In the light of current concerns related to induced seismicity associated with geological carbon sequestration(GCS),this paper summarizes lessons learned from recent modeling studies on fault activation,induced seismi...In the light of current concerns related to induced seismicity associated with geological carbon sequestration(GCS),this paper summarizes lessons learned from recent modeling studies on fault activation,induced seismicity,and potential for leakage associated with deep underground carbon dioxide(CO2) injection.Model simulations demonstrate that seismic events large enough to be felt by humans require brittle fault properties and continuous fault permeability allowing pressure to be distributed over a large fault patch to be ruptured at once.Heterogeneous fault properties,which are commonly encountered in faults intersecting multilayered shale/sandstone sequences,effectively reduce the likelihood of inducing felt seismicity and also effectively impede upward CO2leakage.A number of simulations show that even a sizable seismic event that could be felt may not be capable of opening a new flow path across the entire thickness of an overlying caprock and it is very unlikely to cross a system of multiple overlying caprock units.Site-specific model simulations of the In Salah CO2storage demonstration site showed that deep fractured zone responses and associated microseismicity occurred in the brittle fractured sandstone reservoir,but at a very substantial reservoir overpressure close to the magnitude of the least principal stress.We conclude by emphasizing the importance of site investigation to characterize rock properties and if at all possible to avoid brittle rock such as proximity of crystalline basement or sites in hard and brittle sedimentary sequences that are more prone to injection-induced seismicity and permanent damage.展开更多
In this paper,an elasto-plastic constitutive model is employed to capture the shear failure that may occur in a rock mass presenting mechanical discontinuities,such as faults,fractures,bedding planes or other planar w...In this paper,an elasto-plastic constitutive model is employed to capture the shear failure that may occur in a rock mass presenting mechanical discontinuities,such as faults,fractures,bedding planes or other planar weak structures.The failure may occur in two modes:a sliding failure on the weak plane or an intrinsic failure of the rock mass.The rock matrix is expected to behave elastically or fail in a brittle manner,being represented by a non-associated Mohr-Coulomb behavior,while the sliding failure is represented by the evaluation of the Coulomb criterion on an explicitly defined plane.Failure may furthermore affect the hydraulic properties of the rock mass:the shearing of the weakness plane may create a transmissive fluid pathway.Verification of the mechanical submodel is conducted by comparison with an analytical solution,while the coupled hydro-mechanical behavior is validated with field data and will be applied within a model and code validation initiative.The work presented here aims at documenting the progress in code development,while accurate match of the field data with the numerical results is current work in progress.展开更多
In this work,an approach is developed to study the seismicity associated with the impoundment and level changes of a water reservoir(reservoir induced seismicity e RIS).The proposed methodology features a combination ...In this work,an approach is developed to study the seismicity associated with the impoundment and level changes of a water reservoir(reservoir induced seismicity e RIS).The proposed methodology features a combination of a semi-analytical poroelastic model with an earthquake nucleation approach based on rate-and-state frictional law.The combined approach was applied to the case of the Pertusillo Lake,located in the Val d’Agri area(Italy),whose large seasonal water level changes are believed to induce protracted micro-seismicity(local magnitude ML<3).Results show that the lake impoundment in 1962 could have produced up to 0.5 bar(1 bar=100 kPa)changes in Coulomb failure stress(DCFS),while the seasonal water level variation is responsible for variation up to 0.05 bar.Modeling results of the seismicity rates in 20012014 show that the observed earthquakes are well correlated with the modeled DCFS.Finally,the reason that the seismicity is only observed at southwest of the Pertusillo Lake is provided,which is likely attributed to different rock lithologies and depletion caused by significant hydrocarbon exploitation in the northeastern sector of the lake.展开更多
基金funded by the Assistant Secretary for Fossil Energy,National Energy Technology Laboratory,National Risk Assessment Partnership of the U.S. Department of Energy under Contract No.DEAC02-05CH11231a Swiss National Science Foundation(SNSF) Ambizione Energy grant(PZENP2_160555)
文摘In the light of current concerns related to induced seismicity associated with geological carbon sequestration(GCS),this paper summarizes lessons learned from recent modeling studies on fault activation,induced seismicity,and potential for leakage associated with deep underground carbon dioxide(CO2) injection.Model simulations demonstrate that seismic events large enough to be felt by humans require brittle fault properties and continuous fault permeability allowing pressure to be distributed over a large fault patch to be ruptured at once.Heterogeneous fault properties,which are commonly encountered in faults intersecting multilayered shale/sandstone sequences,effectively reduce the likelihood of inducing felt seismicity and also effectively impede upward CO2leakage.A number of simulations show that even a sizable seismic event that could be felt may not be capable of opening a new flow path across the entire thickness of an overlying caprock and it is very unlikely to cross a system of multiple overlying caprock units.Site-specific model simulations of the In Salah CO2storage demonstration site showed that deep fractured zone responses and associated microseismicity occurred in the brittle fractured sandstone reservoir,but at a very substantial reservoir overpressure close to the magnitude of the least principal stress.We conclude by emphasizing the importance of site investigation to characterize rock properties and if at all possible to avoid brittle rock such as proximity of crystalline basement or sites in hard and brittle sedimentary sequences that are more prone to injection-induced seismicity and permanent damage.
基金the DECOVALEX-2019 funding organisations of Andra,BGR/UFZ,CNSC,US DOE,ENSI,JAEA,IRSN,KAERI,NWMO,RWM,SURAO,SSM and Taipower for their financial and technical support of the work described in this paper。
文摘In this paper,an elasto-plastic constitutive model is employed to capture the shear failure that may occur in a rock mass presenting mechanical discontinuities,such as faults,fractures,bedding planes or other planar weak structures.The failure may occur in two modes:a sliding failure on the weak plane or an intrinsic failure of the rock mass.The rock matrix is expected to behave elastically or fail in a brittle manner,being represented by a non-associated Mohr-Coulomb behavior,while the sliding failure is represented by the evaluation of the Coulomb criterion on an explicitly defined plane.Failure may furthermore affect the hydraulic properties of the rock mass:the shearing of the weakness plane may create a transmissive fluid pathway.Verification of the mechanical submodel is conducted by comparison with an analytical solution,while the coupled hydro-mechanical behavior is validated with field data and will be applied within a model and code validation initiative.The work presented here aims at documenting the progress in code development,while accurate match of the field data with the numerical results is current work in progress.
基金funded by a research agreement between the Swiss Seismological Service(SED)and the Istituto Nazionale di Geofisica e Vulcanologiathe RISE project under the European Union’s Horizon 2020 research and innovation programme(Grant No.821115)financed by a SNSF Ambizione Energy grant(PZENP2160555)。
文摘In this work,an approach is developed to study the seismicity associated with the impoundment and level changes of a water reservoir(reservoir induced seismicity e RIS).The proposed methodology features a combination of a semi-analytical poroelastic model with an earthquake nucleation approach based on rate-and-state frictional law.The combined approach was applied to the case of the Pertusillo Lake,located in the Val d’Agri area(Italy),whose large seasonal water level changes are believed to induce protracted micro-seismicity(local magnitude ML<3).Results show that the lake impoundment in 1962 could have produced up to 0.5 bar(1 bar=100 kPa)changes in Coulomb failure stress(DCFS),while the seasonal water level variation is responsible for variation up to 0.05 bar.Modeling results of the seismicity rates in 20012014 show that the observed earthquakes are well correlated with the modeled DCFS.Finally,the reason that the seismicity is only observed at southwest of the Pertusillo Lake is provided,which is likely attributed to different rock lithologies and depletion caused by significant hydrocarbon exploitation in the northeastern sector of the lake.