Optimized CO2 storage in sloping aquifers (Upslope)

• Andersen, Odd & Sundal, Anja (2021). Estimating Caprock Impact on CO2 Migration in the Gassum Formation Using 2D Seismic Line Data. Transport in Porous Media. ISSN 0169-3913. 138, p. 459–487. doi: 10.1007/s11242-021-01622-1. Full text in Research Archive Show summary

  Realizable CO2 storage potential for saline formations without closed lateral boundaries depends on the combined effects of physical and chemical trapping mechanisms to prevent long-term migration out of the defined storage area. One such mechanism is the topography of the caprock surface, which may retain CO2 in structural pockets along the migration path. Past theoretical and modeling studies suggest that even traps too small to be accurately described by seismic data may play a significant role. In this study, we use real but scarce seismic data from the Gassum Formation of the Norwegian Continental shelf to estimate the impact of topographical features of the top seal in limiting CO2 migration. We seek to estimate the amount of macro- and sub-scale trapping potential of the formation based on a few dozen interpreted 2D seismic lines and identified faults. We generate multiple high-resolution realizations of the top surface, constructed to be faithful to both large-scale topography and small-scale statistical properties. The structural trapping and plume retardation potential of these top surfaces is subsequently estimated using spill-point (static) analysis and dynamical flow simulation. By applying these techniques on a large ensemble of top surface realizations generated using a combination of stochastic realizations and systematic variation of key model parameters, we explore the range of possible impacts on plume advancement, physical trapping and migration direction. The stochastic analysis of trapping capacity and retardation efficiency in statistically generated, sub-seismic resolution features may also be applied for surfaces generated from 3D data.

• Sundal, Anja & Hellevang, Helge (2019). Using Reservoir Geology and Petrographic Observations to Improve CO2 Mineralization Estimates; Examples from the Johansen Formation, North Sea, Norway. Minerals. ISSN 2075-163X. 9(11). doi: 10.3390/min9110671. Full text in Research Archive
• Olivarius, Mette; Sundal, Anja; Weibel, Rikke; Gregersen, Ulrik; Baig, Irfan & Thomsen, T.B. [Show all 9 contributors for this article] (2019). Provenance and sediment maturity as controls on CO2 mineral sequestration potential of the Gassum Formation in Skagerrak. . Frontiers in Earth Science. ISSN 2296-6463. 7. doi: 10.3389/feart.2019.00312. Full text in Research Archive

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• Andersen, Odd & Sundal, Anja (2019). Using 2D seismic line data to estimate impact of caprock morphology on CO2 migration in the Gassum formation. Full text in Research Archive Show summary

  The Gassum Formation on the Norwegian Continental Shelf serves as the principal case study for the CO2-Upslope project. The top surface of this formation is gently sloping, and characterized by a number of macro-scale structural traps, a few large faults, a large number of small faults, and small-scale depth variations that can be inferred and extrapolated from the seismic data. In the study presented in this paper, we estimate the amount of macro- and sub-scale trapping potential of the formation based on interpreted 2D seismic lines and identified faults. The seismic lines provide the depth of the caprock at each point along straight lateral paths. In the available data, a few dozen such lines cross the study area at various angles. A number of medium and large faults could be explicitly identified and mapped, as they correlate between several of these lines. In addition, hundreds of small-scale faults are only visible as discontinuities along individual lines. The extent and shape of these small faults between the seismic sections cannot be explicitly known from the data. In order to investigate trapping potential, we start out by constructing multiple realizations of the top surface, constructed to be faithful to both large-scale topography and small-scale statistical properties. We use a tensor spline surface approximation to represent the surface trend, with added stochastic small-scale variations consistent with the statistical properties of the line data. Moreover, we include a distribution small-scale faults that are only visible as discontinuities in the seismic lines by adding assumptions on their general orientations and lengths. At the timescales associated with long-term CO2 plume migration, it can generally be assumed that vertical equilibrium has been reached and that the CO2 slowly flows as a thin wedge right under the top surface, driven by gravity forces. Based on this assumption, we apply spill-point analysis and upscaling techniques on our sets of top surface realizations to explore the possible range of values for total structural trapping and plume retardation potential, and how they depend on the assumptions made. We also study the impact of the placement of the injection site, and how much of the total structural storage potential can be actually realized based on the position of the site and the injection strategy.

• Sundal, Anja; Miri, Rohaldin; Andersen, Odd; Hellevang, Helge; Gregersen, Ulrik & Olivarius, Mette [Show all 14 contributors for this article] (2019). Optimized CO2 storage in sloping aquifers: Estimation of physical and chemical immobilization potential and retardation along migration path in open storage solutions .
• Gregersen, Ulrik; Baig, Irfan; Sundal, Anja; Nielsen, Lars Henrik; Olivarius, Mette & Weibel, Rikke (2018). Seismic interpretation of a slopping offshore potential CO2 aquifer; the Gassum Formation in Skagerrak between Norway and Denmark.
• Sacco, Tatiana; Sundal, Anja & Hellevang, Helge (2018). Mass estimation of CO2 trapping potential in the Smeaheia reservoir.
• Olivarius, Mette; Sundal, Anja; Gregersen, Ulrik; Thomsen, T.B.; Weibel, Rikke & Nielsen, Lars-Henrik (2018). Using petrography and provenance data to assess the CO2 trapping potential in sloping sandstones in the Skagerrak Strait. EAGE extended abstracts. doi: 10.3997/2214-4609.201801148. Show summary

  80th EAGE Conference and Exhibition 2018 CO2 Capture, Storage and Utilization http://www.earthdoc.org/publication/publicationdetails/?publication=92535

• Gregersen, Ulrik; Baig, Irfan; Sundal, Anja; Nielsen, Lars-Henrik; Olivarius, Mette & Weibel, Rikke (2018). Seismic interpretation of a potential CO2 reservoir; the Gassum Formation, a sloping aquifer in Skagerrak between Norway and Denmark.
• Sundal, Anja; Hellevang, Helge; Olivarius, Mette; Miri, Rohaldin; Nielsen, Lars-Henrik & Gregersen, Ulrik [Show all 10 contributors for this article] (2018). Geological Constraints on the immobilization potential for CO2 in the Gassum Fm. (Skagerrak, Norway).
• Andersen, Odd & Sundal, Anja (2017). Slik kan vi lagre CO2 under havbunnen for alltid. Aftenposten Viten. ISSN 2464-3033. Full text in Research Archive Show summary

  Berggrunnen under Nordsjøen har et stort potensial som felles lagringssted for CO₂ fra industri i hele Nord-Europa.

• Sundal, Anja (2017). KARBONLAGRING: Undergrunn + CO2 = trygt. Show summary

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• Sundal, Anja; Hellevang, Helge & Sacco, Tatiana (2018). CO2 trapping in the Smeaheia reservoir - time mass estimation using geochemical models. Universitetet i Oslo.

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