To quantify the relative contributions of Arctic sea ice and unforced atmospheric internal variability to the “warm Arctic, cold East Asia”(WACE) teleconnection, this study analyses three sets of large-ensemble simu...To quantify the relative contributions of Arctic sea ice and unforced atmospheric internal variability to the “warm Arctic, cold East Asia”(WACE) teleconnection, this study analyses three sets of large-ensemble simulations carried out by the Norwegian Earth System Model with a coupled atmosphere–land surface model, forced by seasonal sea ice conditions from preindustrial, present-day, and future periods. Each ensemble member within the same set uses the same forcing but with small perturbations to the atmospheric initial state. Hence, the difference between the present-day(or future) ensemble mean and the preindustrial ensemble mean provides the ice-loss-induced response, while the difference of the individual members within the present-day(or future) set is the effect of atmospheric internal variability. Results indicate that both present-day and future sea ice loss can force a negative phase of the Arctic Oscillation with a WACE pattern in winter. The magnitude of ice-induced Arctic warming is over four(ten) times larger than the ice-induced East Asian cooling in the present-day(future) experiment;the latter having a magnitude that is about 30% of the observed cooling. Sea ice loss contributes about 60%(80%) to the Arctic winter warming in the present-day(future) experiment. Atmospheric internal variability can also induce a WACE pattern with comparable magnitudes between the Arctic and East Asia. Ice-lossinduced East Asian cooling can easily be masked by atmospheric internal variability effects because random atmospheric internal variability may induce a larger magnitude warming. The observed WACE pattern occurs as a result of both Arctic sea ice loss and atmospheric internal variability, with the former dominating Arctic warming and the latter dominating East Asian cooling.展开更多
The atmospheric carbon dioxide(CO_(2))concentration has been increasing rapidly since the Industrial Revolution,which has led to unequivocal global warming and crucial environmental change.It is extremely important to...The atmospheric carbon dioxide(CO_(2))concentration has been increasing rapidly since the Industrial Revolution,which has led to unequivocal global warming and crucial environmental change.It is extremely important to investigate the interactions among atmospheric CO_(2),the physical climate system,and the carbon cycle of the underlying surface for a better understanding of the Earth system.Earth system models are widely used to investigate these interactions via coupled carbon-climate simulations.The Chinese Academy of Sciences Earth System Model version 2(CAS-ESM2.0)has successfully fixed a two-way coupling of atmospheric CO_(2)with the climate and carbon cycle on land and in the ocean.Using CAS-ESM2.0,we conducted a coupled carbon-climate simulation by following the CMIP6 proposal of a historical emissions-driven experiment.This paper examines the modeled CO_(2)by comparison with observed CO_(2)at the sites of Mauna Loa and Barrow,and the Greenhouse Gases Observing Satellite(GOSAT)CO_(2)product.The results showed that CAS-ESM2.0 agrees very well with observations in reproducing the increasing trend of annual CO_(2)during the period 1850-2014,and in capturing the seasonal cycle of CO_(2)at the two baseline sites,as well as over northern high latitudes.These agreements illustrate a good ability of CAS-ESM2.0 in simulating carbon-climate interactions,even though uncertainties remain in the processes involved.This paper reports an important stage of the development of CAS-ESM with the coupling of carbon and climate,which will provide significant scientific support for climate research and China’s goal of carbon neutrality.展开更多
Mineral carbonation, which precipitates dissolved carbon dioxide(CO_(2)) as carbonate minerals in basaltic groundwater environments, is a potential technique for negative emissions. The Leizhou Peninsula in southwest ...Mineral carbonation, which precipitates dissolved carbon dioxide(CO_(2)) as carbonate minerals in basaltic groundwater environments, is a potential technique for negative emissions. The Leizhou Peninsula in southwest Guangdong province has extensive basalt, indicating a promising potential for CO_(2) storage through rapid mineralization. However, understanding of the basic geological setting, potential, and mechanisms of CO_(2) mineralization in the basalts of the Leizhou Peninsula is still limited. The mineralization processes associated with CO_(2)storage at two candidate sites in the area are investigated in this paper: Yongshi Farm and Tianyang Basin(of the dried maar lake). Petrography,rock geochemistry, basalt petrophysical properties, and groundwater hydrochemistry analyses are included in the study. Numerical simulation is used to examine the reaction process and its effects. The results show that basalts in the study areas mainly comprise plagioclase, pyroxene, and Fe–Ti oxides, revealing a total volume fraction exceeding 85%. Additionally, small amounts of quartz and fayalite are available, with volume fractions of 5.1% and 1.0%, respectively. The basalts are rich in divalent metal cations, which can form carbonate minerals, with an average of approximately 6.2 moles of metal cations per 1 kg of rock. The groundwater samples have a pH of 7.5–8.2 and are dominated by the Mg–Ca–HCO3 type. The basalts demonstrate a porosity range of 10.9% to 28.8%, with over 70% of interconnected pores. A 20-year geochemical simulation revealed that CO_(2) injection dissolves primary minerals, including anorthite, albite, and diopside, while CO_(2)mineralization dissolves precipitation secondary minerals, such as calcite, siderite, and dolomite. Furthermore, a substantial rise in pH from 7.6to 10.6 is observed in the vicinity of the injected well, accompanied by a slight reduction in porosity from 20% to 19.8%. Additionally, 36.8% of the injected CO_(2) underwent complete mineralization within five years, revealing an increasing percentage of 66.1% if the experimental period is extended to 20 years. The presence of abundant divalent metal cations in basalts and water-bearing permeable rocks in the Leizhou Peninsula supports the potential for mineral carbonation in basalts, as indicated by the geochemical simulation results. Additional research is necessary to identify the factors that influence the CO_(2) mineralization, storage, and sensitivity analysis of basalt in the Leizhou Peninsula.展开更多
Asphaltene deposition is a significant problem during gas injection processes,as it can block the porous medium,the wellbore,and the involved facilities,significantly impacting reservoir productivity and ultimate oil re...Asphaltene deposition is a significant problem during gas injection processes,as it can block the porous medium,the wellbore,and the involved facilities,significantly impacting reservoir productivity and ultimate oil recovery.Only a few studies have investigated the numerical modeling of this potential effect in porous media.This study focuses on asphaltene deposition due to natural gas and CO_(2) injection.Predictions of the effect of gas injection on asphaltene deposition behavior have been made using a 3D numerical simulation model.The results indicate that the injection of natural gas exacerbates asphaltene deposition,leading to a significant reduction in permeability near the injection well and throughout the reservoir.This reduction in permeability strongly affects the ability of gas toflow through the reservoir,resulting in an improvement of the displacement front.The displacement effi-ciency of the injection gas process increases by up to 1.40%when gas is injected at 5500 psi,compared to the scenario where the asphaltene model is not considered.CO_(2) injection leads to a miscible process with crude oil,extracting light and intermediate components,which intensifies asphaltene precipitation and increases the viscosity of the remaining crude oil,ultimately reducing the recovery rate.展开更多
Gravity assistance is a critical factor influencing CO_(2)-Oil mixing and miscible flow during EOR and CO_(2)geological storage.Based on the Navier-Stokes equation,component mass conservation equation,and fluid proper...Gravity assistance is a critical factor influencing CO_(2)-Oil mixing and miscible flow during EOR and CO_(2)geological storage.Based on the Navier-Stokes equation,component mass conservation equation,and fluid property-composition relationship,a mathematical model for pore-scale CO_(2) injection in oilsaturated porous media was developed in this study.The model can reflect the effects of gravity assistance,component diffusion,fluid density variation,and velocity change on EOR and CO_(2) storage.For nonhomogeneous porous media,the gravity influence and large density difference help to minimize the velocity difference between the main flow path and the surrounding area,thus improving the oil recovery and CO_(2) storage.Large CO_(2) injection angles and oil-CO_(2) density differences can increase the oil recovery by 22.6% and 4.2%,respectively,and increase CO_(2) storage by 37.9% and 4.7%,respectively.Component diffusion facilitates the transportation of the oil components from the low-velocity region to the main flow path,thereby reducing the oil/CO_(2) concentration difference within the porous media.Component diffusion can increase oil recovery and CO_(2) storage by 5.7% and 6.9%,respectively.In addition,combined with the component diffusion,a low CO_(2) injection rate creates a more uniform spatial distribution of the oil/CO_(2) component,resulting in increases of 9.5% oil recovery and 15.7% CO_(2) storage,respectively.This study provides theoretical support for improving the geological CO_(2) storage and EOR processes.展开更多
This work systematically reviews the complex mechanisms of CO_(2)-water-rock interactions,microscopic simulations of reactive transport(dissolution,precipitation and precipitate migration)in porous media,and microscop...This work systematically reviews the complex mechanisms of CO_(2)-water-rock interactions,microscopic simulations of reactive transport(dissolution,precipitation and precipitate migration)in porous media,and microscopic simulations of CO_(2)-water-rock system.The work points out the key issues in current research and provides suggestions for future research.After injection of CO_(2) into underground reservoirs,not only conventional pressure-driven flow and mass transfer processes occur,but also special physicochemical phenomena like dissolution,precipitation,and precipitate migration.The coupling of these processes causes complex changes in permeability and porosity parameters of the porous media.Pore-scale microscopic flow simulations can provide detailed information within the three-dimensional pore and throat space and explicitly observe changes in the fluid-solid interfaces of porous media during reactions.At present,the research has limitations in the decoupling of complex mechanisms,characterization of differential multi-mineral reactions,precipitation generation mechanisms and characterization(crystal nucleation and mineral detachment),simulation methods for precipitation-fluid interaction,and coupling mechanisms of multiple physicochemical processes.In future studies,it is essential to innovate experimental methods to decouple“dissolution-precipitation-precipitate migration”processes,improve the accuracy of experimental testing of minerals geochemical reaction-related parameters,build reliable characterization of various precipitation types,establish precipitation-fluid interaction simulation methods,coordinate the boundary conditions of different physicochemical processes,and,finally,achieve coupled flow simulation of“dissolution-precipitation-precipitate migration”within CO_(2)-water-rock systems.展开更多
简单介绍MANET(Mobile Ad hoc Network)路由协议后,提出定量评估MANET路由协议性能的六个基本指标。基于网络仿真器NS-2阐述了评估和测试路由协议性能的仿真模型及数据结果的分析方法,并给出仿真实例及其分析。结果表明,模型仿真结果接...简单介绍MANET(Mobile Ad hoc Network)路由协议后,提出定量评估MANET路由协议性能的六个基本指标。基于网络仿真器NS-2阐述了评估和测试路由协议性能的仿真模型及数据结果的分析方法,并给出仿真实例及其分析。结果表明,模型仿真结果接近理论分析和实际情况,该性能评估方法有较强的实用性和通用性。展开更多
基金supported by the Chinese-Norwegian Collaboration Projects within Climate Systems jointly funded by the National Key Research and Development Program of China (Grant No.2022YFE0106800)the Research Council of Norway funded project MAPARC (Grant No.328943)+2 种基金the support from the Research Council of Norway funded project BASIC (Grant No.325440)the Horizon 2020 project APPLICATE (Grant No.727862)High-performance computing and storage resources were performed on resources provided by Sigma2 - the National Infrastructure for High-Performance Computing and Data Storage in Norway (through projects NS8121K,NN8121K,NN2345K,NS2345K,NS9560K,NS9252K,and NS9034K)。
文摘To quantify the relative contributions of Arctic sea ice and unforced atmospheric internal variability to the “warm Arctic, cold East Asia”(WACE) teleconnection, this study analyses three sets of large-ensemble simulations carried out by the Norwegian Earth System Model with a coupled atmosphere–land surface model, forced by seasonal sea ice conditions from preindustrial, present-day, and future periods. Each ensemble member within the same set uses the same forcing but with small perturbations to the atmospheric initial state. Hence, the difference between the present-day(or future) ensemble mean and the preindustrial ensemble mean provides the ice-loss-induced response, while the difference of the individual members within the present-day(or future) set is the effect of atmospheric internal variability. Results indicate that both present-day and future sea ice loss can force a negative phase of the Arctic Oscillation with a WACE pattern in winter. The magnitude of ice-induced Arctic warming is over four(ten) times larger than the ice-induced East Asian cooling in the present-day(future) experiment;the latter having a magnitude that is about 30% of the observed cooling. Sea ice loss contributes about 60%(80%) to the Arctic winter warming in the present-day(future) experiment. Atmospheric internal variability can also induce a WACE pattern with comparable magnitudes between the Arctic and East Asia. Ice-lossinduced East Asian cooling can easily be masked by atmospheric internal variability effects because random atmospheric internal variability may induce a larger magnitude warming. The observed WACE pattern occurs as a result of both Arctic sea ice loss and atmospheric internal variability, with the former dominating Arctic warming and the latter dominating East Asian cooling.
基金the National Key Research and Development Program of China(Grant No.2022YFE0106500)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.2022076)+1 种基金the National Key Scientific and Technological Infrastructure project“Earth System Numerical Simulation Facility”(EarthLab2023-EL-ZD-00012)。
文摘The atmospheric carbon dioxide(CO_(2))concentration has been increasing rapidly since the Industrial Revolution,which has led to unequivocal global warming and crucial environmental change.It is extremely important to investigate the interactions among atmospheric CO_(2),the physical climate system,and the carbon cycle of the underlying surface for a better understanding of the Earth system.Earth system models are widely used to investigate these interactions via coupled carbon-climate simulations.The Chinese Academy of Sciences Earth System Model version 2(CAS-ESM2.0)has successfully fixed a two-way coupling of atmospheric CO_(2)with the climate and carbon cycle on land and in the ocean.Using CAS-ESM2.0,we conducted a coupled carbon-climate simulation by following the CMIP6 proposal of a historical emissions-driven experiment.This paper examines the modeled CO_(2)by comparison with observed CO_(2)at the sites of Mauna Loa and Barrow,and the Greenhouse Gases Observing Satellite(GOSAT)CO_(2)product.The results showed that CAS-ESM2.0 agrees very well with observations in reproducing the increasing trend of annual CO_(2)during the period 1850-2014,and in capturing the seasonal cycle of CO_(2)at the two baseline sites,as well as over northern high latitudes.These agreements illustrate a good ability of CAS-ESM2.0 in simulating carbon-climate interactions,even though uncertainties remain in the processes involved.This paper reports an important stage of the development of CAS-ESM with the coupling of carbon and climate,which will provide significant scientific support for climate research and China’s goal of carbon neutrality.
基金funded by the National Natural Science Foundation of China (U1901217)Guangdong Basic and Applied Basic Research Foundation (2021A1515011298)+1 种基金the National Key R&D Program of China (2021YFF0501202)Special Fund of South China Sea Institute of Oceanology of the Chinese Academy of Sciences (SCSIO2023QY06)。
文摘Mineral carbonation, which precipitates dissolved carbon dioxide(CO_(2)) as carbonate minerals in basaltic groundwater environments, is a potential technique for negative emissions. The Leizhou Peninsula in southwest Guangdong province has extensive basalt, indicating a promising potential for CO_(2) storage through rapid mineralization. However, understanding of the basic geological setting, potential, and mechanisms of CO_(2) mineralization in the basalts of the Leizhou Peninsula is still limited. The mineralization processes associated with CO_(2)storage at two candidate sites in the area are investigated in this paper: Yongshi Farm and Tianyang Basin(of the dried maar lake). Petrography,rock geochemistry, basalt petrophysical properties, and groundwater hydrochemistry analyses are included in the study. Numerical simulation is used to examine the reaction process and its effects. The results show that basalts in the study areas mainly comprise plagioclase, pyroxene, and Fe–Ti oxides, revealing a total volume fraction exceeding 85%. Additionally, small amounts of quartz and fayalite are available, with volume fractions of 5.1% and 1.0%, respectively. The basalts are rich in divalent metal cations, which can form carbonate minerals, with an average of approximately 6.2 moles of metal cations per 1 kg of rock. The groundwater samples have a pH of 7.5–8.2 and are dominated by the Mg–Ca–HCO3 type. The basalts demonstrate a porosity range of 10.9% to 28.8%, with over 70% of interconnected pores. A 20-year geochemical simulation revealed that CO_(2) injection dissolves primary minerals, including anorthite, albite, and diopside, while CO_(2)mineralization dissolves precipitation secondary minerals, such as calcite, siderite, and dolomite. Furthermore, a substantial rise in pH from 7.6to 10.6 is observed in the vicinity of the injected well, accompanied by a slight reduction in porosity from 20% to 19.8%. Additionally, 36.8% of the injected CO_(2) underwent complete mineralization within five years, revealing an increasing percentage of 66.1% if the experimental period is extended to 20 years. The presence of abundant divalent metal cations in basalts and water-bearing permeable rocks in the Leizhou Peninsula supports the potential for mineral carbonation in basalts, as indicated by the geochemical simulation results. Additional research is necessary to identify the factors that influence the CO_(2) mineralization, storage, and sensitivity analysis of basalt in the Leizhou Peninsula.
基金funded by CNOOC Production Research Project(CCL2022SZPS0076).
文摘Asphaltene deposition is a significant problem during gas injection processes,as it can block the porous medium,the wellbore,and the involved facilities,significantly impacting reservoir productivity and ultimate oil recovery.Only a few studies have investigated the numerical modeling of this potential effect in porous media.This study focuses on asphaltene deposition due to natural gas and CO_(2) injection.Predictions of the effect of gas injection on asphaltene deposition behavior have been made using a 3D numerical simulation model.The results indicate that the injection of natural gas exacerbates asphaltene deposition,leading to a significant reduction in permeability near the injection well and throughout the reservoir.This reduction in permeability strongly affects the ability of gas toflow through the reservoir,resulting in an improvement of the displacement front.The displacement effi-ciency of the injection gas process increases by up to 1.40%when gas is injected at 5500 psi,compared to the scenario where the asphaltene model is not considered.CO_(2) injection leads to a miscible process with crude oil,extracting light and intermediate components,which intensifies asphaltene precipitation and increases the viscosity of the remaining crude oil,ultimately reducing the recovery rate.
基金The project supported by National Natural Science Foundation of China(No.51991364,51974347)the Major Scientific and Technological Projects of CNPC under Grant ZD2019-184-002。
文摘Gravity assistance is a critical factor influencing CO_(2)-Oil mixing and miscible flow during EOR and CO_(2)geological storage.Based on the Navier-Stokes equation,component mass conservation equation,and fluid property-composition relationship,a mathematical model for pore-scale CO_(2) injection in oilsaturated porous media was developed in this study.The model can reflect the effects of gravity assistance,component diffusion,fluid density variation,and velocity change on EOR and CO_(2) storage.For nonhomogeneous porous media,the gravity influence and large density difference help to minimize the velocity difference between the main flow path and the surrounding area,thus improving the oil recovery and CO_(2) storage.Large CO_(2) injection angles and oil-CO_(2) density differences can increase the oil recovery by 22.6% and 4.2%,respectively,and increase CO_(2) storage by 37.9% and 4.7%,respectively.Component diffusion facilitates the transportation of the oil components from the low-velocity region to the main flow path,thereby reducing the oil/CO_(2) concentration difference within the porous media.Component diffusion can increase oil recovery and CO_(2) storage by 5.7% and 6.9%,respectively.In addition,combined with the component diffusion,a low CO_(2) injection rate creates a more uniform spatial distribution of the oil/CO_(2) component,resulting in increases of 9.5% oil recovery and 15.7% CO_(2) storage,respectively.This study provides theoretical support for improving the geological CO_(2) storage and EOR processes.
基金Supported by the National Natural Science Foundation of China(52234003,52222402,52304044).
文摘This work systematically reviews the complex mechanisms of CO_(2)-water-rock interactions,microscopic simulations of reactive transport(dissolution,precipitation and precipitate migration)in porous media,and microscopic simulations of CO_(2)-water-rock system.The work points out the key issues in current research and provides suggestions for future research.After injection of CO_(2) into underground reservoirs,not only conventional pressure-driven flow and mass transfer processes occur,but also special physicochemical phenomena like dissolution,precipitation,and precipitate migration.The coupling of these processes causes complex changes in permeability and porosity parameters of the porous media.Pore-scale microscopic flow simulations can provide detailed information within the three-dimensional pore and throat space and explicitly observe changes in the fluid-solid interfaces of porous media during reactions.At present,the research has limitations in the decoupling of complex mechanisms,characterization of differential multi-mineral reactions,precipitation generation mechanisms and characterization(crystal nucleation and mineral detachment),simulation methods for precipitation-fluid interaction,and coupling mechanisms of multiple physicochemical processes.In future studies,it is essential to innovate experimental methods to decouple“dissolution-precipitation-precipitate migration”processes,improve the accuracy of experimental testing of minerals geochemical reaction-related parameters,build reliable characterization of various precipitation types,establish precipitation-fluid interaction simulation methods,coordinate the boundary conditions of different physicochemical processes,and,finally,achieve coupled flow simulation of“dissolution-precipitation-precipitate migration”within CO_(2)-water-rock systems.
文摘简单介绍MANET(Mobile Ad hoc Network)路由协议后,提出定量评估MANET路由协议性能的六个基本指标。基于网络仿真器NS-2阐述了评估和测试路由协议性能的仿真模型及数据结果的分析方法,并给出仿真实例及其分析。结果表明,模型仿真结果接近理论分析和实际情况,该性能评估方法有较强的实用性和通用性。
