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Svalbox Digital Model Database: A geoscientific window into the High Arctic
Abstract
Digital outcrop models (DOMs) have revolutionized the way twenty-first century geoscientists work. DOMs are georeferenced three-dimensional (3-D) digital representations of outcrops that facilitate quantitative work on outcrops at various scales. Outcrop digitalization has been traditionally conducted using laser scanners, but in the past decade, it has seen an exponential growth because of efficient and consumer-friendly structure-from-motion (SfM) algorithms concurrent with the rapid development of cost-effective aerial drones with high-resolution onboard cameras. While DOMs are routinely used in geoscientific research, education, and industry, enhanced DOM usage is restricted because raw data (e.g., photographs) and metadata are often incomplete and/or unavailable. In this contribution, we present the Svalbox Digital Model Database (Svalbox DMDb), a database of metadata and openly available data packages for individual DOMs. The Svalbox DMDb is a regional DOM database geographically constrained to the Norwegian High Arctic archipelago of Svalbard at 74°N–81°N and 10°E–35°E. Svalbard offers exceptional-quality, vegetation-free outcrops with a wide range of lithologies and tectono-magmatic styles, including extension, compression, and magmatism. Data and metadata of the systematically digitalized outcrops across Svalbard are shared according to FAIR principles through the Svalbox DMDb. Fully open-access and downloadable DOMs include not just the DOMs themselves, but also the input data, processing reports and projects, and other data products such as footprints and orthomosaics. Rich metadata for each DOM include both the technical and geological parameters (metadata), enabling visualization and integration with regional geoscientific data available through the Norwegian Polar Institute and the Svalbox online portal. The current release of Svalbox DMDb, documented in this contribution, covers 135 DOMs cumulatively covering 114 km2 of Proterozoic to Cenozoic stratigraphy.
... E) Zoom-in of the detailed region of drill site 2. Geological map (1:250 000) and background orthophoto is courtesy of are courtesy of Norwegian Polar Institute (2016) and Norwegian Polar Institute (2017), respectively. Plotted CO 2 Lab activity data sets are accessed through the Svalbox databases (Senger et al. 2021a;Betlem et al. 2023). The grid uses the WGS 84/UTM Zone 33 N (EPSG:32633) projection. ...
... Deltaneset also proved to be an important site for student education, with several thesis projects investigating the hillside and coastal outcrop sections, thus contributing additional data to the project. The emergence of digital outcrop geology has further facilitated quantitative studies through the integration of digital outcrop and drill core models (e.g., Betlem et al. 2023;Rizzo et al. 2024). Figure 2 shows spatial coverage of the key data sets. ...
... 2013. Traditional fieldwork with compass and measuring tape, fracture mapping along scanlines.Ogata et al. (2012Ogata et al. ( , 2014. 2019-2024. Fieldwork supported with digital outcrop models. Digital fracture mapping.Betlem et al. (2023). ...
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).
... The emergence of DOMs in geoscience has provided an additional tool to facilitate lateral and stratigraphic mapping of facies distribution and the large-scale architecture of outcropping depositional systems (Betlem et al., 2023;Howell et al., 2014;Verwer et al., 2009). To address this, we have used drone-based DOMs to support the mapping of sedimentary architecture and key boundaries of the studied succession. ...
... To address this, we have used drone-based DOMs to support the mapping of sedimentary architecture and key boundaries of the studied succession. The DOMs were created using the Structure from Motion (SfM) method e.g., (Betlem et al., 2023;Chandler & Buckley, 2016;Janocha et al., 2021). With this method, 2514 photos covering areas of 8.19 km 2 square km were acquired using a DJI Mavic 2 Pro drone. ...
... With this method, 2514 photos covering areas of 8.19 km 2 square km were acquired using a DJI Mavic 2 Pro drone. Processing of the DOMs was carried out in Agisoft (2021), following the procedure described in e.g., Janocha et al. (2021) and Betlem et al. (2023). For this study three overview DOMs were created, covering Adriabukta, Burgerbukta, and the Treskelen peninsula, with an average pixel resolution of 23.6 cm/pixel (Figures 4 and 5). ...
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.
... These tests confirmed good injectivity and flow capacity of 39 mD⋅m, but also highlighted that the target reservoir is compartmentalised as two wells, which are 94 m apart, were not in direct communication and thus, lateral flow barriers must be present (Mulrooney et al., 2018). Detailed field mapping of the outcropping reservoir/caprock at Deltaneset 15 km northeast of the Longyearbyen CO 2 Laboratory injection site reveals a series of potential seal bypass systems that include sedimentary intrusions (Ogata et al., 2023) and normal faults that are equally likely to contribute to reservoir compartmentalisation (Ogata et al., 2014;Mulrooney et al., 2018;Betlem et al., 2024Betlem et al., , 2023Ogata et al., 2023). ...
... Our studied site is located in the Deltaneset area (Nordenskiold Land) on the northeast (NE) margin of the CBS (Fig. 2), exposing the shale-dominated succession belonging to the Middle Jurassic to Early Cretaceous Agardhfjellet Formation and the Early Cretaceous Rurikfjellet Formation in Konusdalen and Konusdalen West (Mulrooney et al., 2018;Betlem et al., 2024Betlem et al., , 2023Ogata et al., 2023). The shale-rich sequences of the Agardhfjellet Formation are the outcrop analogues of the lower part of the regional caprock. ...
... For this study, we reprocessed digital outcrop model (DOM) data available through the Svalbox project and the Svalbox Digital Model Database (Betlem and Team, 2021;Betlem et al., 2023). The sub-set of data were originally acquired using a DJI Mavic 2 Pro Unmanned Aerial Vehicle (UAV, i.e., drone) and cover a vertical section of the Konusdalen West Valley, which has a near N-S-trend (location shown in Fig. 2). ...
... Outcrop-based mapping of stratigraphy and structures like folds, faults, and fractures from the centimetre to kilometre scale is therefore pertinent to understanding geological processes, not least those affecting storage and sealing capacity (e.g. Ogata et al., 2014Ogata et al., , 2012Sibson, 1996;Vollgger and Cruden, 2016;Ogata et al., 2023;Betlem et al., 2023). Through SfM photogrammetry, outcrops can be digitalised to scale and geospatially referenced as DOMs to facilitate quantitative interpretation and integration with other spatial data sets (e.g. ...
... Through SfM photogrammetry, outcrops can be digitalised to scale and geospatially referenced as DOMs to facilitate quantitative interpretation and integration with other spatial data sets (e.g. quantifying fracture orientation and spacing; (Senger et al., 2015;Betlem et al., 2023)). ...
... FAIR principles and open accessibility are essential for the reproducibility and re-evaluation of existing work, the application of new methodologies, future studies of temporal processes (e.g. weathering and climatic variation), and the conservation of geological sites as digital replicas (Burnham et al., 2022;Betlem et al., 2023). ...
Structure-from-motion (SfM) photogrammetry has become an important tool for the digitalisation of outcrops as digital outcrop models (DOMs). DOMs facilitate the mapping of stratigraphy and discontinuous structures like folds, faults, and fractures from the centimetre to kilometre scale. With pristine, treeless exposures, the outcropping strata in Svalbard, Arctic Norway, hold exceptional potential for analogue studies and are ideally suited for the acquisition of high-resolution DOMs. Here, we present the acquisition, processing, and integration of the Konusdalen West digital model data set, comprising both DOM and derived digital terrain model (DTM) data. Drone-based image acquisition took place over 2 weeks in July and August 2020. The Konusdalen West DOM and DTM cover a 0.12 km2 area and span a 170 m elevation difference. The DOM covers the upper two-thirds of the mudstone-dominated Late Jurassic–Early Cretaceous Agardhfjellet Formation. The Agardhfjellet Formation and its time equivalents are regional cap rocks for CO2 sequestration and petroleum accumulations on the Norwegian Continental Shelf. A total of 15 differential GNSS control points were used to georeference and quality assure the digital data assets, 5 of which function as reference checkpoints. SfM processing of 5512 acquired images resulted in high-confidence, centimetre-scale resolution point clouds, textured mesh (DOM), tiled model, orthomosaics, and a DTM. The confidence-filtered dense cloud features an average inter-point distance of 1.57 cm and has an average point density of 3824.9 points per metre. The five checkpoints feature root mean square errors of 2.0 cm in X, 1.3 cm in Y, 5.2 cm in Z, and 5.7 cm in XYZ. Increased confidences and densities are present along the western flank of the Konusdalen West outcrop, where a fault fracture network in mudstone-dominated strata is best exposed and photographed most extensively. Top and side view orthomosaics feature maximum resolutions of 8 mm per pixel, enabling the mapping of faults, formation members, marker beds, fractures, and other sub-centimetre features. Additional structural measurements and observations were taken in June 2021 to place the data in the geological context. Data described in this paper can be accessed at Norstore under 10.11582/2022.00027.
... Other parameters such as lighting conditions, depth of field and image overlap were also considered to improve the suitability of the imagery data for photogrammetric processing. We refer to Betlem et al. (2023) for further acquisition and processing details. The resulting DOMs show centimetric to decimetric pixel resolutions and are suitable for high-resolution mapping of geological and geomorphological features. ...
... The photospheres taken during the Woodfjorden 2023 expedition were systematically collected over valleys, fjords, and close to outcrops by UAVs. Data and metadata are available through the Svalbox project under FAIR conditions ( [3] ; Betlem et al. 2023). In addition, photospheres are combined to build virtual field tours [4] and virtual field guides of key points of interest in the study area for teaching and outreach activities, as illustrated on [5] and discussed by . ...
The Woodfjorden area of northern Spitsbergen (NW Svalbard) offers access to the world’s northernmost onshore thermal springs, extinct Pleistocene alkali basaltic volcanoes and Miocene flood basalts including extensive hyaloclastites. In July 2023, we undertook a 14-day international multi-disciplinary geoscientific expedition to Woodfjorden-Bockfjorden to investigate the Cenozoic geological evolution of the area. The expedition objectives spanned a wide range of scientific topics from sampling of fluids and gas in the thermal springs to constraining the lithosphere by acquiring magnetotelluric data and sampling volcanic rocks. More specifically, we have 1) conducted gas, fluid and travertine sampling at the thermal springs of Gygrekjelda, Jotunkjeldene and Trollkjeldene, 2) mapped and sampled the Quaternary volcanic centers at Sverrefjellet and Halvdanpiggen, 3) sampled the Miocene basalts of the Seidfjellet Formation along seven profiles plus the underlying Devonian sedimentary rocks, 4) acquired magnetotelluric data at 12 stations along both coasts of Woodfjorden and Bockfjorden and 5) collected extensive digital geological data (digital outcrop models and photospheres) using unmanned aerial vehicles (UAVs; also known as drones). The collected samples are currently being analyzed for, amongst others, petrology, geochemistry and geochronology. In this contribution, we report on the expedition’s background, scientific objectives and present selected preliminary results such as field parameters from the thermal springs (temperature, pH, electrical conductivity), magnetic susceptibility of volcanic rocks and digital outcrop models plus photospheres.
... To put the gravity data in context, we spatially integrate it with other relevant subsurface data (Table 5). These include magnetic data, petroleum exploration and scientific boreholes onshore Svalbard (Senger et al., 2019), seismic reflection profiles Eiken, 1985), seismic refraction profiles (Ritzmann et al., 2002; Figure 2), regional terrain and bathymetric models (Jakobsson et al., 2008;Norwegian Polar Institute, 2014), nonseismic geophysical profiles (e.g., MT, TEM; Beka et al., 2016Beka et al., , 2017aBeka et al., , 2017b, published maps (e.g., geologic, paleogeographic, tectonic), online map services (e.g., topographic maps, satellite imagery) and digital outcrop models (e.g., Betlem et al., 2023). All of these are integrated in the Svalbox database in the Petrel software . . ...
Gravity data provide constraints on lateral subsurface density variations and thus provide crucial insights into the geological evolution of the region. Previously, gravity data from the Norwegian Arctic archipelago of Svalbard comprised an onshore regional gravity database with coarse station spacing of 2–20 km, offshore gravity profiles acquired in some fjords, airborne gravity, and satellite altimetry. The sparse regional point‐based onshore coverage hampered the direct integration of gravity data with seismic profiles acquired onshore Svalbard in the late 1980s and early 1990s. In April 2022, we acquired gravity data at 260 new stations along seven profiles from western to eastern Spitsbergen, with a cumulative length of 329 km. The profiles were acquired directly along selected seismic profiles and provide much closer station spacing (0.5–2 km) compared to the regional inland grid (2–20 km) acquired in the late 1980s (total number of onshore stations: 1,037). Having processed the data, we compared the first‐order density trends of our new data with the legacy regional grid. The new gravity data are consistent with the regional data, imaging a gravity low in the western part of the area underlying a foreland basin and a gravity high in the northwestern part of the area likely associated with a basement high or denser basement. We compare the new and vintage gravity using maps and profiles, linked to the known major tectonic features such as major basinal axes and fault zones, as well as other geophysical data sets including seismics and magnetics.
... The uptake of virtual field trips has been accelerated due to the COVID-19 pandemic (Whitmeyer and Dordevic, 2020;Pugsley et al., 2022). In the High Arctic, the University Centre in Svalbard has been actively using such digital tools, notably digital outcrop models and drone-based photospheres, to supplement its field-based education since 2016 (Senger et al., 2021;Horota et al., 2022b;Betlem et al., 2023;Horota et al., 2024). ...
The 17 United Nations Sustainable Development Goals (SDGs) collectively represent the global population’s ambition to improve the wellbeing of Earth and its inhabitants by 2030. The ambitious goals require that a dedicated, focused, and integrated effort is taken—now. The geoscientific community is well positioned to positively directly influence many of the SDGs, notably SDGs 7 (Affordable Energy), 11 (Sustainable Cities) and 13 (Climate Action), and may also directly or indirectly contribute to all other SDGs. In this contribution, I systematically review the SDGs in the framework of the broader geosciences. Firstly, I outline the concept of the SDGs and their indicators, before linking them to specific geoscientific disciplines illustrated with case studies. Finally, I present some of the ongoing developments in the geosciences that need to be clearly tied to the global SDG ambitions.
Geologically, the Arctic is one of the least-explored regions of Earth. Obtaining data in the high Arctic is logistically, economically, and environmentally expensive, but the township of Longyearbyen (population of 2617 as of 2024) at 78° N represents a relatively easily accessible gateway to Arctic geology and is home to The University Centre in Svalbard (UNIS). These unique factors provide a foundation from which to teach and explore Arctic geology via the classroom, the laboratory, and the field. UNIS was founded in 1993 as the Norwegian “field university”, offering field-based courses in Arctic geology, geophysics, biology, and technology to students from Norway and abroad.
In this contribution, we present one of the educational components of the international collaboration project NOR-R-AM (a Norwegian-Russian-North American collaboration in Arctic research and collaboration, titled Changes at the Top of the World through Volcanism and Plate Tectonics) which ran from 2017 to 2024. One of the key deliverables of NOR-R-AM was a new graduate (Master's and PhD-level) course called Arctic Tectonics and Volcanism that we have established and taught annually at UNIS since 2018 and detail herein. The course's main objective is to teach the complex geological evolution of the Arctic from the Devonian period (∼ 420 million years ago, Ma) to the present day through integrating multi-scale datasets and a broad range of geoscientific disciplines. We outline the course itself before presenting student perspectives based on both an anonymous questionnaire (n=27) and in-depth perceptions of four selected students. The course, with an annual intake of up to 20 MSc and PhD students, is held over a 6-week period, typically in spring or autumn. The course comprises modules on field and polar safety, Svalbard/Barents Sea geology, wider Arctic geology, plate tectonics, mantle dynamics, geo- and thermochronology, and geochemistry of igneous systems. A field component, which in some years included an overnight expedition, provides an opportunity to appreciate Arctic geology and gather field observations and data. Digital outcrop models, photospheres, and tectonic plate reconstructions provide complementary state-of-the-art data visualization tools in the classroom and facilitate efficient fieldwork through pre-fieldwork preparation and post-fieldwork quantitative analyses. The course assessment is centred around an individual research project that is presented orally and in a short and impactful Geology journal-style article. Considering the complex subject and the diversity of students' backgrounds and level of geological knowledge before the course, the student experiences during this course demonstrate that the multi-disciplinary, multi-lecturer field-and-classroom teaching is efficient and increases their motivation to explore Arctic science.
Geologically, the Arctic is one of the least explored regions of Earth. Its significance, in terms of indigenous populations, resource extraction, tourism, shipping and a rapidly changing climate, is increasing. The Arctic offers geological diversity encompassing onshore and offshore environments, include active subduction zones in Alaska, deep sedimentary basins on the Siberian and Barents Sea shelves, widespread ancient Arctic volcanism and magmatism, the world’s slowest spreading mid-ocean ridge (Gakkel Ridge in the Eurasia Basin), as well as world-class examples of extensional and compressional basins exposed onshore Svalbard. Obtaining data is logistically, economically and environmentally expensive in the high Arctic, but the township of Longyearbyen at 78° N represents a relatively easily accessible gateway to Arctic geology. The year-round settlement on Spitsbergen, the main island of the Svalbard archipelago is home to The University Centre in Svalbard (UNIS). Reached by a year-round airport with regular connections to mainland Norway, Svalbard provides a foundation from which to teach and explore Arctic geology via the classroom, the laboratory, and the field. In this contribution, we present a new graduate course (Masters and PhD level) on Arctic Tectonics and Volcanism that we have established and taught annually at UNIS since 2018. We outline the course itself, before presenting student perspectives based on both an anonymous questionnaire (n = 27) and in-depth perceptions of four selected students. The course, with an intake of up to 20 MSc and PhD international students, is held over a 6-week period, typically in Spring or Autumn. The course comprises modules on field and polar safety, Svalbard/Barents Sea geology, wider Arctic geology, plate tectonics, mantle dynamics, geo- and thermochronology, and geochemistry of igneous systems. All modules include individual and group-based exercises in addition to introductory lectures. A field component, which in some years included an overnight expedition, provides an opportunity to appreciate Arctic geology and gather own field observations and data. Digital outcrop models and photospheres viewed with state-of-the-art visualization in the classroom facilitate efficient fieldwork through pre-fieldwork preparation and post-field work quantitative analyses. The course assessment is centered on an individual research project that is presented orally and in a short and impactful Geology journal-style article. Apart from the course at UNIS we have jointly initiated several one-off research and education-based events at partner institutions, and briefly outline these.
We held the MagellanPlus workshop SVALCLIME “Deep-time Arctic climate archives: high-resolution coring of Svalbard's sedimentary record”, from 18 to 21 October 2022 in Longyearbyen, to discuss scientific drilling of the unique high-resolution climate archives of Neoproterozoic to Paleogene age present in the sedimentary record of Svalbard. Svalbard is globally unique in that it facilitates scientific coring across multiple stratigraphic intervals within a relatively small area. The polar location of Svalbard for some of the Mesozoic and the entire Cenozoic makes sites in Svalbard highly complementary to the more easily accessible mid-latitude sites, allowing for investigation of the polar amplification effect over geological time. The workshop focused on how understanding the geological history of Svalbard can improve our ability to predict future environmental changes, especially at higher latitudes. This topic is highly relevant for the ICDP 2020–2030 Science Plan Theme 4 “Environmental Change” and Theme 1 “Geodynamic Processes”. We concluded that systematic coring of selected Paleozoic, Mesozoic, and Paleogene age sediments in the Arctic should provide important new constraints on deep-time climate change events and the evolution of Earth's hydrosphere–atmosphere–biosphere system. We developed a scientific plan to address three main objectives through scientific onshore drilling on Svalbard: a. Investigate the coevolution of life and repeated icehouse–greenhouse climate transitions, likely forced by orbital variations, by coring Neoproterozoic and Paleozoic glacial and interglacial intervals in the Cryogenian (“Snowball/Slushball Earth”) and late Carboniferous to early Permian time periods.b. Assess the impact of Mesozoic Large Igneous Province emplacement on rapid climate change and mass extinctions, including the end-Permian mass extinction, the end-Triassic mass extinction, the Jenkyns Event (Toarcian Oceanic Anoxic Event), the Jurassic Volgian Carbon Isotopic Excursion and the Cretaceous Weissert Event and Oceanic Anoxic Event 1a.c. Examine the early Eocene hothouse and subsequent transition to a coolhouse world in the Oligocene by coring Paleogene sediments, including records of the Paleocene–Eocene Thermal Maximum, the Eocene Thermal Maximum 2, and the Eocene–Oligocene transition. The SVALCLIME science team created plans for a 3-year drilling programme using two platforms: (1) a lightweight coring system for holes of ∼ 100 m length (4–6 sites) and (2) a larger platform that can drill deep holes of up to ∼ 2 km (1–2 sites). In situ wireline log data and fluid samples will be collected in the holes, and core description and sampling will take place at The University Centre in Svalbard (UNIS) in Longyearbyen. The results from the proposed scientific drilling will be integrated with existing industry and scientific boreholes to establish an almost continuous succession of geological environmental data spanning the Phanerozoic. The results will significantly advance our understanding of how the interplay of internal and external Earth processes are linked with global climate change dynamics, the evolution of life, and mass extinctions.
With increased pressure on energy companies to reduce costs whilst also planning more complex wells with lower carbon emissions, companies worldwide are always looking for ways to be more efficient & successful in their subsurface reservoir characterization. Improved collaboration across the traditional gaps in the Exploration & Production (E&P) disciplines is an important way to achieve these goals. In this paper, we review the vision of the Metaverse, a fully realized digital world that exists beyond the one in which we live and continues to exist even when we do not interact with it. The Metaverse has some key technological concepts that potentially provide a roadmap to help deliver desired improvements for reservoir characterization collaboration. The first is through an immersive three-dimensional world that can bring together people from remote locations to collaborate in one space. The second is through the realization of a Subsurface Digital Twin. We review where we are and what can be achieved with current technologies using our own research and development as examples, and we postulate on how these technologies will be improved in the immediate future.
In this chapter, we present a comprehensive and up-to-date overview of the geology and petroleum geology of the Svalbard Composite Tectono-Sedimentary Element, Barents Sea; SCTSE, herein defined as the Carboniferous–Paleogene sedimentary rock succession and its associated structural elements.
As such, the underlying economic basement consisting of Devonian and older sedimentary rocks, as well as Precambrian igneous and metamorphic rocks, are not considered.
Sedimentary injectites are increasingly documented in many hydrocarbon plays at various scales, either interpreted as potential risks (e.g., top-seal bypass, a drilling hazard) or benefits (e.g., reservoir interconnection, increased hydrocarbon volumes) for production operations. As such, they have potential critical implications for the assessment of suitability for CO2 injection and sequestration. Detailed characterization of such units, especially in terms of diagenesis and (paleo) fluid flow, is directly achievable at outcrop scale, overcoming dimensional and time constraints otherwise unresolvable at seismic scale.
Two sedimentary injection complexes have been recognized in the succession of the Middle Jurassic–Lower Cretaceous Agardhfjellet Formation exposed at Deltaneset, central Spitsbergen, Norway, at different stratigraphic levels. The upper complex comprises two main clastic dikes characterized by different orientation and consolidation, tapering out vertically (upward and downward) within a stratigraphic thickness and lateral extent of more than 50 m and 200 m, respectively. The lower complex is coarser grained, made up by a network of interconnected dikes and sills, shooting off from isolated lenticular and morphologically articulated bodies, interpreted as sedimentary intrusions linked to seafloor extrusion (sand volcano). Petrographic and micromorphological analyses were used to identify the underlying lithologies of the Late Triassic to Middle Jurassic Wilhelmøya Subgroup as the possible source of this remobilized material for both the upper and lower complexes. This subsurface remobilization and consequent intrusion were first achieved in the lower complex during the Late Jurassic at shallow burial conditions, and then at higher confinement pressure for the upper complex, probably during the Late Cretaceous. These results highlight how field data can be used to constrain long-lived spatiotemporal relationships of sedimentary intrusions, allowing a finely tuned upscaling of seismic data and interpretations.
V3Geo is a cloud-based repository for publishing virtual 3D models in geoscience. The system allows storage, search and visualisation of mesh models typically acquired using techniques such as photogrammetry and laser scanning. The platform has been developed to handle models at the range of scales typically used by geoscientists from microscopic, hand samples and fossils through to outcrop sections or terrain covering metres to tens of kilometres. The cloud storage system serves the models to a purpose-built 3D web viewer. Models are tiled to ensure efficient streaming over the Internet. The web viewer allows 3D models to be interactively explored without the need for specialist software to be installed. A measurement tool enables users to gauge simple dimensions, such as widths, thicknesses, and fault throws. V3Geo allows very large models comprising multiple sections and is designed to include additional interpretation layers. The specific focus on geoscience data is supported by defined metadata and a classification schema. Public and private storage is available, and public models are assigned Creative Commons licenses to govern content usage. This paper presents V3Geo as a sustainable resource for the geoscience community, including the motivation and main characteristics and features. Example usage scenarios are highlighted: from undergraduate geology teaching, supporting virtual geoscience education and preparing virtual field trips based on V3Geo models. Finally, best practice guidelines for preparing 3D model contributions for publication on V3Geo are included as the Appendix.
Natural phenomena boundaries and complexity of features in an urban area due to the low spatial resolution, lead to more pixels of satellite images included in reflectance of multiple land-cover/object components. The sub-pixel information extracting model outputs are fractional cover maps of interested class (end-member), with membership values between zero and one. These maps represented gradient change in only one fuzzy phenomenon boundaries such as vegetation cover. However, in multiple fuzzy class area or complex fuzzy phenomena such as mangrove forests, in the northwest of the Qeshm Island, Hormozgan, Iran, displaying several fractional covers may cause confusion and misunderstanding for the end-user. In this study, an additive color composite and spectral mixture analysis method is utilized for multiple fractional cover representation. The proposed method is implemented on images acquired from Operational Land Imager (OLI) sensor in the Landsat 8 satellite to extract three fractional covers (water, vegetation, and soil). An RGB color composite was used for each type and percentage of fractional cover for given pixel to display fractional cover separately. Based on such RGB color composite represented both quantitative and qualitative information, we used the RGB color solid cube as map legend for better understanding and map interpretation. The result of this study showed that suggested sub-pixel visualization method, gives new vision to the end-user understanding of fuzzy phenomena.
The determination of the shape and extent of strata is one of the most important steps in the classification of architectural elements in an outcrop. However, mapping and accessing outcrops with broad lateral and vertical continuity can be difficult due to their geographic position. In this work, UAV-captured outcrop images are used to apply seeding methods to identify and measure strata size. A computational system based on Segmentation Neural Networks was used as an effective method to automatically identify outcrop strata. The results show that the DeepLabV3 semantic segmentation neural network can achieve interesting results when combined with the PointRend technique. The different combinations of architectures were compared with UAV images from outcrops with turbidite systems of the Itararé Group (Paraná Basin, Brazil). The results show that machine learning approaches are alternative and efficient techniques that contribute to the improvement of traditional semi-supervised segmentation methods.KeywordsSemantic segmentationPointRendDeepLabTurbidite system
The Svalbard Composite Tectono-Stratigraphic Element is located on the north-western corner of the Barents Shelf and comprises a Carboniferous to 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 to 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 the archipelago 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 most of the Late Cretaceous and early Danian throughout the Svalbard Composite Tectono-Stratigraphic Element. 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 Palaeogene. This event was followed by formation of yet another major hiatus spanning the Oligocene to Pliocene. Multiple reservoir and source rock units are exposed in Svalbard providing analogues to the offshore prolific offshore acreages in southwest Barents Sea and are important for de-risking of plays and prospects. However, the archipelago itself is regarded as high-risk acreage for petroleum exploration. This is due to Palaeogene contraction and late Neogene uplift of particularly the western and central parts. In the east there is an absence of mature source rocks, and the entire region is subjected to strict environmental protection.
SfM/MVS photogrammetry has received increasing attention due to its convenience, broadening the range of its applications into archaeology and anthropology. Because the accuracy of SfM/MVS depends on photography, one important issue is that incorrect or low-density point clouds are found in 3D models due to poor overlapping between images. A systematic way of taking photographs solve these problems, though it has not been well established and the accuracy has not been examined either, with some exceptions. The present study aims to (i) develop an efficient method for recording pottery using an automated turntable and (ii) assess its accuracy through a comparison with 3D models made by laser scanning. We recorded relatively simple pottery manufactured by prehistoric farmers in the Japanese archipelago using SfM/MVS photogrammetry and laser scanning. Further, by measuring the Hausdorff distance between 3D models made using these two methods, we show that their difference is negligibly small, suggesting that our method is sufficiently accurate to record pottery.
Over the past five years the use of 3D models in the Earth Sciences has become ubiquitous. These models, termed Virtual outcrops, are most commonly generated using Structure from Motion (SfM) photogrammetry, an image-based modelling method that has achieved widespread uptake and utilization. Data for these models is commonly acquired using remotely piloted aerial vehicles (RPVs), commonly called drones. The purpose of this document is to present a basic acquisition methodology, which is based on the workflows used by the authors for the acquisition of over 500 virtual outcrops over the last decade. This article is part of a series from the editors of V3Geo, which is an online forum for sharing high quality virtual 3D geoscience models. Virtual outcrops submitted to V3Geo are subject to a technical quality control to ensure that data can be reliably utilized by the wider professional and scientific community. This document provides guidelines for the robust acquisition of data which are required to build high quality models suitable for sharing in V3Geo. The document focuses on outcrop selection, mission planning, RPV setup, data acquisition and management. Related documents in this series cover data processing and model building.
We use high-resolution aerial photogrammetry to investigate glacier retreat in great spatial and temporal detail in the Ötztal Alps, a heavily glacierized area in Austria. Long-term in situ glaciological observations are available for this region as well as a multitemporal time series of digital aerial images with a spatial resolution of 0.2 m acquired over a period of 9 years. Digital surface models (DSMs) are generated for the years 2009, 2015, and 2018. Using these, glacier retreat, extent, and surface elevation changes of all 23 glaciers in the region, including the Vernagtferner, are analyzed. Due to different acquisition dates of the large-scale photogrammetric surveys and the glaciological data, a correction is successfully applied using a designated unmanned aerial vehicle (UAV) survey across a major part of the Vernagtferner. The correction allows a comparison of the mass balances from geodetic and glaciological techniques – both quantitatively and spatially. The results show a clear increase in glacier mass loss for all glaciers in the region, including the Vernagtferner, over the last decade. Local deviations and processes, such as the influence of debris cover, crevasses, and ice dynamics on the mass balance of the Vernagtferner, are quantified. Since those local processes are not captured with the glaciological method, they underline the benefits of complementary geodetic surveying. The availability of high-resolution multi-temporal digital aerial imagery for most of the glaciers in the Alps provides opportunities for a more comprehensive and detailed analysis of climate-change-induced glacier retreat and mass loss.
Seismic mapping of subsurface faults is hampered by factors such as seismic resolution, velocity control for depth conversion and human bias. Here, we explore the challenges and pitfalls related to interpreting normal faults by comparing objective and subjective uncertainties. A panel of 20 interpreters, with different geoscientific backgrounds, interpreted faults in modern conventional (dominant frequency 40 Hz) and high-resolution P-Cable (dominant frequency 150 Hz) 3D seismic data from the Hoop area, SW Barents Sea. The interpretations created by the test-panel were sorted into 10 scenarios characterized by different fault geometries. These scenarios were explored with 2(3)D Point-Spread Function based convolution seismic modelling to investigate the potential of seismic data to image detailed fault architectures. The results reveal that: (1) Statistical analysis shows considerable variations between manually picked faults. (2) Identifying the location of fault-tips is challenging and smaller antithetic faults are rarely recognizable. (3) Uncertainties arise from masking of closely spaced fault segments even where displacement values are large, showing distorted reflection signatures of apparent extensional fault-tip monoclines. The distortion is larger for conventional versus high-resolution data. (4) In the conventional and high-resolution seismic data the vertical resolution of closely spaced reflections and small offset faults is 20 m and 5 m, respectively. The utilisation of high-resolution seismic data, combined with seismic modelling, add confidence to interpretation of conventional seismic data in the same area. We conclude that subsurface fault mapping with seismic data requires insight in objective uncertainties associated with the data. Automatic machine-learning fault interpretation is void of subjective bias but still hampered by objective limitations. Further, a risking workflow requires acknowledgement of uncertainties that are transferred to seismic based fault analysis techniques such as juxtaposition analysis, quantitative fault seal analysis, and fault stability analysis.
The Lilstock outcrop in the southern Bristol Channel provides exceptional exposures of several limestone beds displaying stratabound fracture networks, providing the opportunity to create a very large, complete, and ground-truthed fracture model. Here we present the result of automated fracture extraction of high-resolution photogrammetric images (0.9 cm/pixel) of the full outcrop, obtained using an unmanned aerial vehicle, to obtain a spatially extensive, full-resolution map of the complete fracture network with nearly 350,000 ground-truthed fractures. We developed graph-based functions to resolve some common issues that arise in automatic fracture tracing such as incomplete traces, incorrect topology, artificial fragmentation, and linking of fracture segments to generate geologically significant trace interpretations. The fracture networks corresponding to different regions within the outcrop are compared using several network metrics and the results indicate both inter- and intra-network (layer to layer) structural variabilities. The dataset is a valuable benchmark in the study of large-scale natural fracture networks and its extension to stochastic network generation in geomodelling. The dataset also highlights the intrinsic spatial variation in natural fracture networks that can occur even in weakly-deformed rocks over relatively short length scales of tens of metres.
Paleokarst breccias are a common feature of sedimentary rift basins. The Billefjorden Trough in the high Arctic archipelago of Svalbard is an example of such a rift. Here the Carboniferous stratigraphy exhibits intervals of paleokarst breccias formed by gypsum dissolution. In this study we integrate digital outcrop models (DOMs) with a 2D ground penetrating radar (GPR) survey, to extrapolate external irregular paleokarst geometries beyond the two-dimensional outcrops. DOMs are obtained through combining a series of overlapping photographs with structure-from-motion photogrammetry, to create mm-to cm-resolution georeferenced DOM's. GPR is typically used for surveying the shallow subsurface and relies on detecting the contrasts in electro-magnetic permittivity. We defined three geophysical facies based on their appearance in GPR. Integrating subsurface geophysical data with DOMs enables the correlation of reflection patterns in GPR with outcrop features. The chaotic nature of paleokarst breccias is seen both in outcrop and GPR. Key horizons in outcrop and the GPR profiles allow tying together observations between these methods. Furthermore, we show that this technique expands the two-dimensional outcrop surface into a three-dimensional domain, thus complementing, strengthening and extending outcrop interpretations.
Carbonates represent major hydrocarbon reservoirs, but often exhibit highly heterogeneous reservoir properties. Outcrop analogues provide important insights into how parameters such as porosity, permeability and natural fractures vary. As such, outcrops can bridge the scale gap between spatially extensive but poor-resolution seismic data and 1D high-resolution well data. However, traditional geological fieldwork typically gathers insufficient data to construct robust geological models. In this study, we have specifically set out to gather key data sets that enable the construction of a geology-driven model. We illustrate this workflow using the exceptionally well-exposed carbonate-dominated outcrops of the Kapp Starostin Formation in central Spitsbergen, Arctic Norway. We fully utilize emerging technologies, notably geo-referenced digital outcrop models (DOMs), to be able to gather quantitative sedimentological-structural data from otherwise inaccessible cliffs. DOMs generated from digital photos are used directly for automatic and manual mapping of fractures. The digital data are complemented with traditional fieldwork (sedimentological logging, scanlines, structural characterization) in order to strengthen the dataset. The geo-modelling involves traditional facies and petrophysical modelling of the 12 identified facies, along with outcrop-based discrete fracture modelling. Finally, the static geo-model is upscaled, and its applications are discussed. The presented workflow uses carbonate outcrops of the Kapp Starostin Formation as input but is highly applicable for other studies where outcrops can be utilized as direct input to constrain a geological model.
A synthesis has been undertaken based on regionally compiled data from the post early Eocene foreland basin succession of Svalbard. The aim has been to generate an updated depositional model and link this to controlling factors. The more than kilometer thick progradational succession includes the offshore shales of the Gilsonryggen Member of the Frysjaodden Formation, the shallow marine sandstones of the Battfjellet Formation and the predominantly heterolithic Aspelintoppen Formation, together recording the progressive eastwards infill of the foredeep flanking the West Spitsbergen fold‐and‐thrust belt.
Here we present a summary of the paleo‐environmental depositional systems across the basin, their facies and regional distribution and link these together in an updated depositional model. The basin‐margin system prograded with an ascending shelf‐edge trajectory in the order of 1°. The basin fill was bipartite, with offset stacked shelf and shelf‐edge deltas, slope clinothems and basin floor fans in the western and deepest part and a simpler architecture of stacked shelf‐deltas in the shallower eastern part. We suggest a foredeep setting governed by flexural loading, likely influenced by buckling, and potentially developing into a wedge top basin in the mature stage of basin filling. High‐subsidence rates probably counteracted eustatic falls with the result that relative sea‐level falls were uncommon. Distance to the source terrain was small and sedimentation rates was temporarily high. Time‐equivalent deposits can be found outbound of Stappen High in the Vestbakken Volcanic Province and the Sørvestsnaget Basin 300 km further south on the Barents Shelf margin. We cannot see any direct evidence of coupling between these more southerly systems and the studied one; southerly diversion of the sediment‐routing, if any, may have taken place beyond the limit of the preserved deposits.
The aim of this paper is to identify a suitable pipeline in order to build high-resolution 3D models and 2D orthophotos of objects and architectural structures of particular historical and cultural importance by means of the photogrammetric method. An accurate reconstruction of architectural elements can be exploited both for a detailed analysis of the artefacts, and also to determine the original position of detached architectural fragments. Structure from Motion (SfM) and Multi View Stereo (MVS) approaches have already been successfully applied in many applications to build 3D models. Moreover, the obtained reconstruction can be exploited in order to build orthographic projections of the object from different directions: the orthophotos generated in this way ensure a very high geometric resolution (even sub-millimetre) and accuracy. Orthophotos are particularly useful for the digital documentation and analysis of archaeological and architectural objects. To such aim, the direction to be used for the computation of the orthophoto, which in certain cases might be non-trivial, should be carefully determined. This work describes a simple procedure for the definition of such projection direction, while also enabling the express the object position according to certain specific requirements. In addition, the use of low-cost smartphone and action cameras was investigated to carry out photogrammetric surveys. Finally, this paper shows the results obtained with an imagery acquisition tool to be mounted on the top of a drone, developed ad hoc in order to properly acquire images for instance of the base of high bridges that cannot be achieved through a terrestrial survey. The developed tools and the overall proposed method is validated on three case studies, two related to terrestrial surveys, whereas the latter consider an example of UAV (Unmanned Aerial Vehicle) photogrammetry with the developed imagery acquisition device.
High-resolution 3D datasets, such as digital outcrop models (DOMs) are increasingly being used by geoscientists to supplement field observations and enable multiscale and repeatable analysis that was previously difficult, if not impossible, to achieve using conventional methods. Despite an increasing archive of DOMs driven by technological advances, the ability to share and visualize these datasets remains a challenge due to large files and the need for specialized software. Together, these issues limit the open exchange of datasets and interpretations. To promote greater data accessibility for a broad audience, we implement three modern platforms for disseminating models and interpretations within an open science framework: Sketchfab, potree, and Unity. Web-based platforms, such as Sketchfab and potree, render interactive 3D models within standard web browsers with limited functionality, whereas game engines, such as Unity, enable development of fully customizable 3D visualizations compatible with multiple operating systems. We review the capabilities of each platform using a DOM of an extensive outcrop exposure of Late Cretaceous fluvial stratigraphy generated from UAV images. Each visualization platform provides end-users with digital access and intuitive controls to interact with large DOM datasets, without the need for specialized software and hardware. We demonstrate a range of features and interface customizability that can be created and suggest potential use cases to share interpretations, reinforce student learning, and enhance scientific communication through unique and accessible visualization experiences.
Research on the Permian-Triassic boundary (PTB) along the northern margins of Pangaea (exposed today in the Arctic region) has been heavily reliant on field observations, where data resolution was consequently determined by outcrop condition and accessibility. Core drilling in central Spitsbergen allowed for a near-complete recovery of two ~90 m cores through the PTB. Analyses of the core and nearby outcrops include stratigraphic logging and sampling, XRF scanning, petrography, biostratigraphy, isotope geochemistry, and geochronology. The First Appearance Datum (FAD) of H. parvus in Svalbard places the base of the Triassic ca. 4 m above the base of the Vikinghøgda Formation, and ca. 2.50 m above the End-Permian Mass Extinction (EPME) and its associated sharp negative δ13C. The PTB therefore falls within the Reduviasporonites chalastus Assemblage Zone in Svalbard. Precise U-Pb TIMS dating of two zircon crystals in a tephra layer just above the first documented Hindeodus parvus in Svalbard gives an age of 252.13 ± 0.62 Ma. High-resolution palaeoenvironmental proxies, including Si/kcps (kilo counts per second), Zr/Rb, K/Ti, Fe/K, and V/Cr, indicate a transition towards a more arid climate in the earliest Triassic, contemporaneous with prolonged bottom-water dysoxic/anoxic conditions, following an increase in volcanic activity in the Late Permian. Statistical analysis of Zr/Rb, K/Ti and V/Cr elemental ratios suggests that the system was impacted by long-eccentricity (400 kyr) cyclicity. The δ13C excursion in organic carbon (δ13Corg) record signals a large negative carbon isotope excursion (CIE) associated with the mass extinction event, but also records a second, smaller negative CIE ca. 22 m above this interval. This younger δ13Corg excursion correlates to similar CIEs in the Dienerian (late Induan) records of other sections, notably in the Tethys Ocean, which have been interpreted as recording a small biotic crisis during the post-extinction recovery. Evidence of this negative CIE in Spitsbergen suggests that the Dienerian crisis may have been global in extent. The negative δ13Corg values are associated with evidence for dysoxia or anoxia in the core, and the occurrence of tephra layers in the same interval suggests a possible connection between the Dienerian crisis and a discrete episode of volcanic activity.
Key words: Permian-Triassic boundary, Hindeodus parvus, climate change, long eccentricity, Dienerian crisis
From 2007 to 2015, eight wells were drilled and fully cored to test the feasibility of storing CO2 emitted from the coal-fueled power plant in
Longyearbyen, Svalbard. The drilling campaign identified three water-bearing sandstone aquifers; i) a lower aquifer in Upper Triassic strata; ii) a middle aquifer in Upper Triassic to Middle Jurassic; and iii) an upper aquifer in Lower Cretaceous strata. Only the two former are regarded as potential CO2 storage units. Both units are unconventional reservoirs (storage units) consisting of fractured, low-porosity and low-permeability sandstones. The storage units are capped by a c. 400 m-thick Middle Jurassic to Lower Cretaceous mudstone-dominated succession, which acts as an efficient top seal. In addition, a c. 120 m-thick zone of permafrost provides an additional seal. Apart from characterising the CO2 storage and cap-rock system, the drilling resulted in several unexpected results. These include: (a) the detection of severe underpressure of approximately 50 bar in the two storage units, (b) the discovery of gravity-flow deposits attributed to a hitherto unknown Hauterivian clastic wedge, and (c) the detection
of producible thermogenic shale gas at a depth of 640 to 700 m. Moreover, core and wireline data from the wells combined with correlation to equivalent strata in nearby outcrops provide new insights into the age and depositional evolution of the succession. Thus, the data obtained from this project contributes to the regional stratigraphic understanding of the Mesozoic succession in Svalbard and the northern Barents Shelf. Until now, nearly 70 papers have been published in international peer-reviewed journals using data from or part of the Longyearbyen CO2 Laboratory. In addition, 13 PhD candidates and 27 master students, linked to the project or using obtained data from the project, have graduated.
The main achievement of our studies is that we have shown that unconventional fractured reservoirs are suitable for storing CO2.
Thermogenic dry gas flowed from Jurassic sections in the DH5R research well drilled onshore in Adventdalen, central Spitsbergen, Arctic Norway. The DH5R gas originates from the organic-rich units of the mudstone-dominated Middle Jurassic to Lower Cretaceous Agardhfjellet Formation, which is the onshore equivalent to the Fuglen Formation and the prolific oil and gas generating Hekkingen Formation in the southern Barents Shelf. Low-permeable, low-porosity sandstones from the Upper Triassic De Geerdalen Formation of the neighbouring DH4 well were oil-stained and gas was also collected from this interval. Gas from the two stratigraphic intervals have different compositions; the gas from the Agardhfjellet Formation is drier and isotopically heavier than the gas from the Upper Triassic succession. Both gases originated from source rocks of maturity near the end of the oil window (1.1 < Ro < 1.4% Ro). Maceral analyses of the Agardhfjellet Formation indicate that the more silty parts contain a high percentage of vitrinite-rich type III kerogen, whereas the clay-dominated parts are rich in liptinitic type II kerogen. The Agardhfjelletv Formation has therefore the potential to generate both oil and gas. Several simulations based on pressure data and flow rates from the DH5R well were run to evaluate if the gas accumulation in the Agardhfjellet Formation is producible, i.e., can it be commercial shale gas. The models demonstrate how changes in the drainage area size and form, well types (vertical versus horizontal), number and length of induced fractures and thickness of the Agardhfjellet Formation affect gas production rates and producible volumes. Despite uncertainties in the input data, simulations indicate that the shale gas accumulation characterised in Adventdalen is producible. This gas can have major environmental benefits as an alternative for local power generation compared to coal.
Structure-from-motion (SfM) photogrammetry enables the cost-effective digital characterisation of seismic- to sub-decimetre-scale geoscientific samples. The technique is commonly used for the characterisation of outcrops, fracture mapping, and increasingly so for the quantification of deformation during geotechnical stress tests. We here apply SfM photogrammetry using off-the-shelf components and software, to generate 25 digital drill core models of drill cores. The selected samples originate from the Longyearbyen CO2 Lab project’s borehole DH4, covering the lowermost cap rock and uppermost reservoir sequences proposed for CO2 sequestration onshore Svalbard. We have come up with a procedure that enables the determination of bulk volumes and densities with precisions and accuracies similar to those of such conventional methods as the immersion in fluid method. We use 3D printed replicas to qualitatively assure the volumes, and show that, with a mean deviation (based on eight samples) of 0.059% compared to proven geotechnical methods, the photogrammetric output is found to be equivalent. We furthermore splice together broken and fragmented core pieces to reconstruct larger core intervals. We unwrap these to generate and characterise 2D orthographic projections of the core edge using analytical workflows developed for the structure-sedimentological characterisation of virtual outcrop models. Drill core orthoprojections can be treated as directly correlatable to optical borehole-wall imagery data, enabling a direct and cost-effective elucidation of in situ drill core orientation and depth, as long as any form of borehole imagery is available. Digital drill core models are thus complementary to existing physical and photographic sample archives, and we foresee that the presented workflow can be adopted for the digitisation and digital storage of other types of geological samples, including degradable and dangerous ice and sediment cores and samples.
The accurate classification and 3D mapping of benthic habitats in coastal ecosystems are vital for developing management strategies for these valuable shallow water environments. However, both automatic and semiautomatic approaches for deriving ecologically significant information from a towed video camera system are quite limited. In the current study, we demonstrate a semiautomated framework for high-resolution benthic habitat classification and 3D mapping using Structure from Motion and Multi View Stereo (SfM-MVS) algorithms and automated machine learning classifiers. The semiautomatic classification of benthic habitats was performed using several attributes extracted automatically from labeled examples by a human annotator using raw towed video camera image data. The Bagging of Features (BOF), Hue Saturation Value (HSV), and Gray Level Co-occurrence Matrix (GLCM) methods were used to extract these attributes from 3000 images. Three machine learning classifiers (k-nearest neighbor (k-NN), support vector machine (SVM), and bagging (BAG)) were trained by using these attributes, and their outputs were assembled by the fuzzy majority voting (FMV) algorithm. The correctly classified benthic habitat images were then geo-referenced using a differential global positioning system (DGPS). Finally, SfM-MVS techniques used the resulting classified geo-referenced images to produce high spatial resolution digital terrain models and orthophoto mosaics for each category. The framework was tested for the identification and 3D mapping of seven habitats in a portion of the Shiraho area in Japan. These seven habitats were corals (Acropora and Porites), blue corals (H. coerulea), brown algae, blue algae, soft sand, hard sediments (pebble, cobble, and boulders), and seagrass. Using the FMV algorithm, we achieved an overall accuracy of 93.5% in the semiautomatic classification of the seven habitats.
The beginning of the Norwegian oil industry is often attributed to the first exploration drilling in the North Sea in 1966, the first discovery in 1967 and the discovery of the supergiant Ekofisk field in 1969. However, petroleum exploration already started onshore Svalbard in 1960 with three mapping groups from Caltex and exploration efforts by the Dutch company Bataaffse (Shell) and the Norwegian private company Norsk Polar Navigasjon AS (NPN). NPN was the first company to spud a well at Kvadehuken near Ny-Ålesund in 1961. This drilling marked the start of an exciting period of petroleum exploration in Svalbard, with eighteen exploration wells drilled in the period from 1961 to 1994. The deepest well so far, Caltex's Ishøgda-I near Van Mijenfjorden, reached 3304 m in 1966. NPN was involved in nine of the eighteen wells. The remaining wells were drilled by American (Caltex/Amoseas), Belgian (Fina), French (Total), Soviet/Russian (Trust Arktikugol), Swedish (Polargas Prospektering) and Norwegian companies Norsk Hydro and Store Norske Spitsbergen Kulkompani. None of the wells resulted in commercial discoveries, though several wells encountered gas in measureable quantities. Only the two wells drilled in the early 1990s were drilled on structures defined using a sparse 2D seismic grid, while the other wells were drilled based on geological mapping at the surface. Furthermore, more recent research and coal exploration boreholes have confirmed moveable hydrocarbons in close proximity to the Longyearbyen and Pyramiden settlements. In this contribution, we present a historical and brief geological overview of the petroleum exploration wells onshore Svalbard. We illustrate that the eighteen petroleum exploration wells have together penetrated over 29 km of stratigraphy, with the Late Palaeozoic-Mesozoic successions particularly well covered. Coal exploration and research boreholes primarily focus on the Mesozoic-Cenozoic successions. As such, the boreholes represent an important window to decipher the stratigraphic evolution of both Svalbard and the greater Barents Shelf.
In recent years, uncertainty has been widely recognized in geosciences, leading to an increased need for its quantification. Predicting the subsurface is an especially uncertain effort, as our information either comes from spatially highly limited direct (1-D boreholes) or indirect 2-D and 3-D sources (e.g., seismic). And while uncertainty in seismic interpretation has been explored in 2-D, we currently lack both qualitative and quantitative understanding of how interpretational uncertainties of 3-D datasets are distributed. In this work, we analyze 78 seismic interpretations done by final-year undergraduate (BSc) students of a 3-D seismic dataset from the Gullfaks field located in the northern North Sea. The students used Petrel to interpret multiple (interlinked) faults and to pick the Base Cretaceous Unconformity and Top Ness horizon (part of the Middle Jurassic Brent Group). We have developed open-source Python tools to explore and visualize the spatial uncertainty of the students' fault stick interpretations, the subsequent variation in fault plane orientation and the uncertainty in fault network topology. The Top Ness horizon picks were used to analyze fault offset variations across the dataset and interpretations, with implications for fault throw. We investigate how this interpretational uncertainty interlinks with seismic data quality and the possible use of seismic data quality attributes as a proxy for interpretational uncertainty. Our work provides a first quantification of fault and horizon uncertainties in 3-D seismic interpretation, providing valuable insights into the influence of seismic image quality on 3-D interpretation, with implications for deterministic and stochastic geomodeling and machine learning.
Sandstone intrusions form large bedding-discordant sandstones that intruded into finer grained, less permeable host strata. They form naturally sand-propped hydraulic fractures that constitute a connected network of permeable conduits through which fluids escape to the Earth's surface. Saucer-shaped sandstone intrusions are among the largest volume intrusions and are commonly resolved on seismic data. Outcrop analogues of seismically-resolved saucers-shaped intrusions reveal that many attendant intrusions, in particular dikes, are undetected in seismic data. Seismic forward modeling of a detailed outcrop description of a saucer-shaped intrusion demonstrates that intrusions steeper than 45 • are undetected and that up to 40% of the entire volume of sandstone intrusions is not seismically imaged. Wedge geometry-associated with discordant contacts between different lithologies-causes constructive and destructive amplitude interference, creating imaging artefacts of sandstone thickness and geometry. Comparison of the outcrop seismic models with 3D seismic data from Volund oilfield demonstrate both the similarity of the saucer-shaped intrusions and the distribution and quantity of dikes that may be undetected (ca. 78%) using subsurface data. Lack of detection of dikes has direct implications on the valuation of upward migration of fluids and an overestimation of seal capacity. This therefore has major implications when using seismic data to evaluate waste sequestration or to execute hydrocarbon or groundwater exploration and production.
Complex landscapes with high topographic relief and intricate geometry present challenges for complete and accurate mapping of both lateral (x, y) and vertical (z) detail without deformation. Although small uninhabited/unmanned aerial vehicles (UAVs) paired with structure-from-motion (SfM) image processing has recently emerged as a popular solution for a range of mapping applications, common image acquisition and processing strategies can result in surface deformation along steep slopes within complex terrain. Incorporation of oblique (off-nadir) images into the UAV–SfM workflow has been shown to reduce systematic errors within resulting models, but there has been no consensus or documentation substantiating use of particular imaging angles. To address these limitations, we examined UAV–SfM models produced from image sets collected with various imaging angles (0–35°) within a high-relief ‘badland’ landscape and compared resulting surfaces with a reference dataset from a terrestrial laser scanner (TLS). More than 150 UAV–SfM scenarios were quantitatively evaluated to assess the effects of camera tilt angle, overlap, and imaging configuration on the precision and accuracy of the reconstructed terrain. Results indicate that imaging angle has a profound impact on accuracy and precision for data acquisition with a single camera angle in topographically complex scenes. Results also confirm previous findings that supplementing nadir image blocks with oblique images in the UAV–SfM workflow consistently improves spatial accuracy and precision and reduces data gaps and systematic errors in the final point cloud. Subtle differences among various oblique camera angles and imaging patterns suggest that higher overlap and higher oblique camera angles (20–35°) increased precision and accuracy by nearly 50% relative to nadir-only image blocks. We conclude by presenting four recommendations for incorporating oblique images and adapting flight parameters to enhance 3D mapping applications with UAV–SfM in high-relief terrain.
The use of three-dimensional (3-D), photo-textured representations of topography from laser scanning and photogrammetry is becoming increasingly common across the geosciences. This rapid adoption is driven by recent innovations in acquisition hardware, software automation, and sensor platforms, including unmanned aerial vehicles. In addition, fusion of surface geometry with imaging sensors, such as multispectral, hyperspectral, thermal, and ground-based radar, and geophysical methods creates complex and visual data sets that provide a fundamental spatial framework to address open geoscience research questions. Despite the current ease of acquiring and processing 3-D photo-textured models, the accessibility of tools for analyzing and presenting data remains problematic, characterized by steep learning curves and custom solutions for individual geoscience applications. Interpretation and measurement is essential for quantitative analysis of 3-D data sets, and qualitative methods are valuable for presentation purposes, for planning, and in education. This contribution presents LIME, a lightweight and high-performance 3-D software for interpreting and co-visualizing 3-D models and related image data. The software allows measurement and interpretation via digitizing in the 3-D scene. In addition, it features novel data integration and visualization of 3-D topography with image sources such as logs and interpretation panels, supplementary wavelength imagery, geophysical data sets, and georeferenced maps and images. High-quality visual output can be generated for dissemination to aid researchers with communication of their results. The motivation and an overview of the software are described, illustrated by example usage scenarios from outcrop geology, multi-sensor data fusion, and geophysical-geospatial data integration.
Background:
Driven by a huge improvement in automation, unmanned areal systems (UAS) are increasingly used for field observations and high-throughput phenotyping. Today, the bottleneck does not lie in the ability to fly a drone anymore, but rather in the appropriate flight planning to capture images with sufficient quality. Proper flight preparation for photography with digital frame cameras should include relevant concepts such as view, sharpness and exposure calculations. Additionally, if mapping areas with UASs, one has to consider concepts related to ground control points (GCPs), viewing geometry and way-point flights. Unfortunately, non of the available flight planning tools covers all these aspects.
Results:
We give an overview of concepts related to flight preparation, present the newly developed open source software PhenoFly Planning Tool, and evaluate other recent flight planning tools. We find that current flight planning and mapping tools strongly focus on vendor-specific solutions and mostly ignore basic photographic properties— our comparison shows, for example, that only two out of thirteen evaluated tools consider motion blur restrictions, and none of them depth of field limits. In contrast, PhenoFly Planning Tool enhances recent sophisticated UAS and autopilot systems with an optical remote sensing workflow that respects photographic concepts. The tool can assist in selecting the right equipment for your needs, experimenting with different flight settings to test the performance of the resulting imagery, preparing the field and GCP setup, and generating a flight path that can be exported as waypoints to be uploaded to an UAS.
Conclusion: By considering the introduced concepts, uncertainty in UAS-based remote sensing and high-throughput phenotyping may be considerably reduced. The presented software PhenoFly Planning Tool (https://shiny.usys. ethz.ch/PhenoFlyPlanningTool) helps users to comprehend and apply these concepts.
Outcrop analogue studies allow detailed investigation of sandstone body geometry and architecture within fluvial systems. Characterization of these elements is fundamental to understanding and quantifying sandstone body connectivity within hydrocarbon reservoir models, and hence improving recovery from those reservoirs being modeled. This study utilized a laterally and vertically continuous terrestrial light detection and ranging (lidar) data set from the La Serrata section of the Oligocene–Miocene Huesca fluvial fan, in the Ebro Basin in Spain. This data set was used to create high-resolution threedimensional digital outcrop model of a 2 km2 cliff section representing the heterogeneity in the medial (midfan) portion of a large fluvial fan. Geostatistical information (i.e., sandstone body width and thickness) extracted from the models using quantitative analytical techniques, integrated with traditional sedimentary log data, allowed the calculation of probability density functions of 42 sandstone bodies from corrected (true) width measurements. These data show that sandstone bodies are up to 6 m thicker and 209 m wider than previous studies have estimated. Furthermore, an observed temporal trend of thickening and widening of sandstone bodies up section before a reduction in the uppermost portion provides evidence for possible avulsion events. These data, compared with previous studies of this and other fluvial systems, illustrate the efficacy of digital outcrop models as quantitative tools for accurate characterization of critical reservoir elements from outcrop analogues.
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.
Collecting quantitative and extensive datasets in the field is fundamental in structural geology, stratigraphy, and sedimentology, rock mechanics, and in other fields of the Earth and planetary sciences. Digital Outcrop Models (DOMs) provide a 3D framework for collecting these large datasets and can be obtained from laser scanning or photogrammetric surveys, carried out either with an avionic platform (airplane, helicopter, drone) or with terrestrial methods. In this chapter we review best‐practice methods for collecting DOMs, focusing particularly on terrestrial and drone photogrammetric surveys and on critical issues that determine their efficiency, reliability, and accuracy. Then we compare the two main formats for DOMs: point clouds (PC‐DOMs) and textured surfaces (TS‐DOMs). Finally, we outline typical goals and workflows for the geological interpretation of DOMs on PC‐ and TS‐DOMs, either from laser scanning or photogrammetric surveys.
Hand scanners are compact, lightweight, and capable of generating 3-D digital models. Although they do not compare to conventional methods (terrestrial laser scanning and photogrammetry) in terms of coverage, resolution, and accuracy, they offer increased mobility, speed, and real-time processing capabilities in the field. This study investigates the use of hand scanners for real-time, 3-D digital outcrop modeling to augment geological field mapping campaigns and highlights the advantages and the limitations. The utility of incorporating hand scanners as an additional tool for augmenting geological mapping is assessed based on 41 outcrop scans from the Gould Lake area, which is located 20 km north of Kingston, Ontario, Canada. The 3-D digital outcrop models gathered included two distinct metamorphic lithologies (marble and quartzofeldspathic gneiss) measuring up to 2.5 m high × 7 m long with an average surface area of 18 m2. This average scan size would take less than 10 min to capture, result in ~18 million individual points per scan, and provide a spatial resolution of ~1 cm for outcrop features. Throughout the course of the investigation, the main benefit of capturing multiple 3-D digital outcrop models was the ability to integrate this real-time, in situ geospatial, and geologic information across multiple visualization scales. This utility and retention of outcrop-scale geospatial information was shown to enhance the understanding of multi-scale geological relationships.
Determination of pore space characteristics is important for carbonate reservoir interpretation and evaluation. Field outcrops can reflect the geology of the subsurface reservoir. The most common method of traditional outcrop research is field investigation, which is likely to cause human errors. Digital image recognition of geological outcrop areas can reduce the problem of inaccurate descriptions of geological structures caused by human factors. Automatic extraction based on convolutional neural networks can greatly reduce the amount of such work. By enhancing the deep-learning model of a convolution neural network, the mask region-convolutional neural network (Mask R-CNN) is proposed. This method adapts to the multiscale features of the cavity by manipulating the scales of the input image. To verify the applicability of the model, the method is applied to automatic cavity identification in the digital outcrop profile of the Dengying Formation (2nd Member) in Xianfeng, Ebian. The parameters are calculated layer by layer, and their distribution characteristics are quantitatively analysed, indicating good application results. To verify the advanced nature of the model, the cavity extraction results of this method are compared with those of traditional image segmentation, machine learning and other depth learning methods. Precision analysis shows that the performance of the method proposed in this paper is superior to the traditional methods. In addition, the cavity feature parameters extracted by this method are compared with the manual extraction. The accuracy for the cavity number, surface porosity, and average cavity area is over 80%, 88%, and 72%, respectively for the proposed method. The results show that the proposed method is reliable and accurate, hence it will help to provide a basis for reservoir prediction in the process of regional geological exploration.
An unmanned aerial vehicle (UAV), popularly known as a drone, is an aircraft without a human pilot aboard. Recent developments in sensor technology and navigation systems have made drones a powerful and reliable basis for professional data acquisition. Today, the use of UAVs has expanded massively in the civil and commercial sectors and this technology has found its way into almost every industrial sector including the petroleum industry. Drone technology offers a great potential to revolutionize the mapping, monitoring, inspection, and surveillance procedures of the petroleum industry by providing a faster, safer, and more cost-efficient way of mass data collection. This article offers a review of the common UAV platforms and sensor systems and highlights the state-of-the-art and application examples of drone remote sensing in the petroleum industry. Six broad areas are recognized comprising offshore oil spill detection, oil leakage detection, pipeline monitoring, gas emission sensing, remote facility inspection, petroleum exploration (i.e., land surveying, geologic mapping, and petroleum exploration), and environmental monitoring. Research gaps and open issues along with opportunities for further developments in each of these areas are highlighted.
Drill cores provide the most reliable fracture information in subsurface formations as they present a clear and direct view of fractures. Core observation and image log interpretation are usually integrated for fracture analysis of underground layers. There has been a strong move towards developing automated fracture detection methods, however, the focus has been on extracting fracture information from log images, such as acoustic or resistivity image logs. Such efforts using core images are significantly less. This study presents a machine learning-based approach for automatic fracture recognition from unwrapped drill-core images. The proposed method applies a state-of-the-art convolutional neural network for object identification and segmentation. The study also investigates the feasibility of using synthetic fracture images for training the machine learning model. This can provide an alternative to real data, and thus address data availability issues common for supervised machine learning applications. We first create two types of synthetic data by using masks of real fractures and creating sinusoidal shaped fractures. The trained model is evaluated on real core images from two boreholes, which provided an average precision of approximately 95%. The identified fractures are further analyzed and compared to the manually segmented fractures in terms of fracture dip angle and dip direction, which achieved average absolute errors of around 2° and 11°, respectively. Overall, the study presents a novel application of an advanced machine learning algorithm for fracture detection and analysis from unwrapped core images.
In 1799 an English surveyor named William Smith published the World’s first geological map. This map, which covers the whole of England and Wales, fundamentally changed the way that geologists visualised the subsurface (Winchester, 2001). For the next 200 years, field geologists across the World worked in much the same way as Smith had done, tracing geological boundaries on the ground and using ink pens and coloured pencils to record the surface expression of the geology onto paper and maps. Even today, the largest single component of any undergraduate degree in the UK is a “mapping project”, where students make detailed maps of a selected area in this way. There can be very few sciences where there have been no significant changes in the basic data collection methods for over 200 years. However, since the turn of the 21st Century we have seen a quiet revolution in the way in which field data are being collected, analysed and displayed. We call this the Virtual Geoscience Revolution and it has come about in a number of discrete phases, each of which have resulted from the development of a number of distinct but parallel technologies.
Fault‐controlled mixed siliciclastic‐carbonate‐evaporite depositional systems exhibit distinct sensitivity to tectonic and eustatic controls that are expressed in the sedimentary architecture. In the Upper Carboniferous Billefjorden Trough (Svalbard, Norway), up to 2000 m of a warm and arid climate syn‐rift basin fill comprises such depositional systems, documented in this study with traditional field techniques supported by helicopter‐ and ground‐based LIDAR models. The basin evolved from siliciclastics‐dominated red beds and paralic units that filled a symmetrical basin, to a rift climax half‐graben with alluvial fans entering the basin along relay ramps of the master fault zone (Billefjorden fault zone). Faults located in the hanging wall dip‐slope prevented progradation of coarser material to the eastern part of the basin. Later, structural reorganisation in the dipslope led to cessation of easternmost faults with deformation focusing along one major lineament (Løvehovden fault zone) antithetic to the master fault zone. The basin subsidence became more symmetrical, with main central depocenter and shallower platforms near the basin flanks. Footwall anticlines from faults displacement gradients were sensitive to periodical exposure and recorded dissolution breccias and footwall synclines preserved evaporites coupled with shallow marine siliciclastic deposits. Concurrently, thick gypsum/anhydrite deposits in the basin centre reflect glacio‐eustatic lowstands whereas evenly thick carbonate deposition characterizes highstands. While most analysis of syn‐rift basin fill are based on siliciclastics deposits, we here demonstrate the complexity of tectonism versus eustatic sea level changes in a mixed carbonate‐evaporite syn‐rift deposits. Tectonic influence is ascribed to deposition of alluvial fans that prograded from the master fault toward the basin centre. On the dipslope glacio‐eustatic signals outperformed tectonic influence on deposition. Sea level lowstands promoted deposition of red sabkha mudstones and gypsum/anhydrite, salinas evaporites, or dissolution breccias, interbedded with highstand carbonate beds.
Unmanned aerial vehicles (UAVs, UAS, drones) combined with Structure-from-Motion (SfM) photogrammetry have emerged over the last decade as the basis for a very efficient workflow in glacial and periglacial geomorphology by filling the spatial gap between traditional ground-based surveys and aerial or satellite remote sensing data. UAV-generated data offer flexible spatial and temporal resolution, thus enabling a shift from a pure description of geomorphological forms to a better understanding of process-form relationships, e.g., by quantification of short-term landscape changes in response to various drivers. In this contribution, we present an overview of current applications of UAV-SfM in studies of modern and past glacial environments that include mostly geomorphological mapping and change-detection analysis. We also indicate potential future applications, e.g., by combining UAV-data with historical archives, terrestrial SfM, and crowd-based image gathering to allow for a better understanding of landscape changes in response to present climate warming.
The high Arctic is a remote place, where geoscientific research and teaching require expensive and logistically demanding expeditions to make use of the short field seasons. The absence of vegetation facilitates the use of modern photogrammetric techniques for the cost-effective generation of high-resolution digital outcrop models (DOMs). These georeferenced models can be used in pre-fieldwork activities to help prepare for traditional geological fieldwork, during fieldwork to record observations, and post-fieldwork to conduct quantitative geological analyses. Analyses of DOMs range in scale from mm-cm (e.g., size and spacing of dinosaur footprints), to hundreds of meters (e.g., seismic modeling of outcrops and outcrop-well-seismic correlations) and can advance research objectives. This integration is strengthened if key geoscientific data, like geological and topographical maps, subsurface profiles, borehole data, remote sensing data, geophysical data and DOMs can be integrated through a common database, such as the Svalbox database that we present in this commentary. Svalbox geographically targets the Svalbard archipelago, where fieldwork is challenging due to the harsh polar environment, risk of polar bear encounters and demanding transport to the field area. The University Centre in Svalbard nonetheless relies on utilizing the natural Svalbard environment for its field-based education, and now makes use of Svalbox to make geological fieldwork more efficient and post-fieldwork analyses more quantitative. Experience and usage of such tools in geoscientific education, particularly in the polar regions, is not well documented. Therefore, we share experiences on both developing and optimizing Svalbox, and on student and lecturer usage. Svalbox includes a web-based interface through which DOMs are shared and displayed together with relevant public-domain geoscientific data sets. Svalbox also serves as a platform to share student and teacher experiences on the entire DOM workflow, from acquisition to data distribution. For the Svalbox users questioned by the project group, DOMs were found to provide many benefits, including quantitative analyses, extended field season, appreciation of scale and data sharing that significantly outweigh present-day challenges, such as the need for expensive hardware and lack of easily accessible interpretation software, the latter being surmountable within the near-term.
Fault damage zones can act as a preferential corridor for fluid flow in the subsurface, and for this reason the characterization of their structure, including the attributes of the associated fracture network, is fundamental. In this work, we characterize the damage zone of the Qala fault, a normal fault developed in platform carbonates of the Gozo Island (Maltese Islands). We propose a new workflow that combines scanline and scan-area analysis applied on a high resolution DOM. Linear scanlines allow to characterize fracture spatial distribution, detect stationary area and identify damage zone width. Areal sampling permits to extract the fracture parameters matching the stationary 1D domains. This new approach allows us to: (1) univocally separate the damage zone from the background fractures, (2) identify fracture corridors, (3) collect fracture parameters (length, trend, density, intensity, spacing and topology), (4) identify the REV of the fracture density, intensity and topology and (5) characterize the fracture network connectivity.
The study of outcrop analogues of petroleum reservoirs is well established in the petroleum industry through the use of digital outcrop models (DOMs). These models, which are also known as virtual outcrop models (VOMs) or 3D outcrops, are of great importance for understanding the behavior of actual reservoirs. This topic has been reviewed by many authors, and the studies vary in detail according to the technologies involved. The present study applies systematic review methodology traversing a number of articles to find the trends in studies utilizing DOMs. The articles included in this review indicate that the technologies used to generate DOMs are still predominantly classified as Light Detection and Ranging (LiDAR) and digital photogrammetry, with the first being present in most of the works, and the latter attracting attention owing to the popularity of unmanned aerial vehicles (UAVs). These studies have attracted a significant amount of attention to outcrop analysis, and the information acquired can be used to better fit reservoir simulations. Furthermore, a trend is identified with a focus on outcrop geometry and structural data. This work also discusses some of the available opportunities related to the generation of DOMs as well as emerging technologies that can improve the quality of the outcrop models in order to provide better reservoir simulations. Finally, this work discusses the findings and highlights of the articles answering the initially raised research questions.
Human activity in the polar regions is increasing, and as a result of this, the positioning performance of global navigation satellite systems (GNSSs) in these regions is attracting more attention. Since the constellation design of GNSS systems (such as GPS, GLONASS, Galileo, and BDS) only provides superior coverage for human activity in the middle and low latitudes, the elevation angles of GNSS satellites are lower in the polar regions. In this study, the authors first analyzed the availability of GPS, GLONASS, Galileo, and BDS in the polar regions using the classic geometric dilution of precision (GDOP) metric. It was discovered that if only a stand-alone navigation system is employed, satellite visibility in the Arctic and Antarctic regions is excellent, but the GDOP is much higher than in the middle and low latitudes areas. Another interesting phenomenon is that a single navigation system other than GPS (i.e., GLONASS, Galileo, or BDS) will have some areas that cannot be located in the middle and low latitudes and will not appear in the polar regions. A simple solution of this problem is to combine multiple navigation systems to attain better GDOP. In reality, there are currently few achievable or practical solutions for the weight ratio of different satellites in the actual multi-system combined GDOP algorithm. Based on the signal-in-space analysis of different GNSS satellites, the authors propose a NEW WDOP metric for the spatial constellation configuration of multi-GNSSs, including detailed mathematical models and algorithms. The NEW WDOP metric was then used to assess the availability of multi-GNSSs in the polar regions with dual-system, three-system, and four-system combinations. This study thus draws some conclusions using the NEW WDOP model and measured data. In particular, when navigating and positioning in polar regions with a stand-alone GNSS, the mean of the NEW WDOP values is approximately 2.5, and there are many outlier values. Meanwhile, the mean of the NEW WDOP values with the dual GNSS combinations is < 1.5, but the value of the NEW WDOP for some combinations in the polar regions is still extremely large and contains some outliers. However, the mean of the NEW WDOP with the three-system or four-system combinations in the polar regions is approximately 1, and the number of outliers is very small; in particular, the four-system combination has no outliers. The results of this study contribute some useful information for the GNSS application of multi-system combinations and satellite selection in the polar regions.
Stacked fluvial distributary channel deposits and palaeovalley fills can form major, multi storey sand bodies with similar thicknesses, and with lateral extents often greater than a single exposure. Consequently, they can be difficult to tell apart from one another using outcrop data. This study addresses this problem by quantitatively analysing the architecture of five stacked fluvial distributary channel deposits and two palaeovalley fills from the Pennsylvanian Pikeville and Hyden formations of the central Appalachian Basin, USA. The a priori interpretation of the sand bodies as stacked distributary channels and palaeovalley fills is possible because a robust in-place coal seam correlation framework allows for the recognition of different basin-scale architectures for each type – aspect ratios <1000 and envelopes of fluvial and deltaic strata for stacked distributary channels, and aspect ratios >1000 and a regional basinward facies shift at the bases of palaeovalley fills. Sand body thickness, storey thickness, position and length of storey contacts within the sand body are similar in both types. However, they can be distinguished by different up-system to down-system changes in their respective architectures. Stacked distributary channel sand bodies thin down system, display a decrease in storey thickness, an increase in the mean position of storey heights in the sand body and a decrease in the length of storey contacts. These trends are the result of down-system decrease in channel size, and confinement associated with radially distributive fluvial systems. Palaeovalley fill sand bodies thicken down-system, display an increase in storey thickness, a decrease in the mean position of storey heights, and a decrease in the length of storey contacts. The increase in sand body and storey thickness are the result of down-system increases in original channel size, consistent with trunk axial fluvial systems fed by tributaries that predominate during valley-formation. The down-system increase in amalgamation reflects a down-system decrease in accommodation, from the higher subsidence rate active margin of the basin, and is therefore not necessarily characteristic of palaeovalley fill architectures in all basin settings. This study emphasises the requirement for detailed correlation work and quantitative analysis of external and internal architectures before the interpretation of sand bodies as stacked distributary channels or palaeovalley fills.
This paper presents an automatic extraction method for discontinuity trace mapping from 3D point cloud of natural rocky slopes. Unlike the methods based only on geometrical information, the proposed method also takes textural information into account. By using the texture mapping method, a texture map and a normal map are generated from the point cloud, which contain textural and geometrical information respectively. Then, the rolling guidance filter and a multi-scale edge chain detector are applied to the image to extract discontinuity traces. Finally, edge chains in the image were projected back to the 3D coordinate system through the previously established texture map. The proposed method is applied to three case studies, each representing a different situation. The results show that the proposed discontinuity trace extraction method is automatic, robust, extensible and performs better than geometry-based methods for smooth rock surfaces along which the curvature changes are not apparent. The proposed method could be used as a supplement to traditional contact discon-tinuity trace mapping methods.
As a topographic modelling technique, structure from motion (SfM) photogrammetry combines the utility of digital photogrammetry with a flexibility and ease of use derived from multi‐view computer vision methods. In conjunction with the rapidly increasing availability of imagery particularly from unmanned aerial vehicles, SfM photogrammetry represents a powerful tool for geomorphological research. However, to fully realise this potential, its application must be carefully underpinned by photogrammetric considerations, surveys should be reported in sufficient detail to be repeatable (if practical) and results appropriately assessed to understand fully the potential errors involved. To deliver these goals, robust survey and reporting must be supported through (i) using appropriate survey design, (ii) applying suitable statistics to identify systematic error (bias) and to estimate precision within results, and (iii) propagating uncertainty estimates into the final data products.