Industrikraft Midt-Norge (IMN) is planning to build a combined heat and power (CHP) plant in the inner part of Trondheimsfjorden (Skogn), Mid-Norway. The plant will utilise natural gas from Haltenbanken, off Mid-Norway. In the EU-funded Gestco project, the total storage capacity for CO2 in aquifers offshore Mid-Norway was estimated to be more than 100 000 Mt, assuming a storage efficiency of 2% for the aquifers. A significant portion of this storage capacity is on the southeastern part of the Trøndelag Platform (east and south of the major hydrocarbon province on the Halten Terrace/Nordland Ridge). CO2 storage in oil and gas fields on the Halten Terrace will not be possible in the next ten to twenty years (except for enhanced oil recovery) due to probable conflicts with the hydrocarbon exploitation. The alternative is thus to store CO2 in aquifers east and south of the major hydrocarbon province, an area which has previously not been mapped in detail for the purpose of CO2 storage. This area has the advantage of being closer to the onland CO2 point sources, which will require shorter pipelines. Because the candidate aquifers are truncated toward land at seabed, potential storage areas are influenced by the sealing capacity of faults.
The first task will be to map geographical distribution of geological storage capacity in the Beitstadfjorden and Frohavet Basins, and of selected aquifers on the Trøndelag Platform, between latitudes 63ºN and 65ºN and limited westward by the Bremstein, Vingleia, and Klakk Fault Complexes. This will include large-scale mapping of geological storage formations/traps. For each of the selected basins/aquifers the storage quality, subsurface storage capacity, and storage seal (top seal, stratigraphic seal, fault seal) will be studied.
We will than perform numerical modelling for prediction of CO2 fluid behaviour and storage capacity of the Beitstadfjorden and Frohavet Basins and selected major aquifers on the Trøndelag Platform. A secondary hydrocarbon migration simulator (SEMI, developed by SINTEF), which has successfully been applied to CO2 migration modelling in the Sleipner case, will be used to predict migration paths and to quantify trap volumes on a regional scale. Commercial reservoir simulation software (Eclipse) will be used to address the distribution of CO2 in individual traps, to quantify dissolution and to include dynamic effects in the simulations.
Finally, we want to investigate and evaluate security and stability of CO2 storage in the study area. Both the risk and mechanisms for, and effect of, potential leakages from the identified, prospective storage formations will be studied.
Trøndelag Platform: The Mid-Norway shelf has been influenced by multiple rift events, and Upper Palaeozoic to Mesozoic sedimentary successions have been deposited in extensional environments, which culminated with the opening of the North Atlantic Ocean in Early Tertiary time. The area is characterized by sedimentary basins developed on top of rocks of Precambrian to Early Palaeozoic age. Major structural domains are the Triassic-Jurassic Trøndelag Platform, the Permo-Triassic Froan Basin (below the Trøndelag Platform), and the Møre and Vøring Basins (mainly Cretaceous-Tertiary basins with locally inverted dome structures of Tertiary age. The two main fault complexes in the region are the ENE-WSW striking Møre-Trøndelag Fault Complex and the N-S striking Klakk Fault Complex.
Beitstadfjorden Basin: The Beitstadfjorden Basin (14 km long and 6 km wide) is located at the northeastern extremity of Trondheimfjorden. It is surrounded by Precambrian migmatitic rocks to the north and Lower Palaeozoic metasediments to the south. Since 1845, the existence of a basin has been discussed due to the findings of coal fragments of Middle Jurassic age along the northwestern coast of the fjord. The basin is related to a southeast-dipping normal fault, which is interpreted as a branch of the Verran Fault System of the Møre-Trøndelag Fault Complex. Sedimentary units in the Jurassic succession dip up to 15 degrees to the NW, towards the deepest part of the basin. The thickness of the Jurassic succession is around 1000 m in the Beitstadfjorden Basin. A poster on this work can be downloaded from this link (2.3 MB)
Frohavet Basin: The Frohavet Basin occurs on the innermost mid-Norwegian continental shelf, between the Froan Islands and the coast, and NE of the Hitra and Frøya islands. Northwest and west of the basin, the Froan Islands and Frøya consist of Lower Palaeozoic intrusive rocks. To the southeast, the Tarva and Melsteinen islands comprise Precambrian migmatitic rocks, while Devonian sedimentary rocks occur in the Asenøya area and in Fosen. The Frohavet Basin (almost 60 km long and 15 km wide) is controlled by two large normal faults that downthrow to the northwest. Both the Tarva and Dolmsundet Faults occur along the southeastern margin of the basin. Sedimentary rocks of middle jurassic age dip up to 14 degrees towards the southeast, and there is a slight thickening of the succession towards the Tarva Fault. Folding of the layerd succession in the southern area is probably associated with slip on this boundary fault. The maximum Jurassic thickness, in the central part of the basin, is ca. 1200 m. Along the western and northwestern margins of the basin, the sedimentary units onlap the basement. A narrow basement ridge separates the main basin from a smaller, elongated basin close to the Froan Islands.
Structural map of Mid-Norway (from Blystad et al. 1995).
