It is of great significance to evaluate the petrophysical properties in shale oil reservoir,which can contribute to geological storage CO_(2).Two-dimensional nuclear magnetic resonance(2D NMR)technology has been appli...It is of great significance to evaluate the petrophysical properties in shale oil reservoir,which can contribute to geological storage CO_(2).Two-dimensional nuclear magnetic resonance(2D NMR)technology has been applied to petrophysical characterization in shale oil reservoir.However,limitations of traditional 2D NMR(T_(1)-T_(2)or T_(2)-D)in detecting short-lived organic matter and the complexity of mineral compositions,pose NMR-based petrophysical challenges.The organic pores were assumed saturated oil and the inorganic pores were assumed saturated water,and the numerical algorithm and theory of T_(1)-T_(2)^(*)in shale oil reservoir were proposed,whose accuracy was validated through T_(2),T_(1)-T_(2)and T_(2)^(*)experiments.The effects of mineral types and contents on the T_(1)-T_(2)^(*)responses were firstly simulated by the random walk algorithm,revealing the NMR response mechanisms in shale oil reservoir with complex mineral compositions at different magnetic field frequency(f).The results indicate that when the pyrite content is 5.43%,dwell time is 4μs,the f is 200 MHz,and echo spacing is 0.4 ms,the T_(1)-T_(2)^(*)-based porosity is 2.39 times that of T_(1)-T_(2)-based porosity.The T_(2LM)^(*)is 0.015 ms,which is 0.015 times that of T_(2)LM.The T_(1LM)is 8.84 ms,which is 0.63 times that of T_(1LM).The T_(1)-T_(2)^(*)-based petrophysical conversion models were firstly created,and the foundation of petrophysical conversion was laid at different f.展开更多
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
Characterizing the petrophysical properties holds significant importance in shale oil reservoirs.Twodimensional(2-D)nuclear magnetic resonance(NMR),a nondestructive and noninvasive technique,has numerous applications ...Characterizing the petrophysical properties holds significant importance in shale oil reservoirs.Twodimensional(2-D)nuclear magnetic resonance(NMR),a nondestructive and noninvasive technique,has numerous applications in petrophysical characterization.However,the complex occurrence states of the fluids and the highly non-uniform distributions of minerals and organic matter pose challenges in the NMR-based petrophysical characterization.A novel T_(1)-T_(2)relaxation theory is introduced for the first time in this study.The transverse and longitudinal relaxivities of pore fluids are determined based on numerical investigation and experimental analysis.Additionally,an improved random walk algorithm is proposed to,on the basis of digital shale core,simulate the effects of the hydrogen index(HI)for the organic matter,echo spacing(T_(E)),pyrite content,clay mineral type,and clay content on T_(1)-T_(2)spectra at different NMR frequencies.Furthermore,the frequency conversion cross-plots for various petrophysical parameters influenced by the above factors are established.This study provides new insights into NMRbased petrophysical characterization and the frequency conversion of petrophysical parameters measured by laboratory NMR instruments and NMR logging in shale oil reservoirs.It is of great significance for the efficient exploration and environmentally friendly production of shale oil.展开更多
CO_(2) huff-n-puff shows great potential to promote shale oil recovery after primary depletion.However,the extracting process of shale oil residing in different types of pores induced by the injected CO_(2) remains un...CO_(2) huff-n-puff shows great potential to promote shale oil recovery after primary depletion.However,the extracting process of shale oil residing in different types of pores induced by the injected CO_(2) remains unclear.Moreover,how to saturate shale core samples with oil is still an experimental challenge,and needs a recommended procedure.These issues significantly impede probing CO_(2) huff-n-puff in extracting shale oil as a means of enhanced oil recovery(EOR)processes.In this paper,the oil saturation process of shale core samples and their CO_(2) extraction response with respect to pore types were investigated using online T1-T2nuclear magnetic resonance(NMR)spectroscopy.The results indicated that the oil saturation of shale core samples rapidly increased in the first 16 days under the conditions of 60℃and 30 MPa and then tended to plateau.The maximum oil saturation could reach 46.2%after a vacuum and pressurization duration of 20 days.After saturation,three distinct regions were identified on the T1-T2NMR spectra of the shale core samples,corresponding to kerogen,organic pores(OPs),and inorganic pores(IPs),respectively.The oil trapped in IPs was the primary target for CO_(2) huff-n-puff in shale with a maximum cumulative oil recovery(COR)of 70%original oil in place(OOIP)after three cycles,while the oil trapped in OPs and kerogen presented challenges for extraction(COR<24.2%OOIP in OPs and almost none for kerogen).CO_(2) preferentially extracted the accessible oil trapped in large IPs,while due to the tiny pores and strong affinity of oil-wet walls,the oil saturated in OPs mainly existed in an adsorbed state,leading to an insignificant COR.Furthermore,COR demonstrated a linear increasing tendency with soaking pressure,even when the pressure noticeably exceeded the minimum miscible pressure,implying that the formation of a miscible phase between CO_(2) and oil was not the primary drive for CO_(2) huff-n-puff in shale.展开更多
The characterization of kerogen nanopores is crucial for predicting the geostorage capacity and recoverability of natural gas in unconventional gas shale reservoirs.Towards this end,a powerful technique is presented w...The characterization of kerogen nanopores is crucial for predicting the geostorage capacity and recoverability of natural gas in unconventional gas shale reservoirs.Towards this end,a powerful technique is presented which integrates 2D NMR T_(1)-T_(2) relaxation measurements with molecular dynamics(MD)simulations of hydrocarbons confined in the nanopores of kerogen.The integrated NMR-MD technique is demonstrated using T_(1)-T_(2) measurements of kerogen isolates and organic-rich chalks saturated with heptane,together with MD simulations of heptane completely dissolved in a realistic kerogen model.The NMR-MD results are used to extract the swelling ratio and nanopore size distribution of kerogen as a function of depth in the reservoir.The effects of organic nanoconfinement on the T_(1) relaxation dispersion and T_(2) residual dipolar coupling of heptane are investigated,as well as the effect of downhole effective stress on the kerogen nanopore size as a function of depth and compaction.Potential applications in partially depleted gas shale reservoirs are discussed,including CO_(2) utilization/geostorage,geostorage of green H_(2),and integration of the NMR-MD technique with thermodynamic models for predicting the competitive sorption of gas mixtures in kerogen.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
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
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
基金funded by the National Natural Science Foundation of China(42174131)。
文摘It is of great significance to evaluate the petrophysical properties in shale oil reservoir,which can contribute to geological storage CO_(2).Two-dimensional nuclear magnetic resonance(2D NMR)technology has been applied to petrophysical characterization in shale oil reservoir.However,limitations of traditional 2D NMR(T_(1)-T_(2)or T_(2)-D)in detecting short-lived organic matter and the complexity of mineral compositions,pose NMR-based petrophysical challenges.The organic pores were assumed saturated oil and the inorganic pores were assumed saturated water,and the numerical algorithm and theory of T_(1)-T_(2)^(*)in shale oil reservoir were proposed,whose accuracy was validated through T_(2),T_(1)-T_(2)and T_(2)^(*)experiments.The effects of mineral types and contents on the T_(1)-T_(2)^(*)responses were firstly simulated by the random walk algorithm,revealing the NMR response mechanisms in shale oil reservoir with complex mineral compositions at different magnetic field frequency(f).The results indicate that when the pyrite content is 5.43%,dwell time is 4μs,the f is 200 MHz,and echo spacing is 0.4 ms,the T_(1)-T_(2)^(*)-based porosity is 2.39 times that of T_(1)-T_(2)-based porosity.The T_(2LM)^(*)is 0.015 ms,which is 0.015 times that of T_(2)LM.The T_(1LM)is 8.84 ms,which is 0.63 times that of T_(1LM).The T_(1)-T_(2)^(*)-based petrophysical conversion models were firstly created,and the foundation of petrophysical conversion was laid at different f.
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funded by the National Natural Science Foundation of China(42174131).
文摘Characterizing the petrophysical properties holds significant importance in shale oil reservoirs.Twodimensional(2-D)nuclear magnetic resonance(NMR),a nondestructive and noninvasive technique,has numerous applications in petrophysical characterization.However,the complex occurrence states of the fluids and the highly non-uniform distributions of minerals and organic matter pose challenges in the NMR-based petrophysical characterization.A novel T_(1)-T_(2)relaxation theory is introduced for the first time in this study.The transverse and longitudinal relaxivities of pore fluids are determined based on numerical investigation and experimental analysis.Additionally,an improved random walk algorithm is proposed to,on the basis of digital shale core,simulate the effects of the hydrogen index(HI)for the organic matter,echo spacing(T_(E)),pyrite content,clay mineral type,and clay content on T_(1)-T_(2)spectra at different NMR frequencies.Furthermore,the frequency conversion cross-plots for various petrophysical parameters influenced by the above factors are established.This study provides new insights into NMRbased petrophysical characterization and the frequency conversion of petrophysical parameters measured by laboratory NMR instruments and NMR logging in shale oil reservoirs.It is of great significance for the efficient exploration and environmentally friendly production of shale oil.
基金the financial support of National Key Research and Development Program of China(2023YFE0120700)National Natural Science Foundation of China(52274041)Distinguished Young Sichuan Science Scholars(2023NSFSC1954)。
文摘CO_(2) huff-n-puff shows great potential to promote shale oil recovery after primary depletion.However,the extracting process of shale oil residing in different types of pores induced by the injected CO_(2) remains unclear.Moreover,how to saturate shale core samples with oil is still an experimental challenge,and needs a recommended procedure.These issues significantly impede probing CO_(2) huff-n-puff in extracting shale oil as a means of enhanced oil recovery(EOR)processes.In this paper,the oil saturation process of shale core samples and their CO_(2) extraction response with respect to pore types were investigated using online T1-T2nuclear magnetic resonance(NMR)spectroscopy.The results indicated that the oil saturation of shale core samples rapidly increased in the first 16 days under the conditions of 60℃and 30 MPa and then tended to plateau.The maximum oil saturation could reach 46.2%after a vacuum and pressurization duration of 20 days.After saturation,three distinct regions were identified on the T1-T2NMR spectra of the shale core samples,corresponding to kerogen,organic pores(OPs),and inorganic pores(IPs),respectively.The oil trapped in IPs was the primary target for CO_(2) huff-n-puff in shale with a maximum cumulative oil recovery(COR)of 70%original oil in place(OOIP)after three cycles,while the oil trapped in OPs and kerogen presented challenges for extraction(COR<24.2%OOIP in OPs and almost none for kerogen).CO_(2) preferentially extracted the accessible oil trapped in large IPs,while due to the tiny pores and strong affinity of oil-wet walls,the oil saturated in OPs mainly existed in an adsorbed state,leading to an insignificant COR.Furthermore,COR demonstrated a linear increasing tendency with soaking pressure,even when the pressure noticeably exceeded the minimum miscible pressure,implying that the formation of a miscible phase between CO_(2) and oil was not the primary drive for CO_(2) huff-n-puff in shale.
基金Vinegar Technologies LLC,Chevron Energy Technology Company,Rice University Consortium for Processes in Porous Media,and the American Chemical Society Petroleum Research Fund(No.ACS PRF 58859-ND6)for their financial support。
文摘The characterization of kerogen nanopores is crucial for predicting the geostorage capacity and recoverability of natural gas in unconventional gas shale reservoirs.Towards this end,a powerful technique is presented which integrates 2D NMR T_(1)-T_(2) relaxation measurements with molecular dynamics(MD)simulations of hydrocarbons confined in the nanopores of kerogen.The integrated NMR-MD technique is demonstrated using T_(1)-T_(2) measurements of kerogen isolates and organic-rich chalks saturated with heptane,together with MD simulations of heptane completely dissolved in a realistic kerogen model.The NMR-MD results are used to extract the swelling ratio and nanopore size distribution of kerogen as a function of depth in the reservoir.The effects of organic nanoconfinement on the T_(1) relaxation dispersion and T_(2) residual dipolar coupling of heptane are investigated,as well as the effect of downhole effective stress on the kerogen nanopore size as a function of depth and compaction.Potential applications in partially depleted gas shale reservoirs are discussed,including CO_(2) utilization/geostorage,geostorage of green H_(2),and integration of the NMR-MD technique with thermodynamic models for predicting the competitive sorption of gas mixtures in kerogen.
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 (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 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.
