Air pollution poses a health hazard in all countries.However,complete data on ambient particulate matter(PM)concentrations are not available in all world regions.Reanalysis data is already a valuable source of exposur...Air pollution poses a health hazard in all countries.However,complete data on ambient particulate matter(PM)concentrations are not available in all world regions.Reanalysis data is already a valuable source of exposure data in epidemiological studies examining the relationship between temperature and health.Nevertheless,the performance of reanalysis data in assessing the short-term health effects of particulate air pollution remains unclear.We assessed the performance of CAMS reanalysis(EAC4)data from the European Centre for Medium-Range Weather Forecasts,compared with daily PM concentrations from field monitoring stations,to estimate short-term exposure to PM with an aerodynamic diameter less than 10μm(PM_(10))on daily mortality in 33 Spanish provincial capital cities using a two-stage time series regression design.The shape of the PM_(10)distribution varied substantially between PM observations and CAMS global reanalysis of atmospheric composition(EAC4)reanalysis data,with correlation ranging from 0.21 to 0.58.The pooled mortality risk for a 10μg/m^(3)increase in PM_(10)showed similar estimates using PM concentrations{relative risks(RR)=1.007,95%confidence intervals(95%CI)=[1.002,1.011]}and EAC4 reanalysis data(RR=1.011,95%CI=[1.006,1.015]).However,the city-specific PM_(10)beta coefficients estimated using PM concentrations and EAC4 reanalysis data showed a low correlation(r=0.22).The use of reanalysis data should be approached with caution when assessing the association between particulate matter air pollution and health outcomes,particularly in cities with small populations.展开更多
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
Geo-energy and geo-engineering applications,such as improved oil recovery(IOR),geologic carbon storage,and enhanced geothermal systems(EGSs),involve coupled thermo-hydro-mechanical(THM)processes that result from fluid...Geo-energy and geo-engineering applications,such as improved oil recovery(IOR),geologic carbon storage,and enhanced geothermal systems(EGSs),involve coupled thermo-hydro-mechanical(THM)processes that result from fluid injection and production.In some cases,reservoirs are highly fractured and the geomechanical response is controlled by fractures.Therefore,fractures should explicitly be included into numerical models to realistically simulate the THM responses of the subsurface.In this study,we perform coupled THM numerical simulations of water injection into naturally fractured reservoirs(NFRs)using CODE_BRIGHT and TOUGH-UDEC codes.CODE_BRIGHT is a finite element method(FEM)code that performs fully coupled THM analysis in geological media and TOUGH-UDEC sequentially solves coupled THM processes by combining a finite volume method(FVM)code that solves nonisothermal multiphase flow(TOUGH2)with a distinct element method(DEM)code that solves the mechanical problem(UDEC).First,we validate the two codes against a semi-analytical solution for water injection into a single deformable fracture considering variable permeability based on the cubic law.Then,we compare simulation results of the two codes in an idealized conceptual model that includes one horizontal fracture and in a more realistic model with multiple fractures.Each code models fractures differently.UDEC calculates fracture deformation from the fracture normal and shear stiffnesses,while CODE_BRIGHT treats fractures as equivalent porous media and uses the equivalent Young’s modulus and Poisson’s ratio of the fracture.Finally,we obtain comparable results of pressure,temperature,stress and displacement distributions and evolutions for the single horizontal fracture model.Despite some similarities,the two codes provide increasingly different results as model complexity increases.These differences highlight the challenging task of accurately modeling coupled THM processes in fractured media given their high nonlinearity.展开更多
文摘Air pollution poses a health hazard in all countries.However,complete data on ambient particulate matter(PM)concentrations are not available in all world regions.Reanalysis data is already a valuable source of exposure data in epidemiological studies examining the relationship between temperature and health.Nevertheless,the performance of reanalysis data in assessing the short-term health effects of particulate air pollution remains unclear.We assessed the performance of CAMS reanalysis(EAC4)data from the European Centre for Medium-Range Weather Forecasts,compared with daily PM concentrations from field monitoring stations,to estimate short-term exposure to PM with an aerodynamic diameter less than 10μm(PM_(10))on daily mortality in 33 Spanish provincial capital cities using a two-stage time series regression design.The shape of the PM_(10)distribution varied substantially between PM observations and CAMS global reanalysis of atmospheric composition(EAC4)reanalysis data,with correlation ranging from 0.21 to 0.58.The pooled mortality risk for a 10μg/m^(3)increase in PM_(10)showed similar estimates using PM concentrations{relative risks(RR)=1.007,95%confidence intervals(95%CI)=[1.002,1.011]}and EAC4 reanalysis data(RR=1.011,95%CI=[1.006,1.015]).However,the city-specific PM_(10)beta coefficients estimated using PM concentrations and EAC4 reanalysis data showed a low correlation(r=0.22).The use of reanalysis data should be approached with caution when assessing the association between particulate matter air pollution and health outcomes,particularly in cities with small populations.
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financial support received from the“Iran’s Ministry of Science Research and Technology”(PhD students’sabbatical grants)funding from the European Research Council under the European Union’s Horizon 2020 Research and Innovation Program through the Starting Grant GEoREST(www.georest.eu)(Grant Agreement No.801809)+1 种基金support by the Korea-EU Joint Research Program of the National Research Foundation of Korea through Grant No.NRF2015K1A3A7A03074226funded by the Korean Government’s Ministry of Science and Information and Communication Technology(ICT)in the framework of the European Union’s Horizon 2020 Research and Innovation Program(Grant No.691728)。
文摘Geo-energy and geo-engineering applications,such as improved oil recovery(IOR),geologic carbon storage,and enhanced geothermal systems(EGSs),involve coupled thermo-hydro-mechanical(THM)processes that result from fluid injection and production.In some cases,reservoirs are highly fractured and the geomechanical response is controlled by fractures.Therefore,fractures should explicitly be included into numerical models to realistically simulate the THM responses of the subsurface.In this study,we perform coupled THM numerical simulations of water injection into naturally fractured reservoirs(NFRs)using CODE_BRIGHT and TOUGH-UDEC codes.CODE_BRIGHT is a finite element method(FEM)code that performs fully coupled THM analysis in geological media and TOUGH-UDEC sequentially solves coupled THM processes by combining a finite volume method(FVM)code that solves nonisothermal multiphase flow(TOUGH2)with a distinct element method(DEM)code that solves the mechanical problem(UDEC).First,we validate the two codes against a semi-analytical solution for water injection into a single deformable fracture considering variable permeability based on the cubic law.Then,we compare simulation results of the two codes in an idealized conceptual model that includes one horizontal fracture and in a more realistic model with multiple fractures.Each code models fractures differently.UDEC calculates fracture deformation from the fracture normal and shear stiffnesses,while CODE_BRIGHT treats fractures as equivalent porous media and uses the equivalent Young’s modulus and Poisson’s ratio of the fracture.Finally,we obtain comparable results of pressure,temperature,stress and displacement distributions and evolutions for the single horizontal fracture model.Despite some similarities,the two codes provide increasingly different results as model complexity increases.These differences highlight the challenging task of accurately modeling coupled THM processes in fractured media given their high nonlinearity.
