This work concludes a study started many years ago in the Rock Deformation Laboratory of ETH Zuri... more This work concludes a study started many years ago in the Rock Deformation Laboratory of ETH Zurich, in which the seismic properties (Vp / Vs) of crustal metapelites at high pressure and temperature were characterised. A particular goal was to map the alpha-beta phase transition in quartz-rich rocks, and to link these effects to areas of above average heat flux. Our interest in metapelites is driven by the observation that they are among the most common metamorphic rock types of continental crust and possibly constitute a significant part of lower crust. Metapelites are rich in quartz and hydrous minerals (e.g. biotite, muscovite, chlorite), and are common in the lithology of areas high geothermal activity due to the higher than average heat flux. They are also good candidates to investigate dehydration reactions and phase transitions of the middle to lower crust. To investigate, we employ a 'Paterson' type apparatus that is configured for petrophysical work, in particular e...
Possibilities to sequester anthropogenic CO2 in deep geological formations are currently under in... more Possibilities to sequester anthropogenic CO2 in deep geological formations are currently under investigation in Switzerland. A first-order appraisal of Switzerland’s potential for CO2 storage in the Swiss Molasse Basin identified a carbonate aquifer (Upper Muschelkalk) sealed by an evaporitic formation (Gipskeuper) as promising seal/aquifer pair. A series of laboratory measurements were carried out at the Rock Deformation Laboratory of ETH Zurich to explore in detail the physical properties in rocks from these geological formations. Permeability and seismic velocity measurements were performed simultaneously under in-situ conditions at temperatures up to 50°C and 20 MPa confining pressure. The comparison of injected Argon and CO2 in gaseous and supercritical state as pore media into dolomite samples brings new insights regarding the reservoir’s characterization. The preliminary results indicate that permeability crucially depends on temperature, confining pressure and pore pressure. Especially at in situ conditions with CO2 being at supercritical state, substantial losses in permeability to a third of the initial value have to be taken into consideration. Such experiments are critical in the framework of CO2 sequestration in order to validate current predictive injection models and seismic techniques to monitor injected CO2 into geological basins.
ABSTRACT The upper Muschelkalk saline aquifer consists of partly dolomitized to completely dolomi... more ABSTRACT The upper Muschelkalk saline aquifer consists of partly dolomitized to completely dolomitized carbonate rocks of mid Triassic age (~230 Ma). This aquifer is present throughout the Swiss Molasse Basin (SMB), north of the Alps. A regional appraisal of the SMB indicates that this Formation is a potential host aquifer for sequestered CO2. However, the spatial distribution and heterogeneity of the porosity, permeability and other relevant physical and mechanical properties of the upper Muschelkalk are still poorly known. The uncertainty in this knowledge stems mainly from the weakly developed oil and gas exploration industry in Switzerland. We use an integrated approach to better constrain the aquifer physical properties, which couples field scale geophysical surveys (borehole logging and seismic reflection profiles) with laboratory analytical data. Here we focus on a set of boreholes from northern Switzerland, where geophysical data and drill core useable for laboratory measurements are available. Two sub-units comprise the upper Muschelkalk Formation. The stratigraphically higher part is a fossiliferous dolomite (>90 vol% CaMg(CO3)2; Trigodonusdolomit). The underlying unit, is composed of micritic calcite and dolomite layers interbedded with fossil-rich layers (Hauptmuschelkalk). Although both units are part of the aquifer formation, they appear to have distinctly different physical properties. The transition from Trigodonusdolomit to the Hauptmuschelkalk is marked by an increase in the sonic velocity, density and acoustic impedance. The magnitude of increase in sonic velocity can be up to 500 m/s, accompanied by an increase in acoustic impedance from 8500 to 15500 (m/s*g/cm3), but varies between the different boreholes. Poisson's ratio, determined from a single borehole, show sharp decrease at the transition. The origin of the changes in the geophysical data is likely reflecting differences in porosity and mineral composition in the Trigodonusdolomit and Hauptmuschelkalk. The boundary between the Trigodonusdolomit and Hauptmuschelkalk is further apparent in reflection seismic lines from surveys near the boreholes. Laboratory measurements of porosity, permeability, ultrasonic velocities and triaxial strength testing were performed at conditions similar to reservoir (in situ) conditions, and when applicable at room conditions, on samples recovered from borehole drill cores. Initial laboratory measurements of porosity, ultrasonic velocities and permeability also show distinct differences between the Trigodonusdolomit and Hauptmuschelkalk. Up-scaling issues, which arise from the comparison of laboratory measurements (small sample size) to field geophysical data, are discussed. Integration of laboratory and geophysical survey data allow us to better understand porosity and permeability distribution in the upper Muschelkalk aquifer on the scale of the Swiss Molasse Basin.
The upper Muschelkalk saline aquifer consists of partly dolomitized to completely dolomitized car... more The upper Muschelkalk saline aquifer consists of partly dolomitized to completely dolomitized carbonate rocks of mid Triassic age (~230 Ma). This aquifer is present throughout the Swiss Molasse Basin (SMB), north of the Alps. A regional appraisal of the SMB indicates that this Formation is a potential host aquifer for sequestered CO2. However, the spatial distribution and heterogeneity of the porosity, permeability and other relevant physical and mechanical properties of the upper Muschelkalk are still poorly known. The uncertainty in this knowledge stems mainly from the weakly developed oil and gas exploration industry in Switzerland. We use an integrated approach to better constrain the aquifer physical properties, which couples field scale geophysical surveys (borehole logging and seismic reflection profiles) with laboratory analytical data. Here we focus on a set of boreholes from northern Switzerland, where geophysical data and drill core useable for laboratory measurements are...
This work concludes a study started many years ago in the Rock Deformation Laboratory of ETH Zuri... more This work concludes a study started many years ago in the Rock Deformation Laboratory of ETH Zurich, in which the seismic properties (Vp / Vs) of crustal metapelites at high pressure and temperature were characterised. A particular goal was to map the alpha-beta phase transition in quartz-rich rocks, and to link these effects to areas of above average heat flux. Our interest in metapelites is driven by the observation that they are among the most common metamorphic rock types of continental crust and possibly constitute a significant part of lower crust. Metapelites are rich in quartz and hydrous minerals (e.g. biotite, muscovite, chlorite), and are common in the lithology of areas high geothermal activity due to the higher than average heat flux. They are also good candidates to investigate dehydration reactions and phase transitions of the middle to lower crust. To investigate, we employ a 'Paterson' type apparatus that is configured for petrophysical work, in particular e...
Possibilities to sequester anthropogenic CO2 in deep geological formations are currently under in... more Possibilities to sequester anthropogenic CO2 in deep geological formations are currently under investigation in Switzerland. A first-order appraisal of Switzerland’s potential for CO2 storage in the Swiss Molasse Basin identified a carbonate aquifer (Upper Muschelkalk) sealed by an evaporitic formation (Gipskeuper) as promising seal/aquifer pair. A series of laboratory measurements were carried out at the Rock Deformation Laboratory of ETH Zurich to explore in detail the physical properties in rocks from these geological formations. Permeability and seismic velocity measurements were performed simultaneously under in-situ conditions at temperatures up to 50°C and 20 MPa confining pressure. The comparison of injected Argon and CO2 in gaseous and supercritical state as pore media into dolomite samples brings new insights regarding the reservoir’s characterization. The preliminary results indicate that permeability crucially depends on temperature, confining pressure and pore pressure. Especially at in situ conditions with CO2 being at supercritical state, substantial losses in permeability to a third of the initial value have to be taken into consideration. Such experiments are critical in the framework of CO2 sequestration in order to validate current predictive injection models and seismic techniques to monitor injected CO2 into geological basins.
ABSTRACT The upper Muschelkalk saline aquifer consists of partly dolomitized to completely dolomi... more ABSTRACT The upper Muschelkalk saline aquifer consists of partly dolomitized to completely dolomitized carbonate rocks of mid Triassic age (~230 Ma). This aquifer is present throughout the Swiss Molasse Basin (SMB), north of the Alps. A regional appraisal of the SMB indicates that this Formation is a potential host aquifer for sequestered CO2. However, the spatial distribution and heterogeneity of the porosity, permeability and other relevant physical and mechanical properties of the upper Muschelkalk are still poorly known. The uncertainty in this knowledge stems mainly from the weakly developed oil and gas exploration industry in Switzerland. We use an integrated approach to better constrain the aquifer physical properties, which couples field scale geophysical surveys (borehole logging and seismic reflection profiles) with laboratory analytical data. Here we focus on a set of boreholes from northern Switzerland, where geophysical data and drill core useable for laboratory measurements are available. Two sub-units comprise the upper Muschelkalk Formation. The stratigraphically higher part is a fossiliferous dolomite (>90 vol% CaMg(CO3)2; Trigodonusdolomit). The underlying unit, is composed of micritic calcite and dolomite layers interbedded with fossil-rich layers (Hauptmuschelkalk). Although both units are part of the aquifer formation, they appear to have distinctly different physical properties. The transition from Trigodonusdolomit to the Hauptmuschelkalk is marked by an increase in the sonic velocity, density and acoustic impedance. The magnitude of increase in sonic velocity can be up to 500 m/s, accompanied by an increase in acoustic impedance from 8500 to 15500 (m/s*g/cm3), but varies between the different boreholes. Poisson's ratio, determined from a single borehole, show sharp decrease at the transition. The origin of the changes in the geophysical data is likely reflecting differences in porosity and mineral composition in the Trigodonusdolomit and Hauptmuschelkalk. The boundary between the Trigodonusdolomit and Hauptmuschelkalk is further apparent in reflection seismic lines from surveys near the boreholes. Laboratory measurements of porosity, permeability, ultrasonic velocities and triaxial strength testing were performed at conditions similar to reservoir (in situ) conditions, and when applicable at room conditions, on samples recovered from borehole drill cores. Initial laboratory measurements of porosity, ultrasonic velocities and permeability also show distinct differences between the Trigodonusdolomit and Hauptmuschelkalk. Up-scaling issues, which arise from the comparison of laboratory measurements (small sample size) to field geophysical data, are discussed. Integration of laboratory and geophysical survey data allow us to better understand porosity and permeability distribution in the upper Muschelkalk aquifer on the scale of the Swiss Molasse Basin.
The upper Muschelkalk saline aquifer consists of partly dolomitized to completely dolomitized car... more The upper Muschelkalk saline aquifer consists of partly dolomitized to completely dolomitized carbonate rocks of mid Triassic age (~230 Ma). This aquifer is present throughout the Swiss Molasse Basin (SMB), north of the Alps. A regional appraisal of the SMB indicates that this Formation is a potential host aquifer for sequestered CO2. However, the spatial distribution and heterogeneity of the porosity, permeability and other relevant physical and mechanical properties of the upper Muschelkalk are still poorly known. The uncertainty in this knowledge stems mainly from the weakly developed oil and gas exploration industry in Switzerland. We use an integrated approach to better constrain the aquifer physical properties, which couples field scale geophysical surveys (borehole logging and seismic reflection profiles) with laboratory analytical data. Here we focus on a set of boreholes from northern Switzerland, where geophysical data and drill core useable for laboratory measurements are...
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