It is acknowledged that injecting CO_(2) into oil reservoirs and saline aquifers for storage is a practical and affordable method for CO_(2) sequestration.Most CO_(2) produced from industrial exhaust contains impurity...It is acknowledged that injecting CO_(2) into oil reservoirs and saline aquifers for storage is a practical and affordable method for CO_(2) sequestration.Most CO_(2) produced from industrial exhaust contains impurity gases such as H_(2)S that might impact CO_(2) sequestration due to competitive adsorption.This study makes a commendable effort to explore the adsorption behavior of CO_(2)/H_(2)S mixtures in calcite slit nanopores.Grand Canonical Monte Carlo(GCMC)simulation is employed to reveal the adsorption of CO_(2),H_(2)S as well as their binary mixtures in calcite nanopores.Results show that the increase in pressure and temperature can promote and inhibit the adsorption capacity of CO_(2) and H_(2)S in calcite nanopores,respectively.CO_(2)exhibits stronger adsorption on calcite surface than H_(2)S.Electrostatic energy plays the dominating role in the adsorption behavior.Electrostatic energy accounts for 97.11%of the CO_(2)-calcite interaction energy and 56.33%of the H_(2)S-calcite interaction energy at 10 MPa and 323.15 K.The presence of H_(2)S inhibits the CO_(2) adsorption in calcite nanopores due to competitive adsorption,and a higher mole fraction of H_(2)S leads to less CO_(2) adsorption.The quantity of CO_(2) adsorbed is lessened by approximately 33%when the mole fraction of H_(2)S reaches 0.25.CO_(2) molecules preferentially occupy the regions near the po re wall and H_(2)S molecules tend to reside at the center of nanopore even when the molar ratio of CO_(2) is low,indicating that CO_(2) has an adsorption priority on the calcite surface over H_(2)S.In addition,moisture can weaken the adsorption of both CO_(2) and H_(2)S,while CO_(2) is more affected.More interestingly,we find that pure CO_(2) is more suitable to be sequestrated in the shallower formations,i.e.,500-1500 m,whereas CO_(2)with H_(2)S impurity should be settled in the deeper reservoirs.展开更多
Accurate characterization of fluid phase behavior is an important aspect of CO_(2) enhanced shale oil recovery.So far,however,there has been little discussion about the nanopore confinement effect,including adsorption...Accurate characterization of fluid phase behavior is an important aspect of CO_(2) enhanced shale oil recovery.So far,however,there has been little discussion about the nanopore confinement effect,including adsorption and capillarity on the phase equilibrium of water-oil-CO_(2) mixtures.In this study,an improved three-phase flash algorithm is proposed for calculating the phase behavior of water-oil-gas mixture on the basis of an extended Young-Laplace equation and a newly developed fugacity calculation model.The fugacity model can consider the effect of water-oil-gas adsorption on phase equilibrium.A water-Bakken oil-CO_(2) mixture is utilized to verify the accuracy of the flash algorithm and investigate the confinement effect.Results show that the confinement effect promotes the transfer of all components in the vapor phase to other phases,while the transfer of water,CO_(2),and lighter hydrocarbons is more significant.This leads to a large decrease,a large increase,and a small increase in the mole fraction of the vapor,oleic,and aqueous phases,respectively.When the confinement effect is considered,the density difference of vaporoleic phases decreases,and the interfacial tension of vapor-oleic phases decreases;however,the density difference of vapor-aqueous phases increases,the interfacial tension of vapor-aqueous phases still decreases.展开更多
高压断路器分合闸过程中触头间隙介质的绝缘强度及其变化是断路器结构设计的重要性能指标。搭建高压断路器触头间隙介质绝缘特性实验回路,测量C_(4)F_(7)N/CO_(2)混合气体断路器空载分合闸过程中不同压强、不同C4F7N含量时触头间隙介质...高压断路器分合闸过程中触头间隙介质的绝缘强度及其变化是断路器结构设计的重要性能指标。搭建高压断路器触头间隙介质绝缘特性实验回路,测量C_(4)F_(7)N/CO_(2)混合气体断路器空载分合闸过程中不同压强、不同C4F7N含量时触头间隙介质的动态击穿电压,研究C_(4)F_(7)N/CO_(2)混合气体断路器的关合预击穿特性和分闸绝缘特性。实验发现,断路器空载分合闸过程中C_(4)F_(7)N/CO_(2)混合气体动态击穿电压存在“低电压击穿”现象;合闸过程中,动态击穿电压分散性较大,C_(4)F_(7)N/CO_(2)混合气体断路器的关合预击穿特性显著劣于SF6断路器,增大压强或增加C4F7N含量对混合气体动态击穿电压分散性的改善不大;正、负极性条件下0.7MPa时9%C_(4)F_(7)N/91%CO_(2)混合气体的分闸平均绝缘强度上升率(rate of rise of dielectric strength,RRDS)分别为49.8kV/ms和42.7kV/ms,具有“反极性”效应;分闸过程中,“低电压击穿”现象主要出现在刚分后2ms(开距约6mm)范围以内,断路器若在此时间(开距)范围内熄弧,极易发生弧后重击穿现象,因此,C_(4)F_(7)N/CO_(2)混合气体断路器结构设计时应避免在此范围内熄弧。展开更多
基金financial support from the National Natural Science Foundation of China (Grant No.52004320)the Science Foundation of China University of Petroleum,Beijing (No.2462021QNXZ012,No.2462022BJRC001,and No.2462021YJRC012)the funding from the State Key Laboratory of Petroleum Resources and Engineering (No.PRP/indep-1-2103)。
文摘It is acknowledged that injecting CO_(2) into oil reservoirs and saline aquifers for storage is a practical and affordable method for CO_(2) sequestration.Most CO_(2) produced from industrial exhaust contains impurity gases such as H_(2)S that might impact CO_(2) sequestration due to competitive adsorption.This study makes a commendable effort to explore the adsorption behavior of CO_(2)/H_(2)S mixtures in calcite slit nanopores.Grand Canonical Monte Carlo(GCMC)simulation is employed to reveal the adsorption of CO_(2),H_(2)S as well as their binary mixtures in calcite nanopores.Results show that the increase in pressure and temperature can promote and inhibit the adsorption capacity of CO_(2) and H_(2)S in calcite nanopores,respectively.CO_(2)exhibits stronger adsorption on calcite surface than H_(2)S.Electrostatic energy plays the dominating role in the adsorption behavior.Electrostatic energy accounts for 97.11%of the CO_(2)-calcite interaction energy and 56.33%of the H_(2)S-calcite interaction energy at 10 MPa and 323.15 K.The presence of H_(2)S inhibits the CO_(2) adsorption in calcite nanopores due to competitive adsorption,and a higher mole fraction of H_(2)S leads to less CO_(2) adsorption.The quantity of CO_(2) adsorbed is lessened by approximately 33%when the mole fraction of H_(2)S reaches 0.25.CO_(2) molecules preferentially occupy the regions near the po re wall and H_(2)S molecules tend to reside at the center of nanopore even when the molar ratio of CO_(2) is low,indicating that CO_(2) has an adsorption priority on the calcite surface over H_(2)S.In addition,moisture can weaken the adsorption of both CO_(2) and H_(2)S,while CO_(2) is more affected.More interestingly,we find that pure CO_(2) is more suitable to be sequestrated in the shallower formations,i.e.,500-1500 m,whereas CO_(2)with H_(2)S impurity should be settled in the deeper reservoirs.
基金The financial support from National Natural Science Foundation of China(52074319,U19B6003-02)Strategic Cooperation Technology Project of CNPC(ZLZX 2020-01-08)。
文摘Accurate characterization of fluid phase behavior is an important aspect of CO_(2) enhanced shale oil recovery.So far,however,there has been little discussion about the nanopore confinement effect,including adsorption and capillarity on the phase equilibrium of water-oil-CO_(2) mixtures.In this study,an improved three-phase flash algorithm is proposed for calculating the phase behavior of water-oil-gas mixture on the basis of an extended Young-Laplace equation and a newly developed fugacity calculation model.The fugacity model can consider the effect of water-oil-gas adsorption on phase equilibrium.A water-Bakken oil-CO_(2) mixture is utilized to verify the accuracy of the flash algorithm and investigate the confinement effect.Results show that the confinement effect promotes the transfer of all components in the vapor phase to other phases,while the transfer of water,CO_(2),and lighter hydrocarbons is more significant.This leads to a large decrease,a large increase,and a small increase in the mole fraction of the vapor,oleic,and aqueous phases,respectively.When the confinement effect is considered,the density difference of vaporoleic phases decreases,and the interfacial tension of vapor-oleic phases decreases;however,the density difference of vapor-aqueous phases increases,the interfacial tension of vapor-aqueous phases still decreases.
文摘高压断路器分合闸过程中触头间隙介质的绝缘强度及其变化是断路器结构设计的重要性能指标。搭建高压断路器触头间隙介质绝缘特性实验回路,测量C_(4)F_(7)N/CO_(2)混合气体断路器空载分合闸过程中不同压强、不同C4F7N含量时触头间隙介质的动态击穿电压,研究C_(4)F_(7)N/CO_(2)混合气体断路器的关合预击穿特性和分闸绝缘特性。实验发现,断路器空载分合闸过程中C_(4)F_(7)N/CO_(2)混合气体动态击穿电压存在“低电压击穿”现象;合闸过程中,动态击穿电压分散性较大,C_(4)F_(7)N/CO_(2)混合气体断路器的关合预击穿特性显著劣于SF6断路器,增大压强或增加C4F7N含量对混合气体动态击穿电压分散性的改善不大;正、负极性条件下0.7MPa时9%C_(4)F_(7)N/91%CO_(2)混合气体的分闸平均绝缘强度上升率(rate of rise of dielectric strength,RRDS)分别为49.8kV/ms和42.7kV/ms,具有“反极性”效应;分闸过程中,“低电压击穿”现象主要出现在刚分后2ms(开距约6mm)范围以内,断路器若在此时间(开距)范围内熄弧,极易发生弧后重击穿现象,因此,C_(4)F_(7)N/CO_(2)混合气体断路器结构设计时应避免在此范围内熄弧。
