Helge Hellevang

• Masoudi, Mohammad; Hassanpouryouzband, Aliakbar; Hellevang, Helge & Haszeldine, R. Stuart (2024). Lined rock caverns: A hydrogen storage solution. Journal of Energy Storage. ISSN 2352-152X. 84. doi: 10.1016/j.est.2024.110927.
• Nooraiepour, Mohammad; Polanski, Krzysztof; Masoudi, Mohammad; Kuczyński, Szymon; Derluyn, Hannelore & Parreiras Nogueira, Liebert [Vis alle 9 forfattere av denne artikkelen] (2024). Assessing salt precipitation and weak acid interaction in subsurface CO2 injection: Potential 50% strength decline in near-wellbore reservoir sandstones. arXiv. doi: 10.48550/arXiv.2401.14852. Vis sammendrag

  Predictive modeling of CO2 storage sites requires a detailed understanding of physico-chemical processes and potential challenges for scale-up. Dramatic injectivity decline may occur due to salt precipitation pore clogging in high-salinity reservoirs, even over a short time frame. This study aims to elucidate the adverse impact of CO2-induced salt crystallization in porous media on the geomechanical properties of near-wellbore reservoir sandstones. As the impact of salt precipitation cannot be isolated from the precursor effects of interaction with CO2 and carbonic acid, we initiated our study by a comprehensive review of CO2 chemo-mechanical interactions with sandstones. We conducted laboratory geochemical CO2-brine-rock interactions at elevated pressures and temperatures on two sets of porous sandstone with contrasting petrophysical qualities. Two paths were followed: treatment with (a) CO2-acidified brine at 10 MPa fluid pressure and 60C for 7 days, and a second subset continuation with (b) supercritical injection until complete dry-out and salt precipitation. Afterward, the core samples were tested in a triaxial apparatus at varying stresses and temperatures. The elastic moduli of intact, CO2-reacted, and salt-damaged sandstones were juxtaposed to elucidate the extent of crystallization damages. The salt-affected specimens showed a maximum of 50 percent reduction in Young's and shear moduli and twice an increase in Poisson's ratio compared to intact condition. The deterioration was notably higher for the tighter rocks with higher initial stiffness.

• Masoudi, Mohammad; Nooraiepour, Mohammad; Deng, Hang & Hellevang, Helge (2024). Mineral precipitation and geometry alteration in porous structures: How to upscale variations in permeability-porosity relationship? EarthArXiv preprint platform. doi: 10.31223/X56Q41. Vis sammendrag

  Porous materials in natural and engineered environments are subject to morphological changes resulting from interacting chemical and physical processes. The complexity of coupled flow, transport, and chemical processes that occur on different temporal and spatial scales makes it difficult to predict the resulting porosity and permeability alterations. Delineating the controls of mineral precipitation reactions is particularly challenging because it requires the implementation of nucleation criteria and precipitation attributes. By conducting pore-scale simulations, we studied how the amount and stochastic distribution of crystallites, controlled by nucleation, affect the pore geometry and permeability in two-dimensional porous structures. The observed relationships between porosity and permeability show characteristics that differ from ones that are typically applicable in dissolving porous media because of the clogging effect. Additionally, we propose a stochastic framework that upscales the co-evolution of permeability and porosity across length scales. This framework enables precise communication of clogging behavior to continuum-scale simulations based on statistical probability distributions of permeability-porosity variations.

• Masoudi, Mohammad; Nooraiepour, Mohammad & Hellevang, Helge (2023). Salt Precipitation during Geological CO2 Storage: Effect of Access to Continuous Brine Source. EarthArXiv preprint platform. doi: 10.31223/X5J68G. Vis sammendrag

  During CO2 storage, the near-wellbore environment experiences significant chemical, physical, thermal, and mechanical perturbations. Therefore, it is crucial to characterize the coupled thermo-hydro-mechanical-chemical (THMC) processes in this region through representative experimental tests and numerical simulations to maximize the safety and cost-efficiency of CO2 storage. One common shortcoming of current experimental methods is failing to facilitate access and replicate the in-situ brine sources within geological repositories, particularly saline aquifers. This failure can significantly alter the dynamics and dimensionality of mineral/crystal growth in porous reservoir rocks due to the availability and continuity of solute. To address this issue, we designed surface mineral precipitation tests and large-scale sandbox experiments to investigate salt precipitation and growth under two different scales and regimes in porous geometries. The laboratory results indicated massive salt accumulation close to the injection port and underlined the effect of solute availability and continuity on intensifying severity of salt accumulation. The observed continued growth highlights the importance of designing representative laboratory experiments in exploring fluid-rock interactions during carbon sequestration in the subsurface geological media.

• Nooraiepour, Mohammad; Masoudi, Mohammad & Hellevang, Helge (2023). Experimental and Numerical Description of Mineral Precipitation Dynamics on Heterogeneous Substrate Surfaces. EarthArXiv preprint platform. doi: 10.31223/X5SQ49. Vis sammendrag

  Mineral precipitation reactions are critical in reactive transport studies of porous media due to their significant impacts on flow and transport properties. Understanding the nucleation process, a probabilistic phenomenon that determines the location and distribution of solid formation in space and time domains, is essential for accurately comprehending the effect of mineral precipitation on porous media surfaces. To this end, this paper presents microfluidic laboratory experiments and reactive transport modeling of mineral precipitation dynamics under different physicochemical conditions and substrate surface properties. Our results demonstrate the importance of the spatial and temporal location and distribution of nucleation and growth events when the interplay among several determining parameters is inevitable. We show mineral precipitation on primary and secondary substrate surfaces under different supersaturations and temperatures. Our high-resolution EDS-SEM surface maps identify the favorable sites and competing locations for attracting solute concentration and continued growth, providing valuable insights into the mineral precipitation mechanism.

• Hellevang, Helge; Ippach, Mats Rouven; Westermann, Sebastian & Nooraiepour, Mohammad (2023). Formation of giant Siberian gas emission craters (GECs). EarthArXiv preprint platform. doi: 10.31223/X59Q3K. Vis sammendrag

  The recent discovery of eight giant gas escape craters (GECs) in the Russian Yamal and Gydan peninsulas has challenged researchers for the past decade. Despite numerous proposed models, ranging from meteor impacts to gas explosions, none provide a comprehensive explanation for why the GECs are found only in this specific region. This study proposes a new general model for the formation of GECs in which local permafrost thinning is linked to the local geology, i.e., discrete conductive faults bring natural gas and heat to the base permafrost, deforming and melting the base leading to the development of domal gas and heat traps. Atmospheric warming results in further local thinning and eventually mechanical collapse. The morphology of the GECs initially reflects the concentric deformation above domal base-permafrost structures but are after a short time disguised by water and sediment infill, and over time peatification, and cannot be distinguished from e.g., thermokarst lakes. Thus, the true number of GECs may largely exceed those already discovered.

• Hellevang, Helge; Nooraiepour, Mohammad & Masoudi, Mohammad (2023). Mineral nucleation and growth in porous and fractured media. Goldschmidt Conference Abstracts. Vis sammendrag

  Early simulation works on carbonization during CO2 storage overpredicted the amount and rate of mineral formation because of unrealistic growth models based on transition state theory (TST), where surface areas for growth were assumed to be present from day one. Inspired by [1], we made our first nucleation-growth model a decade ago [2], providing a zero-dimensional averaged kinetic nucleation-growth model for the continuum scale. This model provided some information on lag time for the onset of mineral growth, which is essential to understand why the lack of mineralization in short-term laboratory experiments cannot be extrapolated in time. The continuum-scale models, however, lack the potential to predict how the pore space geometries change and, thereby, how the permeability-porosity relationship changes in complex ways. Recent efforts have been to implement mineral nucleation and crystal growth in pore-scale models, using classical nucleation theory (CNT) and statistically derived expressions for the induction time of the formation of stable growing crystallites. In the new expressions, the probability of creating a crystallite at each surface site (solid surface area in the pore space) is estimated based on a normal distribution centered around the mean induction time value [τ] (symmetric between t= 0 and 2τ). This has been implemented and tested in 2D pore-scale models, showing strong mutual relations and impacts of transport and crystallization in porous media [3-4]. Another emerging field for nucleation-growth research is how the number of crystallites (or aggregates) and their spatial distribution control the evolution of porosity-permeability relations. 2D nucleation-growth Monte Carlo-type pore-scale RTMs show that the permeability-porosity relationship and the associated uncertainty depend on the number of crystallites (Figs. 1, 2). The relationship evolves predictably if the number of crystallites is small or large. If, on the other hand, the number of crystals is in an intermediate range, the permeability-porosity dynamics vary stochastically and are highly uncertain.

• Nooraiepour, Mohammad; Masoudi, Mohammad & Hellevang, Helge (2023). Nucleation and Crystal Growth on the Secondary Substrate. I Médici, Ezequiel F. & Otero, Alejandro D. (Red.), Album of Porous Media. Springer. ISSN 978-3-031-23800-0. doi: 10.1007/978-3-031-23800-0_14.
• Zając, Michał; Nagy, Stanisław; Kuczyński, Szymon; Dabrowski, Karol M.; Smulski, Rafal & Hellevang, Helge [Vis alle 8 forfattere av denne artikkelen] (2023). Multicomponent and multiphase CO2-brine system in microfluidic characterised in situ by Raman spectroscopy, 84th EAGE Conference & Exhibition 2023. European Association of Geoscientists and Engineers (EAGE). ISSN 000-0-00-000000-0. doi: 10.3997/2214-4609.2023101024. Vis sammendrag

  Deep-saline aquifers could be instrumental in the geological storage of carbon dioxide due to their relatively good reservoir properties, high volume, and prevalence. However, there are a few difficulties which should be overcome to obtain effective stores in such reservoirs. Most problems are related to formation damage caused by salt precipitation. Due to the complexity of such systems, it is necessary to identify crucial processes, phenomena, factors, and products. In our work, we present a novel platform to trace precipitation ‘in situ’ using microfluidics and Raman spectroscopy. We have built a set in which we can investigate not only the salt deposition phenomenon in pores or microchannels by visual observation but also, because of Raman spectroscopy, determine the kinetics of reactions, carbon dioxide solubility, phase composition, and crystal composition. On the basis of our research, we have identified intensive clogging of pores and fast growth of crystals on the rock-like grain boundaries and bottlenecks. Furthermore, in a 20% weight NaCl solution we have found precipitated carbonates, for example, nitrate. Our results can broaden our understanding of CCS in high-saline aquifers and contribute to the development and common use of this process.

• Nooraiepour, Mohammad; Masoudi, Mohammad; Hellevang, Helge; Dąbrowski, Karol; Kuczyński, Szymon & Zając, Michał [Vis alle 8 forfattere av denne artikkelen] (2023). Why is it critical to revisit significance and consequences of salt precipitation during CO2 injection? 84th EAGE Conference & Exhibition 2023. European Association of Geoscientists and Engineers (EAGE). ISSN 000-0-00-000000-0. doi: 10.3997/2214-4609.2023101162. Vis sammendrag

  Among the candidates for CO2 sequestration, deep saline aquifers are considered the best option because of their storage capacity and proximity to emission sources. Injection of large volumes (million tons scale) of supercritical CO2 into the geological formations causes evaporation of formation water near wellbores and precipitation of salt crystals inside the porous medium. CO2-induced salt precipitation can substantially threaten sequestration in saline aquifers. Most available experimental, numerical and theoretical works have focused on predicting the salt's location and amount. However, less attention is given to the precipitation physics, growth dynamics, and behavior of the fluid-solid interface near the evaporation/precipitation front. We report a series of experiments to provide new insights, beyond the current understanding, into the dynamics of brine evaporation and salt growth and to challenge the current understanding that might not be entirely representative of the field conditions. The research outcome highlights the interplay of complex processes (some of which are not yet fully characterized) crucial in investigating salt precipitation induced by million-tons-scale CO2 injection. The observed characteristics call for further in-depth investigation because, in the context of subsurface CO2 storage, we need to redefine how we see injectivity impairment due to salt precipitation.

• Ma, Pengjie; Lin, Chengyan; Dong, Chunmei; Ren, Lihua; Jahren, Jens & Hellevang, Helge [Vis alle 7 forfattere av denne artikkelen] (2023). Effect of faulting on diagenetic processes in the silicate-sulfate-carbonate system: A case study from the Bonan Sag of Jiyang Depression, Bohai Bay Basin. Marine and Petroleum Geology. ISSN 0264-8172. 147. doi: 10.1016/j.marpetgeo.2022.105985.
• Nooraiepour, Mohammad; Masoudi, Mohammad; Shokri, Nima & Hellevang, Helge (2022). Precipitation-induced Geometry Evolution in Porous Media: Numerical and Experimental Insights based on New Model on Probabilistic Nucleation and Mineral Growth. 16th Greenhouse Gas Control Technologies Conference 2022 (GHGT-16). doi: 10.2139/ssrn.4272555. Fulltekst i vitenarkiv Vis sammendrag

  Precipitation and growth of solid phases during a reactive fluid flow and solute transport are critical in many natural and industrial systems. Mineral nucleation and growth is a prime example where (geo)chemical reactions give rise to geometry evolution in porous media. The precipitation reactions can reduce the amount of void space, alter pore space connectivity and morphology, modify tortuosity, deteriorate permeability, and change the fluid flow and solute transport. Additionally, precipitation events reshape the available surface area for growth, leading to changes in reactivity, reaction progress, and reaction rates. The target is to ideally limit the mineral growth in many applications, such as avoiding damage to reservoir permeability due to solid precipitation near CO2 injection wells. In other cases, maximizing mineral growth in porous media can be highly favorable, such as sealing fractured caprocks or increasing mineral trapping in the sequestration sites. Understanding, controlling, and predicting this reactive transport phenomenon is challenging because it requires coupling flow, transport, and chemical processes often characterized by different temporal and spatial resolutions. Nucleation is the pre-growth process that controls the primary position of any mineral precipitation and subsequent growth dynamics. Mineral nucleation is a probabilistic process where crystals might nucleate anywhere given similar conditions, such as surface properties, supersaturation, and temperature. It is imperative to use a probabilistic approach or an upscaled physically sound representation to understand the effect of mineral precipitation on porous medium hydrodynamics. Motivated by the importance of incorporating stochastic dynamics of nucleation and growth kinetics in studying various multiphase and multiscale processes occurring in geo-environmental and geo-energy systems, this paper provides numerical and experimental insights into the recently proposed probabilistic nucleation model. We present laboratory experiments (microfluidic and flow-through column reactor) and pore-scale reactive Lattice Boltzmann Method (LBM) numerical simulations. As variations in the properties of the porous medium are intimately linked to the spatial distribution of the precipitation events, we quantify the evolution of experimental and numerical modeled systems at different physiochemical conditions by mapping the disorder of the system (Shannon's entropy) induced by the spatial mineral distributions across time. We use experimental and numerical results to show the importance of the spatial and temporal location and distribution of nucleation and growth events, particularly when the interplay among several determining parameters is inevitable. The results show that probabilistic nucleation contributes to broad stochastic distributions in both amounts and locations of crystals in temporal and spatial domains.

• Ahmadigoltapeh, Sajjad; Rahman, Md Jamilur; Mondol, Nazmul Haque & Hellevang, Helge (2022). Artificial Neural Network-Based Caprock Structural Reliability Analysis for CO2 Injection Site—An Example from Northern North Sea. Energies. ISSN 1996-1073. 15(9). doi: 10.3390/en15093365. Fulltekst i vitenarkiv
• Ahmadigoltapeh, Sajjad; Abdolahi, Saeed; Jahren, Jens; Miri, Rohaldin & Hellevang, Helge (2022). Drivers of Low Salinity Effect in Carbonate Reservoirs Using Molecular Dynamic Simulation. Journal of Molecular Liquids. ISSN 0167-7322. 360. doi: 10.1016/j.molliq.2022.119490. Fulltekst i vitenarkiv
• Masoudi, Mohammad; Nooraiepour, Mohammad & Hellevang, Helge (2022). The Effect of Preferential Nucleation Sites on the Distribution of Secondary Mineral Precipitates, 83rd EAGE Annual Conference & Exhibition 2022. European Association of Geoscientists and Engineers (EAGE). ISSN 978-90-73834-12-5. doi: 10.3997/2214-4609.202210445. Vis sammendrag

  In the process of mineral nucleation and growth, substrate surface properties and substrate types introduce favorable areas where nucleation events are more likely to occur. The preferential sites for mineral nucleation exist because of the lower interfacial free energy between the precipitating phase and the substrate. In this work, we used a pore-scale Lattice Boltzmann (LB)-based reactive transport model incorporated with the developed probabilistic nucleation model in our previous works to investigate the role of the interfacial free energy between the nucleating phase and the substrate on the nucleation and growth of secondary minerals. We also used Shannon entropy to assess the spatial randomness and the evolution path of the systems as solid phases form. The results showed that the developed model can accurately capture the selective behavior of nucleation processes in the presence of preferential sites. The simulation results demonstrate the importance of using a probabilistic nucleation model to capture the correct physics of this phenomenon. It is also concluded that the probabilistic nucleation models are more relevant in environments with longer induction times.

• Nooraiepour, Mohammad; Masoudi, Mohammad & Hellevang, Helge (2022). Precipitation-Induced Geometry Evolution During Reactive Transport: Experimental and Numerical Insights into Stochastic Dynamics of Mineral Growth, 83rd EAGE Annual Conference & Exhibition 2022. European Association of Geoscientists and Engineers (EAGE). ISSN 978-90-73834-12-5. doi: 10.3997/2214-4609.202210470. Vis sammendrag

  Crystal nucleation, precipitation, and growth during a reactive fluid flow and solute transport are critical in many natural and industrial systems. Mineral growth is a prime example where (geo)chemical reactions give rise to geometry evolution in porous media. Motivated by the importance of incorporating stochastic dynamics of nucleation, crystallization, and growth kinetics in studying a variety of multiphase and multiscale processes occurring in geo-environmental and geo-energy systems, this work presents experimental and numerical results delineating geometry evolution induced by mineral precipitation. A total of 27 microfluidic experiments (3×3×3 sets of supersaturation-temperature-time) extend the understanding of factors controlling crystal nucleation and growth rates, the impact of ambient and aqueous phase properties, and the substrate characteristics. For numerical simulations, we used the Lattice Boltzmann Method (LBM) to solve the advection-diffusion-reaction equation for tracking the concentration of different species. We developed a reactive transport model based on our recently proposed probabilistic nucleation and crystal growth theory. The results indicated the probabilistic nature of the process, which is affected by the physiochemistry of the aqueous phase and governed by fluid-solid surface interactions. We underscore the importance of theoretical reactive transport models considering the probabilistic nature of nucleation events before crystal formation.

• Masoudi, Mohammad; Sundal, Anja & Hellevang, Helge (2021). Estimation of Mutual Solubility of CO2-H2O in Saline Aquifer Systems Using ePC-SAFT Equation of State. I Røkke, Nils Anders & Knuutila, Hanna K (Red.), TCCS–11. CO2 Capture, Transport and Storage. Trondheim 22nd–23rd June 2021. Short Papers from the 11th International Trondheim CCS Conference. SINTEF akademisk forlag. ISSN 978-82-536-1714-5.
• Nooraiepour, Mohammad; Fazeli, Hossein; Masoudi, Mohammad & Hellevang, Helge (2021). Effect of Mineral Heterogeneity on Fracture Dissolution in Carbonate-Rich Caprocks During Subsurface Co2 Injection. I SPE, , (Red.), SPE Europec featured at 82nd EAGE conference and exhibition, October 18-21, 2021, Amsterdam, The Netherlands. Society of Petroleum Engineers. ISSN 9781613997918. doi: 10.3997/2214-4609.202011174. Vis sammendrag

  Chemical interactions between CO2, brine and caprock-forming minerals might lead to the 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 fine-grained shale sample, which showed no detectable fracture alteration. However, the effluent analysis for the shale sample confirmed the calcite dissolution.

• 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. Vis sammendrag

  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 [Vis alle 10 forfattere av denne artikkelen] (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. Fulltekst i vitenarkiv
• 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. Fulltekst i vitenarkiv Vis sammendrag

  Confined fluids in nano-mineral pores show notably different thermodynamic behavior compared with those of the same fluid in bulk. We have extended an equation of state (EoS) inspired by statistical association fluid theory (SAFT) to incorporate the fluid-mineral effect into the pure fluid properties confined in the nanopore. The established EoS is coupled with a Helmholtz free energy contribution which is a function of confinement characteristics: the potential of fluid-mineral interaction, bulk-like density and CF. The novel fitting parameter CF relies on the local properties of confined fluid and measures the density fraction within the layering and bulk-like zones, i.e., . The first-principle molecular dynamics (MD) simulation was utilized to estimate the confinement parameters. At T = 300 K, 350 K, 400 K, and 450 K, the NVT ensemble was applied to simulate slit-pore calcite with a continuous and homogeneous surface in contact with water, with pore widths ranging from 1.5 nm to 5 nm. After running each NVT ensemble for 6 ns, the energy and density of confined water were analyzed, and a deviation was discovered with different behavior from what had previously been reported. Coupling CF parameter with proposed EoS improves the absolute relative errors (ARE) at low temperatures up about 50%, leading to a good agreement between modified SAFT EoS and MD results. The methodology described here may be extended to include a mixture of associating fluids such as those found in oil composition and implemented in all SAFT versions.

• 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, s. 27–31. doi: 10.7185/geochemlet.2130. Fulltekst i vitenarkiv
• 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), s. 28072–28083. doi: 10.1021/acsomega.1c04147. Fulltekst i vitenarkiv
• 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. Fulltekst i vitenarkiv Vis sammendrag

  In the vicinity of fluid-mineral interfaces a transition zone exist in which the order and packing of the molecules differ from that of the bulk phase where the distribution of intermolecular forces exhibit a more homogenous form. To develop an understanding of the thermodynamic properties in the fluid-mineral interface molecular dynamic (MD) simulation was conducted for the water-calcite system. To predict the water properties near the calcite wall, we have defined a contribution for Helmholtz energy extended from PC-SAFT equation of state (EOS). The new energy contribution depends on the confinement parameters i.e. potential of fluid-wall interaction, confinement degree, bulk density, and fraction of confined molecules estimated by MD simulation. The outcomes of MD simulation exhibit the layering transition of water on the water-calcite interface. In addition, MD simulation confirm the energy deviation within the layering transition zone, where the calcite adsorbs the water molecules. In this approach, the modified PC-SAFT showed a good agreement with MD observations. The results of this study can contribute to a better understanding of fluid behavior at the fluid-mineral interface. In addition, this technique is a valuable tool that can be used to estimate solubility limits in multicomponent fluid processing and pipeline transport.

• 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. Fulltekst i vitenarkiv Vis sammendrag

  One important unresolved question in reactive transport is how pore-scale processes can be upscaled and how predictions can be made on the mutual effect of chemical processes and fluid flow in the porous medium. It is paramount to predict the location of mineral precipitation besides their amount for understanding the fate of transport properties. However, current models and simulation approaches fail to predict precisely where crystals will nucleate and grow in the spatiotemporal domain. We present a new mathematical model for probabilistic mineral nucleation and precipitation. A Lattice Boltzmann implementation of the two-dimensional mineral surface was developed to evaluate geometry evolution when probabilistic nucleation criterion is incorporated. To provide high-resolution surface information on mineral precipitation, growth, and distribution, we conducted a total of 27 calcium carbonate synthesis experiments in the laboratory. The results indicate that nucleation events as precursors determine the location and timing of crystal precipitation. It is shown that reaction rate has primary control over covering the substrate with nuclei and, subsequently, solid-phase accumulation. The work provides insight into the spatiotemporal evolution of porous media by suggesting probabilistic and deterministic domains for studying reactive transport processes. We indicate in which length- and time-scales it is essential to incorporate probabilistic nucleation for valid predictions.

• Dypvik, Henning; Hellevang, Helge; Krzesinska, Agata Magdalena; Sætre, Christian; Viennet, Jean-Christophe & Bultel, Benjamin Gabriel Rene [Vis alle 13 forfattere av denne artikkelen] (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. Fulltekst i vitenarkiv
• 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 [Vis alle 7 forfattere av denne artikkelen] (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. Fulltekst i vitenarkiv
• Haile, Beyene Girma; Line, Lina Hedvig; Klausen, Tore Grane; Olaussen, Snorre; Eide, Christian Haug & Jahren, Jens [Vis alle 7 forfattere av denne artikkelen] (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. Fulltekst i vitenarkiv
• 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), s. 1463–1484. doi: 10.1111/bre.12437. Fulltekst i vitenarkiv
• 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), s. 450–457. doi: 10.1021/acs.iecr.9b06048. Vis sammendrag

  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. Fulltekst i vitenarkiv
• 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), s. 249–260. doi: 10.1021/acsearthspacechem.9b00290.
• Gasda, Sarah Eileen; Aavatsmark, Ivar; Bohloli, Bahman; Hellevang, Helge; Nordbotten, Jan Martin & Wangen, Magnus [Vis alle 18 forfattere av denne artikkelen] (2019). Protection of Caprock Integrity for Large-Scale CO2 Storage on the Norwegian Continental Shelf. International Journal of Greenhouse Gas Control. ISSN 1750-5836. doi: 10.2139/ssrn.3365962. Vis sammendrag

  Large-scale CO2 storage requires advanced understanding of the geomechanical response of the caprock subject to pressure build- up in the reservoir. CO2 injection into basin systems will need to approach rates of 100 Mt/y in order to achieve significant reduction in worldwide emissions and realize the large capacity of saline aquifers. High pressure build-up is expected, which may activate existing fractures and faults in the seal and create leakage pathways for the CO2 plume. New fractures may also evolve at higher pressures. To avoid creating leakage pathways for the CO2 plume, the pressure must be kept under an upper bound that is determined by the caprock weakest point or initial stress. To date, there has been great uncertainty in critical knowledge needed for planning and execution of safe large-scale CO2 storage projects. Within the PROTECT project, we advance methods and reduce uncertainty regarding the mechanical response. The research study focuses on three subareas: data collection, experimental studies and computational tasks. The studies are performed at small scale (scale of individual cracks, cm to m) and at large scale (reservoir or basin scale, 10 m to km). Data are synthesized, and a benchmark study of large-scale geomechanical simulation is performed. The Utsira Formation on the Norwegian continental shelf has been used as a common case study for integration and benchmarking activities. Finally, recommendations are made for future research based on knowledge gained in this study.

• Veneranda, Marco; Manrique-Martinez, Jose Antonio; Lopez-Reyes, Guillermo; Medina, Jesus E.; Torre-Fdez, Imanol & Castro, Kepa [Vis alle 13 forfattere av denne artikkelen] (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. [Vis alle 9 forfattere av denne artikkelen] (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. Fulltekst i vitenarkiv
• 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. Fulltekst i vitenarkiv
• 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), s. 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. Fulltekst i vitenarkiv
• Morad, Daniel Jan; Nader, Fadi H.; Morad, Sadoon; Rossi, Carlos; Gasparrini, Marta & Alsuwaidi, Mohammad [Vis alle 8 forfattere av denne artikkelen] (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, s. 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. Fulltekst i vitenarkiv Vis sammendrag

  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, s. 590–603. doi: 10.1016/j.marpetgeo.2019.01.019. Fulltekst i vitenarkiv Vis sammendrag

  Permeability and physical properties of fine-grained clastic sediments show a wide range of variations. Despite rather intensive research, the impact of grain size distribution and mineralogical composition of individual rock constituents is not thoroughly investigated. We performed mechanical compaction of brine-statured reconstituted borehole cuttings and synthetic quartz-clay mixtures to study the evolution of properties in fine-grained clastic sediments during burial. The primary objective was to examine whether the hydraulic and physical properties of fine-grained sediments could be described and constrained by binary quartz-clay mixtures. The synthetic binary mixtures were prepared by mixing quartz with non-swelling (kaolinite) and strongly-swelling (smectite) clays, which can represent the endmember properties within the clay minerals. In addition to vertical permeability, physical and seismic properties, stress-dependence of permeability, and two-phase relative permeability of brine-oil system were investigated. Experimental results show that grain size distribution and mineralogical composition control the vertical permeability. A well-constrained porosity-permeability bound is defined, where the compaction trends of pure quartz and quartz-smectite 15:85 (wt %) mixtures describe the maximum and minimum boundaries, respectively. The quartz-clay mixtures, however, fail to provide bounds to constrain the broad range of variations in physical and seismic properties of reconstituted aggregates, and consequently natural mudstones. It is crucial to incorporate microstructure into the permeability prediction models because the experiments indicated that the microscale characteristics control the macroscale fluid flow properties.

• Sætre, Christian; Hellevang, Helge; Riu, Lucie; Dypvik, Henning; Pilorget, C & Poulet, Francois [Vis alle 7 forfattere av denne artikkelen] (2019). Experimental hydrothermal alteration of basaltic glass with relevance to Mars. Meteoritics and Planetary Science. ISSN 1086-9379. 54(2), s. 357–378. doi: 10.1111/maps.13214. Fulltekst i vitenarkiv
• Haile, Beyene Girma; Czarniecka, Urszula; Xi, Kelai; Smyrak-Sikora, Aleksandra; Jahren, Jens & Braathen, Alvar [Vis alle 7 forfattere av denne artikkelen] (2019). Hydrothermally induced diagenesis: Evidence from shallow marine-deltaic sediments, Wilhelmøya, Svalbard. Geoscience Frontiers. ISSN 1674-9871. 10(2), s. 629–649. doi: 10.1016/j.gsf.2018.02.015. Fulltekst i vitenarkiv
• 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), s. 1345–1361. doi: 10.2110/jsr.2018.70.
• Zhang, Shaomin; Cao, Yingchang; Jahren, Jens; Zhu, Rukai; Mao, Zhiguo & Kelai, XI [Vis alle 8 forfattere av denne artikkelen] (2018). Pore Characteristics of the Fine-Grained Tight Reservoirs in the Yabulai Basin, Northwestern China. Acta Geologica Sinica. ISSN 1000-9515. 92(3), s. 1170–1192. doi: 10.1111/1755-6724.13598.
• Xi, Kelai; Cao, Yingchang; Liu, Keyu; Jahren, Jens; Zhu, Rukai & Yuan, Guanghui [Vis alle 7 forfattere av denne artikkelen] (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. I Vialle, Stéphanie; Ajo-Franklin, Jonathan & Carey, William J. (Red.), Geological Carbon Storage: Subsurface Seals and Caprock Integrity. American Geophysical Union (AGU). ISSN 9781119118657. s. 167–186. doi: 10.1002/9781119118657.ch8. Fulltekst i vitenarkiv Vis sammendrag

  Fluid‐rock interaction in low‐permeable clay‐rich seal units is an important topic for the evaluation of the long‐term seal integrity during geological storage of CO2. In low‐permeable sealing units, the diffusion of CO2 into the matrix is a slow process, and studies of CO2‐initiated fluid‐rock interaction in seals are challenging. In this paper, we present an overview of CO2 transport mechanism and fluid‐rock interaction processes that might alter mechanical and transport properties of seals. The review includes theoretical considerations and simulations, experimentally demonstrated processes, and field examples of flow and fluid‐rock interaction in intact clay‐rich seals as well as for fractures. For clay‐rich seals dominated by minerals like quartz, illite, and smectite, the reactivity due to drop in pH is found to be low, and most reaction observed is found to involve calcite. Only minor porosity changes are observed, and implications for flow and CO2 transport are uncertain due to limited data available. Swelling and shrinking property of smectites due to CO2 sorption and CO2 alterations within fractures in clay‐rich seal is hardly addressed in the literature.

• Elenius, Maria; Skurtveit, Elin; Yarushina, Viktoriya M.; Baig, Irfan; Sundal, Anja & Wangen, Magnus [Vis alle 13 forfattere av denne artikkelen] (2018). Assessment of CO2 storage capacity based on sparse data: Skade Formation. International Journal of Greenhouse Gas Control. ISSN 1750-5836. 79, s. 252–271. doi: 10.1016/j.ijggc.2018.09.004. Fulltekst i vitenarkiv Vis sammendrag

  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. Fulltekst i vitenarkiv Vis sammendrag

  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. s. 3724–3728. doi: 10.1190/segam2018-2991324.1. Vis sammendrag

  This study has investigated rock physics characteristics and geomechanical properties of Middle Miocene mudstones in the Norwegian North Sea as the primary caprock for the 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 semiconsolidated rocks. The more brittle ooze-rich mudstones also indicated the lowest estimation of fracture pressure compared to other scenarios. The research outcomes emphasize the influence of mudstone type and presence of siliceous skeletal material on the macroscale physical properties of shallow semi-compacted mudstones.

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• Nooraiepour, Mohammad; Masoudi, Mohammad & Hellevang, Helge (2023). CO2-induced mineralization in porous reactive system: Implications for mineral precipitation and growth in basaltic layers.
• Masoudi, Mohammad & Hellevang, Helge (2023). Near injector salt scale buildup in CCS due to CO2 plume drying of aquifer.
• Masoudi, Mohammad; Ahmed, Elyes; Raynaud, Xavier Marcel & Hellevang, Helge (2023). Is salt precipitation an issue during geological storage of hydrogen in saline aquifers? from thermodynamic perspective using PC-SAFT EoS.
• Nooraiepour, Mohammad; Masoudi, Mohammad & Hellevang, Helge (2023). Predictive modeling of reactive transport processes during CO2 sequestration: Geometry alteration induced by mineral dissolution and precipitation.
• Nooraiepour, Mohammad; Masoudi, Mohammad & Hellevang, Helge (2023). Nucleation and mineral precipitation during reactive flow and transport: I nsights into porous media geometry alteration.
• Masoudi, Mohammad; Nooraiepour, Mohammad & Hellevang, Helge (2023). How does probabilistic nucleation control the spatiotemporal distribution of minerals in porous media?
• Masoudi, Mohammad; Nooraiepour, Mohammad & Hellevang, Helge (2023). Assessment of hydrogen uptake ability of clay-rich caprocks.
• Nooraiepour, Mohammad; Masoudi, Mohammad & Hellevang, Helge (2023). How probabilistic nucleation controls spatiotemporal dynamics and dimensionality of mineral growth in porous media?
• Nooraiepour, Mohammad; Masoudi, Mohammad & Hellevang, Helge (2023). Pore-scale investigation into dynamics of salt crystal nucleation, precipitation and growth in porous media during CO2 sequestration in saline aquifers Content.
• Nooraiepour, Mohammad; Masoudi, Mohammad & Hellevang, Helge (2022). Reactive transport in porous media: How solid precipitation shapes geometry evolution?
• Ahmadigoltapeh, Sajjad; Miri, Rohaldin; Aagaard, Per & Hellevang, Helge (2022). Corrigendum to “Extension of SAFT equation of state for fluids confined in nano-pores of sedimentary rocks using molecular dynamic simulation” [J. Mol. Liquids (348) (2022) 118045] (Journal of Molecular Liquids (2022) 348, (S0167732221027707), (10.1016/j.molliq.2021.118045)). Journal of Molecular Liquids. ISSN 0167-7322. 367. doi: 10.1016/j.molliq.2022.120440.
• Hellevang, Helge; Masoudi, Mohammad & Nooraiepour, Mohammad (2022). To what degree can the spatial distribution of secondary minerals in porous media be determined?
• Nooraiepour, Mohammad; Masoudi, Mohammad & Hellevang, Helge (2022). new probabilistic framework for nucleation and mineral growth in porous media helps bridge between different spatial and temporal scales— Theory, experiments and simulations.
• Masoudi, Mohammad; Nooraiepour, Mohammad & Hellevang, Helge (2022). How the Probabilistic Nature of the Nucleation Process Affects and Controls the Distribution of Mineral Precipitates in Porous Media. Vis sammendrag

  Nucleation and growth of secondary mineral phases is of great importance in a variety of processes in different fields. Mineral precipitation alters the morphology and hydrodynamics of the porous media by blocking the pore and throats and changing the tortuosity and permeability of flow paths. Even reaction rates are affected by the reshaping of available reactive surfaces. Any mineral precipitation process begins with the nucleation, which is a probabilistic phenomenon. It is often overlooked in studying the reactive transport phenomena. Nucleation controls the location and timing of crystal formation in a porous structure. The spatial distribution of stable secondary nuclei is crucial to precisely predict the hydrodynamics of the porous medium after mineral precipitation. Thus, a deeper understanding of the mineral nucleation and growth process is essential and it is necessary to develop a new probabilistic nucleation approach that could produce more reliable results. Accordingly, we have developed a new probabilistic nucleation model and incorporated it into a pore-scale Lattice Boltzmann reactive transport model to investigate the effect of various factors such as saturation ratio, flow rate, temperature, interfacial free energy, nucleation rate, and growth rates on the distribution of precipitated secondary minerals. In our model, the probabilistic induction time statistically spreads around the measured or reported induction time, either obtained from experiments or approximated by the exponential nucleation rate equation suggested by the classical nucleation theory (CNT). We provide a detailed explanation on how to implement the developed probabilistic nucleation approach into pore-scale reactive transport models. We also gave a thorough description of each parameter of the probabilistic nucleation model and how to measure or calculate them for different fluid and rock systems. Additionally, we used a new approach to measure the disorder of the spatial mineral distributions. The developed models provide new insights into the spatiotemporal evolution of porous media during mineral precipitation. Furthermore, the outcomes provide the basis for implementing mineral nucleation and growth for reactive transport modeling across timescales and length-scales.

• Nooraiepour, Mohammad; Masoudi, Mohammad; Shokri, Nima & Hellevang, Helge (2022). Heterogeneous nucleation and precipitation on solid surfaces: Experimental observation of calcium carbonate formation on primary and secondary substrates. Vis sammendrag

  Mineral nucleation and growth are prime examples of (geo)chemical reactions giving rise to geometry evolution during reactive flow and transport in porous media. The precipitation reactions can reduce porosity, alter pore space connectivity and morphology, modify tortuosity, and deteriorate permeability. Therefore, change the fluid flow and solute transport. Additionally, precipitation reshapes the available surface area for growth, leading to changes in the system's reactivity, reaction progress, and reaction rates. As the probabilistic nucle-ation model highlights, it is necessary to delineate both amount and location of nucleation and precipitation events in the spatiotemporal domain for precise prediction of changes in transport properties. This work aims to improve the understanding of factors controlling crystal nucleation and growth rates, the impact of ambient and aqueous phase properties, and the substrate characteristics. To explore the effect of solute concentration, temperature, and experimental elapsed time on the surface coverage area and the number of precipitated crystals , we carried out a total of 27 mineral synthesis experiments on the surface of heterogeneous quartz-rich sandstone with a solution stoichiometry of close to 1 (Ca/CO3 ≈ 1). The tests were performed at three temperatures (T = 20, 40, and 60℃) and three supersaturations (Ω = 15, 50, and 130x). The principal objective was to evaluate solid formation at different controlling conditions when the solid-liquid interface plays a key role. Effects of primary and secondary substrates and control imposed by preferential precipitation locations are identified and discussed. The results indicate that supersaturation and temperature imposed control on the amount, distribution pattern, and growth rate of crystals while the phenomenon still being probabilistic. Substrate characteristics governed the nucleation and crystal growth location and stochastic dynamics across time and space evolution. Moreover, substrate surface properties introduced preferential sites that were occupied and covered with solids first. For reactive transport modeling, in addition to porous medium's geometry and aqueous phase properties, a stochastic nucleation and growth model is necessary to implement substrate surface properties and compute solute transport and fluid flow for different spatial and temporal locations distinctively.

• Masoudi, Mohammad; Nooraiepour, Mohammad & Hellevang, Helge (2022). On the effect of probabilistic nucleation on the distribution of mineral precipitates in porous media. EGU General Assembly Conference Abstracts. doi: 10.5194/egusphere-egu22-8398.
• Nooraiepour, Mohammad & Hellevang, Helge (2021). Solid and Salt Precipitation Kinetics during CO2 Injection into Reservoir.
• Nooraiepour, Mohammad & Hellevang, Helge (2021). Coupled THMC processes during subsurface CO2 injection.
• 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. Vis sammendrag

  A new probabilistic nucleation model to predict crystal growth in porous medium Tuesday, 1 June 2021 15:10 (15 minutes) Nucleation is the first step of any mineral precipitation and crystal growth process. It is often overlooked in studying the reactive transport phenomena. Nucleation controls the location and timing of crystal formation in a porous structure. The spatial distribution of stable secondary nuclei is crucial to predict hydrodynam-ics of the porous medium after mineral precipitation precisely. To better understand the nucleation process, we developed a new probabilistic nucleation approach in which the induction time is considered a random variable. The random induction time statistically spreads around the measured or reported induction time, either obtained from experiments or approximated by the exponential nucleation rate equation suggested by the classical nucleation theory. In this work, we utilized inputs from the classical nucleation theory. In our model, both location and time of nucleation are probabilistic, affecting transport properties in different time-and length-scales. We developed a pore-scale Lattice Boltzmann reactive transport model and implemented the new probabilistic nucleation model to investigate the effect of nucleation rate and reaction rate on the extent, distribution, and precipitation pattern of the solid phases. The simulation domain is a 2D substrate with an infinite source of the supersaturated solution. We use Shannon entropy to measure the disorder of the spatial mineral distributions. The results of the simulations show that all the reactions follow similar random behavior with different Gauss-Laplace distributions. The simulation scenarios start from a fully ordered system with no solid precipitation on the substrate (entropy of 0). Entropy starts to increase as the secondary phase precipitates and grows on the surface until it reaches its maximum value (entropy of 1). Afterward, the overall disorder declines as more surface areas are getting covered, and eventually, entropy approaches a constant value. The research results indicate that the slower reactions have longer windows of the probabilistic regime before entering the deterministic regime. The outcomes provide the basis for implementing mineral nucleation and growth for reactive transport modeling across timescales and length-scales.

• 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. Vis sammendrag

  Geological CO2 storage and CCS have a crucial role in reducing CO2 emission and therefore mitigating climate change. One of the prerequisites for selecting CO2 storage sites is a low permeability caprock preventing potential CO2 leakage and migration from the storage reservoir. The presence of fractures in the caprock can adversely affect the sealing capacity of caprocks. Chemical interactions between CO2, brine, and caprock-forming minerals can cause fracture evolution, which results in changes in the transmissivity of fractures within the sealing layers. One factor that can affect the chemically induced fracture alterations is mineral het-erogeneity in the caprock. In the present work, we investigate the effect of mineral heterogeneity on fracture geometry evolution when CO2-rich brine flows through a single fracture scribed on different carbonate-rich caprock samples. The rock samples have different carbonate contents and different levels of mineral hetero-geneities. They can represent carbonate-rich caprocks such as some intervals of the Upper Jurassic (Kimmerid-gian) Draupne shales, the caprock for Smeaheia CO2 storage in Norway. An 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 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 the altered layer formed around the fracture (for the heterogeneous samples). Microfluidic experiments were also done for one carbonate-rich fine-grained shale sample, which showed dissolution of calcite with no macroscopic fracture alteration during the ten-day experiment. This indicates that in shale samples where the carbonate minerals, mainly calcite, are armored with other slow reacting minerals such as clays, the rate of fracture geometry evolution will be prolonged, which might be a positive point for the caprock integrity. However, the confirmed fluid-rock geochemical interactions within the shaly sample in a short time frame call for further investigations on the consequent impacts on caprock samples' geomechanical-hydrological properties for more extended periods relevant for subsurface CO2 storage. The microfluidic experiments are also used to validate a reactive transport model. The model will then be utilized to study changes in transport properties of different samples during experiments. The LBM-based model outputs, such as porosity-permeability relationships, can inform reactive models at larger scales to develop a better predictive numerical simulator for processes involved in CO2 storage projects.

• Haile, Beyene Girma; Line, Lina Hedvig; Klausen, Tore Grane; Olaussen, Snorre; Eide, Christian Haug & Jahren, Jens [Vis alle 7 forfattere av denne artikkelen] (2021). Identifying and constraining sedimentary recycling from microscopic fluid inclusions in quartz overgrowth.
• Nooraiepour, Mohammad & Hellevang, Helge (2020). Solid precipitation in porous reservoir rocks near the injection well: State of the art.
• 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 [Vis alle 14 forfattere av denne artikkelen] (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. Vis sammendrag

  We have conducted a series of microfluidic experiments on the glass and geomaterial micromodels at ambient and HPHT conditions to investigate physics and dynamics of salt precipitation, governing mechanisms, and influencing factors. We have shown that the trapped water films in porous or fractured media have enough continuity and conductivity to transport residual brine to an evaporating front, and cause an increase in the rate and amount of precipitated halite crystals. The pressure gradient imposed by capillary-back flow and imbibition processes can produce significant conductivity and stability of the water films. Laboratory observations suggest that the salt precipitation during CO2 injection is a time-evolving and self-enhancing phenomenon which has the following characteristics: (a) in addition to the aqueous phase, salt crystals can precipitate and grow on the interface of rock and CO2 flow pathway. (b) salt crystals are covered with a thin water film of brine that is attracted by surface energy effects and hydrophilic nature of salt crystals. (c) micrometer-sized salts have a porous structure of densely precipitated aggregates with narrow pore throats between the crystals, which provides a potentially large capillarity to the salt aggregates to imbibe water over long distances. (d) micrometer-sized crystals that precipitate on the interface of solid and CO2 stream enhance the distribution of brine, increase the surface area for evaporation and growth, and hence, accelerate the evaporation rate. (e) evaporation, precipitation, and growth of salt bodies induce further nucleation and precipitation, which in turn contributes to an increase in capillary transport and suction. The results also indicate that CO2 phase states and pressure-temperature conditions govern the magnitude, distribution and precipitation patterns of salt precipitates. Injection of gaseous CO2 resulted in higher salt precipitation compared to liquid and supercritical CO2. The thermodynamic conditions influence salt precipitation via water solubility in CO2, maximum water flux into CO2 stream, and balance between the imposed viscous forces and capillary-driven backflow. The CO2 phase states also affect the relationship between the injection rate and extent of precipitated salts. It is shown the higher the injection flow rate, the lower the salt coverage. 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 from fracture networks. The research outcome highlights the mechanisms and processes that are crucial to consider during the investigation of salt precipitation induced by CO2 injection because it has implications for both injectivity and containment assessments. For a better reservoir-scale numerical modeling, such mechanisms need to be incorporated and scaled-up in the reservoir simulator. The present approach for modeling salt precipitation using the volumetric approach in the reservoir-scale numerical simulator may not reflect the required physics for investigation of salt precipitation induced by CO2 injection.

• 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. Vis sammendrag

  Pre-existing and induced fractures and faults can play a role as bypass conduits and fast leaking channels in CO2 storage sites. They should therefore be well characterized during site selection, and monitored thoroughly during operation to track the movement and fate of the CO2 plume. Despite to date extensive research on the geophysical properties of brine- and CO2-saturated porous reservoir rocks, changes in acoustic velocity and electrical resistivity during a sole fracture fluid displacement are, however, rather little investigated. Hence, we herein present a laboratory study of core-scale geophysical monitoring during drainage-imbibition cycles of the brine-CO2 system through a shale caprock core sample with a vertical fracture. The experiments were conducted using both gaseous and scCO2 with 4 and 9 MPa pore pressures, respectively, at 12 MPa confining pressure. The tests were performed at 40°C during the loading and unloading stages in order to look into the hysteresis effect. We used a fractured core sample from the Upper Jurassic organic-rich shales of the Draupne Formation, which is the primary caprock for the Smeaheia CO2 storage site – a full-scale CCS project in Norway. The primary objective of the experiment was to compare the geophysical measurements using gaseous and scCO2 drainage-imbibition cycles during the tests in a core-scale experiment. Moreover, we were interested to see how sensitive acoustic velocity and electrical resistance techniques are to the fracture fluid displacement using different CO2 phase states. The outcomes of our high-pressure high-temperature experiment of simultaneous measurements of fracture flow and geophysical properties indicate that potential leakage of injected CO2 through the fractured-shale caprock can be detected in the core-scale laboratory experiments. The performed drainage-imbibition cycles using gaseous and scCO2 resulted in different behaviors in P-wave velocity (Vp) and electrical resistance in axial and radial directions for these two phase states. The measured Vp during the displacement of fracture fluid, CO2-brine subsequent cycles, showed a limited sensitivity in terms of magnitude and relative change. The electrical resistance, on the other hand, shows higher sensitivity and larger variation during fluid displacement along the fracture. It was also observed that the crossplot of Vp versus electrical resistance could detect and even differentiate the different phases during the loading and unloading stages.

• 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. Vis sammendrag

  In a full-scale CCS, millions of tons of CO2 must be stored underground. Injection of dry or undersaturated (with respect to water) CO2 leads to dry-out of formation water and salt precipitation. Salt precipitation during CO2 injection into the geological formations causes reduced injectivity and negatively influences reservoir rock properties. It also may have the potential to block CO2 leakage pathways within the fractured caprocks. The present-day reservoir-scale models of salt precipitation consider mechanisms such as water evaporation into CO2 and capillary backflow of water into the dried zone. However, it has been suggested that salt precipitation due to these mechanisms fills only a fraction of the pore network and does not significantly impact the permeability. We report microfluidic experiments on glass-microchips and organic-rich shale specimens to provide insights into the physics and dynamics of salt precipitation at pore-scale and to find the possible explanations for the large-scale salt precipitation observed in the field operations. Moreover, we investigate whether salt crystals can partially or entirely clog fracture apertures and leaking pathways in the seal sequences. The experimental results introduce two interrelated phenomena –self-enhancing of salt growth and water film salt transport, which together remarkably intensify the rate and amount of precipitations. It is shown that salt crystals, although at different rates, grow in both aqueous and gas phases. The salt crystals precipitate in two distinct forms: (a) large single cubic halite crystals in the aqueous phase and (b) dense micrometer-sized halite crystals on the interface of rock and CO2 stream. The micrometer-sized crystals in the gas phase create a microporous medium with large capillarity that can strongly imbibe brine over long distances to the evaporation front via capillary connected water films. It is demonstrated that the CO2 phase states influence magnitude, distribution and precipitation patterns of salt accumulations.

• 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 [Vis alle 10 forfattere av denne artikkelen] (2018). Geological Constraints on the immobilization potential for CO2 in the Gassum Fm. (Skagerrak, Norway).
• Hellevang, Helge; Miri, Rohaldin & Masoudi, Mohammad (2021). Near Wellbore Processes during Carbon Capture, Utilization, and Storage (CCUS): An Integrated Modeling Approach. Universitetet i Oslo.
• Elenius, Maria; Sundal, Anja; Gasda, Sarah; Aavatsmark, Ivar; Hellevang, Helge & Hermanrud, Christian [Vis alle 8 forfattere av denne artikkelen] (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 [Vis alle 8 forfattere av denne artikkelen] (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. Universitetet i Oslo.

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