sites, supplemented by conventional photographs and LIDAR imagery. The reservoir quality of Curtis Formation shows a general water-depth related trend: sand-to-mud ratio increases with increasing water-depth during the transgressive phase. The lower succession contains channelized sandstone bodies in a heterolithic matrix, leading to limited connectivity. Tidal flat settimg. High permeability A cleaning upwards trend towards the middle part, corresponds with a transition into a deeper shoreface environment, which in turn represents improved reservoir quality with laterally extensive relatively homogeneous sandstones. The uppermost part displays a dirtying-upwards trend into increasingly heterolithic strata. Lateral connectivity is generally high, whereas siltstone interlayers provide frequent vertical flow baffles. Locally, mud-drapes and shifts in depositional transport directions cause high variance in directional permeability. This depositional model for the Curtis Formation is an inter-well-scale analogue with respect to reservoir property distributions in tidally influenced, heterogeneous reservoirs (e.g. the Tilje, Cook and Knurr formations on the Norwegian continental shelf). Evaluation of the diagenetic imprint proved essential, as reservoir behavior at the original burial depth has to be characterized for relevant comparison. Further studies aim to investigate facies distribution within the succession on a regional scale.

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