First EAGE Workshop on the Triassic and Jurassic Plays in Northwest Europe
- Conference date: February 26-28, 2025
- Location: Sunbury, United Kingdom
- Published: 26 February 2025
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Integrated Analysis of Reservoir Potential in Lower Triassic Red and Bleached Buntsandstein from Vosges Outcrops
More LessAuthors H. Yousaf, R. Swennen and H. ClaesSummaryTriassic Sandstone, Red and Bleached Sandstones, Buntsandstein, Diagenesis, Bleaching, Reservoir Quality, Geothermal, Gas Storage
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Has the Base Cretaceous Unconformity Affected Reservoir Quality of the Underlying Brent Group Sandstones,Tampen Spur,North Sea
More LessSummarySeveral studies have been published assessing the effect of unconformities on reservoir quality and whether there is any relationship between the presence of unconformity surfaces and diagenetic processes above and below these unconformities. Some studies have suggested a direct relationship between the presence of these surfaces and reservoir quality. Whereas, others argue against the existence of such relationship. In this study both hypotheses were examined by evaluating the role of the Base Cretaceous unconformity in the distribution of porosity and kaolinite in Middle Jurassic Brent Group sandstones of the Tampen Spur area, Northern North Sea. The petrographic analysis results indicate that the dissolution of framework grains and carbonate cement are the main source of the generated secondary porosity and authigenic kaolinite within Brent Group sandstones. Detailed petrographic analysis, using both optical microscopy and Scanning Electron Microscopy (SEM), was undertaken on 43 core samples from selected wells in the Tampen Spur region.
The study demonstrates no marked effect of the unconformity surface on the underlying reservoir rock in this region of the North Sea. It is suggested that any such effects that may be noted elsewhere are most likely to be a localised phenomenon.
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New Palaeogeography Reconstruction of the Triassic Stratigraphic Interval in the Norwegian Central North Sea
More LessAuthors L. Di Lauro and A. HartleySummaryFor decades, the Triassic interval of the North Sea remained inadequately understood and, therefore poorly explored. This was due to the combination of structural, burial depth, overpressure, and sedimentological variability related primarily to the depositional environment, halokinesis, post-depositional erosion and diagenesis. In both UK and Norwegian sectors of the Central North Sea, the Triassic interval comprises the mainly Early Triassic Smith Bank Formation, represented by fluvio-lacustrine and aeolian rocks, and the Middle-Late Triassic Skagerrak Formation, consisting of sandstone and mudstone rocks deposited as part of a series of distributive fluvial systems. This study focuses on a portion of the Norwegian North Sea and integrated seismic, well and core data. It revealed the presence of two stable main sediment input points in the area throughout the Triassic time and demonstrated that sedimentation in this time occurred without interference from the local topography. This implies that the Triassic movements of the late Permian Zechstein salt did not affect the topography, thus channels were free to migrate. This part of the study represents a groundbreaking result as it extends the area of subsurface exploration above the salt structures since the sandstones of the channel deposits display the best reservoir properties.
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Investigating Fracture Development within an Early Jurassic Mudrock Seal in the Cleveland Basin, NE England
More LessAuthors A. Szulc, C. Pierce, M. Curtis, S. Vincent, N. Paterson, M. Flowerdew, M. Pointon and B. ToroSummaryThe controls on mechanical failure within mudrock seals is a key factor in de-risking CO2 storage targets. The Early Jurassic Redcar Mudstone Formation of the Cleveland Basin in Yorkshire, NE England, is a direct analogue for offshore carbon storage projects in the North Sea. We present an investigation into the impact of mudrock composition, sedimentary facies and faulting on fracture development within the Redcar Mudstone Formation.
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Enabling Decision Making for Carbon-Storage Sites through Regional Rapid-Turnaround Re-Imaging of Legacy Datasets in the Southern-North-Sea
More LessAuthors C. Tyagi, J. Sutcliffe, A. Cooke and D.P. RathSummaryFollowing the first UK carbon storage license round in September 2022, SLB initiated a fast-track reprocessing project to support license awardees and boost carbon storage investment in the Solepit basin, Southern North Sea. This project aimed to enhance data quality using modern processing techniques, creating a merged volume that reduces uncertainty in storage site screening caused by legacy data. The Solepit area, covered by 26 vintage surveys, had limitations in the acquired data, making regional subsurface evaluation challenging. This reprocessing project produced an integrated regional image and velocity model over the entire area, focusing on two main carbon storage intervals: the shallow Triassic Bunter sandstone and the deeper Permian Leman sandstone. This case study addresses challenges of data pre-conditioning, using techniques like survey matching, adaptive deghosting, and demultiple. Legacy velocity models were merged and pre-conditioned for tomography inversion, resulting in a consistent regional model. The improved imaging techniques enhanced shallow resolution, aiding overburden evaluation, and provided clearer images of geological features, reducing uncertainty in the interpretation of the Bunter sandstone reservoir and the deeper Permian Leman sandstone for carbon storage site assessments.
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Regional Characterisation of the Triassic Bunter Sandstone: Implications for Reservoir Connectivity and Fluid Flow
More LessAuthors M. Shiers, N. Paterson, A. Szulc, S. Schneider, C. Pierce, M. Pointon and S. VincentSummaryThe Bunter Sandstone Formation and correlative strata in the Dutch sector of the Southern North Sea are important candidate reservoirs for the geological storage of CO2 and will play a key role in the UK’s Net Zero Strategy. The formation and its equivalents comprise laterally variable continental red bed sequences deposited under arid to semi-arid conditions in a low-energy, ephemeral fluvial to aeolian-sabkha environment. However, there is notably little published information on its stratigraphy.
This project combines sedimentological analysis with SEM-derived automated mineralogy, petrography and porosity-permeability measurements in order to constrain how reservoir quality is controlled by changes in sedimentary environment of deposition, sandstone composition and diagenetic evolution, as well as to document its lateral and vertical heterogeneity. This data will be used to inform the assessment of CO2 injectivity and plume migration studies to ensure safe, long-term CO2 storage in the subsurface.
Particular focus has been placed on diagenetic sequences and cements. Sampling will has focussed principally on the Bunter Sandstone Formation and the correlative units of the Dutch sector. This project forms part of CASP’s Bunter Sandstone storage complex research theme
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Regional 3D Seismic Tectono-Stratigraphy and Geomorphology Study Documenting Rift Initiation Along the Mid-Norwegian Continental Margin.
More LessAuthors C. Serié, I. Polonio, T. Mosociova and I. MidtkandalSummarySpatio-temporal evolution and paleogeographic reconstructions along rifted margins result from the integration of structural architecture based on magnetics, gravity and log offset 2D seismic, in addition to source-to-sink models based on 3D seismic, well logs, cores, and provenance studies. However, sedimentary records of early rift phases are commonly incomplete due to uplift and erosion, poor preservation due to subsequent deformation and burial, or simply data availability. This research project investigates rift initiation along the Norwegian Continental Margin in two successive time intervals including the Permo-Triassic and Upper Triassic-Lower Jurassic. Detailed tectono-stratigraphic evolution of the Permo-Triassic rifting, including the re-activation of deep inherited structures and the deposition of the Triassic salt has played an important role in controlling the basin morphology and associated depositional systems during the Upper Triassic-Lower Jurassic. Regional, high-resolution seismic tectono-stratigraphy and seismic geomorphology studies are instrumental in developing data-driven models within a regional context. They bring new insights into paleogeographic reconstruction during rift initiation. This holistic approach not only fills the gaps left by incomplete sedimentary records but also offers a predictive framework for future exploration and development.
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A Multiproxy-Multiscale Mudrock Catalogue from the Cleveland Basin, UK — Analogue Analyses to Aid GCS Seal Assessments
More LessSummaryA research programme in the Cleveland Basin, UK has sampled and logged more than 600 m of continuous mudrock and intercalated mudrock-evaporite stratigraphy. The studies have investigated both outcrop exposures and continuous borehole core to document heterogeneity in mudrock units and examine the impacts on seal potential for geological carbon storage. The studied successions include the lower Lias Group in outcrop, primarily at Robin Hood’s Bay, and the entire Haisborough Group and lower Lias groups in a nearby onshore core.
Here we present the first phase of work examining the lower Lias Group in outcrop (~180 m thick) ( Figure 1(A) ). Stratigraphic equivalents of the study interval form primary and secondary seals to an expanding group of GCS complexes across the North Sea region.
The primary aim of this research was to examine potential links between a comprehensive catalogue of primary (compositional/sedimentological) and secondary (i.e. deformational/diagenetic) heterogeneities with variations in seal potential. The analytical (XRF-XRD, SEM, TOC, MICP, etc.) results have allowed characteristic facies-microfacies, compositional and mineralogical sub-groupings to be established and linked to seal potential (i.e., capacity, reactivity and mechanical strength) using a combination of comparative ranges and PCA analysis. These underpin the construction of relative seal-risk or “vulnerability” maps.
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Tectonostratigraphic Evolution of the Permo-Triassic Rift Basin Fill, Offshore Mid-Norway
More LessAuthors T. Mosociova, C. Serie and I. MidtkandalSummaryThe multiphase rifting of the mid-Norwegian continental margin resulted in a complex architecture of the post-Caledonian basins. The earliest rifting period took place in the Permo-Triassic and led to the breakup of the Greenland-Norway conjugate margins. In response to the rifting, a series of mixed siliciclastic-evaporite-carbonate basins developed within the proximal and necking domains of the mid-Norwegian continental margin. This study focuses on the spatio-temporal development of the mid-Norwegian continental margin, structural events, and related depositional patterns. Investigations of the tectonostratigraphic framework of these understudied basins provide knowledge on the evolution of depositional depocenters, rifting character, and growth of intrabasinal highs. While the Jurassic evolution and rifting have been thoroughly investigated for hydrocarbon exploration, the early rifting phases have been poorly documented due to limited data of relative poor quality. Recent advances in seismic acquisition and imaging have greatly enhanced seamless structural and stratigraphic mapping providing a consistent regional framework to support multidisciplinary studies from the regional scale down to the finer details. This project synthesizes previous studies, integrates them, and compares with modern, high-resolution seismic data, new exploration wells, and drill cores.
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Core SM14 from North Yorkshire, UK: an Unrivalled GCS-Related Dataset from the Triassic Haisborough Group
More LessAuthors S. Schneider, M. Flowerdew, N. Paterson, C. Pierce, M. Pointon, M. Shiers, A. Szulc, S. Vincent and D. WarburtonSummaryIn the Southern North Sea region, the Lower Triassic Bunter Sandstone Formation and the overlying Middle to Upper Triassic Haisborough Group form a reservoir-and-seal couplet for prospective geological carbon storage (GCS) in the UK and beyond. Nevertheless, due to a dearth of core material, the mudstones and evaporites of the Haisborough Group are grossly understudied. The SM14 core from the Anglo American Woodsmith Mine site in North Yorkshire, UK, offers a unique opportunity to study a complete, near 300-m-thick succession of the Haisborough Group, which serves as an immediate analogue for potential GCS storage sites offshore. CASP has documented the entire succession via sedimentary logging and facies analysis, and has taken hand-held X-ray fluorescence (XRF) measurements directly from the core. A total of 64 large core samples underwent a comprehensive analytical protocol including quantitative X-ray diffraction (QXRD), optical petrography, scanning electron microscope energy dispersive spectroscopy (SEM-EDS), porosity-permeability and mercury injection capillary pressure (MICP) analyses. Together with a variety of rock strength tests and a comprehensive suite of wireline data, this has led to the production of an unrivalled dataset from the Haisborough Group, which is highly relevant to potential geological carbon storage sites in the Southern North Sea Basin.
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Palynological Approaches to Triassic Basin Analysis: From the North Sea to the Barents Shelf
More LessAuthors N. Paterson, M. Shiers, M. Flowerdew, M. Pointon, E. Fleming, A. Morton and S. VincentSummaryThis study presents a comparison of integrated palynostratigraphy from two significant Triassic successions: the Bunter Sandstone storage complex in the Southern North Sea and the Sassendalen and Kapp Toscana groups on the Barents Shelf. Each study region serves distinct purposes—CO2 storage in the Southern North Sea and hydrocarbon exploration on the Barents Shelf—yet both require refined stratigraphic frameworks for effective resource development. For the Southern North Sea, analysis of 500 samples from 14 wells led to the establishment of a new palynozonation, addressing a critical gap in regional biostratigraphy and improving cross-border correlation between the UK and Dutch sectors. On the Barents Shelf, palynological and macrofossil data were integrated with sequence stratigraphy across 42 localities, refining chronostratigraphy and knowledge of the spatio-temporal distribution of reservoir sands. Our findings highlight how climate and environmental shifts influenced Triassic vegetation and sedimentation, with species turnover paralleling major marine transgressions and/or global climatic changes. The frameworks developed offer broader relevance, with potential applications to other Triassic successions, including those in the East Irish Sea Basin and Central and Northern North Sea.
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Permian and Triassic Climate Recorded in Floodplain Deposits from the SE Part of the Germanic Basin
More LessAuthors K. Jewula, N. Wasielka, W. Trela, A. Kedzior and A. Fijalowska-MaderSummaryThe Permian and Triassic floodplain deposits in the SE part of the Germanic Basin reveal significant climatic oscillations driven by global warming and the onset of supermonsoonal circulation. A detailed analysis of continental deposits, including palaeosols and palustrine horizons, allowed us to extract climatic signals and assess their impact on sedimentary patterns. The Permian-Triassic boundary is marked by a shift from arid floodplains with calcisols to humid conditions fostering inceptisols, accompanied by changes in palynological and detrital compositions. Early Triassic deposits exhibit fluvial instability, transitioning to more stable floodplain systems with evolving soil profiles, indicating gradual climatic stabilisation. The Middle Triassic is characterised by marine sedimentation, while the Late Triassic marks a return to continental conditions with alternating arid and humid intervals, including pluvial events during the Carnian and Norian. The study highlights the value of palaeosols and palustrine horizons as climatic markers and their utility in basin analysis for oil and gas exploration, as well as CCS and hydrogen storage well planning.
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The Challenges Unlocking the Geothermal Energy Potential in the South Permian Basin
More LessAuthors E. Stürup-Toft, H. Cromie and A. Ørskov MadsenSummaryUnlocking the enormous geothermal potential in the South Permian Basin is not without challenges.
Urban data acquisition, drilling and development of production facilities is required in cities where district heating infrastructure is already established and where there is a need for new heat production away from conventional fossil fuel production. A pre-requisite for a geothermal project to be developed is that the subsurface in the urban setting contains a hydrothermal reservoir. One of the main challenges, however, in understanding the risk and uncertainties related to these hydrothermal reservoirs as the subsurface evaluations are usually based on historic subsurface data (acquired for O&G exploration). These legacy data is usually scarce and of poor quality and usually absent in urban settings making the subsurface evaluations prone to high range of uncertainties.
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A Comprehensive Triassic Paleogeographic Reconstruction Utilizing Age-constrained Units in the Tampen Spur Area, Northern North Sea
More LessAuthors S. Saltapidas, A. Hartley, D. Watson, S. Heydenrych and R. SordiSummaryIn this study, we reconstruct the Triassic paleogeographic setting of the Northern North Sea (NNS) through time utilizing core logs and age-constrained units, derived from updated palynological data. In the NNS, the Triassic continental sediments of the Hegre Group consist of sandstone and mudstone units. Facies association proportions derived from cores across the basin, coupled with age-constrained units suggest a single or a series of Distributive Fluvial System (DFS) that prograded westwards and were sourced from the eastern, Norwegian margin. The sandstone units represent the progradation, while the mudstone intervals reflect the retrogradation of the DFS. The Norian, Alke Formation of the NNS represents a wide-dispersal floodplain setting resulting from arid conditions. This mudstone unit is time-equivalent to the Jonathan Mudstone Member of the UK Central North Sea. At a regional scale, this preliminary chronostratigraphic framework sets the foundations for unifying the Triassic stratigraphy of the North Sea and may reveal new targets for HC exploration, CO2 and hydrogen storage. Regional correlations are important as they enable subsequent cross-border paleogeographic reconstruction between Central and Northern North Sea with significant emphasis on all climatic alternations throughout the Triassic interval.
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Stratigraphic and Paleogeographic Evolution of the Triassic Across the Utsira High, Northern North Sea.
More LessAuthors R. Sordi, A. Hartley, S. Heydenrych and S. SaltapidasSummaryThe Northern North Sea is a complex, underexplored region with significant potential for hydrocarbon exploration. The Mesozoic rift basin has proven rich in hydrocarbons for the Jurassic and younger stratigraphic succession. Nevertheless, a comprehensive understanding of the Triassic stratigraphy and its potential for reservoir quality and CO2 storage is still lacking in the literature. The study area is at the limits between the Central North Sea and the Northern North Sea, and the Utsira High has played a key role in shaping the region’s stratigraphic evolution. This study aims to improve our understanding of the Triassic sedimentological evolution and palaeogeography of the Utsira High area throughout the Triassic rifting. By integrating seismic data, wireline logs, and core data, this work identified and mapped intra-Triassic packages and their lateral variations. The analysis presented here has been performed by integrating stratigraphic and biostratigraphic analysis, creating the basis for further and necessary understanding of the region. The results provide new insights into the long-standing nature of the Utsira High and its influence on sediment distribution. This study contributes to a better understanding of the North Sea Rift System’s evolution and has implications for reservoir development and CO2 storage
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REV Modelling of the Triassic Judy and Joanne Sandstones in the Culzean Field, CNS, UK
More LessAuthors C. Priddy, A. Hartley and J. HowellSummaryThe Culzean field is a high pressure - high temperature field located within block 22/25a of the Central North Sea, UK, and contains the Middle Triassic Judy Sandstone and the Middle to Upper Triassic Joanne Sandstone fluvial reservoir units of the Skagerrak Formation. While the sedimentology of the Skagerrak has been studied in detail, it is clear there are a range of heterogeneities that will often be missed when creating reservoir models, particularly when the models are upscaled for flow simulations. This work investigates the scales of heterogeneity that could affect reservoir production by using a mini-permeameter study and multi-scale reservoir modelling approach. Detailed sedimentological analysis of the Judy and Joanne sandstones suggests that the fluvial deposits of these two members were formed by two separate fluvial systems. Results from the mini-permeameter study show a 47% reduction in horizontal permeability, a 78% reduction in vertical permeability, and a 39% difference in the production cumulative as a result of including the small-scale heterogeneities observed within the core. This work highlights the importance of a multi-scale reservoir modelling approach to ensure small-scale heterogeneities are included in the models to more accurately predict production profiles.
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Advanced Core Digitalization for Reservoir Evaluation in Middle Jurassic Sleipner and Triassic Skagerrak Formations
More LessSummaryAccurate subsurface characterization requires detailed, continuous data to understand reservoir heterogeneity. Advanced digital core analysis techniques, such as CoreDNA™, enable high-resolution, non-destructive core logging, while modern laboratory technologies like QEMSCAN (Quantitative Evaluation of Minerals by Scanning Electron Microscopy) provide precise mineralogical insights. This study presents a case from Well 15/12-20 S in the Norwegian Central North Sea, demonstrating how CoreDNA™ data supports subsample selection and upscaling to produce continuous property distributions along the core, effectively bridging the gap between field-scale observations and laboratory-scale measurements in Middle Jurassic Sleipner and Triassic Skagerrak Formations.
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Culzean Field : The Mysterious Unit X Sandstones – Jurassic or Triassic? Implications for Connected Gas
More LessAuthors S. ClarkSummaryThe Culzean field is located in Quadrant 22 of the Central North Sea, 240km east of Aberdeen. It is a tilted fault block dipping to the East with bounding faults to the North and West. Gas-condensate was discovered in 2008 by the 22/25a-9Z well in the Jurassic Pentland and Triassic Skagerrak Formations. These two formations are separated by the mid-Cimmerian unconformity, with the Upper Triassic absent. It is a high-pressure / high-temperature field with initial conditions around 930 bar and 170 °C at 4500m TVDSS. The field was appraised in 2010–2012 by the 22/25a-10, -10Z 10Y and -11 wells.
Development well drilling started in 2016 and the field came on production in 2019, initially from the Joanne Member of the Skagerrak Formation with 5 wells, followed by a single Pentland producer well.
Field understanding has increased with time as more production and monitoring data became available through geological, geophysical and reservoir engineering data synthesis. One synthesis result discussed in this paper is an updated correlation scheme and age reclassification of some gas-bearing sandstones from the Jurassic into the Triassic. This has led to a deeper understanding of the field and may lead to future development opportunities in Culzean.
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The Pentland Formation at Culzean: A Heterogeneous Fluvial Reservoir with Proven Production Performance
More LessAuthors C. BuggSummaryThe Jurassic Pentland Formation in the Central North Sea is is regionally placed in a humid upper delta to alluvial plain setting and is known for its heterolithic facies. There have been a limited number of economically successful hydrocarbon field developments and there have been some sizeable discoveries, e.g. the Kessog field, that have not been developed. At the HPHT Culzean field the Pentland Formation has relatively favourable petrophysical properties compared to nearby fields. It been on production for 4 years with and delivered gas at high initial production rates and demonstrated economically significant connected volumes. Further development of the Pentland has been derisked through pulsed neutron log acquisition and executed adding perforation to existing Triassic production wells. Again excellent production rates and connected volumes have been proven following perforation. The production performance of the Pentland Formation at Culzean is a case study demonstrating the economic viability of the middle Jurassic play in the Central North Sea. Follow up potential to further increase recovery from the Pentland Formation exists at Culzean as well as there being exploration targets in the middle Jurassic in the acreage surrounding Culzean
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