一维核磁共振(nuclear magnetic resonance,NMR)测量方法无法分辨驱替过程中油水弛豫信号,因此采用T_(1)-T_(2)二维核磁共振测量方法分辨岩心中流体类型及分布。通过驱替实验研究聚合物BRH-325和表面活性剂GSS-A复合体系分别在65、70、7...一维核磁共振(nuclear magnetic resonance,NMR)测量方法无法分辨驱替过程中油水弛豫信号,因此采用T_(1)-T_(2)二维核磁共振测量方法分辨岩心中流体类型及分布。通过驱替实验研究聚合物BRH-325和表面活性剂GSS-A复合体系分别在65、70、75℃条件下的驱油效果,并利用纵向弛豫-横向弛豫(T_(1)-T_(2))二维NMR测量方法对岩心内部的油水两相驱替规律及分布特征进行可视化研究,并对比实验测量结果与NMR测量结果。结果表明:70℃下,复合驱提高采收率的效果最为明显。因此,T_(1)-T_(2)二维核磁共振能够直接、直观区分驱替过程中油水的弛豫信号。展开更多
Acidity-activatable magnetic resonance imaging(MRI)nanoprobes offer great potential for in vivo cancer imaging by targeting the acidic tumor microenvironment(TME).However,their effectiveness is limited by the delayed ...Acidity-activatable magnetic resonance imaging(MRI)nanoprobes offer great potential for in vivo cancer imaging by targeting the acidic tumor microenvironment(TME).However,their effectiveness is limited by the delayed response at tumor sites and uncontrollable background noise,compromising imaging accuracy and reliability.Herein,an acidic TME-responsive nanoprobe,SPIO@ZIF-8@Gd(SZG),with dually activatable T_(1) and T_(2) MR signals is shown for acidity-selective contrast enhancement in a rapid response manner.It shows decreased T_(1) and T_(2) contrast intensity in normal physiological conditions.Once targeting acidic TME,the zeolitic imidazolate framework-8(ZIF-8)layer undergoes instantaneous decomposition,releasing Gd^(3+)(T_(1)-weighted),and exposing the inner SPIO(T_(2)-weighted)core,thereby sequentially recovering the signals.Compared to previously reported T_(1)-T_(2) nanoprobes,SZG demonstrates noticeable“dual activation”after just 30 min and reaches its peak 4 h after acid incubation.Additionally,it shows an excellent“acidity correlation”between relaxation times and pH values.When the SZG nanoprobe is used combined with“dual-contrast enhanced subtraction(DESI)”,the contrast difference between diseased and normal tissue can be increased by 10 times,which is significantly higher than traditional single-mode T_(1)/T_(2) contrast agents.Collectively,these findings demonstrate a rapid imaging strategy of dual-activation MR imaging of the acidic TME and simultaneous background suppression,thus paving the way for precise tumor malignancy differentiation,early tumor detection,and accurate tumor grading.展开更多
The behavior of oil and water in tight rocks can change the distribution of oil or water in pores,which affects the production of crude oil.Nuclear Magnetic Resonance(NMR)method is an effective and nondestructive tool...The behavior of oil and water in tight rocks can change the distribution of oil or water in pores,which affects the production of crude oil.Nuclear Magnetic Resonance(NMR)method is an effective and nondestructive tool for evaluating rocks with comparison and analysis both quantitatively and qualitatively.In our study,20 MHz NMR Relaxometry is used as a key technique to study the changes of water and oil behaviors in Chinese lacustrine Qingshankou shales under different saturated states(imbibition and evaporation without pressure).The results show that variation in different proton populations(water,oil and organic)can be distinguished using 2D T_(1)-T_(2)maps.The comparison among T_(1)-T_(2)maps with different saturated states shows that different signal regions changed during oil and water migrations,which the 1D NMR Relaxometry may be not easy to approach.Combined with the pyrolysis analysis,T2 shift and differences of signal regions in T_(1)-T_(2)maps can reflect properties such as wettability and composition(organic matter,clay and magnetic minerals)to some extent.This study provides better insight into oil and water behaviors in lacustrine oil shales with further understanding of 20 MHz NMR 2D T_(1)-T_(2)maps both in qualitative and quantitative analysis.展开更多
An accurate evaluation of the shale oil mobility is crucial to its cost-effective exploitation.This study presents a method to assess shale oil mobility by integrating the pore structure and oil states distributions.F...An accurate evaluation of the shale oil mobility is crucial to its cost-effective exploitation.This study presents a method to assess shale oil mobility by integrating the pore structure and oil states distributions.First,a set of three discrete organic extracts(EOM-A,B and C)were obtained by sequential extraction.The relationships among the EOMs and the oil states were inferred from the group compositions and fluorescence properties of the produced shale oil(free state).The results showed that EOMs A and B represent free oil in the open and closed pores,respectively,while the EOM-C represents adsorbed oil.Then,NMR T_(1)-T_(2)map is used to determine the T_(2-cutoff)values that indicate the pore size ranges of different oil states.Free oil resides mainly in larger pore space(T_(2)>0.5 ms),while the adsorbed oil in smaller pore space(0.2 ms<T_(2)<0.5 ms).Finally,the ratio of free to adsorbed oil(F/A)>0.5 and T_(2-cutoff)>1.0 ms suggest that the free oil in connected pores has the highest mobility.This work can provide a reference for evaluating the shale oil potential and prospectivity in other regions.展开更多
文摘一维核磁共振(nuclear magnetic resonance,NMR)测量方法无法分辨驱替过程中油水弛豫信号,因此采用T_(1)-T_(2)二维核磁共振测量方法分辨岩心中流体类型及分布。通过驱替实验研究聚合物BRH-325和表面活性剂GSS-A复合体系分别在65、70、75℃条件下的驱油效果,并利用纵向弛豫-横向弛豫(T_(1)-T_(2))二维NMR测量方法对岩心内部的油水两相驱替规律及分布特征进行可视化研究,并对比实验测量结果与NMR测量结果。结果表明:70℃下,复合驱提高采收率的效果最为明显。因此,T_(1)-T_(2)二维核磁共振能够直接、直观区分驱替过程中油水的弛豫信号。
基金supported by the National Natural Science Foundation of China (82272057 and 32301160)。
文摘Acidity-activatable magnetic resonance imaging(MRI)nanoprobes offer great potential for in vivo cancer imaging by targeting the acidic tumor microenvironment(TME).However,their effectiveness is limited by the delayed response at tumor sites and uncontrollable background noise,compromising imaging accuracy and reliability.Herein,an acidic TME-responsive nanoprobe,SPIO@ZIF-8@Gd(SZG),with dually activatable T_(1) and T_(2) MR signals is shown for acidity-selective contrast enhancement in a rapid response manner.It shows decreased T_(1) and T_(2) contrast intensity in normal physiological conditions.Once targeting acidic TME,the zeolitic imidazolate framework-8(ZIF-8)layer undergoes instantaneous decomposition,releasing Gd^(3+)(T_(1)-weighted),and exposing the inner SPIO(T_(2)-weighted)core,thereby sequentially recovering the signals.Compared to previously reported T_(1)-T_(2) nanoprobes,SZG demonstrates noticeable“dual activation”after just 30 min and reaches its peak 4 h after acid incubation.Additionally,it shows an excellent“acidity correlation”between relaxation times and pH values.When the SZG nanoprobe is used combined with“dual-contrast enhanced subtraction(DESI)”,the contrast difference between diseased and normal tissue can be increased by 10 times,which is significantly higher than traditional single-mode T_(1)/T_(2) contrast agents.Collectively,these findings demonstrate a rapid imaging strategy of dual-activation MR imaging of the acidic TME and simultaneous background suppression,thus paving the way for precise tumor malignancy differentiation,early tumor detection,and accurate tumor grading.
基金supported by the Opening Fund of Key Laboratory of Continental Shale Accumulation and Development(Northeast Petroleum University,China)the National Natural Science Foundation of China(Grant No.51605089,Grant No.41972156)
文摘The behavior of oil and water in tight rocks can change the distribution of oil or water in pores,which affects the production of crude oil.Nuclear Magnetic Resonance(NMR)method is an effective and nondestructive tool for evaluating rocks with comparison and analysis both quantitatively and qualitatively.In our study,20 MHz NMR Relaxometry is used as a key technique to study the changes of water and oil behaviors in Chinese lacustrine Qingshankou shales under different saturated states(imbibition and evaporation without pressure).The results show that variation in different proton populations(water,oil and organic)can be distinguished using 2D T_(1)-T_(2)maps.The comparison among T_(1)-T_(2)maps with different saturated states shows that different signal regions changed during oil and water migrations,which the 1D NMR Relaxometry may be not easy to approach.Combined with the pyrolysis analysis,T2 shift and differences of signal regions in T_(1)-T_(2)maps can reflect properties such as wettability and composition(organic matter,clay and magnetic minerals)to some extent.This study provides better insight into oil and water behaviors in lacustrine oil shales with further understanding of 20 MHz NMR 2D T_(1)-T_(2)maps both in qualitative and quantitative analysis.
基金supported by the National Natural Science Foundation of China(Grant No.41972156)the Science and Technology Project of Heilongjiang Province(Grant No.2020ZX05A01).
文摘An accurate evaluation of the shale oil mobility is crucial to its cost-effective exploitation.This study presents a method to assess shale oil mobility by integrating the pore structure and oil states distributions.First,a set of three discrete organic extracts(EOM-A,B and C)were obtained by sequential extraction.The relationships among the EOMs and the oil states were inferred from the group compositions and fluorescence properties of the produced shale oil(free state).The results showed that EOMs A and B represent free oil in the open and closed pores,respectively,while the EOM-C represents adsorbed oil.Then,NMR T_(1)-T_(2)map is used to determine the T_(2-cutoff)values that indicate the pore size ranges of different oil states.Free oil resides mainly in larger pore space(T_(2)>0.5 ms),while the adsorbed oil in smaller pore space(0.2 ms<T_(2)<0.5 ms).Finally,the ratio of free to adsorbed oil(F/A)>0.5 and T_(2-cutoff)>1.0 ms suggest that the free oil in connected pores has the highest mobility.This work can provide a reference for evaluating the shale oil potential and prospectivity in other regions.
