ABSTRACT: Carbon capture and storage in deep geological formations is necessary to achieve a mean... more ABSTRACT: Carbon capture and storage in deep geological formations is necessary to achieve a meaningful reduction of anthropogenic CO2 emissions into the atmosphere. Given the buoyancy of the injected CO2, it is essential to adequately characterize the sealing caprocks commonly comprised of clay-rich formations, including shales. If the inherent anisotropy of shales is not considered, model prediction errors will propagate with time and space. To limit errors, the accurate experimental laboratory measurements should be scaled up and the in-situ behavior of the caprock should be studied in detail. Underground rock laboratories (URLs) offer a unique opportunity to investigate the caprock sealing capacity at a few meters scale in a well-defined and well-monitored environment. This perspective applies to the CO2 Long-term Periodic Injection Experiment (CO2LPIE) at the Swiss Mont Terri URL. In the experiment, it is planned to inject gaseous CO2 into Opalinus Clay, which is considered as a representative caprock for underground storage. Opalinus Clay shows large-scale anisotropic behavior due to the presence of bedding planes and heteorogeneities. We numerically simulate the CO2LPIE experiment using a 3D hydro-mechanical model and assuming linear poroelastic transverse isotropic behavior of the rock. We find that the CO2 is unlikely to penetrate the rock in free phase, while the diffusive front of dissolved CO2 in resident brine hardly propagates half a meter after two years of injection. The overpressure and induced deformation and stress changes preferentially develop along the bedding planes, although not sufficiently to lead to shear failure. 1. INTRODUCTION To limit global warming to 1.5 °C, net carbon removal after 2050 should be targeted (IPCC, 2014). To reach this goal, it is critical to develop novel technologies and a promising approach is Carbon Capture and Storage (CCS). CCS is generally understood as the set of CO2 capture from a large stationary source, transport to an injection site, and permanent storage in the subsurface (Benson and Cook, 2005). CO2 density at the pressure and temperature of typical underground storage formations in sedimentary basins is approximately 65 % of the in-situ brine density. As a result, the plume of the injected CO2 will not only migrate outwards from the injection well, but also upwards until it finds a sealing layer called caprock (Tsang and Niemi, 2017). To assure long-term CO2 trapping, it is of fundamental importance to properly characterize the caprock sealing capacity, commonly presented in terms of permeability, porosity, capillary entry pressure and relative permeability curves, and their evolution with time (Kaldi et al., 2011).
Geomechanics and geophysics for geo-energy and geo-resources, Sep 29, 2022
well-monitored environment. In particular, the CO 2 Long-term Periodic Injection Experiment (CO 2... more well-monitored environment. In particular, the CO 2 Long-term Periodic Injection Experiment (CO 2 LPIE) at the Mont Terri rock laboratory, Switzerland, aims at quantifying the advance of CO 2 in Opalinus Clay, an anisotropic clay-rich rock with bedding planes dipping 45° at the experiment location. To assist in the design of CO 2 LPIE and have an initial estimate of the system response, we perform plane-strain coupled Hydro-Mechanical simulations using a linear transversely isotropic poroelastic model of periodic CO 2 injection for 20 years. Simulation results show that pore pressure changes and the resulting stress variations are controlled by the anisotropic behavior of the material, producing a preferential advance along the bedding planes. CO 2 cannot penetrate into Opalinus Clay due to the strong capillary effects in the nanoscale pores, but advances dissolved into the resident brine. We find that the pore pressure oscillations imposed at the injection well are attenuated within tens of cm, requiring a close location of the Abstract Guaranteeing the sealing capacity of caprocks becomes paramount as CO 2 storage scales up to the gigaton scale. A significant number of laboratory experiments have been performed with samples of intact rock, showing that low-permeability and high-entry pressure caprocks have excellent sealing capacities to contain CO 2 deep underground. However, discontinuities, such as bedding planes, fractures and faults, affect the rock properties at the field scale, being at the same time challenging to monitor in industrial-scale applications. To bridge these two spatial scales, Underground Research Laboratories (URLs) provide a perfect setting to investigate the field-scale sealing capacity of caprocks under a
CO2 Long-term Periodic Injection Experiment (CO2LPIE) is planned to be carried out in Opalinus Cl... more CO2 Long-term Periodic Injection Experiment (CO2LPIE) is planned to be carried out in Opalinus Clay at the Mont Terri rock laboratory, canton Jura in Switzerland. The experiment aims at investigating the sealing capacity of the formation as a representative caprock for geologic carbon storage. The laboratory is at a depth of over 200 m and has been used as a field research environment to study the behavior of argillaceous rocks for more than 20 years in the context of more than 130 projects. With the new expansion, started in 2018, 10 new experiments are planned, one of which will be CO2LPIE. We performed several hydro-mechanical numerical simulations to assist the design process of CO2LPIE. In this presentation, I will explain these simulations and the gained insights into the hydro-mechanical processes raised by CO2 injection. The numerical model becomes complicated by the presence of bedding planes in Opalinus Clay. We assume Young’s moduli parallel and perpendicular to the bedding planes of 1.7 GPa and 2.1 GPa, respectively, and permeabilities parallel and perpendicular to the bedding planes of 2.4·10-20 m2 and 0.8·10-20 m2, respectively, all obtained from laboratory experiments. The orientation of the bedding planes is supposed to be of 45° dip. The injected fluid (i.e. CO2) imposes on the undisturbed rock a mean overpressure of 1 MPa that fluctuates with an amplitude and a period. While the period is fixed for all simulations at 835 f0b2 day (≈1.57 d), we investigate the effect of varying amplitudes.Peer reviewe
Geomechanics and Geophysics for Geo-Energy and Geo-Resources
Guaranteeing the sealing capacity of caprocks becomes paramount as CO2 storage scales up to the g... more Guaranteeing the sealing capacity of caprocks becomes paramount as CO2 storage scales up to the gigaton scale. A significant number of laboratory experiments have been performed with samples of intact rock, showing that low-permeability and high-entry pressure caprocks have excellent sealing capacities to contain CO2 deep underground. However, discontinuities, such as bedding planes, fractures and faults, affect the rock properties at the field scale, being at the same time challenging to monitor in industrial-scale applications. To bridge these two spatial scales, Underground Research Laboratories (URLs) provide a perfect setting to investigate the field-scale sealing capacity of caprocks under a well-monitored environment. In particular, the CO2 Long-term Periodic Injection Experiment (CO2LPIE) at the Mont Terri rock laboratory, Switzerland, aims at quantifying the advance of CO2 in Opalinus Clay, an anisotropic clay-rich rock with bedding planes dipping 45° at the experiment loca...
ABSTRACT: Carbon capture and storage in deep geological formations is necessary to achieve a mean... more ABSTRACT: Carbon capture and storage in deep geological formations is necessary to achieve a meaningful reduction of anthropogenic CO2 emissions into the atmosphere. Given the buoyancy of the injected CO2, it is essential to adequately characterize the sealing caprocks commonly comprised of clay-rich formations, including shales. If the inherent anisotropy of shales is not considered, model prediction errors will propagate with time and space. To limit errors, the accurate experimental laboratory measurements should be scaled up and the in-situ behavior of the caprock should be studied in detail. Underground rock laboratories (URLs) offer a unique opportunity to investigate the caprock sealing capacity at a few meters scale in a well-defined and well-monitored environment. This perspective applies to the CO2 Long-term Periodic Injection Experiment (CO2LPIE) at the Swiss Mont Terri URL. In the experiment, it is planned to inject gaseous CO2 into Opalinus Clay, which is considered as a representative caprock for underground storage. Opalinus Clay shows large-scale anisotropic behavior due to the presence of bedding planes and heteorogeneities. We numerically simulate the CO2LPIE experiment using a 3D hydro-mechanical model and assuming linear poroelastic transverse isotropic behavior of the rock. We find that the CO2 is unlikely to penetrate the rock in free phase, while the diffusive front of dissolved CO2 in resident brine hardly propagates half a meter after two years of injection. The overpressure and induced deformation and stress changes preferentially develop along the bedding planes, although not sufficiently to lead to shear failure. 1. INTRODUCTION To limit global warming to 1.5 °C, net carbon removal after 2050 should be targeted (IPCC, 2014). To reach this goal, it is critical to develop novel technologies and a promising approach is Carbon Capture and Storage (CCS). CCS is generally understood as the set of CO2 capture from a large stationary source, transport to an injection site, and permanent storage in the subsurface (Benson and Cook, 2005). CO2 density at the pressure and temperature of typical underground storage formations in sedimentary basins is approximately 65 % of the in-situ brine density. As a result, the plume of the injected CO2 will not only migrate outwards from the injection well, but also upwards until it finds a sealing layer called caprock (Tsang and Niemi, 2017). To assure long-term CO2 trapping, it is of fundamental importance to properly characterize the caprock sealing capacity, commonly presented in terms of permeability, porosity, capillary entry pressure and relative permeability curves, and their evolution with time (Kaldi et al., 2011).
Geomechanics and geophysics for geo-energy and geo-resources, Sep 29, 2022
well-monitored environment. In particular, the CO 2 Long-term Periodic Injection Experiment (CO 2... more well-monitored environment. In particular, the CO 2 Long-term Periodic Injection Experiment (CO 2 LPIE) at the Mont Terri rock laboratory, Switzerland, aims at quantifying the advance of CO 2 in Opalinus Clay, an anisotropic clay-rich rock with bedding planes dipping 45° at the experiment location. To assist in the design of CO 2 LPIE and have an initial estimate of the system response, we perform plane-strain coupled Hydro-Mechanical simulations using a linear transversely isotropic poroelastic model of periodic CO 2 injection for 20 years. Simulation results show that pore pressure changes and the resulting stress variations are controlled by the anisotropic behavior of the material, producing a preferential advance along the bedding planes. CO 2 cannot penetrate into Opalinus Clay due to the strong capillary effects in the nanoscale pores, but advances dissolved into the resident brine. We find that the pore pressure oscillations imposed at the injection well are attenuated within tens of cm, requiring a close location of the Abstract Guaranteeing the sealing capacity of caprocks becomes paramount as CO 2 storage scales up to the gigaton scale. A significant number of laboratory experiments have been performed with samples of intact rock, showing that low-permeability and high-entry pressure caprocks have excellent sealing capacities to contain CO 2 deep underground. However, discontinuities, such as bedding planes, fractures and faults, affect the rock properties at the field scale, being at the same time challenging to monitor in industrial-scale applications. To bridge these two spatial scales, Underground Research Laboratories (URLs) provide a perfect setting to investigate the field-scale sealing capacity of caprocks under a
CO2 Long-term Periodic Injection Experiment (CO2LPIE) is planned to be carried out in Opalinus Cl... more CO2 Long-term Periodic Injection Experiment (CO2LPIE) is planned to be carried out in Opalinus Clay at the Mont Terri rock laboratory, canton Jura in Switzerland. The experiment aims at investigating the sealing capacity of the formation as a representative caprock for geologic carbon storage. The laboratory is at a depth of over 200 m and has been used as a field research environment to study the behavior of argillaceous rocks for more than 20 years in the context of more than 130 projects. With the new expansion, started in 2018, 10 new experiments are planned, one of which will be CO2LPIE. We performed several hydro-mechanical numerical simulations to assist the design process of CO2LPIE. In this presentation, I will explain these simulations and the gained insights into the hydro-mechanical processes raised by CO2 injection. The numerical model becomes complicated by the presence of bedding planes in Opalinus Clay. We assume Young’s moduli parallel and perpendicular to the bedding planes of 1.7 GPa and 2.1 GPa, respectively, and permeabilities parallel and perpendicular to the bedding planes of 2.4·10-20 m2 and 0.8·10-20 m2, respectively, all obtained from laboratory experiments. The orientation of the bedding planes is supposed to be of 45° dip. The injected fluid (i.e. CO2) imposes on the undisturbed rock a mean overpressure of 1 MPa that fluctuates with an amplitude and a period. While the period is fixed for all simulations at 835 f0b2 day (≈1.57 d), we investigate the effect of varying amplitudes.Peer reviewe
Geomechanics and Geophysics for Geo-Energy and Geo-Resources
Guaranteeing the sealing capacity of caprocks becomes paramount as CO2 storage scales up to the g... more Guaranteeing the sealing capacity of caprocks becomes paramount as CO2 storage scales up to the gigaton scale. A significant number of laboratory experiments have been performed with samples of intact rock, showing that low-permeability and high-entry pressure caprocks have excellent sealing capacities to contain CO2 deep underground. However, discontinuities, such as bedding planes, fractures and faults, affect the rock properties at the field scale, being at the same time challenging to monitor in industrial-scale applications. To bridge these two spatial scales, Underground Research Laboratories (URLs) provide a perfect setting to investigate the field-scale sealing capacity of caprocks under a well-monitored environment. In particular, the CO2 Long-term Periodic Injection Experiment (CO2LPIE) at the Mont Terri rock laboratory, Switzerland, aims at quantifying the advance of CO2 in Opalinus Clay, an anisotropic clay-rich rock with bedding planes dipping 45° at the experiment loca...
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