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ABSTRACT: Fluid injection into the subsurface may trigger seismic events when shear stress acting on a fracture/fault plane exceeds its shear strength. During injection tests at the CO2 storage pilot at Longyearbyen (LYB), Svalbard, seismic- and non-seismic slipevents were experienced. Two approaches are used to explain the seismic versus non-seismic events occurring at the site. An analytical approach, based on Mohr-Coulomb failure criteria, was employed to evaluate the slip tendency of faults. It shows that vertical faults are more likely to slip at deeper intervals where microseismic events were observed. At shallow injection intervals, where no seismicity was observed, horizontal faults are more likely to slip. The second approach, a velocity stepping direct shear test, showed that the friction coefficient of LYB shale (clay-rich) increases with increasing velocity for bedding parallel faults. This experiment shows that the shale present at shallow interval is prone to velocity-strengthening behavior, which may explain the non-seismic failure during injection tests. 1 INTRODUCTION Capturing carbon dioxide from source points such as power plants and refineries and storing in the subsurface formations is suggested as one of the main measures to mitigate atmospheric greenhouse gases. The Longyearbyen (LYB) CO2 storage pilot is a potential site for CO2 storage on Svalbard, Norway. Longyearbyen is a small city with a population of about 2000 people in the polar wilderness of central Spitzbergen-the main island of the Svalbard archipelago at the northwestern margin of the Barents Sea Shelf (Braathen et al. 2012). The city has a 10 MW coal combusting power plant, which emits about 64,000 tons of CO2 annually (Ogata et al. 2012). The LYB pilot project was initiated by the University Centre on Svalbard (UNIS) to explore feasibility of the site to store the produced CO2 and convert the Longyearbyen to a carbon neutral community. The site is located 5 km east of the Longyearbyen city and eight boreholes (Fig. 1) have been drilled to study properties of the overburden, cap rock and reservoir.
Fomin, Y.V.. V. (Moscow Institute of Physics and Technology (State University), Russia) | Zhmur, V.V.. V. (Moscow Institute of Physics and Technology (State University), Russia) | Marchenko, A.V.. V. (The University Center in Svalbard, Norway) | Onishchenko, D.A.. A. (Gazprom VNIIGAZ Ltd, Russia)
Abstract Research sire for the monitoring of heat transfer processes in soils around the pipeline landfall from the shore to sea was organized and equipped in Longyearbyen, Spitsbergen. The data on soil temperature and pore pressure, sea water temperature and tidal variations of the water level are collected for one year of the measurement. Semi-diurnal variations of soil temperature and pore pressure are discovered in all measurement locations. Vertical and horizontal heat fluxes are calculated using the collected data.
ABSTRACT A field simulation of ice accretion has been performed in the harbour area of Longyearbyen, Spitsbergen, during the winter of 2011. Cylinders with diameters of 10, 20, 40 and 100 mm were exposed to a freezing artificially created periodic spray. This paper presents the density, crystalline structure and salinity of the accreted glaze ice. Hydrostatic weighing was used to measure the ice density, which is a well-established method in fields not related to ice. The method is simple, does not require special equipment and can be accurate to better than 1%. The dependence of the ice properties from the weather conditions is discussed. The experiments demonstrated that the ice salinity was smaller on the larger vertical objects.
Farokhpoor, R.. (NTNU (Norwegian University of Science and Technology)) | Torsæter, O.. (NTNU (Norwegian University of Science and Technology)) | Baghbanbashi, T.. (NTNU (Norwegian University of Science and Technology)) | Mork, A.. (Sintef) | Lindeberg, E.G.B.. G.B. (Sintef)
Abstract Sequestration of carbon dioxide in a saline aquifer is currently being evaluated as a possible way to handle carbon dioxide emitted from a coal-fuelled power plant in Svalbard. The chosen reservoir is a 300 m thick, laterally extensive, shallow marine formation of late Triassic-mid Jurassic age, located below Longyearbyen in Svalbard. The reservoir consists of 300 m of alternating sandstone and shale and is capped by 400 meter shale. Experimental and numerical studies have been performed to evaluate CO2 storage capacity and long term behaviour of the injected CO2 in rock pore space. Laboratory core flooding experiments were conducted during which air was injected into brine saturated cores at standard conditions. Analysis of the results shows that the permeability is generally less than 2 millidarcies and the capillary entry pressure is high. For most samples, no gas flow was detected in the presence of brine, when employing a reasonable pressure gradient. This poses a serious challenge with respect to achieving viable levels of injectivity and injection pressure. A conceptual numerical simulation of CO2 injection into a segment of the planned reservoir was performed using commercial reservoir simulation software and available petrophysical data. The results show that injection using vertical wells yields the same injectivity but more increases in field pressure compare to injection through horizontal wells. In order to keep induced pressure below top-seal fracturation pressure and preventing the fast propagation and migration of CO2 plume, slow injection through several horizontal wells into the lower part of the "high" permeability beds appears to offer the best solution. The high capillary pressure causes slow migration of the CO2 plume, and regional groundwater flow provides fresh brine for CO2 dissolution. In our simulations, half of the CO2 was dissolved in brine and the other half dispersed within a radius of 1000 meter from the wells after 4000 years. Dissolution of CO2 in brine and lateral convective mixing from CO2 saturated brine to surrounding fresh brine are the dominant mechanisms for CO2 storage in this specific site and this guarantees that the CO2 plume will be stationary for thousands of years.