Helge Hellevang

• Fazeli, Hossein; Nooraiepour, Mohammad; Masoudi, Mohammad & Hellevang, Helge (2021). Effect of Mineral Heterogeneity on Fracture Dissolution in Carbonate-Rich Caprocks During Subsurface Co2 Injection. EAGE extended abstracts. doi: 10.3997/2214-4609.202011174. Show summary

  Chemical interactions between CO2, brine, and caprock-forming minerals might lead to dissolution of the fractures present in the caprock of CO2 storage sites. One factor that can affect the chemically induced fracture alterations is mineral heterogeneity in the caprock. In this study, we investigate the effect of mineral heterogeneity on fracture dissolution of four carbonate-rich caprock samples, having different levels of heterogeneity, where CO¬2-rich brine flows through the fractured caprocks. A HPHT geomaterial microfluidic experimental setup is used to monitor the evolution of the fractures. Results indicate that the homogeneous caprock samples, i.e. the samples that are mainly composed of calcite, show a uniform fracture wall dissolution while fracture wall roughness increases for heterogeneous samples. The effluent chemistry analyses show that the sample-scale calcite dissolution rate decreases over time, which can be due to the mass transfer limitations in the boundary layer near the fracture wall (for the homogeneous sample) or in the altered layer formed around the fracture (for the heterogeneous samples). Microfluidic experiments were also done for one carbonate rich finegrained shale sample, which showed no detectable fracture alteration. However, the effluent analysis for the shale sample confirmed the calcite dissolution.

• Ma, Pengjie; Lin, Chengyan; Ren, Lihua; Jahren, Jens Sigurd; Dong, Daotao & Yu, Guoding [Show all 10 contributors for this article] (2021). Linkage and growth of the independent and coherent faults: Insight into the effect of relay ramps on sedimentation patterns in the northern Bonan Sag, Bohai Bay Basin. Marine and Petroleum Geology. ISSN 0264-8172. 127. doi: 10.1016/j.marpetgeo.2021.104985.
• Masoudi, Mohammad; Fazeli, Hossein; Miri, Rohaldin & Hellevang, Helge (2021). Pore scale modeling and evaluation of clogging behavior of salt crystal aggregates in CO2-rich phase during carbon storage. International Journal of Greenhouse Gas Control. ISSN 1750-5836. 111. doi: 10.1016/j.ijggc.2021.103475. Full text in Research Archive
• Ahmadigoltapeh, Sajjad; Miri, Rohaldin; Aagaard, Per & Hellevang, Helge (2021). Extension of SAFT equation of state for fluids confined in nano-pores of sedimentary rocks using molecular dynamic simulation. Journal of Molecular Liquids. ISSN 0167-7322. 348. doi: 10.1016/j.molliq.2021.118045. Full text in Research Archive
• Hellevang, Helge; Line, Lina Hedvig; Eide, Christian Haug; Jahren, Jens Sigurd & Haile, Beyene Girma (2021). Insights into past tectonism from authigenic quartz. Geochemical Perspectives Letters. ISSN 2410-339X. 19, p. 27–31. doi: 10.7185/geochemlet.2130. Full text in Research Archive
• Nooraiepour, Mohammad; Masoudi, Mohammad; Shokri, Nima & Hellevang, Helge (2021). Probabilistic Nucleation and Crystal Growth in Porous Medium: New Insights from Calcium Carbonate Precipitation on Primary and Secondary Substrates. ACS Omega. ISSN 2470-1343. 6(42), p. 28072–28083. doi: 10.1021/acsomega.1c04147. Full text in Research Archive
• Ahmadigoltapeh, Sajjad; Abdolahi, Saeed; Miri, Rohaldin & Hellevang, Helge (2021). Extension of PC-SAFT equation of state to include mineral surface effect in fluid properties using molecular dynamic simulation. Sustainable Energy Technologies and Assessments. ISSN 2213-1388. 48. doi: 10.1016/j.seta.2021.101624. Full text in Research Archive
• Nooraiepour, Mohammad; Masoudi, Mohammad & Hellevang, Helge (2021). Probabilistic nucleation governs time, amount, and location of mineral precipitation and geometry evolution in the porous medium. Scientific Reports. ISSN 2045-2322. 11. doi: 10.1038/s41598-021-95237-7. Full text in Research Archive
• Dypvik, Henning; Hellevang, Helge; Krzesinska, Agata Magdalena; Sætre, Christian; Viennet, Jean-Christophe & Bultel, Benjamin Gabriel Rene [Show all 13 contributors for this article] (2021). The Planetary Terrestrial Analogues Library (PTAL) – An exclusive lithological selection of possible martian earth analogues. Planetary and Space Science. ISSN 0032-0633. 208. doi: 10.1016/j.pss.2021.105339. Full text in Research Archive
• Ma, Pengije; Lin, Chengyan; Jahren, Jens; Dong, Chunmei; Ren, Lihua & Hellevang, Helge (2021). Cyclic zoning in authigenic saddle dolomite-ankerite: Indications of a complex interplay between fault-rupturing and diagenetic alteration. Chemical Geology. ISSN 0009-2541. 559. doi: 10.1016/j.chemgeo.2020.119831.
• An, Senyou; Erfani, Hamidreza; Hellevang, Helge & Niasar, Vahid (2021). Lattice-Boltzmann simulation of dissolution of carbonate rock during CO2-saturated brine injection. Chemical Engineering Journal. ISSN 1385-8947. 408. doi: 10.1016/j.cej.2020.127235.
• Xi, Kelai; Cao, Yingchang; Haile, Beyene Girma; Zhu, Ning; Liu, Keyu & Wu, Songtao [Show all 7 contributors for this article] (2021). Diagenetic variations with respect to sediment composition and paleo-fluids evolution in conglomerate reservoirs: A case study of the Triassic Baikouquan Formation in Mahu Sag, Junggar Basin, Northwestern China. Journal of Petroleum Science and Engineering. ISSN 0920-4105. 197. doi: 10.1016/j.petrol.2020.107943.
• Sætre, Christian; Hellevang, Helge; Dennehy, C. & Dypvik, Henning (2021). Reactive transport modelling of an intra-basalt sandstone reservoir, Rosebank, UK. Scientific Reports. ISSN 2045-2322. 11. doi: 10.1038/s41598-021-86421-w. Full text in Research Archive
• Haile, Beyene Girma; Line, Lina Hedvig; Klausen, Tore Grane; Olaussen, Snorre; Eide, Christian Haug & Jahren, Jens [Show all 7 contributors for this article] (2020). Quartz overgrowth textures and fluid inclusion thermometry evidence for basin-scale sedimentary recycling: An example from the Mesozoic Barents Sea Basin. Basin Research. ISSN 0950-091X. doi: 10.1111/bre.12531. Full text in Research Archive
• Line, Lina Hedvig; Müller, Reidar; Klausen, Tore Grane; Jahren, Jens & Hellevang, Helge (2020). Distinct petrographic responses to basin reorganization across the Triassic–Jurassic boundary in the southwestern Barents Sea. Basin Research. ISSN 0950-091X. 32(6), p. 1463–1484. doi: 10.1111/bre.12437. Full text in Research Archive
• Fazeli, Hossein; Nooraiepour, Mohammad & Hellevang, Helge (2020). Microfluidic Study of Fracture Dissolution in Carbonate-Rich Caprocks Subjected to CO2-Charged Brine. Industrial & Engineering Chemistry Research. ISSN 0888-5885. 59(1), p. 450–457. doi: 10.1021/acs.iecr.9b06048. Show summary

  Investigating fracture evolutions triggered by chemical interactions in caprocks of CO2 storage sites is of great importance when caprock integrity is concerned. Mineral heterogeneity is one of the factors affecting fracture evolution. We present results from flow-through experiments deploying a unique high pressure geo-material microfluidic cell to monitor the fracture evolution of four carbonate-rich caprocks: (1) a homogeneous carbonate-rich sample, (2) a heterogeneous carbonate-rich sample, (3) a heterogeneous carbonate-rich shale sample, and (4) a heterogeneous carbonate-rich organic shale sample, representing different levels of mineral heterogeneity. The results show rather smooth fracture wall dissolution for the homogeneous rock sample. For the heterogeneous sample without shale, however, an altered layer is formed around the fracture that leads to an increase in the fracture roughness. Chemical analyses of effluent solutions demonstrate a decrease in the bulk dissolution rate of calcite over time at a constant flow rate. For the two carbonate-rich shale samples, visual observations using optical microscopy showed little changes in fracture dissolution, although analysis of effluent chemistry confirmed calcite dissolution.

• Masoudi, Mohammad; Miri, Rohaldin; Hellevang, Helge & Kord, S. (2020). Modified PC-SAFT characterization technique for modeling asphaltenic crude oil phase behavior. Fluid Phase Equilibria. ISSN 0378-3812. 513. doi: 10.1016/j.fluid.2020.112545. Full text in Research Archive
• Fazeli, Hossein; Masoudi, Mohammad; Patel, Ravi A.; Aagaard, Per & Hellevang, Helge (2020). Pore-Scale Modeling of Nucleation and Growth in Porous Media. ACS Earth and Space Chemistry. ISSN 2472-3452. 4(2), p. 249–260. doi: 10.1021/acsearthspacechem.9b00290.
• Veneranda, Marco; Manrique-Martinez, Jose Antonio; Lopez-Reyes, Guillermo; Medina, Jesus E.; Torre-Fdez, Imanol & Castro, Kepa [Show all 13 contributors for this article] (2019). Spectroscopic study of olivine-bearing rocks and its relevance to the ExoMars rover mission. Spectrochimica Acta Part A - Molecular and Biomolecular Spectroscopy. ISSN 1386-1425. 223. doi: 10.1016/j.saa.2019.117360.
• 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
• 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
• Fazeli, Hossein; Patel, Ravi A.; Ellis, Brian R & Hellevang, Helge (2019). Three-Dimensional Pore-Scale Modeling of Fracture Evolution in Heterogeneous Carbonate Caprock Subjected to CO2-Enriched Brine. Environmental Science and Technology. ISSN 0013-936X. 53(8), p. 4630–4639. doi: 10.1021/acs.est.8b05653.
• Hellevang, Helge; Wolff-Boenisch, Domenik & Nooraiepour, Mohammad (2019). Kinetic control on the distribution of secondary precipitates during CO2-basalt interactions. E3S Web of Conferences. ISSN 2267-1242. 98. doi: 10.1051/e3sconf/20199804006. Full text in Research Archive
• Morad, Daniel Jan; Nader, Fadi H.; Morad, Sadoon; Rossi, Carlos; Gasparrini, Marta & Alsuwaidi, Mohammad [Show all 8 contributors for this article] (2019). Limited thermochemical sulfate reduction in hot, anhydritic, sour gas carbonate reservoirs: The Upper Jurassic Arab Formation, United Arab Emirates. Marine and Petroleum Geology. ISSN 0264-8172. 106, p. 30–41. doi: 10.1016/j.marpetgeo.2019.04.023.
• Naseryan Moghadam, Javad; Nooraiepour, Mohammad; Hellevang, Helge; Mondol, Nazmul Haque & Aagaard, Per (2019). Relative permeability and residual gaseous CO2 saturation in the Jurassic Brentskardhaugen Bed sandstones, Wilhelmøya Subgroup, western central Spitsbergen, Svalbard. Norwegian Journal of Geology. ISSN 2387-5844. 99(2). doi: 10.17850/njg005. Full text in Research Archive Show summary

  This study investigates fluid-flow properties of the low-permeability Brentskardhaugen Bed (Knorringfjellet Formation), Wilhelmøya Subgroup, western central Spitsbergen, Svalbard. To evaluate the two-phase relative permeability of the water-CO2 system, we performed unsteady state core-flooding experiments using deionised water and gaseous CO2. The absolute permeability and residual fluid saturations were also studied. Moreover, a core plug of the Berea sandstone was tested as a reference sample. The core-flooding experiments recorded microDarcy permeability values (0.022–0.039 mD) for various differential pressures (4 to 12 MPa). The poor grain sorting and the abundance of cement were the main factors controlling the low matrix permeabilities. Closure of sub-micron fractures was the likely reason for reduced permeability with increasing effective stresses. The experimental measurements showed that CO2 fractional flow reached unity at relatively low CO2 saturation (approximately 0.35–0.45). The irreducible water saturation and trapped CO2 saturation were 56% and 23%, respectively. The corresponding endpoint CO2 and water relative permeability were 0.18 and 0.47, respectively. The results, therefore, demonstrate low endpoint CO2 saturation and low relative permeability, in addition to high CO2 fractional flow at high water saturation. The trapped CO2 saturation was relatively high, which suggests a high CO2 immobilisation capability of the Wilhelmøya Subgroup sandstones. Moreover, a lower relative permeability was observed for gaseous CO2 compared to published results for supercritical CO2. In addition, the examined core sample showed a higher trapped CO2 saturation and higher endpoint CO2 relative permeability compared with the porous and permeable Berea sandstone.

• Nooraiepour, Mohammad; Mondol, Nazmul Haque & Hellevang, Helge (2019). Permeability and physical properties of semi-compacted fine-grained sediments – A laboratory study to constrain mudstone compaction trends. Marine and Petroleum Geology. ISSN 0264-8172. 102, p. 590–603. doi: 10.1016/j.marpetgeo.2019.01.019. Full text in Research Archive
• Sætre, Christian; Hellevang, Helge; Riu, Lucie; Dypvik, Henning; Pilorget, C & Poulet, Francois [Show all 7 contributors for this article] (2019). Experimental hydrothermal alteration of basaltic glass with relevance to Mars. Meteoritics and Planetary Science. ISSN 1086-9379. 54(2), p. 357–378. doi: 10.1111/maps.13214. Full text in Research Archive
• Haile, Beyene Girma; Czarniecka, Urszula; Xi, Kelai; Smyrak-Sikora, Aleksandra; Jahren, Jens & Braathen, Alvar [Show all 7 contributors for this article] (2019). Hydrothermally induced diagenesis: Evidence from shallow marine-deltaic sediments, Wilhelmøya, Svalbard. Geoscience Frontiers. ISSN 1674-9871. 10(2), p. 629–649. doi: 10.1016/j.gsf.2018.02.015. Full text in Research Archive
• Morad, Daniel Jan; Nader, Fadi H.; Morad, Sadoon; Darmaki, Fatima AL & Hellevang, Helge (2018). Impact of Stylolitization On Fluid Flow and Diagenesis in Foreland Basins: Evidence from an Upper Jurassic Carbonate Gas Reservoir, Abu Dhabi, United Arab Emirates. Journal of Sedimentary Research. ISSN 1527-1404. 88(12), p. 1345–1361. doi: 10.2110/jsr.2018.70.
• Zhang, Shaomin; Cao, Yingchang; Jahren, Jens; Zhu, Rukai; Mao, Zhiguo & Kelai, XI [Show all 8 contributors for this article] (2018). Pore Characteristics of the Fine-Grained Tight Reservoirs in the Yabulai Basin, Northwestern China. Acta Geologica Sinica. ISSN 1000-9515. 92(3), p. 1170–1192. doi: 10.1111/1755-6724.13598.
• Xi, Kelai; Cao, Yingchang; Liu, Keyu; Jahren, Jens; Zhu, Rukai & Yuan, Guanghui [Show all 7 contributors for this article] (2018). Authigenic minerals related to wettability and their impacts on oil accumulation in tight sandstone reservoirs: An example from the Lower Cretaceous Quantou Formation in the southern Songliao Basin, China. Journal of Asian Earth Sciences. ISSN 1367-9120. doi: 10.1016/j.jseaes.2018.04.025.
• Skurtveit, Elin; Miri, Rohaldin & Hellevang, Helge (2018). Fluid‐Rock Interactions in Clay‐Rich Seals: Impact on Transport and Mechanical Properties. In Vialle, Stéphanie; Ajo-Franklin, Jonathan & Carey, William J. (Ed.), Geological Carbon Storage: Subsurface Seals and Caprock Integrity. American Geophysical Union (AGU). ISSN 9781119118657. p. 167–186. doi: 10.1002/9781119118657.ch8. Full text in Research Archive
• Elenius, Maria; Skurtveit, Elin; Yarushina, Viktoriya M.; Baig, Irfan; Sundal, Anja & Wangen, Magnus [Show all 13 contributors for this article] (2018). Assessment of CO2 storage capacity based on sparse data: Skade Formation. International Journal of Greenhouse Gas Control. ISSN 1750-5836. 79, p. 252–271. doi: 10.1016/j.ijggc.2018.09.004. Full text in Research Archive Show summary

  Large North Sea aquifers of high quality are the likely major target for 12 Gt of European CO2 emissions that should be stored in the subsurface by 2050. This involves an upscaling of the present combined injection rate from all European projects, which requires careful examination of the storage feasibility. Many aquifers are closed or semi-closed, with storage capacity mainly constrained by consideration of caprock failure criteria. Because the induced overpressure can propagate to sensitive regions far from the injector, the risk of caprock failure must be examined in terms of large volumes and for long times. This poses challenges with respect to fluid-flow simulation in the presence of highly uncertain aquifer properties. In this work, experts on geology, geophysics, geomechanics and simulation technique collaborate to optimize the use of existing data in an efficient simulation framework. The workflow is applied to the large North Sea Skade Formation, with potential for secondary storage and pressure dissipation in the overlying Utsira Formation. Injection at three locations in Skade gives an overall practical capacity of 1–6 Gt CO2 injected over a 50-year period, depending on the reservoir permeability and compressibility. The capacity is limited by local pressure buildup around wells for the lowest estimated reservoir permeability, and otherwise by regional pressure buildup in shallow zones far from the injection sites. Local deformation of clay due to viscoelastoplastic effects do not have an impact on leakage from the aquifer, but these effects may modify the properties of clay layers within the aquifer, which reduces the risk of lateral compartmentalization. Uplift of the seafloor does not impose constraints on the capacity beyond those set by pressure buildup.

• Fazeli, Hossein; Patel, Ravi A. & Hellevang, Helge (2018). Effect of Pore-Scale Mineral Spatial Heterogeneity on Chemically Induced Alterations of Fractured Rock: A Lattice Boltzmann Study. Geofluids. ISSN 1468-8115. doi: 10.1155/2018/6046182. Full text in Research Archive Show summary

  Fractures are the main flow path in rocks with very low permeability, and their hydrodynamic properties might change due to interaction with the pore fluid or injected fluid. Existence of minerals with different reactivities and along with their spatial distribution can affect the fracture geometry evolution and correspondingly its physical and hydrodynamic properties such as porosity and permeability. In this work, evolution of a fracture with two different initial spatial mineral heterogeneities is studied using a pore-scale reactive transport lattice Boltzmann method- (LBM-) based model. The previously developed LBM transport solver coupled with IPHREEQC in open-source Yantra has been extended for simulating advective-diffusive reactive transport. Results show that in case of initially mixed structures for mineral assemblage, a degraded zone will form after dissolution of fast-dissolving minerals which creates a resistance to flow in this region. This causes the permeability-porosity relationship to deviate from a power-law behavior. Results show that permeability will reach a steady-state condition which also depends on transport and reaction conditions. In case of initially banded structures, a comb-tooth zone will form and the same behavior as above is observed; however, in this case, permeability is usually less than that of mixed structures

• Nooraiepour, Mohammad; Haile, Beyene Girma & Hellevang, Helge (2018). Rock-physics characterization and geomechanical properties of mudstones rich in siliceous ooze: A case study from the primary caprock for Skade Formation, North Sea, SEG Technical Program Extended Abstract 2018. SEGEAB. ISSN 978-5-8670-8577-3. p. 3724–3728. doi: 10.1190/segam2018-2991324.1.
• Sætre, Christian; Hellevang, Helge; Dennehy, Cleona; Dypvik, Henning & Clark, Samantha (2018). A diagenetic study of intrabasaltic siliciclastics sandstones from the Rosebank field. Marine and Petroleum Geology. ISSN 0264-8172. 98, p. 335–355. doi: 10.1016/j.marpetgeo.2018.08.026.
• Line, Lina Hedvig; Jahren, Jens & Hellevang, Helge (2018). Mechanical compaction in chlorite-coated sandstone reservoirs - Examples from Middle - Late Triassic channels in the southwestern Barents Sea. Marine and Petroleum Geology. ISSN 0264-8172. 96, p. 348–370. doi: 10.1016/j.marpetgeo.2018.05.025. Full text in Research Archive
• Morad, Daniel Jan; Nader, Fadi H.; Gasparrini, Marta; Morad, Sadoon; Rossi, Carlos & Marchionda, Elisabetta [Show all 9 contributors for this article] (2018). Comparison of the diagenetic and reservoir quality evolution between the anticline crest and flank of an Upper Jurassic carbonate gas reservoir, Abu Dhabi, United Arab Emirates. Sedimentary Geology. ISSN 0037-0738. 367, p. 96–113. doi: 10.1016/j.sedgeo.2018.02.008.
• Haile, Beyene Girma; Klausen, Tore Grane; Jahren, Jens; Braathen, Alvar & Hellevang, Helge (2018). Thermal history of a Triassic sedimentary sequence verified by a multi-method approach: Edgeøya, Svalbard, Norway. Basin Research. ISSN 0950-091X. 30(6), p. 1075–1097. doi: 10.1111/bre.12292.
• Haile, Beyene Girma; Klausen, Tore Grane; Czarniecka, Urszula; Xi, Kelai; Jahren, Jens & Hellevang, Helge (2018). How are diagenesis and reservoir quality linked to depositional facies? A deltaic succession, Edgeøya, Svalbard. Marine and Petroleum Geology. ISSN 0264-8172. 92, p. 519–546. doi: 10.1016/j.marpetgeo.2017.11.019.
• Nooraiepour, Mohammad; Fazeli, Hossein; Miri, Rohaldin & Hellevang, Helge (2018). Effect of CO2 phase states and flow rate on salt precipitation in shale caprocks — a microfluidic study. Environmental Science and Technology. ISSN 0013-936X. 52(10), p. 6050–6060. doi: 10.1021/acs.est.8b00251. Full text in Research Archive Show summary

  Fracture networks inside the caprock for CO2 storage reservoirs may serve as leakage pathways. Fluid flow through fractured caprocks and bypass conduits, however, can be restrained or diminished by mineral precipitations. This study investigates precipitation of salt crystals in an artificial fracture network as a function of pressure–temperature conditions and CO2 phase states. The impact of CO2 flow rate on salt precipitation was also studied. The primary research objective was to examine whether salt precipitation can block potential CO2 leakage pathways. In this study, we developed a novel microfluidic high-pressure high-temperature vessel to house geomaterial micromodels. A fracture network was laser-scribed on the organic-rich shales of the Draupne Formation, the primary caprock for the Smeaheia CO2 storage in Norway. Experimental observations demonstrated that CO2 phase states influence the magnitude, distribution, and precipitation patterns of salt accumulations. The CO2 phase states also affect the relationship between injection rate and extent of precipitated salts due to differences in solubility of water in CO2 and density of different CO2 phases. Injection of gaseous CO2 resulted in higher salt precipitation compared to liquid and supercritical CO2. It is shown that micrometer-sized halite crystals have the potential to partially or entirely clog fracture apertures.

• Nooraiepour, Mohammad; Haile, Beyene Girma & Hellevang, Helge (2017). Compaction and mechanical strength of Middle Miocene mudstones in the Norwegian North Sea - the major seal for the Skade CO2 storage reservoir. International Journal of Greenhouse Gas Control. ISSN 1750-5836. 67, p. 49–59. doi: 10.1016/j.ijggc.2017.10.016. Show summary

  This study has investigated petrophysical, acoustic and geomechanical properties of Middle Miocene mudstones in the Norwegian North Sea as the primary caprock for Skade CO2 storage reservoir. To evaluate the seal properties, we analyzed collected drill cuttings and measured well logs from well 16/4-1, in addition to an extensive well log database in the Northern North Sea. The studied caprock was identified as siliceous ooze-rich mudstones with low bulk density, high shear wave velocity, and low Vp/Vs ratio. The abundance of siliceous skeletal material resulted in a significant shift from the overall trend of mudstones within the Hordaland Group. The estimated scenarios for S-wave velocity depicted that the ooze-rich mudstones have the highest brittleness of the Hordaland Group semi-consolidated rocks. The brittleness indices in well 16/4-1 illustrated that the mineralogical composition-based indices significantly overestimate brittleness compared to the elastic-based indices. While the caprock for Skade CO2 storage reservoir showed an overall ductility, the bottom 30 m demonstrated an increased brittleness profile. The more brittle ooze-rich mudstones also indicated the lowest estimation of fracture pressure compared to other scenarios. The research outcomes emphasize on the influence of mudstone type and microstructure on the macroscale physical properties of shallow semi-compacted CO2 caprocks.

• Sundal, Anja; Miri, Rohaldin; Hellevang, Helge; Tveranger, Jan; Midtkandal, Ivar & Zuchuat, Valentin [Show all 8 contributors for this article] (2017). Movement of CO 2 charged fluids in low permeability rocks during deformation: migration patterns in the Carmel Formation, Utah. Energy Procedia. ISSN 1876-6102. 114, p. 4537–4544. doi: 10.1016/j.egypro.2017.03.1570.
• Nooraiepour, Mohammad; Mondol, Nazmul Haque; Hellevang, Helge & Bjørlykke, Knut (2017). Experimental mechanical compaction of reconstituted shale and mudstone aggregates: Investigation of petrophysical and acoustic properties of SW Barents Sea cap rock sequences. Marine and Petroleum Geology. ISSN 0264-8172. 80, p. 265–292. doi: 10.1016/j.marpetgeo.2016.12.003. Show summary

  This study investigates petrophysical and acoustic properties of experimentally compacted reconstituted samples of seal sequences from the southwestern Barents Sea. The aggregates were collected from drill cuttings of mudstone and shale formations of two exploration wells, 7220/10-1 (Salina discovery) and 7122/7-3 (Goliat field). The washed and freeze-dried samples were characterized for grain size distributions, geochemical analyses, and mineralogical compositions. A total of 25 compaction tests (12 dry and 13 brine-saturated) were performed with a maximum effective vertical stress of 50 MPa. The laboratory measurements demonstrated that petrophysical and acoustic properties of argillaceous sediments can change within a sedimentary basin and even within a given formation. The results show that the collected aggregates from Goliat field are compacted more compared to Salina discovery. The maximum and minimum compaction are measured in samples collected from Snadd and Fuglen formations, respectively. The final porosity of brine-saturated specimens varies between 5% and 22%. The ultrasonic velocity measurements depict that samples with the same porosity values can have a broad range of velocity values. The resulting compaction trends in this study were compared to published compaction curves for synthetic mixtures of quartz and clay. All compaction trends show higher porosity reduction than the silt fraction with 100% quartz. Comparison of experimental compaction result of each mudstone and shale aggregate with its corresponding acquired well log data helps to delineate the burial history and exhumation in the study area. A net exhumation of 950 m and 800 m is estimated at Salina and Goliat wells, respectively. The outcomes of this study can provide insights for hydrocarbon prospect discovery in a pre-mature sedimentary basin in terms of exploration and production, and also for geological CO2 storage sites. The experimental results may provide information for well log and seismic interpretation, basin modeling and seal integrity of investigated horizons.

• Hellevang, Helge; Haile, Beyene Girma & Abednego, Tetteh (2017). Experimental study to better understand factors affecting the CO2 mineral trapping potential of basalt. Greenhouse Gases: Science and Technology. ISSN 2152-3878. 7(1), p. 143–157. doi: 10.1002/ghg.1619.
• Ahmad, Nawaz; Anders, Wörman; Xavier, Sanchez-Vila; Jerker, Jarsjö; Andrea, Bottacin-Busolin & Hellevang, Helge (2016). Injection of CO2-saturated brine in geological reservoir: A way to enhanced storage safety. International Journal of Greenhouse Gas Control. ISSN 1750-5836. 54(1), p. 129–144. doi: 10.1016/j.ijggc.2016.08.028.
• Szabo, Zsuzanna; Hellevang, Helge; Kiraly, Csilla; Sendula, Eszter; Kónya, Péter & Falus, György [Show all 8 contributors for this article] (2016). Experimental-modelling geochemical study of potential CCS caprocks in brine and CO2-saturated brine. International Journal of Greenhouse Gas Control. ISSN 1750-5836. 44, p. 262–275. doi: 10.1016/j.ijggc.2015.11.027.
• Xi, Kelai; Cao, Yingchang; Zhu, Rukai; Haile, Beyene Girma & Hellevang, Helge (2016). Evidences of localized CO2-induced diagenesis in the Cretaceous Quantou Formation, southern Songliao Basin, China. International Journal of Greenhouse Gas Control. ISSN 1750-5836. 52, p. 155–174. doi: 10.1016/j.ijggc.2016.07.010.
• Naseryan Moghadam, Javad; Mondol, Nazmul Haque; Aagaard, Per & Hellevang, Helge (2016). Effective stress law for the permeability of clay-bearing sandstones by the Modified Clay Shell model. Greenhouse Gases: Science and Technology. ISSN 2152-3878. 6(6), p. 752 –774. doi: 10.1002/ghg.1612. Show summary

  In this study, the effective stress law for the permeability of two core plugs selected from Berea (Cleveland Quarries, OH, USA) and Knorringfjellet (Longyearbyen, Svalbard, Norway) sandstones is studied experimentally by measuring the core permeability (k) under varying confining stress (σc) and pore pressures (Pp). The obtained results demonstrate that the permeabilities of the two core plugs decrease with increasing σc or decreasing Pp. The effective stress coefficient for the permeability (αk) values are more than 1.0 for both sandstone core plugs indicating higher sensitivity of the permeability with respect to the applied Pp compared to the applied σc. The previously presented models for calculating αk, such as the Clay Free, Clay Shell, and Clay Particle models, are discussed and a new modified Clay Shell model considering spherical geometry is presented to account for the considerable contrast between the elastic moduli of quartz and clay minerals. The discussed models strongly depend on the magnitude of the considered elastic moduli for the clay minerals. While the Clay Shell and Clay Particle models are capable of describing the observed αk values by considering extremely low elastic moduli for clays, the new modified Clay Shell model is capable of predicting αk values by considering moderate to low values of elastic moduli of clays. The increasing trend of αk values by increasing the σc is discussed and a new correlation based on the observed k values for calculation of αk is presented.

• Kirstein, Jens; Hellevang, Helge; Haile, Beyene Girma; Gleixner, Gerd & Gaupp, Reinhard (2016). Experimental determination of natural carbonate rock dissolution rates with a focus on temperature dependency. Geomorphology. ISSN 0169-555X. 261, p. 30–40. doi: 10.1016/j.geomorph.2016.02.019.
• Xi, Kelai; Cao, Yingchang; Haile, Beyene Girma; Zhu, Rukai; Jahren, Jens & Bjørlykke, Knut [Show all 8 contributors for this article] (2016). How does the pore-throat size control the reservoir quality and oiliness of tight sandstones? The case of the Lower Cretaceous Quantou Formation in the southern Songliao Basin, China. Marine and Petroleum Geology. ISSN 0264-8172. 76, p. 1–15. doi: 10.1016/j.marpetgeo.2016.05.001.
• Miri, Rohaldin & Hellevang, Helge (2016). Salt precipitation during CO2 storage - a review. International Journal of Greenhouse Gas Control. ISSN 1750-5836. 51, p. 136–147. doi: 10.1016/j.ijggc.2016.05.015.
• Hellevang, Helge; Haile, Beyene Girma & Miri, Rohaldin (2016). A Statistical Approach to Explain the Solution Stoichiometry Effect on Crystal Growth Rates. Crystal Growth & Design. ISSN 1528-7483. 16(3), p. 1337–1348. doi: 10.1021/acs.cgd.5b01466.
• Naseryan Moghadam, Javad; Mondol, Nazmul Haque; Aagaard, Per & Hellevang, Helge (2016). Experimental investigation of seismic velocity behavior of CO2 saturated sandstones under varying temperature and pressure conditions. Greenhouse Gases: Science and Technology. ISSN 2152-3878. 6(6), p. 734–751. doi: 10.1002/ghg.1603. Show summary

  Subsurface storage of CO2 into geological formations is considered an important strategy to mitigate increasing atmospheric CO2. Time-lapse seismic monitoring is an integral component of a geological CO2 sequestration project because the seismic behavior of the rock is a function of both mineralogical composition and pore fluid properties. At the uppermost kilometer of the sedimentary basin, CO2 can be present at gaseous, liquid, and supercritical states, with the supercritical and liquid states preferred in CO2 storage operations due to the higher sweep efficiency. In this study, the seismic velocities [both compressional (Vp) and shear (Vs) waves] of two CO2-saturated sandstone core plugs (Red Wildmoor and Knorringfjellet formations) have been measured under a range of temperatures and pressures in which CO2 phase transitions occur. The experiments were done using a uniaxial hydrostatic cell equipped with seismic wave transmitting and receiving transducers. The experimental investigation illustrated that seismic velocities (both Vp and Vs) decreased until the critical point was reached. Further increases in the CO2 pressure above the critical point led to a gradual increasing of Vp while the Vs remained unchanged. The effect of CO2 on the seismic velocity of the sandstone was compared with the effects of N2 and distilled water at the same conditions. It was further indicated that the seismic velocity changes were mainly connected to significant changes of CO2 density and the corresponding bulk rock moduli over the critical point. The observed velocities are in good agreement with Gassmann-predicted velocities as well as literature data.

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• Masoudi, Mohammad; Fazeli, Hossein; Miri, Rohaldin & Hellevang, Helge (2021). Toward Probabilistic Modeling of Halite Nucleation and Growth during Carbon Storage Process: Pore Scale Modeling .
• Masoudi, Mohammad; Parvin, Saeed; Miri, Rohaldin; Kord, Shahin & Hellevang, Helge (2021). Implementation of PC-SAFT Equation of State into MRST Compositional for Modelling of Asphaltene Precipitation.
• Sundal, Anja; Meneguolo, Renata & Hellevang, Helge (2021). CO2 storage – dynamic trapping mechanisms due to mineralization. .
• Ahmadigoltapeh, Sajjad; Abdolahi, Saeed; Miri, Rohaldin & Hellevang, Helge (2021). Extension of SAFT equation of state to include calcite wall effect in water properties within water-calcite interface using molecular dynamic simulations.
• Sundal, Anja; Meneguolo, Renata; Kruber, Claudia; Olsen, Elin & Hellevang, Helge (2021). Geological site assessment: geochemical review of the Aurora Storage Complex, Northern Lights project, North Sea.
• Nooraiepour, Mohammad & Hellevang, Helge (2021). Reactive transport and geometry evolution of the porous medium: A geochemical perspective.
• Masoudi, Mohammad; Nooraiepour, Mohammad; Berntsen, Andreas Nicolas & Hellevang, Helge (2021). How to bridge between different time and length scales using a new probabilistic approach for mineral nucleation and growth.
• Masoudi, Mohammad; Nooraiepour, Mohammad; Berntsen, Andreas Nicolas & Hellevang, Helge (2021). A new probabilistic nucleation model to predict crystal growth in porous medium.
• Nooraiepour, Mohammad; Masoudi, Mohammad; Fazeli, Hossein & Hellevang, Helge (2021). Geometry evolution and fracture alteration controlled by spatial mineral heterogeneity during CO2 sequestration -A reactive transport study.
• Haile, Beyene Girma; Line, Lina Hedvig; Klausen, Tore Grane; Olaussen, Snorre; Eide, Christian Haug & Jahren, Jens [Show all 7 contributors for this article] (2021). Identifying and constraining sedimentary recycling from microscopic fluid inclusions in quartz overgrowth.
• Hellevang, Helge; Nooraiepour, Mohammad; Masoudi, Mohammad & Fazeli, Hossein (2020). Statistical Model for Mineral Nucleation and Growth.
• Masoudi, Mohammad; Fazeli, Hossein; Miri, Rohaldin & Hellevang, Helge (2020). Probabilistic Modeling of Halite Nucleation and Growth in Porous Media: Pore Scale Modeling.
• Masoudi, Mohammad; Parvin, Saeed; Miri, Rohaldin & Hellevang, Helge (2020). Implementation of ePc-SAFT Equation of State into MRST Compositional for Modelling of Salt Precipitation during CO2 Storage in Saline Aquifers.
• Weber, Ulrich Wolfgang; Sundal, Anja; Hellevang, Helge & Kipfer, Rolf (2020). Experiences from the ICO2P Project applied to Migration Monitoring of Injected CO2.
• 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 .
• Nooraiepour, Mohammad; Fazeli, Hossein; Miri, Rohaldin & Hellevang, Helge (2019). Formation dry-out and salt precipitation in porous and fractured media: Laboratory insights on physics and dynamics of CO2-induced halite accumulations.
• Hellevang, Helge; Nooraiepour, Mohammad & Fazeli, Hossein (2018). CO2-H2O-basalt interactions – reactive transport experiments and simulations .
• Nooraiepour, Mohammad; Soldal, Magnus; Park, Joonsang; Mondol, Nazmul Haque; Hellevang, Helge & Bohloli, Bahman (2018). Geophysical Monitoring of Gaseous and Supercritical CO2 Fracture Flow Through a Brine-Saturated Shale Caprock.
• Nooraiepour, Mohammad; Fazeli, Hossein; Miri, Rohaldin & Hellevang, Helge (2018). Salt Precipitation During Injection of CO2 into Saline Aquifers: Lab-on-Chip Experiments on Glass and Geomaterial Microfluidic Specimens.
• Nooraiepour, Mohammad; Fazeli, Hossein & Hellevang, Helge (2018). Brine-CO2-Rock Geochemical Interactions: A novel HPHT microfluidic pressure vessel for lab-on-chip investigations.
• Sacco, Tatiana; Sundal, Anja & Hellevang, Helge (2018). Mass estimation of CO2 trapping potential in the Smeaheia reservoir.
• 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).
• Gasda, Sarah; Elenius, Maria; Skurtveit, Elin; Sundal, Anja; Yarushina, Viktoriya M. & Baig, Irfan [Show all 13 contributors for this article] (2018). Skade Case Study.
• Nooraiepour, Mohammad; Hellevang, Helge & Mondol, Nazmul Haque (2018). From field-scale to pore-scale: Investigation of caprock properties for CO2 sequestration.
• Nooraiepour, Mohammad; Fazeli, Hossein; Miri, Rohaldin & Hellevang, Helge (2018). Geomaterial microfluidic experiment at reservoir conditions: Insights on salt precipitation in fractured shale caprocks during CO2 injection. Show summary

  In this study, we have developed a novel microfluidic high-pressure high-temperature vessel to house geomaterial (natural rock or mineral chips) micromodel specimens. Realistic fracture patterns were laser-scribed on the organic-rich shales of Draupne Formation, the primary caprock for the Smeaheia CO2 storage site (the full-scale CCS project) in Norway. The primary research objective was to examine salt precipitation in fracture networks of shale during CO2 injection under different thermodynamic conditions and for various CO2 phase states to investigate whether authigenic precipitation of salt crystals can partially or entirely block potential CO2 leakage pathways in caprocks. Moreover, the impact of CO2 injection flow rate on the extent of salt accumulations was studied. A conceptual framework was introduced that suggests salt precipitation may be not only a near-well phenomenon but also a sealing mechanism that can impede CO2 leakage. We observed that salt crystals precipitate in two distinct forms: (a) large and semi-large single cubic crystals of halite in the aqueous phase, and (b) dense porous aggregates of micrometer-sized halite crystals that form on the interface of rock and CO2 stream. Experimental observations demonstrated that injection of different CO2 phase states affects the magnitude, distribution and salt precipitation patterns. Analysis of the fracture network after complete drying of shale specimen showed that the higher the injection flow rate, the lower the salt coverage. Three drying regimes (diffusive, capillary and evaporative) governed precipitation of salt crystals through stabilized capillary and evaporative fluxes. The CO2 phase states influence the relationship between injection rate and extent of precipitated salts. A higher impact of the rate on salt coverage was found for supercritical- compared to gaseous CO2. Reducing injection flow rate caused the initial salt nuclei to form closer to the inlet and from there toward different branches of fracture pattern. It is shown that bulk and dense aggregates of micrometer-sized halite crystals, that precipitate on the interface of fracture walls and CO2 stream, has the potential to partly or entirely block the fracture aperture and consequently leakage pathways. The development of salt crystals toward the point where leakage begins, the affinity of salt bodies to become connected, and extent of accumulations suggest that the salt precipitation during injection of CO2 into the geologic formations can be considered as a fracture healing mechanism.

• Line, Lina Hedvig; Jahren, Jens & Hellevang, Helge (2017). Diagenesis and Reservoir quality of Anisian and Carnian channels in the southwestern Barents Sea.
• Elenius, Maria; Hellevang, Helge; Skurtveit, Elin; Yurushina, Viktoriya; Baig, Irfan & Sundal, Anja [Show all 12 contributors for this article] (2017). Workflow for evaluation of large-scale CO2 storage feasibility: Skade.
• Elenius, Maria; Hellevang, Helge; Skurtveit, Elin; Yurushina, Viktoriya; Baig, Irfan & Sundal, Anja [Show all 12 contributors for this article] (2017). Storage feasibility in North Sea aquifers.
• Elenius, Maria; Hellevang, Helge; Skurtveit, Elin; Yurushina, Viktoriya; Baig, Irfan & Sundal, Anja [Show all 12 contributors for this article] (2017). Workflow for assessment of storage based on sparse data: Skade.
• Line, Lina Hedvig; Jahren, Jens & Hellevang, Helge (2017). Diagenesis and Reservoir Quality of Anisian and Carnian channels in the southwestern Barents Sea.
• Haile, Beyene Girma; Klausen, Tore Grane; Czarniecka, Urszula; Xi, Kelai; Jahren, Jens & Braathen, Alvar [Show all 7 contributors for this article] (2017). Diagenesis of Upper Triassic sandstones, Edgeøya, Svalbard.
• Nooraiepour, Mohammad; Fazeli, Hossein & Hellevang, Helge (2017). Effect of CO2 phase state and flow rate on salt formation in shale caprocks – a microfluidics study.
• Zuchuat, Valentin; Midtkandal, Ivar; Braathen, Alvar; Sundal, Anja; Skurtveit, Elin & Hellevang, Helge [Show all 9 contributors for this article] (2017). COPASS - CO2 seal bypass.
• Bjørlykke, Knut; Jahren, Jens; Mondol, Nazmul Haque; Hellevang, Helge & Aagaard, Per (2017). Mechanical compaction of sand and clay: Constraints from experimental compaction, chemical reactions and fluid flow during burial-An overview.
• Moghadam, Javad Naseryan; Mondol, Nazmul Haque; Aagaard, Per & Hellevang, Helge (2017). Determination of CO2-Brine relative permeability curves for CO2 storage sandstone reservoirs.
• Line, Lina Hedvig; Jahren, Jens & Hellevang, Helge (2017). Reservoir characterization of Triassic sandstones in the southwestern Barents Sea.
• Haile, Beyene Girma; Jahren, Jens & Hellevang, Helge (2017). New insights about thermally driven diagenetic changes due to the emplacement of magmatic sills into reservoir sediments at Wilhelmøya (Svalbard): Implications for reservoir quality.
• Sundal, Anja; Miri, Rohaldin; Hellevang, Helge; Tveranger, Jan; Midtkandal, Ivar & Zuchuat, Valentin [Show all 7 contributors for this article] (2016). Movement of CO2 charged fluids in low permeability rocks during deformation: migration patterns in the Carmel Formation, Utah.
• Sætre, Christian; Dypvik, Henning & Hellevang, Helge (2016). Basaltic glass alteration and its reservoir importance.
• Sundal, Anja; Petrie, Elizabeth; Hellevang, Helge; Midtkandal, Ivar & Braathen, Alvar (2016). REACTIVE FLUID EXPULSION DURING PROGRESSIVE DEFORMATION IN THE FOLD LIMB OF THE SAN RAFAEL SWELL, UTAH, USA. Show summary

  A series of reaction fronts radiating from fractures are observed in the Navajo Formation in the eastern flank of the San Rafael Swell (monocline structure) in central Utah, USA. Mobilization of metals by reducing fluids and reprecipitation of oxides may be linked to the structural deformation history and the successive opening and closing of fractures and faults, facilitating pumping of fluids. In the field area the Navajo Formation comprises crossbedded sandstone units interpreted as sand dunes deposited in an aeolian environment during early Jurassic. During the Laramide orogeny the sedimentary succession of Jurassic sandstones and mudstones were uplifted and folded over NS striking underlying faults. Later uplift and erosion has exposed the section and the geology may be investigated in numerous cross cutting gullies. Relict plumes sourced from in between bedding surfaces and from fractures are observed at the field locality as successive reaction fronts where oxides have precipitated and formed solid rims, interpreted as resulting from pressure driven intrusion of reducing fluids. Dendritic growth of Mnoxides is observed from solid precipitation fronts, indicating that diffusiondriven transport succeeds advection and carry large mass fractions. Numerous deformation bands in six directional populations are observed to both obstruct and allow fluid migration between generations of expulsion events. The latest generation of fractures is roughly perpendicular to the regional foldaxis, displaces reaction fronts and deformation bands, and do not appear to expel fluids before becoming completely sealed by oxide precipitates, quartz and carbonate. Thus it appears that the bulk part of advective and diffusive mass transfer took place during the earlier stages of deformation. Understanding these processes is of importance in reservoirseal characterization for CO2 storage, as leakage and reactive transport may be quantified in relation to deformation type and force.

• Haile, Beyene Girma; Klausen, Tore Grane; Hellevang, Helge; Jahren, Jens & Bjørlykke, Knut (2016). Burial diagenesis of De Geerdalen Formation control by depositional facies distribution, Edgeøya, Svalbard.
• Elenius, Maria; Sundal, Anja; Gasda, Sarah; Aavatsmark, Ivar; Hellevang, Helge & Hermanrud, Christian [Show all 8 contributors for this article] (2018). Storage Capability [FME SUCCESS Synthesis report Volume 1]. SUCCESS [Christian Michelsen Research AS].
• Miri, Rohaldin; Hellevang, Helge; Aagaard, Per; Kvamme, Bjørn; Skurtveit, Elin & Wangen, Magnus (2018). Critical Factors for Considering CO2 Injectivity in Saline Aquifers [FME SUCCESS Synthesis report Volume 3]. SUCCESS [Christian Michelsen Research AS].
• Yarushina, Viktoriya M.; Van Noort, Reinier; Wangen, Magnus; Skurtveit, Elin; Hermanrud, Christian & Hellevang, Helge [Show all 8 contributors for this article] (2018). Potential leakage mechanisms and their relevance to CO2 storage site risk assessment and safe operations [FME SUCCESS Synthesis report Volume 2] . SUCCESS [Christian Michelsen Research AS].
• Sundal, Anja; Hellevang, Helge & Sacco, Tatiana (2018). CO2 trapping in the Smeaheia reservoir - time mass estimation using geochemical models. University of Oslo.
• Haile, Beyene Girma; Hellevang, Helge & Jahren, Jens (2018). Reservoir quality of the Upper Triassic to Lower Jurassic sediments, NW Barents Shelf. Understanding porosity evolution through diagenesis and sedimentology. Universitetet i Oslo. ISSN 1501-7710.

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