During the development of low or ultra-low permeability oil resources,the alternative energy supply becomes a prominent issue.In recent years,carbon dots(CDs)have drawn much attention owing to their application potent...During the development of low or ultra-low permeability oil resources,the alternative energy supply becomes a prominent issue.In recent years,carbon dots(CDs)have drawn much attention owing to their application potential in oil fields for reducing injection pressure and augmenting oil recovery.However,carbon dots characterized of small size,high surface energy are faced with several challenges,such as self-aggregation and settling.The preparation of stably dispersed carbon dots nanofluids is the key factor to guarantee its application performance in formation.In this work,we investigated the stability of hydrophilic carbon dots(HICDs)and hydrophobic carbon dots-Tween 80(HOCDs)nanofluids.The influences of carbon dots concentration,sorts and concentration of salt ions as well as temperature on the stability of CDs were studied.The results showed that HICDs are more sensitive to sort and concentration of salt ions,while HOCDs are more sensitive to temperature.In addition,the core flooding experiments demonstrated that the pressure reduction rate of HICDs and HOCDs nanofluids can be as high as 17.88%and 26.14%,respectively.Hence,the HICDs and HOCDs nanofluids show a good application potential in the reduction of injection pressure during the development of low and ultra-low permeability oil resources.展开更多
Active control of the optical parameters in strontium titanate(SrTiO_(3),STO)thin films is highly desirable for tunable terahertz(THz)integrated devices such as filters,phase modulators,and electro-optical devices.In ...Active control of the optical parameters in strontium titanate(SrTiO_(3),STO)thin films is highly desirable for tunable terahertz(THz)integrated devices such as filters,phase modulators,and electro-optical devices.In this work,optically tuned dielectric parameters of a STO thin film epitaxially grown on a silicon wafer were characterized in the THz region with an 800 nm laser pump-THz detection system.The refractive index,extinction coefficient,and complex dielectric constant of the STO thin film were calculated using thin-film parameter extraction.Owing to carrier transportation and soft-mode oscillation,the above optical parameters changed notably with the pump power of the external laser.This study is of great significance for rapid and non-contact THz phase-modulation technology and may serve as a powerful tool to tune the dielectric properties of the STO thin films.展开更多
基金supported by the National Natural Science Foundation of China(51704313)the Chang Jiang Scholars Program(No.T2014152)。
文摘During the development of low or ultra-low permeability oil resources,the alternative energy supply becomes a prominent issue.In recent years,carbon dots(CDs)have drawn much attention owing to their application potential in oil fields for reducing injection pressure and augmenting oil recovery.However,carbon dots characterized of small size,high surface energy are faced with several challenges,such as self-aggregation and settling.The preparation of stably dispersed carbon dots nanofluids is the key factor to guarantee its application performance in formation.In this work,we investigated the stability of hydrophilic carbon dots(HICDs)and hydrophobic carbon dots-Tween 80(HOCDs)nanofluids.The influences of carbon dots concentration,sorts and concentration of salt ions as well as temperature on the stability of CDs were studied.The results showed that HICDs are more sensitive to sort and concentration of salt ions,while HOCDs are more sensitive to temperature.In addition,the core flooding experiments demonstrated that the pressure reduction rate of HICDs and HOCDs nanofluids can be as high as 17.88%and 26.14%,respectively.Hence,the HICDs and HOCDs nanofluids show a good application potential in the reduction of injection pressure during the development of low and ultra-low permeability oil resources.
基金supported by the National Natural Science Foundation of China(Grant No.62075248)the National Key R&D Program of China(Grant Nos.2017YFB0405400 and 2020YFB2009300)the Program for the Innovation Team of Science and Technology in University of Henan,China(Grant No.20IRTSTHN014).
文摘Active control of the optical parameters in strontium titanate(SrTiO_(3),STO)thin films is highly desirable for tunable terahertz(THz)integrated devices such as filters,phase modulators,and electro-optical devices.In this work,optically tuned dielectric parameters of a STO thin film epitaxially grown on a silicon wafer were characterized in the THz region with an 800 nm laser pump-THz detection system.The refractive index,extinction coefficient,and complex dielectric constant of the STO thin film were calculated using thin-film parameter extraction.Owing to carrier transportation and soft-mode oscillation,the above optical parameters changed notably with the pump power of the external laser.This study is of great significance for rapid and non-contact THz phase-modulation technology and may serve as a powerful tool to tune the dielectric properties of the STO thin films.
