Abstract
The Upper Triassic to Middle Jurassic Wilhelmoya Subgroup forms one of the more suitable reservoir units on the Norwegian Arctic archipelago of Svalbard. The target siliciclastic storage unit, which is encountered at approx. 670 m depth at the potential injection site in Adventdalen, central Spitsbergen, is a severely under-pressured (at least 35 bar), tight and compartmentalised reservoir with significant contribution of natural fractures to permeability. In this contribution, we characterise the 15–24 m-thick Wilhelmoya Subgroup storage unit using both borehole and outcrop data and present water-injection test results that indicate the presence of fluid-flow barriers and the generation of new, and propagation of pre-existing natural fractures during injection. Whole core samples from drillcores and outcrops were sampled for pore network characterisation and analysed using high-resolution X-ray computed tomography (Micro-CT). We demonstrate that heterogeneities such as structural discontinuities, igneous bodies and lateral facies variations, as examined in well core and equivalent outcrops, will strongly influence fluid flow in the target reservoir, both by steering and baffling fluid migration. Many of these heterogeneities are considered to be subseismic, and their detailed characterisation is important to predict subsurface CO2 storage potential and optimise injection strategy.
Highlights
Longyearbyen is a small isolated community situated on the Arctic archipelago of Svalbard at 78° north (Fig. 1)
Test 1 Injection and falloff results from DH7A are shown in Fig. 5, with a log-log diagnostic plot in Fig. 5A of test data from the extended falloff and data from an analytical model with a uniform-flux fracture with half-length xf = 83 m orientated parallel to a flow barrier 58 m from the well, and a test overview plot in Fig. 5B of the entire data set from DH7A along with output from the analytical model
The progressive transformation of smectite to illite via mixed-layer illite/ smectite (I/S) correlates with changes in temperature due to burial depth, the function curve for this process is very coarse (Kubler, 1967; Hower et al, 1976; Boles & Franks, 1979; Pollastro, 1993; Árkai et al, 2002)
Summary
Longyearbyen is a small isolated community situated on the Arctic archipelago of Svalbard at 78° north (Fig. 1). The Longyearbyen CO2 Lab was established in 2007 by the University Centre in Svalbard (UNIS) as a pilot-scale, onshore carbon capture and storage (CCS) study. The project aim was to assess the feasibility of capturing CO2 emitted by the local, coal-fuelled power plant 60,000 tons of CO2 emitted annually) and storing it in a saline aquifer underground. Increase in anthropogenic emission of CO2 into the Earth’s atmosphere since the industrial revolution and its contribution to global climate change is unequivocal. M.J., Larsen, L., Van Stappen, J., Rismyhr, B., Senger, K., Braathen, A., Olaussen, S., Mørk, M.B.E., Ogata, K. 2019: Fluid flow properties of the Wilhelmøya Subgroup, a potential unconventional CO2 storage unit in central Spitsbergen.
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