The study presents a comprehensive coupled thermo-bio-chemo-hydraulic(T-BCH)modeling framework for stabilizing soils using microbially induced calcite precipitation(MICP).The numerical model considers relevant multiph...The study presents a comprehensive coupled thermo-bio-chemo-hydraulic(T-BCH)modeling framework for stabilizing soils using microbially induced calcite precipitation(MICP).The numerical model considers relevant multiphysics involved in MICP,such as bacterial ureolytic activities,biochemical reactions,multiphase and multicomponent transport,and alteration of the porosity and permeability.The model incorporates multiphysical coupling effects through well-established constitutive relations that connect parameters and variables from different physical fields.It was implemented in the open-source finite element code OpenGeoSys(OGS),and a semi-staggered solution strategy was designed to solve the couplings,allowing for flexible model settings.Therefore,the developed model can be easily adapted to simulate MICP applications in different scenarios.The numerical model was employed to analyze the effect of various factors,including temperature,injection strategies,and application scales.Besides,a TBCH modeling study was conducted on the laboratory-scale domain to analyze the effects of temperature on urease activity and precipitated calcium carbonate.To understand the scale dependency of MICP treatment,a large-scale heterogeneous domain was subjected to variable biochemical injection strategies.The simulations conducted at the field-scale guided the selection of an injection strategy to achieve the desired type and amount of precipitation.Additionally,the study emphasized the potential of numerical models as reliable tools for optimizing future developments in field-scale MICP treatment.The present study demonstrates the potential of this numerical framework for designing and optimizing the MICP applications in laboratory-,prototype-,and field-scale scenarios.展开更多
The sealing capacity of caprock is critical for preventing CO_(2)migration and ensuring the safety of geological storage.However,existing research lacks a comprehensive overview of its sealing mechanisms and failure r...The sealing capacity of caprock is critical for preventing CO_(2)migration and ensuring the safety of geological storage.However,existing research lacks a comprehensive overview of its sealing mechanisms and failure risks.Here,recent findings on caprock sealing mechanisms,its influencing factors,failure risks,and evaluation methods are summarized.The main results include the following:(i)Caprock sealing mechanisms include capillary,hydraulic,hydrocarbon concentration,and hydrate sealing.(ii)Capillary and hydrate sealing block fluid-phase CO_(2),hydrocarbon concentration sealing prevents diffusive CO_(2),and hydraulic sealing prevents fluid and water-soluble phases.(iii)The sealing capacity is influenced by the storage site,stratigraphic environment,and caprock properties,with breakthrough pressure ranked as follows:gypsum rock>salt rock>mudstone/shale>limestone>silty mudstone.(iv)Diffusion leakage occurs when the diffusion coefficients is less than 10^(-12)m^(2)/s,the seepage leakage ranges between 10^(-8)m^(2)/s and 10^(-12)m^(2)/s,and the fracture leakage is greater than 10^(-8)m^(2)/s.(v)Hydro-mechanical(HM)coupling mechanisms,including CO_(2)diffusion,breakthrough migration,uplift deformation,and fracture flow,are essential for leakage risk simulations.Future research should address sealing mechanisms under complex conditions,define leakage risk thresholds,optimize multiphysical coupling computations,and implement effective engineering solutions to mitigate leakage risk.展开更多
本文针对高压直流输电(high-voltage direct current,HVDC)工程中交流滤波电容器桥差保护电流表测量值异常偏大的问题展开研究。理论分析与现场实测表明,因电流表测量导线与电容器塔、导线与地面以及导线之间存在杂散电容,且导线对地布...本文针对高压直流输电(high-voltage direct current,HVDC)工程中交流滤波电容器桥差保护电流表测量值异常偏大的问题展开研究。理论分析与现场实测表明,因电流表测量导线与电容器塔、导线与地面以及导线之间存在杂散电容,且导线对地布线存在物理不对称,引起差模干扰,导致不平衡电流测量值大于真实值。研究建立了杂散电容的等效电路模型,推导了测量误差的计算公式,并分析了杂散电容对测量结果的影响程度。为精确量化杂散电容参数,基于COMSOL Multiphysics软件构建了电容器塔与测量导线的高保真三维静电场模型,为误差分析提供了关键输入。最后结合新疆哈密某±800 kV特高压直流工程实例,通过现场试验验证了理论分析的正确性,并提出以采集电压替代电流的方案,实现不平衡电流的等效测量。展开更多
基金support from the OpenGeoSys communitypartially funded by the Prime Minister Research Fellowship,Ministry of Education,Government of India with the project number SB21221901CEPMRF008347.
文摘The study presents a comprehensive coupled thermo-bio-chemo-hydraulic(T-BCH)modeling framework for stabilizing soils using microbially induced calcite precipitation(MICP).The numerical model considers relevant multiphysics involved in MICP,such as bacterial ureolytic activities,biochemical reactions,multiphase and multicomponent transport,and alteration of the porosity and permeability.The model incorporates multiphysical coupling effects through well-established constitutive relations that connect parameters and variables from different physical fields.It was implemented in the open-source finite element code OpenGeoSys(OGS),and a semi-staggered solution strategy was designed to solve the couplings,allowing for flexible model settings.Therefore,the developed model can be easily adapted to simulate MICP applications in different scenarios.The numerical model was employed to analyze the effect of various factors,including temperature,injection strategies,and application scales.Besides,a TBCH modeling study was conducted on the laboratory-scale domain to analyze the effects of temperature on urease activity and precipitated calcium carbonate.To understand the scale dependency of MICP treatment,a large-scale heterogeneous domain was subjected to variable biochemical injection strategies.The simulations conducted at the field-scale guided the selection of an injection strategy to achieve the desired type and amount of precipitation.Additionally,the study emphasized the potential of numerical models as reliable tools for optimizing future developments in field-scale MICP treatment.The present study demonstrates the potential of this numerical framework for designing and optimizing the MICP applications in laboratory-,prototype-,and field-scale scenarios.
基金supported by the Joint Funds of the National Natural Science Foundation of China(Grant No.U23A20671)the Major Project of Inner Mongolia Science and Technology,China(Grant No.2021ZD0034)the Creative Groups of Natural Science Foundation of Hubei Province(Grant No.2021CFA030).
文摘The sealing capacity of caprock is critical for preventing CO_(2)migration and ensuring the safety of geological storage.However,existing research lacks a comprehensive overview of its sealing mechanisms and failure risks.Here,recent findings on caprock sealing mechanisms,its influencing factors,failure risks,and evaluation methods are summarized.The main results include the following:(i)Caprock sealing mechanisms include capillary,hydraulic,hydrocarbon concentration,and hydrate sealing.(ii)Capillary and hydrate sealing block fluid-phase CO_(2),hydrocarbon concentration sealing prevents diffusive CO_(2),and hydraulic sealing prevents fluid and water-soluble phases.(iii)The sealing capacity is influenced by the storage site,stratigraphic environment,and caprock properties,with breakthrough pressure ranked as follows:gypsum rock>salt rock>mudstone/shale>limestone>silty mudstone.(iv)Diffusion leakage occurs when the diffusion coefficients is less than 10^(-12)m^(2)/s,the seepage leakage ranges between 10^(-8)m^(2)/s and 10^(-12)m^(2)/s,and the fracture leakage is greater than 10^(-8)m^(2)/s.(v)Hydro-mechanical(HM)coupling mechanisms,including CO_(2)diffusion,breakthrough migration,uplift deformation,and fracture flow,are essential for leakage risk simulations.Future research should address sealing mechanisms under complex conditions,define leakage risk thresholds,optimize multiphysical coupling computations,and implement effective engineering solutions to mitigate leakage risk.
文摘本文针对高压直流输电(high-voltage direct current,HVDC)工程中交流滤波电容器桥差保护电流表测量值异常偏大的问题展开研究。理论分析与现场实测表明,因电流表测量导线与电容器塔、导线与地面以及导线之间存在杂散电容,且导线对地布线存在物理不对称,引起差模干扰,导致不平衡电流测量值大于真实值。研究建立了杂散电容的等效电路模型,推导了测量误差的计算公式,并分析了杂散电容对测量结果的影响程度。为精确量化杂散电容参数,基于COMSOL Multiphysics软件构建了电容器塔与测量导线的高保真三维静电场模型,为误差分析提供了关键输入。最后结合新疆哈密某±800 kV特高压直流工程实例,通过现场试验验证了理论分析的正确性,并提出以采集电压替代电流的方案,实现不平衡电流的等效测量。
