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low-field nmr inversion based on low-rank and sparsity restraint of relaxation spectra

Petroleum Science 2022年第6期19卷 2741-2756页

作者： Si-Hui Luo Li-Zhi Xiao Yan Jin Jiang-Feng Guo Xiao-Bo Qu Zhang-Ren Tu Gang Luo Can Liang College of Artificial Intelligence and College of Petroleum Engineering China University of PetroleumBeijing102249China State Key Laboratory of Petroleum Resources and Prospecting China University of PetroleumBeijing102249China School of Electronic Science and Engineering(National Model Microelectronics College) Xiamen UniversityFujian361005China School of Electronic Science and Engineering National Model Microelectronics College Xiamen University Changzhou Institute of Technology ChangzhouJiangsu213000China

In this paper,we proposed a novel method for low-field nuclear magnetic resonance(nmr)inversion based on low-rank and sparsity restraint(LRSR)of relaxation spectra,with which high quality construction is made possible for one-and two-dimensional low-field and low signal to noise ratio nmr data.In this method,the low-rank and sparsity restraints are introduced into the objective function instead of the smoothing term.The low-rank features in relaxation spectra are extracted to ensure the local characteristics and morphology of spectra.The sparsity and residual term are contributed to the resolution and precision of spectra,with the elimination of the redundant relaxation components.Optimization process of the objective function is designed with alternating direction method of multiples,in which the objective function is decomposed into three subproblems to be independently solved.The optimum solution can be obtained by alternating iteration and updating process.At first,numerical simulations are conducted on synthetic echo data with different signal-to-noise ratios,to optimize the desirable regularization parameters and verify the feasibility and effectiveness of proposed method.Then,nmr experiments on solutions and artificial sandstone samples are conducted and analyzed,which validates the robustness and reliability of the proposed method.The results from simulations and experiments have demonstrated that the suggested method has unique advantages for improving the resolution of relaxation spectra and enhancing the ability of fluid quantitative identification.

关键词： low-field nmr Inversion method low-rank and sparsity restraint Relaxation spectra Data processing

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A machine learning framework for low-field nmr data processing

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Petroleum Science 2022年第2期19卷 581-593页

作者： Si-Hui Luo Li-Zhi Xiao Yan Jin Guang-Zhi Liao Bin-Sen Xu Jun Zhou Can Liang College of Artificial Intelligence and College of Petroleum Engineering China University of PetroleumBeijing102249China China National Logging Corporation Xi©anShaanxi 710076China Changzhou Institute of Technology ChangzhouJiangsu213000China

low-field(nuclear magnetic resonance)nmr has been widely used in petroleum industry,such as well logging and laboratory rock core analysis.However,the signal-to-noise ratio is low due to the low magnetic field strength of nmr tools and the complex petrophysical properties of detected samples.Suppressing the noise and highlighting the available nmr signals is very important for subsequent data processing.Most denoising methods are normally based on fixed mathematical transformation or handdesign feature selectors to suppress noise characteristics,which may not perform well because of their non-adaptive performance to different noisy signals.In this paper,we proposed a“data processing framework”to improve the quality of low field nmr echo data based on dictionary learning.Dictionary learning is a machine learning method based on redundancy and sparse representation theory.Available information in noisy nmr echo data can be adaptively extracted and reconstructed by dictionary learning.The advantages and application effectiveness of the proposed method were verified with a number of numerical simulations,nmr core data analyses,and nmr logging data processing.The results show that dictionary learning can significantly improve the quality of nmr echo data with high noise level and effectively improve the accuracy and reliability of inversion results.

关键词： Dictionary learning low-field nmr Denoising Data processing T_(2)distribution

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low-field nmr application in the characterization of CO_(2)geological storage and utilization related to shale gas reservoirs:a brief review

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Frontiers of Earth Science 2023年第3期17卷 739-751页

作者： Zhaohui LU Ke LI Xingbing LIU Peng ZHAO Jun LIU National and Local Joint Engineering Research Center of Shale Gas Exploration and Development Chongqing Institute of Geology and Mineral ResourceChongqing 401120China Key Laboratory of Shale Gas Exploration(Ministry of Natural Resources) Chongqing Institute of Geology and Mineral ResourcesChongqing 401120China MOE Key Laboratory of Deep Earth Science and Engineering Institute of New Energy and Low-Carbon TechnologySichuan UniversityChengdu 610065China State Key Laboratory of Coal Mine Disaster Dynamics and Control School of Resources and Safety EngineeringChongqing UniversityChongqing 400044China Chongqing Institute of Geological Survey Chongqing 401122China

CO_(2)geological storage and utilization(CGSU)is considered a far-reaching technique to meet the demand of increasing energy supply and decreasing CO_(2)emissions.For CGSUs related to shale gas reservoirs,experimental investigations have attracted variable methodologies,among which low-field nmr(LF-nmr)is a promising method and is playing an increasingly key role in reservoir characterization.Herein,the application of this nondestructive,sensitive,and quick LF-nmr technique in characterizing CGSU behavior in shale gas reservoirs is reviewed.First,the basic principle of LF-nmr for 1H-fluid detection is introduced,which is the theoretical foundation of the reviewed achievements in this paper.Then,the reviewed works are related to the LF-nmr-based measurements of CH_(4)adsorption capacity and the CO_(2)-CH_(4)interaction in shale,as well as the performance on CO_(2)sequestration and simultaneous enhanced gas recovery from shale.Basically,the reviewed achievements have exhibited a large potential for LF-nmr application in CGSUs related to shale gas reservoirs,although some limitations and deficiencies still need to be improved.Accordingly,some suggestions are proposed for a more responsible development of the LF-nmr technique.Hopefully,this review is helpful in promoting the expanding application of the LF-nmr technique in CGSU implementation in shale gas reservoirs.

关键词： CO_(2)/CH_(4)competitive adsorption shale gas reservoir CO_(2)geological storage gas recovery enhancement low-field nmr

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Probing Development of Microstructure of Early Cement Paste using ~1H low-field nmr

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Journal of Wuhan University of Technology(Materials Science) 2013年第5期28卷 963-967页

作者：俞洋孙振平 PANG Min YANG Peiqiang Key Laboratory of Advanced Civil Engineering Materials Ministry of EducationTongji University Shanghai Niumag Corporation

Development of microstructure of early cement paste (0–6 h) was investigated with 1H low-field nmr. It was found that T 2 (transverse relaxation time) distributions of fresh cement paste were bimodal and two peaks were ‘long component’ and ‘short component’. Separation degree of two peaks was a sign of exchange of water within flocculation and outside flocculation. Factors such as water cement ratio, specific surface area and dosage of superplasticizer had influences on the separation degree: the separation degree increased with the water cement ratio; the separation degree of cement paste prepared with cement with a high specific surface area was zero; dosage of superplasticizer will decrease separation degree. Results also suggested that T 2 distribution gradually moved to the left and T 2 of long component and initial fluidity were linearly correlated.

关键词： low-field nmr microstructure of cement paste superplasticizer specific surface area T 2 distribution

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Advances in low-field nuclear magnetic resonance(nmr) technologies applied for characterization of pore space inside rocks:a critical review

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Petroleum Science 2020年第5期17卷 1281-1297页

作者： Jian-Chun Guo Hang-Yu Zhou Jie Zeng Kun-Jie Wang Jie Lai Yu-Xuan Liu State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengdu 610500China Department of Chemical Engineering School of EngineeringThe University of Western Australia35 Stirling HighwayPerthWA 6009Australia Downhole Operation Branch Southwest Petroleum Engineering Co.LtdSinopecDeyang 618014China

nmr serves as an important technique for probing rock pore space,such as pore structure characterization,fluid identification,and petrophysical property testing,due to the reusability of cores,convenience in sample processing,and time efficiency in laboratory tests.In practice,nmr signal collection is normally achieved through polarized nuclei relaxation which releases crucial relaxation messages for result interpretation.The impetus of this work is to help engineers and researchers with petroleum background obtain new insights into nmr principals and extend existing methodologies for characterization of unconventional formations.This article first gives a brief description of the development history of relaxation theories and models for porous media.Then,the widely used nmr techniques for characterizing petrophysical properties and pore structures are presented.Meanwhile,limitations and deficiencies of them are summarized.Finally,future work on improving these insufficiencies and approaches of enhancement applicability for nmr technologies are discussed.

关键词： low-field nmr Critical review Relaxation theory Unconventional formation

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Porosity of gas shale:Is the nmr-based measurement reliable?

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Petroleum Science 2022年第2期19卷 509-517页

作者： Peng Zhao Bo He Bo Zhang Jun Liu Key Laboratory of Deep Underground Science and Engineering(Ministry of Education) College of Architecture and EnvironmentSichuan UniversityChengduSichuan 610065China Institute of New Energy and low-Carbon Technology Sichuan UniversityChengduSichuan 610065China Institute of Science and Technology China Three Gorges CorporationBeijing100038China

Aiming at obtaining an accurate porosity of gas shale,various approaches are attempted.Therein,nuclear magnetic resonance(nmr),being treated as a kind of new-developed technique,possesses the representative significance.However,as a booming technique,the reliability of nmr-based porosity of shale is not exactly defined.Depending on nmr device,this work measured the porosity of shale experiencing different water soaking time,accordingly,judging the reliability of nmr-based porosity.Results indicate the nmr outcomes vary with the water soaking time,making a doubt about the objectivity of nmrbased porosity in reflecting the real shale porosity.Furthermore,some supplementary means were adopted to verify the water soaking-induced variation in the pore system of shale sample,which intensities the suspicion if the nmr-based porosity is reliable or not.To sum up,this work considers that the nmr-based porosity of shale is not reliable enough when water is used as the probe.Besides,this work also offers some suggestions on how to enhance the reliability of nmr-based porosity of shale sample.Basically,this work selects a fresh perspective to analyze the nmr approach in determining shale porosity,which is hopefully helpful in promoting the development of nmr technique in the shale-related field.

关键词： Gas shale low-field nmr Porosity measurement low-temperature nitrogen adsorption

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Functional group resolved nmr relaxation of 3-carbon adsorbates in mesoporous alumina

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Magnetic Resonance Letters 2023年第3期3卷 248-255,I0004页

作者： Neil Robinson Carmine D’Agostino Michael LJohns Department of Chemical Engineering The University of Western Australia35 Stirling HighwayPerthWA 6009Australia Department of Chemical Engineering The University of ManchesterOxford RoadManchesterM139PLUK Dipartimento di Ingegneria Civile ChimicaAmbientale e Dei Materiali(DICAM)Alma Mater Studiorum e Universita di BolognaVia Terracini28Bologna40131Italy

nmr relaxation analysis provides a unique and non-invasive probe of fluid dynamics within porous materials,and may be applied to the interpretation of a wide variety of material and interfacial characteristics.Here,we report two-dimensional^(1)H T_(1)-T_(2)relaxation correlation measurements of a range of three-carbon adsorbates(1-propanol,2-propanol and propanoic acid)imbibed within the mesoporous metal oxide gamma-alumina.Our data,acquired across field strengths of 2 MHz,12.7 MHz and 43 MHz,clearly reveal two populations in each measurement,identified as the alkyl and hydroxyl moieties of each adsorbate.These results expand the range of materials in which such functional group resolved relaxation is known to occur,and demonstrate the clear persistence of such phenomena using a range of typical benchtop nmr systems employed to study fluid-saturated porous media.

关键词： nmr relaxation Adsorption Porous media low-field nmr

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Experimental study on characteristics of pore water conversion during methane hydrates formation in unsaturated sand

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China Geology 2022年第2期5卷 276-284页

作者： Yun-kai Ji Chang-ling Liu Zhun Zhang Qing-guo Meng Le-le Liu Yong-chao Zhang Neng-you Wu Key Laboratory of Gas Hydrate Ministry of Natural ResourcesQingdao Institute of Marine GeologyQingdao 266237China Laboratory for Marine Mineral Resources Pilot National Laboratory for Marine Science and TechnologyQingdao 266237China Faculty of Engineering China University of GeosciencesWuhan 430074China

Understanding the pore water conversion characteristics during hydrate formation in porous media is important to study the accumulation mechanism of marine gas hydrate.In this study,low-field nmr was used to study the pore water conversion characteristics during methane hydrate formation in unsaturated sand samples.Results show that the signal intensity of T_(2) distribution isn’t affected by sediment type and pore pressure,but is affected by temperature.The increase in the pressure of hydrogen-containing gas can cause the increase in the signal intensity of T_(2) distribution.The heterogeneity of pore structure is aggravated due to the hydrate formation in porous media.The water conversion rate fluctuates during the hydrate formation.The sand size affects the water conversion ratio and rate by affecting the specific surface of sand in unsaturated porous media.For the fine sand sample,the large specific surface causes a large gas-water contact area resulting in a higher water conversion rate,but causes a large water-sand contact area resulting in a low water conversion ratio(C_(w)=96.2%).The clay can reduce the water conversion rate and ratio,especially montmorillonite(C_(w)=95.8%).The crystal layer of montmorillonite affects the pore water conversion characteristics by hindering the conversion of interlayer water.

关键词： Porous media Unsaturated sand Methane hydrates low-field nmr Pore water conversion Hydrate formation NGHs exploration trial engineering Oil and gas exploration engineering Shenhu area South China Sea

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Evaluation of Cinnamon by Solid-State nmr Employing Relaxometry

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Materials Sciences and Applications 2023年第3期14卷 142-147页

作者： Pedro Paulo Merat Roberto Cucinelli Neto Vitor Santos Ramos Maria Inês Bruno Tavares Instituto de Macromoléculas Professora Eloisa Mano (IMA) da Universidade Federal do Rio de Janeiro UFRJ Centro de Tecnologia Ilha do Fund&atildeo Rio de Janeiro Brasil IFRJ Avenida República do Paraguai Duque de Caxias Brasil

To evaluate the molecular dynamics and the molecular regions presented in the cinnamon types it was chosen to evaluate them without any treatment, and for that it was used low-field nuclear magnetic resonance (nmr) through the pulse sequence such as MSE-FID, an nmr sequence in the time domain, and from the longitudinal relaxation time (with a time constant T1), employing the inversion-recovery pulse sequence. The low-field nmr results indicate that the techniques chosen were a very good alternative to evaluate these types of samples food and their structural organization according to their constituents. The molecular mobility is different.

关键词： Cinnamon low-field nmr nmr Relaxation Functional Food

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