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Niemi, Auli
Publications (10 of 91) Show all publications
Yang, Z., Meheust, Y., Neuweiler, I., Hu, R., Niemi, A. & Chen, Y.-F. (2019). Modeling Immiscible Two-Phase Flow in Rough Fractures From Capillary to Viscous Fingering. Water resources research, 55(3), 2033-2056
Open this publication in new window or tab >>Modeling Immiscible Two-Phase Flow in Rough Fractures From Capillary to Viscous Fingering
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2019 (English)In: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 55, no 3, p. 2033-2056Article in journal (Refereed) Published
Abstract [en]

We develop an efficient computational model for simulating fluid invasion patterns emerging in variable aperture fractures. This two‐dimensional model takes into account the effect of capillary force on the fluid‐fluid interfaces and viscous pressure drop in both fluid phases. The pressure distribution is solved at each time step based on mass balance and local cubic law, considering an imposed pressure jump condition at the fluid‐fluid interface. This pressure jump corresponds to the Laplace pressure which includes both terms related to the out‐of‐plane (aperture‐spanning) curvature and to the in‐plane curvature. Simulating a configuration that emulates viscous fingering in two‐dimensional random porous media confirms that the model accounts properly for the role of viscous forces. Furthermore, direct comparison with previously obtained experimental results shows that the model reproduces the observed drainage patterns in a rough fracture reasonably well. The evolutions of tip location, the inlet pressures, and the invading phase fractal dimensions are analyzed to characterize the transition from capillary fingering to viscous fingering regimes. A radial injection scenario of immiscible invasion is also studied with varying modified capillary number and viscosity ratio, showing displacement patterns ranging from capillary fingering to viscous fingering to stable displacement. Such simulations using two contact angles show that the invading phase becomes more compact when the wetting condition changes from strong to weak drainage, as already observed in 2‐D porous media. The model can be used to bridge the gap in spatial scales of two‐phase flow between pore‐scale modeling approaches and the continuum Darcy‐scale models.

Abstract [en]

Plain Language Summary: The flow of two or more fluids in fractured media is an important process involved in many industrial and environmental applications in the subsurface with examples spanning from contaminant transport to petroleum recovery to geological storage of carbon dioxide. Understanding and controlling two‐phase flow in fractures is critical from both the scientific and technological points of view. In this study, we focus on the displacement of one fluid by another immiscible one in a rough fracture, a fundamental process underlying two‐phase flow in fractured media. We develop an efficient computational model for simulating fluid invasion patterns emerging in rough fractures. This model takes into account the effect of capillary force on the fluid‐fluid interfaces and viscous pressure drop in both fluid phases. Direct comparison with experimental results shows that the model output matches the observed patterns reasonably well. In addition, generic simulations demonstrate the ability of the model to produce flow patterns that fall into regimes whose dependence on the viscosity ratio and capillary number is similar to that of the classical phase diagram. The model can be used to bridge the gap in spatial scales of two‐phase flow between pore‐scale modeling approaches and the continuum Darcy‐scale models.

Keywords
immiscible displacement, rough fracture, numerical simulation, viscous fingering, capillary fingering, wettability
National Category
Fluid Mechanics and Acoustics Oceanography, Hydrology and Water Resources
Identifiers
urn:nbn:se:uu:diva-383002 (URN)10.1029/2018WR024045 (DOI)000464660000016 ()
Available from: 2019-05-21 Created: 2019-05-21 Last updated: 2019-05-21Bibliographically approved
Dessirier, B., Tsang, C.-F. & Niemi, A. (2018). A new scripting library for modeling flow and transport in fractured rock with channel networks. Computers & Geosciences, 111, 181-189
Open this publication in new window or tab >>A new scripting library for modeling flow and transport in fractured rock with channel networks
2018 (English)In: Computers & Geosciences, ISSN 0098-3004, E-ISSN 1873-7803, Vol. 111, p. 181-189Article in journal (Refereed) Published
Abstract [en]

Deep crystalline bedrock formations are targeted to host spent nuclear fuel owing to their overall low permeability. They are however highly heterogeneous and only a few preferential paths pertaining to a small set of dominant rock fractures usually carry most of the flow or mass fluxes, a behavior known as channeling that needs to be accounted for in the performance assessment of repositories. Channel network models have been developed and used to investigate the effect of channeling. They are usually simpler than discrete fracture networks based on rock fracture mappings and rely on idealized full or sparsely populated lattices of channels. This study reexamines the minimal requirements to describe a channel network in terms of groundwater flow and solute transport, leading to an extended description suitable for unstructured arbitrary networks of channels. An implementation of this formalism in a Python scripting library is presented and released along with this article. A new algebraic multigrid preconditioner delivers a significant speedup in the flow solution step compared to previous channel network codes. 3D visualization is readily available for verification and interpretation of the results by exporting the results to an open and free dedicated software. The new code is applied to three example cases to verify its results on full uncorrelated lattices of channels, sparsely populated percolation lattices and to exemplify the use of unstructured networks to accommodate knowledge on local rock fractures.

Keywords
channel network, groundwater flow, solute transport, graph theory
National Category
Oceanography, Hydrology and Water Resources
Research subject
Hydrology
Identifiers
urn:nbn:se:uu:diva-321572 (URN)10.1016/j.cageo.2017.11.013 (DOI)000423005900018 ()
Funder
Swedish Radiation Safety Authority, SSM2016-763
Available from: 2017-05-08 Created: 2017-05-08 Last updated: 2018-03-06Bibliographically approved
Figueiredo, B., Tsang, C.-F., Rutqvist, J. & Niemi, A. (2018). Corrigendum to “The effects of nearby fractures on hydraulically induced fracture propagation and permeability changes”[Eng. Geol. 228 (2017) 197–213]. Engineering Geology, 239, 344-344
Open this publication in new window or tab >>Corrigendum to “The effects of nearby fractures on hydraulically induced fracture propagation and permeability changes”[Eng. Geol. 228 (2017) 197–213]
2018 (English)In: Engineering Geology, ISSN 0013-7952, E-ISSN 1872-6917, Vol. 239, p. 344-344Article in journal (Other academic) Published
National Category
Geology
Identifiers
urn:nbn:se:uu:diva-359373 (URN)10.1016/j.enggeo.2018.03.006 (DOI)000432769300030 ()
Funder
The Geological Survey of Sweden (SGU), 1724EU, Horizon 2020, 636811
Note

WoS title: The effects of nearby fractures on hydraulically induced fracture propagation and permeability changes (vol 228, pg 197, 2017)

Correction to: Engineering Geology, vol. 228, pages 197-213. DOI: 10.1016/j.enggeo.2017.08.011

Available from: 2018-09-04 Created: 2018-09-04 Last updated: 2018-09-04Bibliographically approved
Hedayati, M., Wigston, A., Wolf, J. L., Rebscher, D. & Niemi, A. (2018). Impacts of SO2 gas impurity within a CO2 stream on reservoir rock of a CCS pilot site: Experimental and modelling approach. International Journal of Greenhouse Gas Control, 70, 32-44
Open this publication in new window or tab >>Impacts of SO2 gas impurity within a CO2 stream on reservoir rock of a CCS pilot site: Experimental and modelling approach
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2018 (English)In: International Journal of Greenhouse Gas Control, ISSN 1750-5836, E-ISSN 1878-0148, Vol. 70, p. 32-44Article in journal (Refereed) Published
Abstract [en]

In order to evaluate chemical impacts of SO2 impurity on reservoir rock during CO2 capture and storage in deep saline aquifers, several batch reactor experiments were performed on laboratory scale using core rock samples from the pilot CO2 injection site in Heletz. In this experiment, the samples were exposed to pure N-2(g), pure CO2(g), and CO2(g) with an impurity of 1.5% SO2(g) under reservoir conditions for pressure and temperature (14.5 MPa, 60 degrees C). Based on the set-up and the obtained experimental results, a batch chemical model was established using the numerical simulation program TOUGHREACT V3.0-OMP. Comparing laboratory and simulation data provides a better understanding of the rock-brine-gas interactions. In addition, it offers an evaluation of the capability of the model to predict chemical interactions in the target injection reservoir during exposure to pure and impure CO2. The best match between the geochemical model and experimental data was achieved when the reactive surface area of minerals in the model was adjusted in order to calibrate the kinetic rates of minerals. The simulations indicated that SO2(g) tends to dissolve rather quickly and oxidizes under a kinetic control. Hence, it has a stronger effect on the acidity of the brine than pure CO2(g) and as a result, increased mineral dissolution and caused the precipitation of sulfate and sulfide minerals. Ankerite, dolomite, and siderite, the most abundant carbonates in the sandstone rock sample, are subject to stronger dissolution in the presence of SO2 gas. The performed simulations confirmed a slower dissolution rate for ankerite and siderite than for dolomite. The model reproduced the precipitation of pyrite and anhydrite as observed in the laboratory. The dissolution of dolomite observed in the batch reaction test with pure N-2 is assumed to be due to slight contamination with oxygen and modelling supported this. The inclusion of SO2 increased the porosity over that of the pure CO2 case, and is thus considered to increase the permeability and injectivity of the reservoir as well. Exposure to SO2 also increased the concentration of trace elements. The calibrated kinetic parameters determined in this study will be used to model the injection and long-term behavior of CO2 at the Heletz field site, and may be used for similar geologic reservoirs.

National Category
Geochemistry
Identifiers
urn:nbn:se:uu:diva-340872 (URN)10.1016/j.ijggc.2018.01.003 (DOI)000428773100004 ()
Funder
EU, FP7, Seventh Framework Programme, 309102, 309067
Available from: 2018-02-05 Created: 2018-02-05 Last updated: 2018-06-01Bibliographically approved
Tsang, C.-F., Figueiredo, B. & Niemi, A. (2018). Importance of stress effects on inputs to fracture network models used for subsurface flow and transport studies. International Journal of Rock Mechanics And Mining Sciences, 101, 13-17
Open this publication in new window or tab >>Importance of stress effects on inputs to fracture network models used for subsurface flow and transport studies
2018 (English)In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 101, p. 13-17Article in journal (Refereed) Published
National Category
Geosciences, Multidisciplinary
Identifiers
urn:nbn:se:uu:diva-334138 (URN)10.1016/j.ijrmms.2017.11.012 (DOI)000418717200002 ()
Funder
Swedish Radiation Safety Authority, SSM2016-763The Geological Survey of Sweden (SGU), 1724
Available from: 2017-11-21 Created: 2017-11-21 Last updated: 2018-01-18Bibliographically approved
Rasmusson, K., Rasmusson, M., Tsang, Y., Benson, S., Hingerl, F., Fagerlund, F. & Niemi, A. (2018). Residual trapping of carbon dioxide during geological storage: insight gained through a pore-network modeling approach. International Journal of Greenhouse Gas Control, 74, 62-78
Open this publication in new window or tab >>Residual trapping of carbon dioxide during geological storage: insight gained through a pore-network modeling approach
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2018 (English)In: International Journal of Greenhouse Gas Control, ISSN 1750-5836, E-ISSN 1878-0148, Vol. 74, p. 62-78Article in journal (Refereed) Published
Abstract [en]

To reduce emissions of the greenhouse gas CO2 to the atmosphere, sequestration in deep saline aquifers is a viable strategy. Residual trapping is a key containment process important to the success of CO2 storage operations. While residual trapping affects CO2 migration over large scales, it is inherently a pore-scale process. Pore-network models (PNMs), capturing such processes, are useful for our understanding of residual trapping, and for upscaling trapping parameters for larger scale models. A PNM for simulation of quasi-static two-phase flow; CO2 intrusion (drainage) followed by water flooding (imbibition) was developed. It accounts for pore-scale displacement mechanisms, and was used to investigate residual CO2 trapping. The sensitivity of the residual CO2 saturation to several parameters was studied, to validate a trapping behavior in agreement with earlier studies. Then the PNM was calibrated to core sample data and used to simulate drainage-imbibition scenarios with different turning point saturations. From these the initial-residual saturation curves of CO2 in Heletz sandstone were estimated, essential for future macroscopic-scale simulations. Further, the occurrence of different pore-scale mechanisms were quantified and the size distribution of the residual clusters was shown to exhibit a bimodal appearance. The findings improve the understanding of residual trapping in Heletz sandstone.

National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:uu:diva-327991 (URN)10.1016/j.ijggc.2018.04.021 (DOI)000434428100007 ()
Funder
EU, FP7, Seventh Framework Programme, 309067Swedish Energy Agency, 43526-1
Available from: 2017-08-15 Created: 2017-08-15 Last updated: 2018-08-30Bibliographically approved
Niemi, A., Bensabat, J., Joodaki, S., Basirat, F., Hedayati, M., Yang, Z., . . . Fagerlund, F. (2018). Study of CO2 Residual Trapping In-Situ – Results from Push- Pull Experiments at Heletz (Israel) Pilot CO2 Injection Site. In: IEAGHG (Ed.), International Conference on Greenhouse Gas Control Technologies, GHGT-14 21st -25th October 2018, Melbourne, Australia: . Paper presented at 14th International Conference on Greenhouse Gas Control Technologies, GHGT-14 21st -25th October 2018, Melbourne, Australia.
Open this publication in new window or tab >>Study of CO2 Residual Trapping In-Situ – Results from Push- Pull Experiments at Heletz (Israel) Pilot CO2 Injection Site
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2018 (English)In: International Conference on Greenhouse Gas Control Technologies, GHGT-14 21st -25th October 2018, Melbourne, Australia / [ed] IEAGHG, 2018Conference paper, Published paper (Refereed)
Keywords
Residual trapping, in-situ experiments, push-pull experiments, hydraulc tests, tracer tests, core samples, pore network modeling
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:uu:diva-393663 (URN)
Conference
14th International Conference on Greenhouse Gas Control Technologies, GHGT-14 21st -25th October 2018, Melbourne, Australia
Funder
Swedish Energy Agency, 43526-1EU, FP7, Seventh Framework Programme, n 309607
Available from: 2019-09-25 Created: 2019-09-25 Last updated: 2019-12-06Bibliographically approved
Snæbjörnsdóttir, S., Tómasdóttir, S., Sigfússon, B., Aradóttir, E. S., Gunnarsson, G., Niemi, A., . . . Oelkers, E. H. (2018). The geology and hydrology of the CarbFix2 site, SW-Iceland. Energy Procedia, 146, 146-157
Open this publication in new window or tab >>The geology and hydrology of the CarbFix2 site, SW-Iceland
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2018 (English)In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 146, p. 146-157Article in journal (Refereed) Published
Abstract [en]

Injection of CO2 and H2S emissions from the Hellisheidi Geothermal Power Plant, SW-Iceland, as part of the CarbFix project, is currently taking place in the Húsmúli reinjection zone. Here we present detailed descriptions of the geology of the reservoir rock in Húsmúli including descriptions of its intrusions, secondary mineralogy and sources of permeability. We further present preliminary results from a modelling study of the Húsmúli reinjection zone that was conducted to obtain better understanding of flow paths in the area. The model was calibrated using results from an extensive tracer test that was carried out in 2013-2015.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
CarbFix, SulFix, CO2, H2S, Hellisheidi Power Plant, Húsmúli, numerical modelling, mineralization
National Category
Geology Oceanography, Hydrology and Water Resources
Research subject
Hydrology
Identifiers
urn:nbn:se:uu:diva-393595 (URN)10.1016/j.egypro.2018.07.019 (DOI)
Available from: 2019-09-25 Created: 2019-09-25 Last updated: 2019-11-14Bibliographically approved
Rasmusson, M., Rasmusson, K., Fagerlund, F., Tsang, Y. & Niemi, A. (2018). The impact of co-contaminant SO2, versus salinity and thermodynamic conditions, on residual CO2 trapping during geological storage. Greenhouse Gases: Science and Technology, 8(6), 1053-1065
Open this publication in new window or tab >>The impact of co-contaminant SO2, versus salinity and thermodynamic conditions, on residual CO2 trapping during geological storage
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2018 (English)In: Greenhouse Gases: Science and Technology, E-ISSN 2152-3878, Vol. 8, no 6, p. 1053-1065Article in journal (Refereed) Published
Abstract [en]

During geological storage in deep saline aquifers, immobilization of CO2 in reservoir rock determines both storage safety and capacity. Assessment of the sensitivity of residual trapping to different parameters (interfacial tension and contact angles) and the storage conditions affecting these is therefore of great importance. One aspect of concern is the presence of co-contaminants such as SO2 in the injected gas. Using experimentally measured values of interfacial tensions and contact angles, we apply pore-network modelling (which accounts for pore-scale mechanisms such as snap-off, cooperative pore body filling and piston-type displacement) to a generic sandstone network to quantify the impact of SO2 co-injection on residual CO2 trapping, and its relative importance as compared to the influences of thermodynamic conditions and salinity. We show that the presence of small amounts of SO2 in the injected CO2 has a notable positive effect on the amount of CO2 becoming residually trapped (similar to 3% increase at 1 wt% SO2). However, this effect is small compared to that of the brine salinity (similar to 20% decrease in residually trapped CO2 over the salinity range 0.2 to 5 M NaCl). Still, co-injection of SO2 could potentially favour the residual trapping of CO2 in reservoir rocks, especially at storage sites with inclined aquifers where the CO2 is set to migrate hydro-dynamically over long distances. The salinity of the resident brine is of primary importance during storage site selection. Furthermore, sensitivity analysis shows that the advancing contact angle strongly impacts residual CO2 trapping. 

Place, publisher, year, edition, pages
WILEY PERIODICALS, INC, 2018
Keywords
capillary trapping, carbon dioxide, co-injection, impurities, pore-network model, sulfur dioxide
National Category
Oceanography, Hydrology and Water Resources
Identifiers
urn:nbn:se:uu:diva-371116 (URN)10.1002/ghg.1816 (DOI)000451042600006 ()
Funder
Swedish Research Council, 2010-3657EU, FP7, Seventh Framework Programme, 282900EU, FP7, Seventh Framework Programme, 309102
Available from: 2018-12-28 Created: 2018-12-28 Last updated: 2018-12-28Bibliographically approved
Wolf, J. L., Niemi, A., Bensabat, J., May, F., Ruetters, H. & Rebscher, D. (2017). 2D reactive transport simulations of CO2 streams containing impurities in a saline aquifer, Heletz, Israel. In: Dixon, T Laloui, L Twinning, S (Ed.), 13Th International Conference on Greenhouse Gas Control Technologies, Ghgt-13: . Paper presented at 13th International Conference on Greenhouse Gas Control Technologies (GHGT), NOV 14-18, 2016, Lausanne, SWITZERLAND (pp. 3537-3546). Elsevier
Open this publication in new window or tab >>2D reactive transport simulations of CO2 streams containing impurities in a saline aquifer, Heletz, Israel
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2017 (English)In: 13Th International Conference on Greenhouse Gas Control Technologies, Ghgt-13 / [ed] Dixon, T Laloui, L Twinning, S, Elsevier, 2017, p. 3537-3546Conference paper, Published paper (Refereed)
Abstract [en]

In order to evaluate the chemical impacts of CO2 stream impurities on reservoir rocks, 2D reactive transport simulations using the code TOUGHREACT V3.0 were performed. The underlying reservoir properties are based on in-situ data from the CO2 injection test site Heletz, Israel. Two different CO2 compositions (mole fractions 99 % CO2 + 1 % SO2 and 98.8 % CO2 + 1 % SO2 + 0.2 % NO2, respectively) were chosen to represent oxidising impurities. Different modelling approaches, namely trace gas transport (TGT) and additional brine injection (ABI), were applied to investigate the influence of these modelling approaches on qualitative and quantitative simulation results. The simulations using either approach show an accumulation of SO2 and NO2 close to the injection well due to the preferential dissolution of these acidic impurities compared to CO2. Both modelling approaches indicate the same general chemical impact and related mineral reactions. Within the affected rock volume a distinct ankerite to anhydrite conversion occurs, which slightly enhances porosity. While the same qualitative conclusions independently from the chosen modelling approach were obtained, the quantitative magnitude of mineral conversion and the spatial extent of impurity affected rock material depend on the chosen modelling approach and thus need further investigation with respect to e.g. validation by field test data. (C) 2017 The Authors. Published by Elsevier Ltd.

Place, publisher, year, edition, pages
Elsevier, 2017
Series
Energy Procedia, ISSN 1876-6102 ; 114
Keywords
Impurities, reactive transport, SO2, NO2, TOUGHREACT V3.0, CCS
National Category
Geosciences, Multidisciplinary
Identifiers
urn:nbn:se:uu:diva-349328 (URN)10.1016/j.egypro.2017.03.1483 (DOI)000419147303068 ()
Conference
13th International Conference on Greenhouse Gas Control Technologies (GHGT), NOV 14-18, 2016, Lausanne, SWITZERLAND
Funder
EU, FP7, Seventh Framework Programme, 309102
Available from: 2018-04-26 Created: 2018-04-26 Last updated: 2018-04-26Bibliographically approved
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