| 1. |
- AHLBERG, PER, et al.
(författare)
-
Integrated Cambrian biostratigraphy and carbon isotope chemostratigraphy of the Grönhögen-2015 drill core, Öland, Sweden
- 2019
-
Ingår i: Geological Magazine. - 0016-7568. ; 156:06, s. 935-949
-
Tidskriftsartikel (refereegranskat)abstract
- The Grönhögen-2015 core drilling on southern Öland, Sweden, penetrated 50.15 m of Cambrian Series 3, Furongian and Lower–Middle Ordovician strata. The Cambrian succession includes the Äleklinta Member (upper Stage 5) of the Borgholm Formation and the Alum Shale Formation (Guzhangian–Tremadocian). Agnostoids and trilobites allowed subdivision of the succession into eight biozones, in ascending order: the uppermost Cambrian Series 3 (Guzhangian) Agnostus pisiformis Zone and the Furongian Olenus gibbosus, O. truncatus, Parabolina spinulosa, Sphaerophthalmus? flagellifer, Ctenopyge tumida, C. linnarssoni and Parabolina lobata zones. Conspicuous lithologic unconformities and the biostratigraphy show that the succession is incomplete and that there are several substantial gaps of variable magnitudes. Carbon isotope analyses (δ13Corg) through the Alum Shale Formation revealed two globally significant excursions: the Steptoean Positive Carbon Isotope Excursion (SPICE) in the lower–middle Paibian Stage, and the negative Top of Cambrian Excursion (TOCE), previously referred to as the HERB Event, in Stage 10. The δ13Corg chemostratigraphy is tied directly to the biostratigraphy and used for an improved integration of these excursions with the standard agnostoid and trilobite zonation of Scandinavia. Their relations to that of coeval successions in Baltoscandia and elsewhere are discussed. The maximum amplitudes of the SPICE and TOCE in the Grönhögen succession are comparable to those recorded in drill cores retrieved from Scania, southern Sweden. The results of this study will be useful for assessing biostratigraphic relations between shale successions and carbonate facies on a global scale.
|
|
| 2. |
- Taromi Sandström, Olof, et al.
(författare)
-
Stratigraphy of the Gorstian and Ludfordian (upper Silurian) Hemse Group reefs on Gotland, Sweden
- 2021
-
Ingår i: GFF. - : Informa UK Limited. - 1103-5897 .- 2000-0863. ; 143:1, s. 71-83
-
Tidskriftsartikel (refereegranskat)abstract
- The Hemse Group is one of the least understood stratigraphic units of the Silurian sequence of Gotland, Sweden. New results from airborne transient electromagnetic (ATEM) measurements in combination with previously published data from field studies and geophysical investigations shed new light on carbonate platform development during the early- to mid-Ludlow Hemse Group. ATEM reveals a transgressive phase that began near the Wenlock-Ludlow boundary, which resulted in deposition of marls and corresponds roughly to the Hemse limestone units a-c and the Hemse Marl NW. In this phase little or no reef development occurs. The end of the transgressive phase coincides with the weak Linde Event. The following highstand favoured extensive reef growth forming a reef barrier system of both fringing reefs and more rampiform settings with stromatoporoid biostromes and occasional biohermal buildups. The Kuppen-Snabben Unconformity Complex marks an erosional (karstic) sequence boundary and rocky shoreline and the transition from a rampiform setting with reef biostromes towards a more rimmed setting with patch reefs.
|
|
| 3. |
|
|
| 4. |
- Ahlberg, Anders, et al.
(författare)
-
The Jurassic of Skåne, Southern Sweden
- 2003
-
Ingår i: Geological Survey of Denmark and Greenland Bulletin. - 1811-4598. ; 1, s. 527-541
-
Tidskriftsartikel (refereegranskat)abstract
- In Sweden, Jurassic strata are restricted to Skåne and adjacent offshore areas. Jurassic sedimentary rocks predominantly comprise sandy to muddy siliciclastics, with subordinate coal beds and few carbonate-rich beds. During Mesozoic times, block-faulting took place in the Sorgenfrei– Tornquist Zone, a tectonic zone which transects Skåne in a NW–SE direction. The Jurassic depositional environments in Skåne were thus strongly influenced by uplift and downfaulting, and to some extent by volcanism. Consequently, the sedimentary record reveals evidence of numerous transgressions, regressions and breaks in sedimentation. Relative sea-level changes played a significant role in controlling the facies distribution, as deposition mainly took place in coastal plain to shallow shelf environments. The alluvial deposits in Skåne include floodplain palaeosols, autochthonous coals, overbank sandstones, and stream channel pebbly sandstones. Restricted marine strata comprise intertidal heteroliths with mixed freshwater and marine trace fossil assemblages, and intertidal delta distributary channel sandstones. Shallow marine sediments encompass subtidal and shoreface sandstones with herringbone structures, and bioturbated mudstones with tempestite sandstones. Offshore deposits typically comprise extensively bioturbated muddy sandstones. Floral remains, palaeopedology, clay mineralogy and arenite maturity indicate a warm and humid climate in Skåne throughout the Jurassic, possibly with slightly increasing aridity towards the end of the period. Most Jurassic strata in Skåne have been subjected to mild burial diagenesis, and the petroleum generative window has rarely been reached.
|
|
| 5. |
- Chasset, Coralie, et al.
(författare)
-
Scenario simulations of CO(2) injection feasibility, plume migration and storage in a saline aquifer, Scania, Sweden
- 2011
-
Ingår i: International Journal of Greenhouse Gas Control. - : Elsevier BV. - 1750-5836 .- 1878-0148. ; 5:5, s. 1303-1318
-
Tidskriftsartikel (refereegranskat)abstract
- Deep saline aquifers have large capacity for geological CO(2) storage, but are generally not as well characterized as petroleum reservoirs. We here aim at quantifying effects of uncertain hydraulic parameters and uncertain stratigraphy on CO(2) injectivity and migration, and provide a first feasibility study of pilot-scale CO(2) injection into a multilayered saline aquifer system in southwest Scania, Sweden. Four main scenarios are developed, corresponding to different possible interpretations of available site data. Simulation results show that, on the one hand, stratigraphic uncertainty (presence/absence of a thin mudstone/claystone layer above the target storage formation) leads to large differences in predicted CO(2) storage in the target formation at the end of the test (ranging between 11% and 98% of injected CO(2) remaining), whereas other parameter uncertainty (in formation and cap rock permeabilities) has small impact. On the other hand, the latter has large impact on predicted injectivity, on which stratigraphic uncertainty has small impact. Salt precipitation at the border of the target storage formation affects CO(2) injectivity for all considered scenarios and injection rates. At low injection rates, salt is deposited also within the formation, considerably reducing its availability for CO(2) storage.
|
|
| 6. |
- Elhami, Ehsan, et al.
(författare)
-
Physical Properties of Core Samples from the Swedish Part of the Southern Baltic Sea: Implications for CO2 Storage
- 2016
-
Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; 97, s. 356-363
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents the results from a series of physical measurements conducted on core samples from the Swedish part of the southern Baltic Sea. The samples consist of 16 Cambrian sandstone samples (potential reservoir rock) and 9 Ordovician limestone samples (potential caprock). The two rock types reveal contrasting properties; axial P-wave velocity and density for the sandstone samples are 3.14±0.95km/s and 2.26±0.12 gr/cm3, respectively while for the limestone samples they are 6.09±0.22km/s and 2.58±0.08 gr/cm3, respectively. The scatter of the evaluated properties indicates aleatory variability and epistemic uncertainty in the properties which can be better addressed by further tests on more samples.
|
|
| 7. |
- Erlström, Mikael, et al.
(författare)
-
Geophysical well log-motifs, lithology, stratigraphical aspects and correlation of the Ordovician succession in the Swedish part of the Baltic Basin
- 2019
-
Ingår i: International Journal of Earth Sciences. - : Springer Science and Business Media LLC. - 1437-3254 .- 1437-3262. ; 108:4, s. 1387-1407
-
Tidskriftsartikel (refereegranskat)abstract
- The geophysical characteristics of the carbonate-dominated Ordovician succession is described using wire-line logging data from exploration wells located within the Swedish part of the Baltic Basin, both offshore and from the island of Gotland. The petrophysical properties and log-motifs are compared and correlated with the lithology of cores from the Hamra-10, Skåls-1 and Grötlingbo-1 wells on southern Gotland. The 80–125-m-thick Ordovician succession is divided into five log stratigraphic units O a –O e , which are correlated throughout the study area. The proposed log stratigraphy and wire-line log characteristics are evaluated and compared with the established Ordovician stratigraphy from the adjacent areas of Öland, Östergötland and South Estonia. The newly established log stratigraphy is also linked to the existing seismic stratigraphic framework for the study area and exemplified with a selection of interpreted seismic type sections from Gotland and the south Baltic Sea. The presented characterization, division and correlation provide a basis for understanding the lateral and vertical variation of the petrophysical properties, which are essential in assessing the sealing capacity of the Ordovician succession, in conjunction with storage of CO 2 in the underlying Cambrian sandstone reservoir.
|
|
| 8. |
|
|
| 9. |
- Erlström, Mikael, et al.
(författare)
-
Stratigraphy and geothermal assessment of Mesozoic sandstone reservoirs in the Öresund Basin - exemplified by well data and seismic profiles
- 2018
-
Ingår i: Bulletin of the Geological Society of Denmark. - 0011-6297. ; 66, s. 123-149
-
Tidskriftsartikel (refereegranskat)abstract
- The Øresund Basin in the transnational area between Sweden and Denmark forms a marginal part of the Danish Basin. The structural outline and stratigraphy of the Mesozoic succession is described, and a novel interpretation and description of the subsurface geology and geothermal potential in the North Sjælland Half-graben is presented. The subsurface bedrock in the basin includes several Mesozoic intervals with potential geothermal sandstone reservoirs. Parts of the succession fulfill specific geological requirements about distribution, composition and quality of the sandstones. A characterisation of these is presently of great interest in the attempt to identify geothermal reservoirs suitable for district heating purposes. The results presented in this paper include for the first time a comprehensive description of the stratigraphic intervals as well as the characteristics of the potential Mesozoic geothermal reservoirs in the Øresund region, including their distribution, composition and physical properties. This is illustrated by seismic cross-sections and well sections. In addition, results from analyses and evaluations of porosity, permeability, formation fluids and temperature are presented. Six potential geothermal reservoirs in the Mesozoic succession are described and assessed. Primary focus is placed on the characteristics of the reservoirs in the Lower Triassic and Rhaetian–Lower Jurassic succession. The study shows that the Mesozoic reservoir sandstones vary considerably with respect to porosity and permeability. Values range between 5–25% for the pre-Rhaetian Triassic sandstones, but are commonly > 25% for the Rhaetian–Lower Jurassic and Lower Cretaceous sandstones. The corresponding permeability rarely reaches above 500 mD for the pre-Rhaetian Triassic reservoirs, but often reach >1 Darcy for the Rhaetian–Lower Jurassic and the Lower Cretaceous sandstones. The interpreted formation temperatures for the reservoirs in the Øresund Basin are: 45–50°C at 1500 m, 60–70°C at 2000 m and 70–90°C at 2500 m depth . The combined results provide a geological framework for making site specific predictions regarding appraisal of viable geothermal projects for district heating purposes in the region as well as reducing the risk of unsuccessful wells
|
|
| 10. |
|
|
| 11. |
- Hesselbrandt, Max, et al.
(författare)
-
Multidisciplinary approaches for assessing a high temperature borehole thermal energy storage facility at linköping, sweden
- 2021
-
Ingår i: Energies. - : MDPI AG. - 1996-1073. ; 14:14
-
Tidskriftsartikel (refereegranskat)abstract
- Assessing the optimal placement and design of a large‐scale high temperature energy storage system in crystalline bedrock is a challenging task. This study applies and evaluates various methods and strategies for pre‐site investigation for a potential high temperature borehole thermal energy storage (HT‐BTES) system at Linköping in Sweden. The storage is required to shift approximately 70 GWh of excess heat generated from a waste incineration plant during the summer to the winter season. Ideally, the site for the HT‐BTES system should be able to accommodate up to 1400 wells to 300 m depth. The presence of major fracture zones, high groundwater flow, anisotropic thermal properties, and thick Quaternary overburden are all factors that play an important role in the performance of an HT‐BTES system. Inadequate input data to the modeling and design increases the risk of unsatisfactory performance, unwanted thermal impact on the surroundings, and suboptimal placement of the HT‐BTES system, especially in a complex crystalline bedrock setting. Hence, it is crucial that the subsurface geological conditions and associated thermal properties are suitably characterized as part of pre‐investigation work. In this study, we utilize a range of methods for pre-site investigation in the greater Distorp area, in the vicinity of Linköping. Ground geophysical methods, including magnetic and Very Low‐Frequency (VLF) measurements, are collected across the study area together with outcrop observations and lab analysis on rock samples. Borehole investigations are conducted, including Thermal Response Test (TRT) and Distributed Thermal Response Test (DTRT) measurements, as well as geophysical wireline logging. Drone‐based photogrammetry is also applied to characterize the fracture distribution and orientation in outcrops. In the case of the Distorp site, these methods have proven to give useful information to optimize the placement of the HT‐BTES system and to inform design and modeling work. Furthermore, many of the methods applied in the study have proven to require only a fraction of the resources required to drill a single well, and hence, can be considered relatively efficient.
|
|
| 12. |
- Japsen, Peter, et al.
(författare)
-
Episodic burial and exhumation of the southern Baltic Shield : Epeirogenic uplifts during and after break-up of Pangaea
- 2016
-
Ingår i: Gondwana Research. - : Elsevier BV. - 1342-937X .- 1878-0571. ; 35, s. 357-377
-
Tidskriftsartikel (refereegranskat)abstract
- Abstract Cratons are conventionally assumed to be areas of long-term stability. However, whereas Precambrian basement crops out across most of the Baltic Shield, Palaeozoic and Mesozoic sediments rest on basement in southern Sweden, and thus testify to a complex history of exhumation and burial. Our synthesis of published stratigraphic landscape analysis and new apatite fission-track analysis data reveals a history involving five steps after formation of the extremely flat, Sub-Cambrian Peneplain. (1) Cambrian to Lower Triassic rocks accumulated on the peneplain, interrupted by late Carboniferous uplift and exhumation. (2) Middle Triassic uplift removed the Palaeozoic cover along the south-western margin of the shield, leading to formation of a Triassic peneplain with a predominantly flat relief followed by deposition of Upper Triassic to Lower Jurassic rocks. (3) Uplift that began during the Middle Jurassic to earliest Cretaceous caused denudation leading to deep weathering that shaped an undulating, hilly relief that was buried below Upper Cretaceous to Oligocene sediments. (4) Early Miocene uplift and erosion produced the South Småland Peneplain with scattered hills. (5) Early Pliocene uplift raised the Miocene peneplain to its present elevation leading to reexposure of the sub-Cretaceous hilly relief near the coast. Our results thus provide constraints on the magnitude and timing of episodes of deposition and removal of significant volumes of Phanerozoic rocks across the southern portion of the Baltic Shield. Late Carboniferous, Middle Triassic and mid-Jurassic events of uplift and exhumation affected wide areas beyond the Baltic Shield, and we interpret them as epeirogenic uplifts accompanying fragmentation of Pangaea, caused by accumulation of mantle heat beneath the supercontinent. Early Miocene uplift affected north-west Europe but not East Greenland, and thus likely resulted from compressive stresses from an orogeny on the Eurasian plate. Early Pliocene uplift related to changes in mantle convection and plate motion affected wide areas beyond North-East Atlantic margins.
|
|
| 13. |
- Joodaki, Saba, et al.
(författare)
-
Simulation of CO2 injection into a Baltic Sea saline aquifer and seismic monitoring of the plume
- 2013
-
Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; , s. 355-364
-
Tidskriftsartikel (refereegranskat)abstract
- TOUGH2/ECO2N was used to simulate CO2 injection into a saline aquifer in the Baltic Sea and the effect of different amounts of CO2 injection on the seismic response. The Biot-Gassmann model was used to convert the simulated saturation and densities to seismic velocities and synthetic seismic responses before and after injection were compared. The results show that the amplitude changes in the seismic response are detectable even for small amounts of injected CO2, while noticeable signs of velocity pushdown, as a signature of the CO2 substitution, could only be observed if the injection rate is high enough.
|
|
| 14. |
- Levendal, Tegan Corinne, et al.
(författare)
-
Ordovician carbonate mud mounds of the Baltoscandian Basin in time and space : a geophysical approach
- 2019
-
Ingår i: Palaeogeography, Palaeoclimatology, Palaeoecology. - : Elsevier. - 0031-0182 .- 1872-616X. ; 535
-
Tidskriftsartikel (refereegranskat)abstract
- Carbonate mud mounds developed within the Baltoscandian Basin, an epicratonic basin on the Baltica palaeocontinent, during the Ordovician. In the Upper Ordovician succession of the Baltoscandian Basin, a large number of mud mounds are present at three stratigraphic levels namely, the Kullsbergs mounds (late Sandbian-early Katian), Nabala and Rakvere mounds (middle Katian), and the Boda mounds (late Katian). These formed in a subtropical-tropical carbonate platform environment, covered by a shallow epicontinental sea. The mud mounds at these stratigraphic levels beneath and around Gotland have been characterized using a comprehensive seismic and well dataset acquired during a period of hydrocarbon exploration and exploitation which began more than 30 years ago. Interpretation of the largely unpublished seismic data in this study provides details on the distribution of mound complexes in the basin and constraints on the geometry of the mounds. Detailed structure contour maps of the top and the base of the Ordovician succession beneath Gotland based on the seismic interpretation are presented. The results give a comprehensive characterization of carbonate mud mound generation on Gotland which may help in understanding the distribution patterns of similar mound complexes in other parts of the Ordovician world formed in similar environments.
|
|
| 15. |
|
|
| 16. |
- Lindström, Sofie, et al.
(författare)
-
The Jurassic-Cretaceous transition of the Fararp-1 core, southern Sweden: Sedimentological and phytological indications of climate change
- 2011
-
Ingår i: Palaeogeography, Palaeoclimatology, Palaeoecology. - : Elsevier BV. - 1872-616X .- 0031-0182. ; 308:3-4, s. 445-475
-
Tidskriftsartikel (refereegranskat)abstract
- The 116m deep Fararp-1 core drilled in the Vomb Trough in southernmost Sweden is dated by integrated terrestrial and marine palynostratigraphy. The lower part of the succession (ca 84 m) encompasses uppermost Jurassic to lowermost Cretaceous (uppermost Tithonian to Valanginian) strata. An unconformity separates the Valanginian strata from an overlying ca 1 m thick interval of upper Albian to Cenomanian Arnager Greensand Formation. The uppermost part of the core is a repetitive succession of lowermost Cretaceous sediments. During the Jurassic-Cretaceous U/K) transition NW Europe was located in mid latitudes, and comprised an archipelago of large and small islands separated by deeper grabens and epicontinental seaways that connected the Boreal Sea to the north with the warmer Tethys Ocean to the south. Boundary strata in England, France, the Netherlands and Germany are characterised by relatively prominent climatic change from arid/semi arid to subhumid/humid conditions. Southernmost Sweden was located on the margin of a large landmass comprising most of the Fennoscandian Shield bordering a large epicontinental sea to the west. By combining sedimentology, clay mineralogy and palynofacies the Tithonian to Valanginian cored succession of the Fararp-1 core provides complementary information on how marginal deposits from the eastern part of the epicontinental sea reflect the climatological and environmental changes observed in other parts of NW Europe. The Fararp-1 core shows that during the Tithonian to earliest Berriasian deposition took place in a terrestrial but near-marine depositional setting, in coastal lakes or lagoons with little marine influence. A dry climatic regime favoured stagnant water conditions with common algal blooms of primarily Bonyococcus and zygnemataceae. Palynofacies and sedimentology indicate limited transport of freshwater and material to the basin. The stagnant depositional environment was terminated by a marine flooding in the early Berriasian. During the remaining Berriasian and the early Valanginian conditions shifted between near marine and marine settings in a dynamic coastal environment, similar to contemporaneous assemblages reported from the Danish Island of Bornholm. A shift in clay mineralogy, from a dominance of 10 A minerals to increasing amounts of mixed layer and kaolinite indicates a change to more humid conditions in the latest Tithonian. Cheirolepidacean pollen (Classopollis) are present but never common in the cored succession, and a similar conspicuous decrease of these pollen, as previously reported from England, Germany and France, is not evident in the Fararp-1 core. Instead a subsequent shift in both palynofacies and palynoflora, marked by an increase in abundance of heavy terrigenous material, i.e. wood and coal particles, upland pollen grains and reworked palynomorphs is also observed in the uppermost Tithonian-lowermost Berriasian interval. At the same level spores and pollen classified as warmer/drier elements decrease in abundance. This is interpreted as representing a shift to more humid climatic conditions with increased runoff from the hinterland. Thus, the combined sedimentological and palynological data from the Fararp-1 core suggest that climatic conditions in the area changed from more seasonally dry (semi-arid) to more humid (semi-humid) across the J/K boundary (latest Tithonian to earliest Berriasian) and hence earlier than the mid-Berriasian climatic shift recorded from e.g. England and the Netherlands. (C) 2011 Elsevier B.V. All rights reserved.
|
|
| 17. |
- Lindström, Sofie, et al.
(författare)
-
The late Rhaetian transgression in southern Sweden: Regional (and global) recognition and relation to the Triassic-Jurassic boundary
- 2006
-
Ingår i: Palaeogeography, Palaeoclimatology, Palaeoecology. - : Elsevier BV. - 1872-616X .- 0031-0182. ; 241:3-4, s. 339-372
-
Tidskriftsartikel (refereegranskat)abstract
- Palynological investigations of Rhaetian outcrops and drillcores in combination with subsurface data from wells in Scania, southern Sweden, have revealed the presence of marine dinoflagellate cysts in sedimentary strata that were previously considered to have been deposited in a mainly terrestrial environment. Two distinct dinocyst events are identified. One older event where persistent, rare to common occurrences of Rhaetogonyaulax rhaetica and Lunnomidinium scaniense indicates deposition in shallow marine and marginal marine environments. This Lunnomidinium interval is preceded and succeeded by assemblages with rare to common R. rhaetica, and can be correlated with the mid to late Rhaetian R. rhaetica Zone. It is associated with spore/pollen assemblages of the mid Rhaetian Rhaetipollis-Limbosporites Zone. The younger event, the R. rhaetica maximum interval, is characterised by mass-occurrence of R. rhaetica, with less common or absent Dapcodinium priscum, in association with a dark grey to black mudstone/shale. The introduction of D. priscum in association with the over-whelming abundance of R. rhaetica allows correlation with the transition between the R. rhaetica Zone and the succeeding D. priscum Zone, and signals fully marine conditions. The R. rhaetica maximum interval is associated with spore/pollen assemblages of the late Rhaetian Ricciisporites-Polypodiisporites Zone, and is in Sweden succeeded both lithostratigraphically and palynostratigraphically by the T-J transition. The R. rhaetica maximum interval corresponds to a late Rhaetian maximum flooding event that took place in a shallow, gently sloping embayment that covered the Danish Basin area during the Late Triassic-Early Jurassic. This maximum flooding event can be recognised in late Rhaetian strata from different parts of the Northern Hemisphere. It is an important temporal constraint on the T-J boundary as it is associated with the disappearance of Triassic marine faunas, appears to coincide with the onset of the main pulse of CAMP volcanism, immediately precedes the initial carbon isotope excursion and the global sea-level drop that characterises the T-J transition.
|
|
| 18. |
- Perttu, Nils, et al.
(författare)
-
Magnetic resonance sounding and radiomagnetotelluric measurements used to characterize a limestone aquifer in Gotland, Sweden
- 2012
-
Ingår i: Journal of Hydrology. - : Elsevier BV. - 0022-1694 .- 1879-2707. ; 424-425, s. 184-195
-
Tidskriftsartikel (refereegranskat)abstract
- Almost all drinking water in Gotland is groundwater and is mainly found in karst limestone. However, the unpredictable location and geometry of the karst cracks and caverns makes it very difficult to estimate groundwater storage and movement, as well as contaminant transport. The aim of this study was to test the performance of different geophysical techniques like Magnetic Resonance Sounding (MRS), Radiomagnetotelluric (RMT), Vertical Electrical Sounding (VES) and Ground Penetrating Radar (GPR) to characterize aquifers in Gotland, in respect to geometry and storage as well as connectivity over a wider area. The investigated area is located on the south-eastern part of Gotland. The geology here is dominated by 50 to 60 m thick successions of limestone that gradually turn into marlstone. The use of multiple techniques has shown to give a more coherent interpretation. However, the shallow penetration depth of GPR and the lack of soil cover in some places of the investigated area limit the use of geoelectrical methods and GPR. With MRS, water are found down to 60 m in depth, with a maximum water content at depths of 20 to 30 m. This coincides with the most resistive sections of the limestone. The water content varies between 0 and 3%, with a relaxation time (T1MRS) less than 400 ms suggesting that the aquifer is hosted in small fractures, molds and vugs rather than larger karst fractures and caverns. Two potential aquifers were identified with MRS, possibly separated by marlstone. From modelling it can be seen that such boundary separating two aquifer apart can be more easily discriminated in the N/S-, than in the E/W direction. In summary, MRS is therefore the only method in this survey that can detect and determine the vertical and lateral distribution of water within the aquifer together with the total volume of free water. The RMT method has shown to be effective in characterizing the limestone/marl interface, but also to locate anomalous low resistive zones, possibly associated with salt water. RMT also helps to constrain the final MRS model by choosing a suitable regularization for the MRS 3D inversion. All together, the combination of MRS and RMT seems most efficient of the tested methods and therefore most promising for future groundwater explorations in geological environments like in eastern Gotland.
|
|
| 19. |
- Rasmusson, Kristina, et al.
(författare)
-
Subsurface characterisation and modeling of a CO2 test site in south Scania, Sweden, with special emphasis on the treatment of hydrogeological heterogeneity
- 2011
-
Konferensbidrag (refereegranskat)abstract
- The south Scania site is one of the five test sites included in the MUSTANG project (EU FP7 programme) with an objective to understand - by means of experimental and simulation studies - the spreading and trapping of injected CO2 in different type saline formations. The geological setting of the site is an example of a typical multilayered sequence commonly found in sedimentary basins all over the world. It is analyzed here as an example of such sequence of primary and secondary traps and seal units. Particular emphasis is given for the characterization and quantification of the geological heterogeneity, in terms of what can be described in deterministic terms and where a stochastic representation is needed.For constructing the conceptual model, detailed hydrogeological and hydrogeochemical data is available in one deep well originally drilled for geothermal investigations, including an extensive hydrogeological testing programme. In addition, comprehensive data sets and analyses exist in 15 adjacent wells, allow definition of the characteristics of different lithological units and boundary layers with some confidence. The geology is dominated by a relatively thick (1200–1600 m) sequence of Upper Cretaceous strata, overlying a 400–600 m thick Lower Cretaceous, Jurassic and Triassic sequence of claystone and sandstone layers. Eight lithologic units have been mapped and characterised, the primary trap aquifer for this study being about 10 m thick sandstone and secondary traps having thicknesses between 10 and 50 metres, with lower overall permeabilities than the primary target. The primary seal consist of a several hundred meters thick limestone and the intermediate seals of claystone and mudstone. The lateral correlations of the layers between wells are based on lithological descriptions of cuttings, biostratigraphical analyses and geophysical well log correlation.One of the challenges for modeling the spreading of injected CO2 is to understand and to be able to quantify the characteristics of the horizontal heterogeneity and continuity of the layers between the boreholes. For this purpose, both a deterministic and a probabilistic/stochastic approach are used here to describe 1) the distribution of the depositional settings and 2) the properties (heterogeneity) within the units, in particular in terms of the distribution of the permeability values. Importance of the choice of the approach is discussed based on preliminary model simulations of CO2 injection using the various assumptions.
|
|
| 20. |
- Rosberg, Jan Erik, et al.
(författare)
-
Evaluation of deep geothermal exploration drillings in the crystalline basement of the Fennoscandian Shield Border Zone in south Sweden
- 2021
-
Ingår i: Geothermal Energy. - : Springer Science and Business Media LLC. - 2195-9706. ; 9:1
-
Tidskriftsartikel (refereegranskat)abstract
- The 3.1- and 3.7-km-deep FFC-1 and DGE-1 geothermal explorations wells drilled into the Precambrian crystalline basement on the southern margin of the Fennoscandian Shield are evaluated regarding experiences from drilling, geological conditions, and thermal properties. Both wells penetrate an approximately 2-km-thick succession of sedimentary strata before entering the crystalline basement, dominated by orthogneiss, metabasite and amphibolite of the (1.1–0.9 Ga) Eastern Interior Sveconorwegian Province. The upper c. 400 m of the basement is in FFC-1 severely fractured and water-bearing which disqualified the use of percussion air drilling and conventional rotary drilling was, therefore, performed for the rest of the borehole. The evaluation of the rotary drillings in FFC-1 and DGE-1 showed that the average bit life was very similar, 62 m and 68 m, respectively. Similarly, the average ROP varied between 2 and 4 m/h without any preferences regarding bit-type (PDC or TCI) or geology. A bottomhole temperature of 84.1 °C was measured in FFC-1 borehole with gradients varying between 17.4 and 23.5 °C/km for the main part of the borehole. The calculated heat flow varies between 51 and 66 mW/m2 and the average heat production is 3.0 µW/m3. The basement in FFC-1 is, overall, depleted in uranium and thorium in comparison to DGE-1 where the heat productivity is overall higher with an average of 5.8 µW/m3. The spatial distribution of fractures was successfully mapped using borehole imaging logs in FFC-1 and shows a dominance of N–S oriented open fractures, a fracture frequency varying between 0.85 and 2.49 frac/m and a fracture volumetric density between 1.68 and 3.39 m2/m3. The evaluation of the two boreholes provides insight and new empirical data on the thermal properties and fracturing of the concealed crystalline basement in the Fennoscandian Shield Border Zone that, previously, had only been assessed by assumptions and modelling. The outcome of the drilling operation has also provided insight regarding the drilling performance in the basement and statistical data on various drill bits used. The knowledge gained is important in feasibility studies of deep geothermal projects in the crystalline basement in south Sweden.
|
|
| 21. |
- Rosberg, Jan Erik, et al.
(författare)
-
Evaluation of the Lund deep geothermal exploration project in the Romeleåsen Fault Zone, South Sweden : a case study
- 2019
-
Ingår i: Geothermal Energy. - : Springer Science and Business Media LLC. - 2195-9706. ; 7:1
-
Tidskriftsartikel (refereegranskat)abstract
- The bedrock of Skåne, the southernmost province of Sweden, has been targeted for geothermal feasibility studies since the late 1970s. An exploration project concerning the geothermal potential in the Romeleåsen Fault Zone was launched outside the town of Lund in 2001. Besides geophysical imaging of the thrust fault zone, the investigations included drilling and investigations of a 3701.8-m-deep exploration well, DGE-1, with the aim to find > 100 °C warm and hydraulically conductive fractured crystalline bedrock associated to the fault zone. The well penetrates a heavily thrusted and predominantly strongly inclined sedimentary succession in hanging rock blocks along the main fault before entering the fractured crystalline basement at 1946 m, primarily composed of gneiss, granite, and metabasite. This paper represents the first comprehensive description and evaluation of the geological, physical, and hydrological properties of the bedrock at these depths in the Romeleåsen Fault Zone coupled to a geothermal assessment. In addition, the applicability of the four drilling methods used in the crystalline basement section is discussed. The outcome of the DGE-1 well shows significant fracturing in the crystalline bedrock at target depth. The investigations show an average thermal gradient of 22 °C/km, an average heat flow of 58 mW/m 2 , and an average heat production of 5.8 µW/m 3 . The values are relatively high in comparison to thermal conditions noted in other deep wells in the Fennoscandian Shield. However, a bottomhole temperature of around 85 °C and insufficient fluid production rate made a commercial geothermal system unviable. Despite this, the experiences from drilling and investigations of the crystalline bedrock at several kilometers depth constitute important proxies for assessing the geothermal potential in similar geological settings and for engineered geothermal systems in the crystalline bedrock of south Sweden.
|
|
| 22. |
- Shan, Chunling, 1986-, et al.
(författare)
-
Portable audio magnetotellurics - experimental measurements and joint inversion with radiomagnetotelluric data from Gotland, Sweden
- 2017
-
Ingår i: Journal of Applied Geophysics. - : Elsevier. - 0926-9851 .- 1879-1859. ; 143, s. 9-22
-
Tidskriftsartikel (refereegranskat)abstract
- Field setup of an audio magnetotelluric (AMT) station is a very time consuming and heavy work load. In contrast, radio magnetotelluric (RMT) equipment is more portable and faster to deploy but has shallower investigation depth owing to its higher signal frequencies. To increase the efficiency in the acquisition of AMT data from 10 to 300 Hz, we introduce a modification of the AMT method, called portable audio magnetotellurics (PAMT), that uses a lighter AMT field system and (owing to the disregard of signals at frequencies of less than 10 Hz) shortened data acquisition time. PAMT uses three magnetometers pre-mounted on a rigid frame to measure magnetic fields and steel electrodes to measure electric fields. Field tests proved that the system is stable enough to measure AMT fields in the given frequency range. A PAMT test measurement was carried out on Gotland, Sweden along a 3.5 km profile to study the ground conductivity and to map shallow Silurian marlstone and limestone formations, deeper Silurian, Ordovician and Cambrian sedimentary structures and crystalline basement. RMT data collected along a coincident profile and regional airborne very low frequency (VLF) data support the interpretation of our PAMT data. While only the RMT and VLF data constrain a shallow (similar to 20-50 m deep) transition between Silurian conductive (<30 Omega m resistivity) marlstone and resistive (>1000 Omega m resistivity) limestone, the single-method inversion models of both the PAMT and the RMT data show a transition into a conductive layer of 3 to 30 Omega m resistivity at similar to 80 m depth suggesting the compatibility of the two data sets. This conductive layer is interpreted as saltwater saturated succession of Silurian, Ordovician and Cambrian sedimentary units. Towards the lower boundary of this succession (at 600 m depth according to boreholes), only the PAMT data constrain the structure. As supported by modelling tests and sensitivity analysis, the PAMT data only contain a vague indication of the underlying crystalline basement. A PAMT and RMT joint inversion model reveals all the aforementioned units including the less than 80 m deep limestone and marlstone formations and the conductive sedimentary succession of Silurian, Ordovician and Cambrian units. Our test measurements have proven the PAMT modification to be time saving and easy to set up. However, PAMT data suffer from the same noise disturbances as regular AMT data. Since man-made EM noise can propagate over great distances through resistive underground, PAMT measurements are recommended to be carried out in areas with low resistivity. The PAMT method is proven to be applicable in shallow depth studies, especially in areas where normal AMT measurements are inconvenient and/or too expensive to carry out.
|
|
| 23. |
- Sopher, Daniel, et al.
(författare)
-
Evaluation of the subsurface compressed air energy storage (CAES) potential on Gotland, Sweden
- 2019
-
Ingår i: Environmental Earth Sciences. - : Springer Science and Business Media LLC. - 1866-6280 .- 1866-6299. ; 78:6
-
Tidskriftsartikel (refereegranskat)abstract
- Wind energy is an important field of development for the island of Gotland, Sweden, especially since the island has set targets to generate 100% of its energy from renewable sources by 2025. Due to the variability of wind conditions, energy storage will be an important technology to facilitate the continued development of wind energy on Gotland and ensure a stable and secure supply of electricity. In this study, the feasibility of utilizing the Middle Cambrian Faludden sandstone reservoir on Gotland for Compressed Air Energy Storage (CAES) is assessed. Firstly, a characterization of the sandstone beneath Gotland is presented, which includes detailed maps of reservoir thickness and top reservoir structure. Analysis of this information shows that the properties of the Faludden sandstone and associated cap rock appear favorable for the application of CAES. Seven structural closures are identified below the eastern and southern parts of Gotland, which could potentially be utilized for CAES. Scoping estimates of the energy storage capacity and flow rate for these closures within the Faludden sandstone show that industrial scale CAES could be possible on Gotland.
|
|
| 24. |
- Sopher, Daniel, et al.
(författare)
-
The structure and stratigraphy of the sedimentary succession in the Swedish sector of the Baltic Basin : new insights from vintage 2D marine seismic data
- 2016
-
Ingår i: Tectonophysics. - : Elsevier BV. - 0040-1951 .- 1879-3266. ; 676, s. 90-111
-
Tidskriftsartikel (refereegranskat)abstract
- We present five interpreted regional seismic profiles, describing the full sedimentary sequence across the Swedish sector of the Baltic Sea. The data for the study are part of an extensive and largely unpublished 2D seismic dataset acquired between 1970 and 1990 by the Swedish Oil Prospecting Company (OPAB). The Baltic Basin is an intracratonic basin located in northern Europe. Most of the Swedish sector of the basin constitutes the NW flank of a broad synclinal depression, the Baltic Basin. In the SW of the Swedish sector lies the Hand Bay Basin, formed by subsidence associated with inversion of the Tornquist Zone during the Late Cretaceous. The geological history presented here is broadly consistent with previously published works. We observe an area between the Hand Bay and the Baltic Basin where the Palaeozoic strata has been affected by transpression and subsequent inversion, associated with the Tornquist Zone during the late Carboniferous-Early Permian and Late Cretaceous, respectively. We propose that the Christianso High was a structural low during the Late Jurassic, which was later inverted in the Late Cretaceous. We suggest that a fan shaped feature in the seismic data, adjacent to the Christianso, Fault within the Hand Bay Basin, represents rapidly deposited, coarse-grained sediments eroded from the inverted Christianso High during the Late Cretaceous. We identify a number of faults within the deeper part of the Baltic Basin, which we also interpret to be transpressional in nature, formed during the Caledonian Orogeny in the Late Silurian-Early Devonian. East of Gotland a number of sedimentary structures consisting of Silurian carbonate reefs and Ordovician carbonate mounds, as well as a large Quaternary glacial feature are observed. Finally, we use the seismic interpretation to infer the structural and stratigraphic history of the Baltic and Hand Bay basins within the Swedish sector.
|
|
| 25. |
- Tian, Liang, et al.
(författare)
-
Integrated simulations of CO2 spreading and pressure response in the multilayer saline aquifer of South Scania Site, Sweden
- 2016
-
Ingår i: Greenhouse Gases. - : Wiley. - 2152-3878. ; 6:4, s. 531-545
-
Tidskriftsartikel (refereegranskat)abstract
- An integrated modeling approach/workflow, in which a series of mathematical models of different levels of complexity are applied to evaluate the geological storage capacity of the Scania Site, southwest Sweden, is presented. The storage formation at the site is a layered formation limited by bounding fault zones, and injection is assumed to take place from one existing deep borehole into all layers. A semi-analytical model for two-phase flow is first used to evaluate the pressure response and related parameter sensitivity, as well as the first estimates of acceptable injection rates. These results are then used to guide the more detailed numerical simulations that address both pressure response and plume migration. The vertical equilibrium (VE) model is used to obtain a preliminary understanding of the plume migration with a larger number of simulations. Finally the full TOUGH2/ECO2N simulations are performed for the most detailed analyses of pressure responses and plume migration. Throughout, the results of the different modeling approaches are compared against each other. It is concluded that the key limiting factor for the storage capacity at the site in the injection scenario considered is the fast CO2 migration within the high permeability layer. Future studies can address alternative injection scenarios, including horizontal injection wells and injection to other layers than the high permeability layer.
|
|
| 26. |
- Yang, Zhibing, et al.
(författare)
-
Modeling of pressure build-up and estimation of maximum injection rate for geological CO2 storage at the South Scania site, Sweden
- 2015
-
Ingår i: Greenhouse Gases. - : Wiley. - 2152-3878. ; 5:3, s. 277-290
-
Tidskriftsartikel (refereegranskat)abstract
- Carbon dioxide (CO2) injection in deep saline formations causes pressure increase which may be detrimental to the mechanical integrity of the storage reservoir. Injection induced pressure build-up is a limiting factor for CO2 injection rates and storage capacity. In this study, we extend a semi-analytical solution (based on one-dimensional, two-phase, two-component radial flow) for application to estimate pressure build-up and maximum injection rate of CO2 at a field site (South Scania, Sweden) using the method of superposition of image well solutions to account for the straight-line boundaries imposed by three fault zones. The semi-analytical approach for estimating pressure build-up is validated by comparison to numerical simulations based on TOUGH2-ECO2N. We analyze injection pressure sensitivity due to uncertainty in reservoir parameters as well as boundary conditions. Maximum injection rates and pressure limited capacity estimates are presented. This work demonstrates the use of semi-analytical solutions to analyze pressure limitation on storage capacity for realistic reservoirs with irregular (non-circular) boundaries. It is also shown that the semi-analytical approach can also be used to evaluate the benefit of having multiple injection wells in terms of increasing the injection-pressure-limited storage capacity. The methodology presented in this study is useful for screening analysis of storage sites as well as for operation design and optimization where pressure build-up as a limiting factor influences the objective function.
|
|
| 27. |
- Yang, Zhibing, et al.
(författare)
-
Modelling of far-field pressure plumes for carbon dioxide sequestration
- 2013
-
Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; , s. 472-480, s. 472-480
-
Tidskriftsartikel (refereegranskat)abstract
- We apply both numerical modelling, by means of single-phase and two-phase models, and analytical calculation for estimation of far-field pressure buildup, considering a generic scenario of dipping aquifer and a site-specific scenario for the Scania site, southwest Sweden. We examine the effect of depth-dependent fluid and material properties as well as formation geometries on far-field pressure buildup. The use of simple analytical calculations, including the Theis equation and superposition based on the method of images, for the estimation of pressure buildup is evaluated. The results are also discussed in terms of comparison between the numerical simulations and simple analytical calculations.
|
|
