Mohammad Nooraiepour

• 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.

• 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.
• 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 (2019). Laboratory Compaction of Synthetic and Reconstituted Mixtures: Implications for Rock Physics Properties of Siliciclastic Fine-Grained Sediments, In N/A N/A (ed.),  81th EAGE Annual Conference & Exhibition 2019.  European Association of Geoscientists and Engineers.  ISBN 9781510888036.  81st EAGE Conference and Exhibition 2019. Vis sammendrag

  Muds and mudstones are the most common sediments around the world. They have the primary control on fluid flow in sedimentary basins and near-surface environments. The fine-grained sediments are of key importance in CCS, waste repositories, petroleum exploration, and increasingly more in production. This study presents mechanical compaction of brine-saturated reconstituted borehole cuttings and synthetic quartz-clay mixtures to investigate the evolution of properties in fine-grained clastic sediments during burial. The primary research question was whether rock physics and hydraulic properties 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. A well-constrained porosity-permeability bound is defined, where the compaction trends of pure quartz and quartz-smectite 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. The well log analysis shows a broad range of variation in properties of studied caprock sequences. The results indicate the importance of incorporating micro-scale properties into the geological and geophysical interpretations through rock physics understanding.

• 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.

• Nooraiepour, Mohammad; Bohloli, Bahman; Park, Joonsang; Sauvin, Guillaume; Skurtveit, Elin & Mondol, Nazmul Haque (2018). Effect of brine-CO2 fracture flow on velocity and electrical resistivity of naturally fractured tight sandstones. Geophysics.  ISSN 0016-8033.  83(1), s WA37- WA48 . doi: 10.1190/GEO2017-0077.1 Fulltekst i vitenarkiv. Vis sammendrag

  Fracture networks inside geological CO2 storage reservoirs can serve as primary fluid flow conduit, particularly in low-permeability formations. While some experiments focused on the geophysical properties of brine- and CO2-saturated rocks during matrix flow, geophysical monitoring of fracture flow when CO2 displaces brine inside the fracture seems to be overlooked. We have conducted laboratory geophysical monitoring of fluid flow in a naturally fractured tight sandstone during brine and liquid CO2 injection. For the experiment, the low-porosity, low-permeability naturally fractured core sample from the Triassic De Geerdalen Formation was acquired from the Longyearbyen CO2 storage pilot at Svalbard, Norway. Stress-dependence, hysteresis and the influence of fluid-rock interactions on fracture permeability were investigated. The results suggest that in addition to stress level and pore pressure, mobility and fluid type can affect fracture permeability during loading and unloading cycles. Moreover, the fluid-rock interaction may impact volumetric strain and consequently fracture permeability through swelling and dry out during water and CO2 injection, respectively. Acoustic velocity and electrical resistivity were measured continuously in the axial direction and three radial levels. Geophysical monitoring of fracture flow revealed that the axial P-wave velocity and axial electrical resistivity are more sensitive to saturation change than the axial S-wave, radial P-wave, and radial resistivity measurements when CO2 was displacing brine, and the matrix flow was negligible. The marginal decreases of acoustic velocity (maximum 1.6% for axial Vp) compared to 11% increase in axial electrical resistivity suggest that in the case of dominant fracture flow within the fractured tight reservoirs, the use of electrical resistivity methods have a clear advantage compared to seismic methods to monitor CO2 plume. The knowledge learned from such experiments can be useful for monitoring geological CO2 storage where the primary fluid flow conduit is fracture network.

• 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), s 6050- 6060 . doi: 10.1021/acs.est.8b00251 Fulltekst i vitenarkiv. Vis sammendrag

  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 (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, In  SEG Technical Program Extended Abstract 2018.  SEGEAB.  ISBN 978-5-8670-8577-3.  SEG Technical Program Expanded Abstracts 2018.  s 3724 - 3728 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.

• 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, s 49- 59 . doi: 10.1016/j.ijggc.2017.10.016 Vis sammendrag

  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.

• 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, s 265- 292 . doi: 10.1016/j.marpetgeo.2016.12.003 Vis sammendrag

  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.

• Nooraiepour, Mohammad & Mondol, Nazmul Haque (2016). Petrophysical and acoustic properties of mechanically compacted shales - evaluating two Barents Sea top seal sequences, In .. .. (ed.),  7th EAGE Saint Petersburg International Conference and Exhibition.  European Association of Geoscientists and Engineers (EAGE).  ISBN 9781510822498.  We STZ0 01. Vis sammendrag

  This study investigates petrophysical and acoustic properties of two experimentally compacted reconstituted seal sequences (Late Triassic Snadd and Early Cretaceous Kolmule Formations) from two localities (Goliat field and Saline discovery) in the SW Barents Sea. Four samples were chosen from cuttings of two exploration wells 7122/7-3 (Goliat) and 7220/10-1 (Salina) drilled in the study area. The washed and freeze dried cutting samples were characterized for grain size analysis, geochemical (organic content) and mineralogical compositions. A total of eight compaction tests (four dry and four brine-saturated) were performed in the laboratory to apply a maximum vertical effective stress of 50 MPa. The maximum compaction observed in Snadd shale aggregates collected from the Goliat well (4.5% porosity). In order to study compaction history and seal integrity, the experimental results were compared with well log data. It is clear from comparison that the mechanical compaction of reconstituted shale and mudstone samples can be capable of describing natural processes, providing valuable insights on the state of mechanical/chemical compaction, and helping the seal integrity assessments. The results of this study will have applications in rock physics, basin modelling and top seal integrity.

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• Hellevang, Helge; Nooraiepour, Mohammad; Masoudi, Mohammad & Fazeli, Hossein (2020). Statistical Model for Mineral Nucleation and Growth.
• 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.

• 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.

• Hellevang, Helge; Nooraiepour, Mohammad & Fazeli, Hossein (2018). CO2-H2O-basalt interactions – reactive transport experiments and simulations.
• Nooraiepour, Mohammad (2018). Rock Properties and Sealing Efficiency in Fine-grained Siliciclastic Caprocks — Implications for CCS and Petroleum Industry. Series of dissertations submitted to the Faculty of Mathematics and Natural Sciences, University of Oslo.. 2061.
• Nooraiepour, Mohammad; Fazeli, Hossein & Hellevang, Helge (2018). Brine-CO2-Rock Geochemical Interactions: A novel HPHT microfluidic pressure vessel for lab-on-chip investigations.
• 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. Vis sammendrag

  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.

• Nooraiepour, Mohammad; Hellevang, Helge & Mondol, Nazmul Haque (2018). From field-scale to pore-scale: Investigation of caprock properties for CO2 sequestration.
• 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.

• Bohloli, Bahman; Park, Joonsang; Sauvin, Guillaume; Grande, Lars; Soldal, Magnus; Nooraiepour, Mohammad; Olaussen, Snorre & Omolo, Lameck (2017). Triaxial testing and geophysical monitoring of reservoir and cap rock samples from UNIS CO2 LAB pilot, Longyearbyen Svalbard, Norway.
• Nooraiepour, Mohammad; Fazeli, Hossein & Hellevang, Helge (2017). Effect of CO2 phase state and flow rate on salt formation in shale caprocks – a microfluidics study.
• Nooraiepour, Mohammad & Mondol, Nazmul Haque (2017). Experimental mechanical compaction of reconstituted mudrocks from the SW Barents Sea: implication for exhumation estimation.
• Park, Joonsang; Soldal, Magnus; Sauvin, Guillaume; Nooraiepour, Mohammad; Mondol, Nazmul Haque & Bohloli, Bahman (2017). On wave propagation in a CO2/Brine-saturated fractured core.
• Nooraiepour, Mohammad (2016). Crucial rock properties for sealing CO2 storage sites.
• Nooraiepour, Mohammad (2016). Investigation of top seal integrity for subsurface geological CO2 storage.
• Nooraiepour, Mohammad & Mondol, Nazmul Haque (2016). Petrophysical and Acoustic Properties of Mechanically Compacted Shales - Evaluating Two Barents Sea Top Seal Sequences.

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