The intricate distribution of oil and water in tight rocks makes pinpointing oil layers challenging.While conventional identification methods offer potential solutions,their limited accuracy precludes them from being ...The intricate distribution of oil and water in tight rocks makes pinpointing oil layers challenging.While conventional identification methods offer potential solutions,their limited accuracy precludes them from being effective in their applications to unconventional reservoirs.This study employed nuclear magnetic resonance(NMR)spectrum decomposition to dissect the NMR T_(2)spectrum into multiple subspectra.Furthermore,it employed laboratory NMR experiments to ascertain the fluid properties of these sub-spectra,aiming to enhance identification accuracy.The findings indicate that fluids of distinct properties overlap in the T_(2)spectra,with bound water,movable water,bound oil,and movable oil appearing sequentially from the low-value zone to the high-value zone.Consequently,an oil layer classification scheme was proposed,which considers the physical properties of reservoirs,oil-bearing capacity,and the characteristics of both mobility and the oil-water two-phase flow.When applied to tight oil layer identification,the scheme's outcomes align closely with actual test results.A horizontal well,deployed based on these findings,has produced high-yield industrial oil flow,underscoring the precision and dependability of this new approach.展开更多
Micro-nano scale pores can accurately and fastly be measured by the nuclear magnetic resonance(NMR)technique,which provides a new method to quantitatively characterize pore structures in tight sandstone.Based on the m...Micro-nano scale pores can accurately and fastly be measured by the nuclear magnetic resonance(NMR)technique,which provides a new method to quantitatively characterize pore structures in tight sandstone.Based on the method of calibration of mercury pressure data for NMR T_(2) spectrum,for the measurement inaccuracy due to the mercury saturation less than 100%in tight sandstone,the mercury pressure curve and T_(2) spectrum is used to cumulate from the maximum pore on the right boundary to the small pores in the left,the range of pore-throat radius measured by the mercury injection in the leftward cumulative curve is selected as a comparable interval of NMR pore-throat radius,and the longitudinal interpolation method and the least square method are utilized to construct the distribution curve of pore-throat radius transformed by T_(2) spectrum.The modified method is used to obtain NMR T_(2) spectrum,conversion coefficient of pore-throat radius and pore-throat radius distribution of the Carboniferous-Permian tight sandstone gas reservoirs in the eastern Linqing depression,and characteristics of reservoir pore structures are quantitatively investigated;in addition,in combination with analysis of thin section and scanning electron microscopy,the reservoir effectiveness and cause of the pore structure variability in the tight sandstone are also well studied.The results show that the NMR pore-throat radius curve obtained by the modified method has a high consistency with the mercury injection curve,and the NMR test accuracy of tight sandstone is significantly improved.In the study area,the pore-throat radius of the Carboniferous-Permian tight sandstone mainly ranges from 0.002 to 2 mm,the pore is generally submicro-nano scale,but the pore-throat radius distribution of different types of sandstone varies significantly.The lithic quartz sandstone is rich in siliceous matter and poor in plastic detritus and matrix,generally dominated by submicro-scale pore-throats including micro-scale porethroats;lithic feldspar sandstone展开更多
D-T_(2)two-dimensional nuclear magnetic resonance(2D NMR)logging technology can distinguish pore fluid types intuitively,and it is widely used in oil and gas exploration.Many 2D NMR inversion methods(e.g.,truncated si...D-T_(2)two-dimensional nuclear magnetic resonance(2D NMR)logging technology can distinguish pore fluid types intuitively,and it is widely used in oil and gas exploration.Many 2D NMR inversion methods(e.g.,truncated singular value decomposition(TSVD),Butler-Reds-Dawson(BRD),LM-norm smoothing,and TIST-L1 regularization methods)have been proposed successively,but most are limited to numerical simulations.This study focused on the applicability of different inversion methods for NMR logging data of various acquisition sequences,from which the optimal inversion method was selected based on the comparative analysis.First,the two-dimensional NMR logging principle was studied.Then,these inversion methods were studied in detail,and the precision and computational efficiency of CPMG and diffusion editing(DE)sequences obtained from oil-water and gas-water models were compared,respectively.The inversion results and calculation time of truncated singular value decomposition(TSVD),Butler-Reds-Dawson(BRD),LM-norm smoothing,and TIST-L1 regularization were compared and analyzed through numerical simulations.The inversion method was optimized to process SP mode logging data from the MR Scanner instrument.The results showed that the TIST-regularization and LM-norm smoothing methods were more accurate for the CPMG and DE sequence echo trains of the oil-water and gas-water models.However,the LM-norm smoothing method was less time-consuming,making it more suitable for logging data processing.A case study in well A25 showed that the processing results by the LM-norm smoothing method were consistent with GEOLOG software.This demonstrates that the LM-norm smoothing method is applicable in practical NMR logging processing.展开更多
为探究砂土在冻融循环下未冻水含量的变化特征,采用低场核磁共振(Nuclear Magnetic Resonance,NMR)仪器测试饱和砂土在一个冻融循环下不同温度点的T_(2)谱变化曲线,从中分析出冻土未冻水含量的变化趋势与与其升温时的滞后现象.结果表明...为探究砂土在冻融循环下未冻水含量的变化特征,采用低场核磁共振(Nuclear Magnetic Resonance,NMR)仪器测试饱和砂土在一个冻融循环下不同温度点的T_(2)谱变化曲线,从中分析出冻土未冻水含量的变化趋势与与其升温时的滞后现象.结果表明:1)未冻水的冻结在降温时是从大孔隙中自由水开始冻结,而融化时是从薄膜水开始融化的;2)冻融循环下未冻水含量的滞后现象明显,在固态冰完全融化前,相同温度下的升温过程未冻水含量一直低于降温过程;3)一个冻融循环结束后土体孔隙结构改变,水分被重分布.展开更多
In this paper,a new method for converting the T_(2)(relaxation time) of NMR(nuclear magnetic resonance) into the pore radius is proposed.Combined with NMR and centrifugation experiments,the relationship between pore r...In this paper,a new method for converting the T_(2)(relaxation time) of NMR(nuclear magnetic resonance) into the pore radius is proposed.Combined with NMR and centrifugation experiments,the relationship between pore radius and T_(2) of the sample was established.The results show that the new method is more reasonable than the traditional method.When the sample was denser and the mercury saturation was lower,the pore distribution curve was obtained by traditional method had a worse agreement with mercury injection experiment,while pore distribution curve of the new method had a better agreement with the mercury injection curve,which reflected the greater advantage of the new method as the reservoir becomes denser.The new method can obtain all the pore information in the sample.The results show that the pores in tight sandstone are mainly consisted with mesopore and macropore,and the connectivity of macropore is better than that of mesopore.The new method can effectively characterize the full pore distribution and the seepage characteristics in different pores interval of tight reservoirs,which had a great significance to evaluate the recoverable resources of tight reservoir.展开更多
基金funded by a major special project of PetroChina Company Limited(No.2021DJ1003No.2023ZZ2).
文摘The intricate distribution of oil and water in tight rocks makes pinpointing oil layers challenging.While conventional identification methods offer potential solutions,their limited accuracy precludes them from being effective in their applications to unconventional reservoirs.This study employed nuclear magnetic resonance(NMR)spectrum decomposition to dissect the NMR T_(2)spectrum into multiple subspectra.Furthermore,it employed laboratory NMR experiments to ascertain the fluid properties of these sub-spectra,aiming to enhance identification accuracy.The findings indicate that fluids of distinct properties overlap in the T_(2)spectra,with bound water,movable water,bound oil,and movable oil appearing sequentially from the low-value zone to the high-value zone.Consequently,an oil layer classification scheme was proposed,which considers the physical properties of reservoirs,oil-bearing capacity,and the characteristics of both mobility and the oil-water two-phase flow.When applied to tight oil layer identification,the scheme's outcomes align closely with actual test results.A horizontal well,deployed based on these findings,has produced high-yield industrial oil flow,underscoring the precision and dependability of this new approach.
基金The work was supported by the Natural Science Foundation of China(No.41372151)National Science and Technology Major Project of China(No.2017ZX05008-004)National Key Basic Research Program of China(973 Program)(2015CB250902).
文摘Micro-nano scale pores can accurately and fastly be measured by the nuclear magnetic resonance(NMR)technique,which provides a new method to quantitatively characterize pore structures in tight sandstone.Based on the method of calibration of mercury pressure data for NMR T_(2) spectrum,for the measurement inaccuracy due to the mercury saturation less than 100%in tight sandstone,the mercury pressure curve and T_(2) spectrum is used to cumulate from the maximum pore on the right boundary to the small pores in the left,the range of pore-throat radius measured by the mercury injection in the leftward cumulative curve is selected as a comparable interval of NMR pore-throat radius,and the longitudinal interpolation method and the least square method are utilized to construct the distribution curve of pore-throat radius transformed by T_(2) spectrum.The modified method is used to obtain NMR T_(2) spectrum,conversion coefficient of pore-throat radius and pore-throat radius distribution of the Carboniferous-Permian tight sandstone gas reservoirs in the eastern Linqing depression,and characteristics of reservoir pore structures are quantitatively investigated;in addition,in combination with analysis of thin section and scanning electron microscopy,the reservoir effectiveness and cause of the pore structure variability in the tight sandstone are also well studied.The results show that the NMR pore-throat radius curve obtained by the modified method has a high consistency with the mercury injection curve,and the NMR test accuracy of tight sandstone is significantly improved.In the study area,the pore-throat radius of the Carboniferous-Permian tight sandstone mainly ranges from 0.002 to 2 mm,the pore is generally submicro-nano scale,but the pore-throat radius distribution of different types of sandstone varies significantly.The lithic quartz sandstone is rich in siliceous matter and poor in plastic detritus and matrix,generally dominated by submicro-scale pore-throats including micro-scale porethroats;lithic feldspar sandstone
基金sponsored by the National Natural Science Foundation of China(Nos.42174149,41774144)the National Major Projects(No.2016ZX05014-001).
文摘D-T_(2)two-dimensional nuclear magnetic resonance(2D NMR)logging technology can distinguish pore fluid types intuitively,and it is widely used in oil and gas exploration.Many 2D NMR inversion methods(e.g.,truncated singular value decomposition(TSVD),Butler-Reds-Dawson(BRD),LM-norm smoothing,and TIST-L1 regularization methods)have been proposed successively,but most are limited to numerical simulations.This study focused on the applicability of different inversion methods for NMR logging data of various acquisition sequences,from which the optimal inversion method was selected based on the comparative analysis.First,the two-dimensional NMR logging principle was studied.Then,these inversion methods were studied in detail,and the precision and computational efficiency of CPMG and diffusion editing(DE)sequences obtained from oil-water and gas-water models were compared,respectively.The inversion results and calculation time of truncated singular value decomposition(TSVD),Butler-Reds-Dawson(BRD),LM-norm smoothing,and TIST-L1 regularization were compared and analyzed through numerical simulations.The inversion method was optimized to process SP mode logging data from the MR Scanner instrument.The results showed that the TIST-regularization and LM-norm smoothing methods were more accurate for the CPMG and DE sequence echo trains of the oil-water and gas-water models.However,the LM-norm smoothing method was less time-consuming,making it more suitable for logging data processing.A case study in well A25 showed that the processing results by the LM-norm smoothing method were consistent with GEOLOG software.This demonstrates that the LM-norm smoothing method is applicable in practical NMR logging processing.
文摘为探究砂土在冻融循环下未冻水含量的变化特征,采用低场核磁共振(Nuclear Magnetic Resonance,NMR)仪器测试饱和砂土在一个冻融循环下不同温度点的T_(2)谱变化曲线,从中分析出冻土未冻水含量的变化趋势与与其升温时的滞后现象.结果表明:1)未冻水的冻结在降温时是从大孔隙中自由水开始冻结,而融化时是从薄膜水开始融化的;2)冻融循环下未冻水含量的滞后现象明显,在固态冰完全融化前,相同温度下的升温过程未冻水含量一直低于降温过程;3)一个冻融循环结束后土体孔隙结构改变,水分被重分布.
基金supported by the CNPC basic advanced reserve technology (No.2018A-0908)。
文摘In this paper,a new method for converting the T_(2)(relaxation time) of NMR(nuclear magnetic resonance) into the pore radius is proposed.Combined with NMR and centrifugation experiments,the relationship between pore radius and T_(2) of the sample was established.The results show that the new method is more reasonable than the traditional method.When the sample was denser and the mercury saturation was lower,the pore distribution curve was obtained by traditional method had a worse agreement with mercury injection experiment,while pore distribution curve of the new method had a better agreement with the mercury injection curve,which reflected the greater advantage of the new method as the reservoir becomes denser.The new method can obtain all the pore information in the sample.The results show that the pores in tight sandstone are mainly consisted with mesopore and macropore,and the connectivity of macropore is better than that of mesopore.The new method can effectively characterize the full pore distribution and the seepage characteristics in different pores interval of tight reservoirs,which had a great significance to evaluate the recoverable resources of tight reservoir.
