ABSTRACT Pore pressure variation resulting from geological CO2 storage may compromise reservoir, ... more ABSTRACT Pore pressure variation resulting from geological CO2 storage may compromise reservoir, caprock and fault integrity. Therefore, we investigate the mechanical impact of industrial-scale CO2 storage at a prospective Danish site by coupled 3D hydro-mechanical simulations carried out by two independent modelling groups. Even though the two chosen modelling strategies are not identical, simulation results demonstrate that storage integrity is maintained at any time. Vertical displacements are mainly determined by hydraulic fault conductivity influencing spatial pore pressure elevation. The introduced fault zone implementation in the hydro- mechanical model allows for localization of potential leakage pathways for formation fluids along the fault plane.
International Journal of Greenhouse Gas Control, 2013
The aim of this work was to quantify long-term mineral trapping at a reservoir scale for the Ketz... more The aim of this work was to quantify long-term mineral trapping at a reservoir scale for the Ketzin pilot site for CO 2 storage. An integrative approach coupling geochemical to reservoir simulations was therefore used. The main advantage compared to fully coupled reactive transport simulations is the reduction of computational time. Reactive transport simulations have not yet been performed to validate the approach. Data needed for the numerical simulations is supplied by geophysical and geological investigations at the site as well as by core and fluid sample analysis.
Temperature is one of the main parameters influencing CO2 properties during storage in saline aqu... more Temperature is one of the main parameters influencing CO2 properties during storage in saline aquifers, since it controls along with pressure the phase behavior of the CO2/brine mixture. When CO2 replaces brine as a free gas it is known to affect the elastic properties of porous media considerably. In order to track the migration of geologically stored CO2 in a saline aquifer at the Ketzin pilot site (Germany), 3D time-lapse seismic data were acquired by means of a baseline (pre-injection) survey in 2005 and monitor surveys in 2009 and 2012. At Ketzin, CO2 was injected from 2008 to 2013 in a sandstone reservoir at a depth of about 630 -650 m. In total about 67 kilotons of CO2 were injected. The present study is devoted to the 4D seismic dataset of 2005 -2009. The temperature in the storage reservoir near the injection well was observed to have increased from 34 °C in 2005 to 38 °C in 2009. This temperature increase led us to investigate the impact of temperature on the seismic response to CO2 injection and on our estimations of spatial CO2 mass distribution in the reservoir based on the Ketzin 4D seismic data. Both temperature scenarios in the reservoir of 2005 and 2009 were studied using multiphase fluid flow modeling. The isothermal simulations carried out for both 34°C and 38°C
Cet article fait partie du dossier thématique ci-dessous publié dans la revue OGST, Vol. 70, n°4,... more Cet article fait partie du dossier thématique ci-dessous publié dans la revue OGST, Vol. 70, n°4, et téléchargeable ici Le sud de l'Adriatique, un secteur potentiel pour le stockage du CO 2
Aktuelle Forschung in der Bodenmechanik 2015, 2015
ABSTRACT Die numerische Simulation einer geologischen CO2-Speicherung stellt aufgrund ihrer Formu... more ABSTRACT Die numerische Simulation einer geologischen CO2-Speicherung stellt aufgrund ihrer Formulierung als Mehrphasenflussproblem einen erheblichen Aufwand in der Modellierung dar. Bei der Kopplung von Ergebnissen aus geomechanischen Verformungsberechnungen und hydraulischen Simulationen kommen hydro-mechanische Einweg- und Zweiwegkopplungen zum Einsatz. Einwegkopplungen liefern häufig zu ungenaue Ergebnisse. Zweiwegkopplungen hingegen sind aufgrund ihres iterativen Charakters für Risikoanalysen, in denen mehrere hundert Szenarien betrachtet werden, sehr aufwändig. In diesem Beitrag wird basierend auf einer breit angelegten Parameterstudie ein Kriterium für die Notwendigkeit der Anwendung einer Zweiwegkopplung dargestellt und ein neuer Ansatz für eine hydro-mechanische quasi-Zweiwegkopplung von Störzonen erläutert.
Geological storage of carbon-dioxide (CO2) in saline aquifers has emerged as a promising method t... more Geological storage of carbon-dioxide (CO2) in saline aquifers has emerged as a promising method to reduce greenhouse gas emissions. Deep saline aquifers are quite common in sedimentary basins and are overlaid by natural sealing features such as impervious caprocks that prevent the CO2 and formation fluids from leakage. However, pressure buildup during injection as well as pressure falloff once injection stops can induce hydro-mechanical processes that can alter the physical properties within the reservoir and permeability distribution in the surrounding units. These transient hydro-physical conditions will in turn affect the migration of both, the CO2 plume and residual brine. To numerically study these phenomena, the flow and the mechanical equations have to be solved together, requiring a hydro-mechanical coupling. In the present study, numerical simulations of coupled pore pressure and stress are used to investigate the hydro-mechanical behavior of the CO2 storage system with reg...
ABSTRACT While risk assessment for CO2-storage often has been conducted by using a lot of simplif... more ABSTRACT While risk assessment for CO2-storage often has been conducted by using a lot of simplifications and conservatisms, our approach developed in the CO2RINA-research project is based on the integration of all models, existing at a moment in time. These models will be coupled by the so called transfer function approach which has been proven to be very powerful in the risk assessment for low level radioactive waste. This concept ensures, that the risk assessment is always consistent with the state of the models existing for a specific site. It can be immediately improved if the existing models will be improved over time. The approach was verified by comparison of the direct coupling of different process models in an overall model with a coupling by transfer functions by conducting a wide range of test calculations showing very good accuracy of the approach. The new coupling approach allows the incorporation of a variety of additional effects which are difficult to handle in an overall model. Examples for such processes are complex chemical and microbiological interactions, geomechanical feedback loops and migration of CO2 in the atmosphere. In the project there have been developed specified models for a generic site with parameters similar to the Ketzin site. These models include a reservoir model, a model for the alteration of the cementation of a mature well, a fault model, a model describing advection and diffusion through the cap rock, a complex model for the migration in a Quaternary aquifer including complex chemical interactions and a geomechanical model. Additionally there was shown the way of integration of microbiological processes which have been modelled in detail in the CO2BIOPERM project. The new approach is ready to be adapted to a specific CO2-storage site.
ABSTRACT Excess energy produced from renewables can be stored and reused via the “power-to-gas-to... more ABSTRACT Excess energy produced from renewables can be stored and reused via the “power-to-gas-to-power” (PGP) technology. We present an innovative idea which represents a decarbonised extension of PGP based on a closed carbon cycle. Our show case for the cities Potsdam and Brandenburg/Havel (Germany) outlines an overall efficiency for the entire process chain of 28% with total costs of electricity of 20 eurocents/kWh. If existing locations in Europe, where natural gas storage in porous formations is performed, were to be extended by CO2 storage sites, a significant quantity of wind and solar energy could be stored economically as methane.
... Michael Kühn, Thomas Kempka, Axel Liebscher, Stefan Lüth, Sonja Martens, Cornelia Schmidt-Hat... more ... Michael Kühn, Thomas Kempka, Axel Liebscher, Stefan Lüth, Sonja Martens, Cornelia Schmidt-Hattenberger Deutsches GeoForschungsZentrum GFZ ... Speichergesteinen handelt es sich im Wesentli-chen um Sandsteine mit ausreichender Porosität und Perme-abilität, die hohe ...
ABSTRACT Pore pressure variation resulting from geological CO2 storage may compromise reservoir, ... more ABSTRACT Pore pressure variation resulting from geological CO2 storage may compromise reservoir, caprock and fault integrity. Therefore, we investigate the mechanical impact of industrial-scale CO2 storage at a prospective Danish site by coupled 3D hydro-mechanical simulations carried out by two independent modelling groups. Even though the two chosen modelling strategies are not identical, simulation results demonstrate that storage integrity is maintained at any time. Vertical displacements are mainly determined by hydraulic fault conductivity influencing spatial pore pressure elevation. The introduced fault zone implementation in the hydro- mechanical model allows for localization of potential leakage pathways for formation fluids along the fault plane.
International Journal of Greenhouse Gas Control, 2013
The aim of this work was to quantify long-term mineral trapping at a reservoir scale for the Ketz... more The aim of this work was to quantify long-term mineral trapping at a reservoir scale for the Ketzin pilot site for CO 2 storage. An integrative approach coupling geochemical to reservoir simulations was therefore used. The main advantage compared to fully coupled reactive transport simulations is the reduction of computational time. Reactive transport simulations have not yet been performed to validate the approach. Data needed for the numerical simulations is supplied by geophysical and geological investigations at the site as well as by core and fluid sample analysis.
Temperature is one of the main parameters influencing CO2 properties during storage in saline aqu... more Temperature is one of the main parameters influencing CO2 properties during storage in saline aquifers, since it controls along with pressure the phase behavior of the CO2/brine mixture. When CO2 replaces brine as a free gas it is known to affect the elastic properties of porous media considerably. In order to track the migration of geologically stored CO2 in a saline aquifer at the Ketzin pilot site (Germany), 3D time-lapse seismic data were acquired by means of a baseline (pre-injection) survey in 2005 and monitor surveys in 2009 and 2012. At Ketzin, CO2 was injected from 2008 to 2013 in a sandstone reservoir at a depth of about 630 -650 m. In total about 67 kilotons of CO2 were injected. The present study is devoted to the 4D seismic dataset of 2005 -2009. The temperature in the storage reservoir near the injection well was observed to have increased from 34 °C in 2005 to 38 °C in 2009. This temperature increase led us to investigate the impact of temperature on the seismic response to CO2 injection and on our estimations of spatial CO2 mass distribution in the reservoir based on the Ketzin 4D seismic data. Both temperature scenarios in the reservoir of 2005 and 2009 were studied using multiphase fluid flow modeling. The isothermal simulations carried out for both 34°C and 38°C
Cet article fait partie du dossier thématique ci-dessous publié dans la revue OGST, Vol. 70, n°4,... more Cet article fait partie du dossier thématique ci-dessous publié dans la revue OGST, Vol. 70, n°4, et téléchargeable ici Le sud de l'Adriatique, un secteur potentiel pour le stockage du CO 2
Aktuelle Forschung in der Bodenmechanik 2015, 2015
ABSTRACT Die numerische Simulation einer geologischen CO2-Speicherung stellt aufgrund ihrer Formu... more ABSTRACT Die numerische Simulation einer geologischen CO2-Speicherung stellt aufgrund ihrer Formulierung als Mehrphasenflussproblem einen erheblichen Aufwand in der Modellierung dar. Bei der Kopplung von Ergebnissen aus geomechanischen Verformungsberechnungen und hydraulischen Simulationen kommen hydro-mechanische Einweg- und Zweiwegkopplungen zum Einsatz. Einwegkopplungen liefern häufig zu ungenaue Ergebnisse. Zweiwegkopplungen hingegen sind aufgrund ihres iterativen Charakters für Risikoanalysen, in denen mehrere hundert Szenarien betrachtet werden, sehr aufwändig. In diesem Beitrag wird basierend auf einer breit angelegten Parameterstudie ein Kriterium für die Notwendigkeit der Anwendung einer Zweiwegkopplung dargestellt und ein neuer Ansatz für eine hydro-mechanische quasi-Zweiwegkopplung von Störzonen erläutert.
Geological storage of carbon-dioxide (CO2) in saline aquifers has emerged as a promising method t... more Geological storage of carbon-dioxide (CO2) in saline aquifers has emerged as a promising method to reduce greenhouse gas emissions. Deep saline aquifers are quite common in sedimentary basins and are overlaid by natural sealing features such as impervious caprocks that prevent the CO2 and formation fluids from leakage. However, pressure buildup during injection as well as pressure falloff once injection stops can induce hydro-mechanical processes that can alter the physical properties within the reservoir and permeability distribution in the surrounding units. These transient hydro-physical conditions will in turn affect the migration of both, the CO2 plume and residual brine. To numerically study these phenomena, the flow and the mechanical equations have to be solved together, requiring a hydro-mechanical coupling. In the present study, numerical simulations of coupled pore pressure and stress are used to investigate the hydro-mechanical behavior of the CO2 storage system with reg...
ABSTRACT While risk assessment for CO2-storage often has been conducted by using a lot of simplif... more ABSTRACT While risk assessment for CO2-storage often has been conducted by using a lot of simplifications and conservatisms, our approach developed in the CO2RINA-research project is based on the integration of all models, existing at a moment in time. These models will be coupled by the so called transfer function approach which has been proven to be very powerful in the risk assessment for low level radioactive waste. This concept ensures, that the risk assessment is always consistent with the state of the models existing for a specific site. It can be immediately improved if the existing models will be improved over time. The approach was verified by comparison of the direct coupling of different process models in an overall model with a coupling by transfer functions by conducting a wide range of test calculations showing very good accuracy of the approach. The new coupling approach allows the incorporation of a variety of additional effects which are difficult to handle in an overall model. Examples for such processes are complex chemical and microbiological interactions, geomechanical feedback loops and migration of CO2 in the atmosphere. In the project there have been developed specified models for a generic site with parameters similar to the Ketzin site. These models include a reservoir model, a model for the alteration of the cementation of a mature well, a fault model, a model describing advection and diffusion through the cap rock, a complex model for the migration in a Quaternary aquifer including complex chemical interactions and a geomechanical model. Additionally there was shown the way of integration of microbiological processes which have been modelled in detail in the CO2BIOPERM project. The new approach is ready to be adapted to a specific CO2-storage site.
ABSTRACT Excess energy produced from renewables can be stored and reused via the “power-to-gas-to... more ABSTRACT Excess energy produced from renewables can be stored and reused via the “power-to-gas-to-power” (PGP) technology. We present an innovative idea which represents a decarbonised extension of PGP based on a closed carbon cycle. Our show case for the cities Potsdam and Brandenburg/Havel (Germany) outlines an overall efficiency for the entire process chain of 28% with total costs of electricity of 20 eurocents/kWh. If existing locations in Europe, where natural gas storage in porous formations is performed, were to be extended by CO2 storage sites, a significant quantity of wind and solar energy could be stored economically as methane.
... Michael Kühn, Thomas Kempka, Axel Liebscher, Stefan Lüth, Sonja Martens, Cornelia Schmidt-Hat... more ... Michael Kühn, Thomas Kempka, Axel Liebscher, Stefan Lüth, Sonja Martens, Cornelia Schmidt-Hattenberger Deutsches GeoForschungsZentrum GFZ ... Speichergesteinen handelt es sich im Wesentli-chen um Sandsteine mit ausreichender Porosität und Perme-abilität, die hohe ...
Abstract Estimating the efficiency and sustainability of geological subsurface utilization, i.e.,... more Abstract Estimating the efficiency and sustainability of geological subsurface utilization, i.e., Carbon Capture and Storage (CCS) requires an integrated risk assessment approach, considering the occurring coupled processes, beside others, the potential reactivation of existing faults. In this context, hydraulic and mechanical parameter uncertainties as well as different injection rates have to be considered and quantified to elaborate reliable environmental impact assessments. Consequently, the required sensitivity analyses consume significant computational time due to the high number of realizations that have to be carried out. Due to the high computational costs of two-way coupled simulations in large-scale 3D multiphase fluid flow systems, these are not applicable for the purpose of uncertainty and risk assessments. Hence, an innovative semi-analytical hydromechanical coupling approach for hydraulic fault reactivation will be introduced. This approach determines the void ratio evolution in representative fault elements using one preliminary base simulation, considering one model geometry and one set of hydromechanical parameters. The void ratio development is then approximated and related to one reference pressure at the base of the fault. The parametrization of the resulting functions is then directly implemented into a multiphase fluid flow simulator to carry out the semi-analytical coupling for the simulation of hydromechanical processes. Hereby, the iterative parameter exchange between the multiphase and mechanical simulators is omitted, since the update of porosity and permeability is controlled by one reference pore pressure at the fault base. The suggested procedure is capable to reduce the computational time required by coupled hydromechanical simulations of a multitude of injection rates by a factor of up to 15.
At Ketzin, located west of Berlin, the GFZ German Research Centre for Geosciences operates Europe... more At Ketzin, located west of Berlin, the GFZ German Research Centre for Geosciences operates Europe's longestrunning on-shore CO2 storage site. The Ketzin pilot site has been developed since 2004 and comprises three wells to depths of 750 m to 800 m and one shallow observation well, an injection facility and permanently installed monitoring devices. Since June 2008, CO 2 is injected into 630 m to 650 m deep sandstone units (Upper Triassic Stuttgart Formation) in an anticlinal structure of the Northeast German Basin. Until mid of May 2012, about 61,400 t of CO2 have been stored safely. One of the most comprehensive monitoring concepts worldwide is applied and capable of detecting the behaviour of the CO2 in the subsurface. The Ketzin project demonstrates safe CO2 storage in a saline aquifer on a research scale and effective monitoring. This paper summarizes the key results obtained after four years of CO2 injection.
To assess the long-term reservoir stabilisation at the Ketzin pilot site (Germany), the contribut... more To assess the long-term reservoir stabilisation at the Ketzin pilot site (Germany), the contribution of the four CO2 trapping mechanisms (structural, residual, dissolution and mineralisation trapping) was determined by numerical modelling. In the first step, dynamic flow simulations were undertaken using a reservoir simulator. The second step comprised batch simulations applying a geochemical simulator. Coupling between both simulators was achieved by time-step dependent integration of water saturation calculated in the reservoir simulations. After a simulation time of 16,000 years, about 98.3 % of the injected CO2 is dissolved in the formation fluid and 1.5 % mineralised, while residual trapping contributes with 0.2 % and structural trapping is negligible.
Geological storage of CO2 in deep saline aquifers is considered as option for reducing anthropoge... more Geological storage of CO2 in deep saline aquifers is considered as option for reducing anthropogenic greenhouse gas emissions into the atmosphere. Most often the same aquifers might allow for provision of geothermal energy potentially resulting in a competitive situation. Within the frame of the present study we evaluated the feasibility of synergetic utilisation of a reservoir suitable for both, CO2 storage and geothermal heat exploitation, by 3D numerical simulations of simultaneous CO2 and brine (re-) injection and brine production. Based on structural and petrophysical data from a prospective storage site in the North East German Basin different scenarios were investigated taking into account reservoir permeability anisotropy and varying flow related descriptions of existing faults. Simulation results show that for an isotropic horizontal permeability distribution synergetic use is feasible for at least 30 years. Nevertheless, permeability anisotropy and open faults do have an impact on the CO2 arrival time at the brine production well and should be taken into account for implementation of a synergetic utilisation in the study area.
In this study we integrate reservoir simulation with 3D reflection seismic time-lapse data from t... more In this study we integrate reservoir simulation with 3D reflection seismic time-lapse data from the Ketzin CO2 storage pilot site using density and velocity models, a porosity model and a fluid flow simulation model. To simulate the seismic response corresponding to the real data, detailed density and velocity models are properly generated from the stratigraphic model and available borehole logging data. The reservoir simulation model providing the spatial CO2 saturation in the reservoir based on numerical simulations history-matched to the site monitoring data is used to calculate the bulk densities and compressional wave velocities of the rock after CO2 injection using a fluid substitution method. 3D synthetic seismic data are generated by convolving the density and velocity models with two different sources to study the change in seismic response after CO2 injection and to investigate the impact of the different source types on CO2 monitoring. Our results provide estimates of the time-lapse anomalies caused by CO2 injection and demonstrate that the choice of source type is a critical factor for time-lapse seismic monitoring to assess the distribution of injected CO2. The same source type should be used in the baseline and repeat surveys for site operation.
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