Soil water content measurement is critical in practical engineering.The actively heated fiber Bragg grating optic sensor(FBGS)has great potential of multi-point measurement for soil water content measurement in field....Soil water content measurement is critical in practical engineering.The actively heated fiber Bragg grating optic sensor(FBGS)has great potential of multi-point measurement for soil water content measurement in field.In this study,the effect of heating time on the measurement accuracy is discussed,and modifications are made for actively heated fiber optic(AHFO)sensors.The results demonstrate that if an integration data analysis method is used,the accuracy and reliability of soil water content measurement with AHFO sensors will be improved.Both a short fiber length and a short-term heating pattern are effective and can help to reduce soil disturbance.With the proposed integration method,a short heating time is guaranteed for measuring the soil water content.Such improvements will reduce the thermal disturbance to soil sample and improve the reliability of measurement.展开更多
It is important to understand the process of multiphase carbon dioxide(CO_(2))leakage in faults for the risk assessment of carbon capture and storage(CCS).To quantitatively characterize the CO_(2)leakage process in th...It is important to understand the process of multiphase carbon dioxide(CO_(2))leakage in faults for the risk assessment of carbon capture and storage(CCS).To quantitatively characterize the CO_(2)leakage process in the fault,pressure sensors,fiber Bragg grating(FBG)temperature and strain sensors were simultaneously used to monitor CO_(2)leakage in the fault.Ten experiments were carried out,including five groups of gaseous CO_(2)leakage tests with initial pressures of 1-5 MPa and five groups of liquid CO_(2)leakage tests with initial pressures of 6-10 MPa.The results indicate that when liquid CO_(2)leaked with an initial pressure of 7-10 MPa,the pressure and temperature of CO_(2)dropped rapidly in the first few seconds and then remained unchanged.The behavior that CO_(2)continues to leak while maintaining temperature and pressure unchanged is defined as“temporary pseudo-sealing(TPS)”behavior,which continues for the first 1/3 of the leakage period.However,this TPS behavior did not occur in gaseous CO_(2)leakage.If only the pressure and temperature data were used to evaluate whether CO_(2)leakage occurred,we would misjudge the risk of leakage in CCS projects during the TPS period.The causes and conditions of TPS behavior were further studied experimentally.The results show that:(1)TPS behavior is caused by the phase transition energy generated when liquid CO_(2)leaks.(2)The condition for TPS behavior is a small leak aperture(0.2 mm).Only a small leakage rate can make the phase transition energy and pressure change from a dynamic equilibrium,and(3)The compression zone caused by the Bernoulli effect and fault“barrier”could reduce the CO_(2)leakage rate and further promote the occurrence of TPS behavior.This study provides technical and theoretical support for the quantitative characterization of the CO_(2)leakage process in faults of CCS projects.展开更多
To investigate the impacts of mineral composition on physical and mechanical properties of carbonate rocks,limestone specimens containing different contents in calcite and dolomite are selected to perform CO_(2)-water...To investigate the impacts of mineral composition on physical and mechanical properties of carbonate rocks,limestone specimens containing different contents in calcite and dolomite are selected to perform CO_(2)-water-rock reaction experiments.The X-ray Diffraction(XRD) and Nuclear Magnetic Resonance(NMR) are carried out to examine the change characteristics of mineral dissolution and pore structure after reaction.The core flooding experiments with Fiber Bragg gratings are implemented to examine the stress sensitivity of carbonate rocks.The results show that the limestones containing pure calcite are more susceptible to acid dissolution compared to limestone containing impure dolomite.The calcite content in pure limestone decreases as the reaction undergoes.The dissolution of dolomite leads to the formation of calcite in impure limestone.Calcite dissolution leads to the formation of macropore and flow channels in pure limestone,while the effects of impure dolomite in impure limestone results in mesopore formation.When confining pressure is lower than 12 MPa,pure limestones demonstrate higher strain sensitivity coefficients compared to impure limestone containing dolomite after reaction.When confining pressure exceeds 12 MPa,the strain sensitivity coefficients of both pure and impure limestones become almost equal.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.51979002).
文摘Soil water content measurement is critical in practical engineering.The actively heated fiber Bragg grating optic sensor(FBGS)has great potential of multi-point measurement for soil water content measurement in field.In this study,the effect of heating time on the measurement accuracy is discussed,and modifications are made for actively heated fiber optic(AHFO)sensors.The results demonstrate that if an integration data analysis method is used,the accuracy and reliability of soil water content measurement with AHFO sensors will be improved.Both a short fiber length and a short-term heating pattern are effective and can help to reduce soil disturbance.With the proposed integration method,a short heating time is guaranteed for measuring the soil water content.Such improvements will reduce the thermal disturbance to soil sample and improve the reliability of measurement.
基金The research was partially supported by the Major Project of Inner Mongolia Science and Technology(Grant No.2021ZD0034)the National Natural Science Foundation of China(Grant Nos.41872210 and 41274111)The equipment and methodology we have developed for this research have applied for a national invention patent(ZL 202110708668.1).
文摘It is important to understand the process of multiphase carbon dioxide(CO_(2))leakage in faults for the risk assessment of carbon capture and storage(CCS).To quantitatively characterize the CO_(2)leakage process in the fault,pressure sensors,fiber Bragg grating(FBG)temperature and strain sensors were simultaneously used to monitor CO_(2)leakage in the fault.Ten experiments were carried out,including five groups of gaseous CO_(2)leakage tests with initial pressures of 1-5 MPa and five groups of liquid CO_(2)leakage tests with initial pressures of 6-10 MPa.The results indicate that when liquid CO_(2)leaked with an initial pressure of 7-10 MPa,the pressure and temperature of CO_(2)dropped rapidly in the first few seconds and then remained unchanged.The behavior that CO_(2)continues to leak while maintaining temperature and pressure unchanged is defined as“temporary pseudo-sealing(TPS)”behavior,which continues for the first 1/3 of the leakage period.However,this TPS behavior did not occur in gaseous CO_(2)leakage.If only the pressure and temperature data were used to evaluate whether CO_(2)leakage occurred,we would misjudge the risk of leakage in CCS projects during the TPS period.The causes and conditions of TPS behavior were further studied experimentally.The results show that:(1)TPS behavior is caused by the phase transition energy generated when liquid CO_(2)leaks.(2)The condition for TPS behavior is a small leak aperture(0.2 mm).Only a small leakage rate can make the phase transition energy and pressure change from a dynamic equilibrium,and(3)The compression zone caused by the Bernoulli effect and fault“barrier”could reduce the CO_(2)leakage rate and further promote the occurrence of TPS behavior.This study provides technical and theoretical support for the quantitative characterization of the CO_(2)leakage process in faults of CCS projects.
基金partially supported by Creative Group of Natural Science Foundation of Hubei Province (Grant No. 2021CFA030)National Natural Science Foundation of China (Grant No. 41872210)。
文摘To investigate the impacts of mineral composition on physical and mechanical properties of carbonate rocks,limestone specimens containing different contents in calcite and dolomite are selected to perform CO_(2)-water-rock reaction experiments.The X-ray Diffraction(XRD) and Nuclear Magnetic Resonance(NMR) are carried out to examine the change characteristics of mineral dissolution and pore structure after reaction.The core flooding experiments with Fiber Bragg gratings are implemented to examine the stress sensitivity of carbonate rocks.The results show that the limestones containing pure calcite are more susceptible to acid dissolution compared to limestone containing impure dolomite.The calcite content in pure limestone decreases as the reaction undergoes.The dissolution of dolomite leads to the formation of calcite in impure limestone.Calcite dissolution leads to the formation of macropore and flow channels in pure limestone,while the effects of impure dolomite in impure limestone results in mesopore formation.When confining pressure is lower than 12 MPa,pure limestones demonstrate higher strain sensitivity coefficients compared to impure limestone containing dolomite after reaction.When confining pressure exceeds 12 MPa,the strain sensitivity coefficients of both pure and impure limestones become almost equal.
