| 1. |
- Ahmad, Nawaz, et al.
(författare)
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Injection of CO2-saturated brine in geological reservoir : A way to enhanced storage safety
- 2016
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Ingår i: International Journal of Greenhouse Gas Control. - : Elsevier. - 1750-5836 .- 1878-0148. ; 54, s. 129-144
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Tidskriftsartikel (refereegranskat)abstract
- Injection of free-phase supercritical CO2 into deep geological reservoirs is associated with risk of considerable return flows towards the land surface due to the buoyancy of CO2, which is lighter than the resident brine in the reservoir. Such upward movements can be avoided if CO2 is injected in the dissolved phase (CO2aq). In this work, injection of CO2-saturated brine in a subsurface carbonate reservoir was modelled. Physical and geochemical interactions of injected low-pH CO2-saturated brine with the carbonate minerals (calcite, dolomite and siderite) were investigated in the reactive transport modelling. CO2-saturated brine, being low in pH, showed high reactivity with the reservoir minerals, resulting in a significant mineral dissolution and CO2 conversion in reactions. Over the injection period of 10 yr, up to 16% of the injected CO2 was found consumed in geochemical reactions. Sorption included in the transport analysis resulted in additional quantities of CO2 mass stored. However, for the considered carbonate minerals, the consumption of injected CO2aq was found mainly in the form of ionic trapping.
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| 2. |
- Ahmad, Nawaz, et al.
(författare)
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Reactive transport modeling of leaking CO2-saturated brine along a fractured pathway
- 2015
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Ingår i: International Journal of Greenhouse Gas Control. - : Elsevier. - 1750-5836 .- 1878-0148. ; 42, s. 672-689
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Tidskriftsartikel (refereegranskat)abstract
- One concern regarding the underground storage of carbon dioxide (CO2) is its potential leakage from reservoirs. Over short period of time, the leakage risk is related mainly to CO2 as a separate supercritical fluid phase. However, over longer periods upon complete dissolution of injected CO2 in the fluid, the leakage risk is associated with dissolved phase CO2. Over the geological time scales, large-scale groundwater motion may cause displacement of brine containing dissolved CO2 along the conducting pathways. In this paper, we present a comprehensive modeling framework that describes the reactive transport of CO2-saturated brine along a fracture in the clay caprock based on the future, hypothetical leakage of the dissolved phase CO2. This study shows that the transport of leaked dissolved CO2 is significantly retarded by a combination of various physical and geochemical processes, such as mass exchange between conducting fracture and the neighboring rock matrix through molecular diffusion, sorption and calcite dissolution in the rock matrix. Mass stored in aqueous and adsorbed states in the rock matrix caused retention of dissolved CO2 along the leakage pathway. Calcite dissolution reaction in the rock matrix resulted in consumption of leaking dissolved CO2 and reduced its mass along the leakage pathway. Consumption and retention of dissolved CO2 along the leakage pathway have important implications for analyzing the potential reduction of CO2 fluxes from storage reservoirs over large periods and long travel pathways.
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| 3. |
- Basirat, Farzad, et al.
(författare)
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Experimental and modeling investigation of CO2 flow and transport in a coupled domain of porous media and free flow
- 2015
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Ingår i: International Journal of Greenhouse Gas Control. - : Elsevier BV. - 1750-5836 .- 1878-0148. ; 42, s. 461-470
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Tidskriftsartikel (refereegranskat)abstract
- A solid understanding of the transport mechanisms of gaseous CO2 near the land surface is necessary for developing reliable monitoring techniques and predictive models for possible CO2 leakage from deep underground storage. The objective of this work has been to develop an experimental method along with a simulation model for gaseous CO2 flow and transport in a system including both the porous media and the free air space above it. The experimental system consisted of a two-dimensional bench scale rectangular sandbox containing homogenous sand with an open space of still air above it. Gaseous CO2 was injected in different modes and the CO2 breakthrough was measured on specified ports in the system by using CO2 concentration sensors. A numerical model combining the gas flow in the porous medium and the free flow region was developed and used to model the experimental data. In this quest, the Discontinuous One-Domain approach was selected for modeling transport between the free flow and porous regions. The observed and simulated CO2 breakthrough curves both in the dried sand and in the free flow matched very well in the case of uniform injection and satisfactorily even in the case of point injection. Consequently, it seems that the model reasonably matches the observed data in the cases where the boundary condition is well defined. In summary, our results show that the developed experimental setup provides capability to study gaseous CO2 flow and transport in a coupled porous medium - free flow system and that our modeling approach is able to predict the flow and transport in this system with good accuracy.
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| 4. |
- Basirat, Farzad, et al.
(författare)
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Numerical modelling of CO2 injection at small-scale field experimental site in Maguelone, France
- 2016
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Ingår i: International Journal of Greenhouse Gas Control. - : Elsevier BV. - 1750-5836 .- 1878-0148. ; 54, s. 200-210
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Tidskriftsartikel (refereegranskat)abstract
- To evaluate the performance of downhole and surface geophysical monitoring methods, a series of shallow gas injection-monitoring experiments has been performed in a coastal saline aquifer at Maguelone, France. The recorded data include pressure measurements with a Westbay multilevel completion and CO2 saturation at an observation well derived from electrical resistivity with a modified Waxman-Smits (MWS) model. In this work, the aim is to develop a simulation model capturing the gas transport behavior and consistent with field data. For this purpose, the simulation of the CO2 injection experiment is carried out with two conceptual models, a homogeneous model and a heterogeneous model treated with multiple realization Monte Carlo simulations. Numerical simulator TOUGH2 with the equation of state module EOS7C is used for the simulations. Comparison of the model results with field data suggests that the pressure responses are captured with relatively good accuracy. Similarly, the model also provides an overall reasonable agreement and correct order of magnitude for predicted gas saturation values. However, as the heterogeneity pattern in the field data remains largely unknown, the model predictions can only be used to capture the mean behavior as well as to provide insights into how heterogeneity can influence the system behavior, by means of sensitivity analyses of the influence of heterogeneities on individual realizations.
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| 5. |
- Biermann, Maximilian, et al.
(författare)
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Excess heat-driven carbon capture at an integrated steel mill : Considerations for capture cost optimization
- 2019
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Ingår i: International Journal of Greenhouse Gas Control. - : Elsevier. - 1750-5836 .- 1878-0148. ; 91
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Tidskriftsartikel (refereegranskat)abstract
- Primary steelmaking in blast and basic oxygen furnaces is inherently carbon-intensive. Partial capture, i.e., capturing only a share of the CO2, is discussed as an option to reduce the cost of carbon capture and storage (CCS) and to realize a near-term reduction in emissions from the steel industry. This work presents a techno-economic assessment of partial capture based on amine absorption of CO2. The cost of steam from excess heat is assessed in detail. Using this steam to drive the capture process yields costs of 28–50 €/t CO2-captured. Capture of CO2 from the blast furnace gas outperforms end-of-pipe capture from the combined-heat-and-power plant or hot stove flue gases onsite by 3–5 €/t CO2-captured. The study shows that partial capture driven exclusively by excess heat represents a lower cost for a steel mill owner, estimated in the range of 15–30 €/t CO2-captured, as compared to full capture driven by the combustion of extra fuel. In addition, the full-chain CCS cost (capture, transport and storage) for partial capture is discussed in light of future carbon prices. We conclude that implementation of partial capture in the steel industry in the 2020s is possible and economically viable if policymakers ensure long-term regulation of carbon prices in line with agreed emission reduction targets beyond Year 2030.
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| 6. |
- Ditaranto, M., et al.
(författare)
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Concept of hydrogen fired gas turbine cycle with exhaust gas recirculation : Assessment of combustion and emissions performance
- 2015
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Ingår i: International Journal of Greenhouse Gas Control. - : Elsevier BV. - 1750-5836 .- 1878-0148. ; 37, s. 377-383
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Tidskriftsartikel (refereegranskat)abstract
- A novel gas turbine cycle concept applicable to power plants with pre-combustion CO2 capture or integrated gasification combined cycle (IGCC) is presented. These power plants use a hydrogen rich fuel with high reactive combustion properties which makes fuel dilution necessary to achieve low NOx emissions. The proposed novel gas turbine arrangement is set up as to avoid both fuel dilution and its consequent efficiency penalty, and breakthrough in low NOx combustion technology. In this concept, a high exhaust gas recirculation (EGR) rate is applied in order to generate an oxygen depleted working fluid entering the combustor, enough to reduce the high reactivity of hydrogen rich fuels. As a result, the combustion temperature in this environment is inherently limited, thus, keeping NOx formation rate low. A first order assessment of the combustion characteristics under such gas turbine operating conditions is made in the light of a numerical analysis of stability and NOx emissions potential. Both diffusion and premixed types combustor are considered according to the selected EGR rate. It is first shown that the flame stability could be maintained at EGR rates well above the maximum EGR limit found in conventional natural gas fired gas turbines. The study further shows that at these high EGR rates, considerable reductions in NOx emissions can be expected. The conclusion of this first order analysis is that there is a true potential in reducing the efficiency penalty induced by diluting the fuel in power plants with pre-combustion CO2 capture.
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| 7. |
- Edlmann, K., et al.
(författare)
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Lessons learned from using expert elicitation to identify, assess and rank the potential leakage scenarios at the Heletz pilot CO2 injection site
- 2016
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Ingår i: International Journal of Greenhouse Gas Control. - : Elsevier BV. - 1750-5836 .- 1878-0148. ; 49, s. 473-487
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Tidskriftsartikel (refereegranskat)abstract
- Expert elicitation is a useful approach to synthesis expert knowledge, experience and insight when the input data and analysis is limited. During the early stages of the EU FP7 MUSTANG pilot CO2 injection experiment at Heletz, Israel there was very little input data available, yet decisions had to be made regarding data collection, drilling, operation and monitoring strategies. An expert elicitation study was undertaken to identify, assess and rank potential CO2 leakage scenarios at Heletz to provide guidance to support the decision making processes. This paper presents a critique of the expert elicitation process undertaken, presenting the methodology and a discussion of the results. We present the lessons learned during the expert elicitation process, highlighting its advantages and limitations and provide suggestions on ways to overcome these limitations. Our findings show that prudent expert elicitation can make a valuable contribution to decision making, however if done improperly it can equally lead to invalid or misleading results and wrong decisions.
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| 8. |
- Edlmann, K., et al.
(författare)
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Mineralogical properties of the caprock and reservoir sandstone of the Heletz field scale experimental CO2 injection site, Israel; and their initial sensitivity to CO2 injection
- 2016
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Ingår i: International Journal of Greenhouse Gas Control. - : Elsevier BV. - 1750-5836 .- 1878-0148. ; 48, s. 94-104
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the initial database of the mineralogy of the caprock and reservoir sandstones of the Heletz field scale experimental CO2 injection site, Israel. The XRD mineralogy results show that the Heletz caprock has K-feldspar as the primary mineral (40%) followed by kaolinite (15%) and plagioclase feldspar (12%) then illite (6%) and muscovite (6%) with minor quartz, calcite, pyrite, chlorite and ankerite with traces of siderite. The Heletz reservoir rock is primarily quartz (70%) followed by K-feldspar (12%) and plagioclase feldspar (4%) with minor illite, kaolinite, muscovite, chlorite ankerite and pyrite with traces of dolomite, calcite and siderite. "Cook and look" bench experiments were conducted on the Heletz caprock and reservoir sandstone samples to identify if there was any immediate mineral reactivity that would influence permeability on exposure to CO2 that may cause concerns during well completion and initial injection of CO2 at Heletz. The sandstone exhibited reactivity under brine dis-equilibrium which was observed in the field with loss of injectivity which was restored by injecting KCL into the well and performing 20 swab-suctions. The caprock revealed no reactivity of immediate concern to the well completion and injection strategy and will retain its integrity.
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| 9. |
- Elhami, Ehsan, et al.
(författare)
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Physical- and geomechanical properties of a drill core sample from 1.6 km depth at the Heletz site in Israel : Some implications for reservoir rock and CO2 storage
- 2016
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Ingår i: International Journal of Greenhouse Gas Control. - : Elsevier BV. - 1750-5836 .- 1878-0148. ; 48:1, s. 84-93
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Tidskriftsartikel (refereegranskat)abstract
- We have measured physical- and geomechanical properties of a core sample that was collected from 1.6 km depth at the Heletz site in Israel, within reservoir rock, layer A. The core sample is composed of poorly consolidated sandstone, with several layers of coarser grain sizes. Average bulk density and porosity are 1.93 ± 0.11 g/cm3 and 36 ± 5%, respectively.Both nondestructive and destructive tests have been made on the core sample and its subsamples, including CT-scanning, oedometer tests, drained direct shear tests, as well as measurements of index properties, X-ray fluorescence and X-ray diffraction. These tests provide an initial evaluation of the properties of the reservoir rock, but are far from capturing epistemic variability of the reservoir rock. The results support the macroscopic observation, that the sample is poorly consolidated compared to its depth of deposition. The effective pre-consolidation pressure is less than 0.2 MPa and the maximum peak shear strength obtained is less than 1 MPa (normal stress = 1 MPa). In comparison, effective vertical stress from weight of the overlying rocks is estimated to 14 MPa using the average bulk density of the core. All measurements suggest that our reservoir rock sample is extremely weak with respect to its depth of deposition.
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| 10. |
- Figueiredo, Bruno, et al.
(författare)
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Coupled hydro-mechanical processes and fault reactivation induced by Co-2 Injection in a three-layer storage formation
- 2015
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Ingår i: International Journal of Greenhouse Gas Control. - : Elsevier BV. - 1750-5836 .- 1878-0148. ; 39, s. 432-448
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Tidskriftsartikel (refereegranskat)abstract
- The interaction between mechanical deformation and fluid flow in fault zones gives rise to a host of coupled hydro-mechanical processes fundamental to fault instability, induced seismicity, and associated fluid migration. Fault stability is studied in the context of the Heletz site which was chosen as a test site for CO2 injection experiment in the framework of the EU-MUSTANG project. The potential reservoir for CO2 storage at the Heletz site consists of three sandstone layers that are approximately one, two and nine meters in thickness, separated by impermeable shale layers of various thicknesses, and overlaid by a five-meter limestone and a thick impermeable shale, which serves as caprock. The storage formation is intersected by two pre-existing sub-vertical normal faults (F1 and F2) on two opposite sides of the injection point. A hydro-mechanical model was developed to study the interaction between mechanical deformation and fluid flow in the two faults during CO2 injection and storage. We evaluate the consequences caused by potential fault reactivation, namely, the fault slip and the CO2 leakage through the caprock. The difference in the results obtained by considering the three-layer storage formation as an equivalent single-layer storage formation is analysed. It was found that for the two cases the pore pressure evolution is similar, but the differences in the evolution of CO2 saturation are significant, which is attributed to the differences in CO2 spread in a single and three-layer storage. No fault reactivation was observed in either case. A sensitivity analysis was made to study the influence of the fault dip angle, the ratio between the horizontal and vertical stresses, the offset of the layers across fault F2, the initial permeability of the fault and the permeability of the confinement formations. Results show that reactivation of faults Fl and F2 is most sensitive to the stress ratio, the initial permeability of the faults and the permeability of the confinement formations. The offset of the layers across the fault F2 was also found to be an important parameter, mainly because an offset leads to an increase in CO2 leakage. Changes in permeability were found to be small because plastic shear strains induced by the reactivation of the faults and associated increase in volumetric strains and permeability, occur mainly in a fault section of only 10 m length, which is the approximate total thickness of the storage layers.
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