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de Pierri L, Novotny EH, Pellegrino Cerri CE, José de Souza A, Mattos BB, Tornisielo VL, Regitano JB. Accessing biochar's porosity using a new low field NMR approach and its impacts on the retention of highly mobile herbicides. CHEMOSPHERE 2022; 287:132237. [PMID: 34543894 DOI: 10.1016/j.chemosphere.2021.132237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2021] [Revised: 09/03/2021] [Accepted: 09/09/2021] [Indexed: 06/13/2023]
Abstract
Agrowaste biochars [sugarcane straw (SS), rice husk (RH), poultry manure (PM), and sawdust (SW)] were synthesized at different pyrolysis temperatures (350, 450, 550, and 650 °C) to evaluate their potential to retain highly mobile herbicides, such as hexazinone and tebuthiuron that often contaminate water resources around sugarcane plantations. A new low field nuclear magnetic resonance approach based on decay due to diffusion in internal magnetic field (NMR-DDIF) was successfully used to determine biochar's porosity and specific surface area (SSA) to clear the findings of this work. SSA of pores with diameters >5.0 μm increased with pyrolysis temperatures and seemed to dictate biochar's retention, which was >70% of the applied amounts at 650 °C. These macropores appear to act as main arteries for herbicide intra-particle diffusion into smaller pores, thus enhancing herbicides retention. Biochar granulometry had little, but herbicide aging had a significant effect on sorption, mainly of tebuthiuron. However, soils amended with 10,000 kg ha-1 of the biochars showed low sorption potential. Therefore, higher than usual biochar rates or proper incorporation strategies, i.e., surface incorporation, will be needed to remediate areas contaminated with these highly mobile herbicides, thus precluding their leaching to groundwaters.
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Affiliation(s)
- Letícia de Pierri
- Luiz de Queiroz College of Agriculture (ESALQ), Dept. of Soil Science, University of São Paulo, Piracicaba, C.P. 09, 13418-260, SP, Brazil.
| | | | - Carlos Eduardo Pellegrino Cerri
- Luiz de Queiroz College of Agriculture (ESALQ), Dept. of Soil Science, University of São Paulo, Piracicaba, C.P. 09, 13418-260, SP, Brazil.
| | - Adijailton José de Souza
- Luiz de Queiroz College of Agriculture (ESALQ), Dept. of Soil Science, University of São Paulo, Piracicaba, C.P. 09, 13418-260, SP, Brazil.
| | - Bianca Braz Mattos
- Brazilian Agricultural Research Corporation, Embrapa Soils, Rio de Janeiro, 22460-000, RJ, Brazil.
| | - Valdemar Luiz Tornisielo
- Center of Nuclear Energy in Agriculture (CENA), University of São Paulo, Piracicaba, 03178-200, SP, Brazil.
| | - Jussara Borges Regitano
- Luiz de Queiroz College of Agriculture (ESALQ), Dept. of Soil Science, University of São Paulo, Piracicaba, C.P. 09, 13418-260, SP, Brazil.
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Stepišnik J, Ardelean I, Mohorič A. Molecular self-diffusion in internal magnetic fields of porous medium investigated by NMR MGSE method. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2021; 328:106981. [PMID: 33971583 DOI: 10.1016/j.jmr.2021.106981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Revised: 04/08/2021] [Accepted: 04/09/2021] [Indexed: 06/12/2023]
Abstract
Inhomogeneous magnetic fields generated in porous media due to differences in magnetic susceptibility at solid/liquid interfaces and due to intrinsic or artificially doped magnetic impurities can be used to gain insight into the molecular dynamics of fluid in the structure of a porous medium using the concept of NMR modulated gradient spin echo method. We extended the theory of this method to the case of an inhomogeneous magnetic field that cannot be approximated by an uniform gradient, in order to explain the CPMG measurements of self-diffusion in water soaked ceramics, which are doped with magnetic impurities of different contents. The new interpretation provides the spin relaxation times, the average pore size and their distribution, as well as the strength of the internal magnetic gradient fields in the doped ceramics.
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Affiliation(s)
- Janez Stepišnik
- University of Ljubljana, Faculty of Mathematics and Physics, Physics Department, Jadranska 19, 1000 Ljubljana, Slovenia.
| | - Ioan Ardelean
- Physics Department, Faculty of Materials Science and Engineering, Technical University of Cluj-Napoca, Romania
| | - Aleš Mohorič
- University of Ljubljana, Faculty of Mathematics and Physics, Physics Department, Jadranska 19, 1000 Ljubljana, Slovenia
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3
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Distribution Model of Fluid Components and Quantitative Calculation of Movable Oil in Inter-Salt Shale Using 2D NMR. ENERGIES 2021. [DOI: 10.3390/en14092447] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Some inter-salt shale reservoirs have high oil saturations but the soluble salts in their complex lithology pose considerable challenges to their production. Low-field nuclear magnetic resonance (NMR) has been widely used in evaluating physical properties, fluid characteristics, and fluid saturation of conventional oil and gas reservoirs as well as common shale reservoirs. However, the fluid distribution analysis and fluid saturation calculations in inter-salt shale based on NMR results have not been investigated because of existing technical difficulties. Herein, to explore the fluid distribution patterns and movable oil saturation of the inter-salt shale, a specific experimental scheme was designed which is based on the joint adaptation of multi-state saturation, multi-temperature heating, and NMR measurements. This novel approach was applied to the inter-salt shale core samples from the Qianjiang Sag of the Jianghan Basin in China. The experiments were conducted using two sets of inter-salt shale samples, namely cylindrical and powder samples. Additionally, by comparing the one-dimensional (1D) and two-dimensional (2D) NMR results of these samples in oil-saturated and octamethylcyclotetrasiloxane-saturated states, the distributions of free movable oil and water were obtained. Meanwhile, the distributions of the free residual oil, adsorbed oil, and kerogen in the samples were obtained by comparing the 2D NMR T1-T2 maps of the original samples with the sample heated to five different temperatures of 80, 200, 350, 450, and 600 °C. This research puts forward a 2D NMR identification graph for fluid components in the inter-salt shale reservoirs. Our experimental scheme effectively solves the problems of fluid composition distribution and movable oil saturation calculation in the study area, which is of notable importance for subsequent exploration and production practices.
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Du Q, Xiao L, Zhang Y, Liao G, Liu H, Guo J. A novel two-dimensional NMR relaxometry pulse sequence for petrophysical characterization of shale at low field. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2020; 310:106643. [PMID: 31756633 DOI: 10.1016/j.jmr.2019.106643] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 11/06/2019] [Accepted: 11/07/2019] [Indexed: 06/10/2023]
Abstract
Low field two-dimensional nuclear magnetic resonance (2D-NMR) relaxometry is a powerful probe for the characterization of heterogenous, porous media and provides geometrical, physical and chemical information about samples at a molecular level and has been widely used in shale studies. However, NMR signals of shale decay so rapidly, dry sample for particular, that the conventional two-dimensional pulse sequence is either not sensitive enough to short relaxation components or takes too much measurement time. In this paper, 2D-NMR relaxometry correlation based on partial inversion recovery CPMG (PIR-CPMG) pulse sequence is proposed and illustrated to improve the contrast over saturation recovery CPMG (SR-CPMG) and reduces the T1 encoding time of inversion recovery CPMG (IR-CPMG) for petrophysical characterization of shale. Subsequently, the kernel function and inversion method of this sequence are presented and the reliability of the inversion method is testified by numerical simulation. Next, theoretical analysis is conducted to validate the advantages of PIR-CPMG. Ultimately, experiments on copper sulfate solution, artificial sandstone, and shale samples are performed, respectively, to verify the feasibility and effectiveness of the proposed pulse sequence. The results demonstrate that the PIR-CPMG sequence is time-saving and high-contrast, especially for the short relaxation components. This pulse sequence can be utilized in bench-top NMR core analyzer and downhole well logging, potentially, to achieve integrated petrophysical characterization of shale.
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Affiliation(s)
- Qunjie Du
- State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China; Sinopec Shengli Oilfield Service Corporation Well Logging Company, Dongying 257100, Shandong, China
| | - Lizhi Xiao
- State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China; Harvard SEAS-CUPB Joint Laboratory on Petroleum Science, Cambridge, MA 02138, USA.
| | - Yan Zhang
- State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China
| | - Guangzhi Liao
- State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China
| | - Huabing Liu
- State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China; Beijing Limecho Technology Co., Ltd, Beijing 102299, China
| | - Jiangfeng Guo
- State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China
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Chen J, Peng H, Fan J, Zhang X, Liu W, Jiang D. Microscopic investigations on the healing and softening of damaged salt by uniaxial deformation from CT, SEM and NMR: effect of fluids (brine and oil). RSC Adv 2020; 10:2877-2886. [PMID: 35496133 PMCID: PMC9048590 DOI: 10.1039/c9ra05866d] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 01/06/2020] [Indexed: 11/21/2022] Open
Abstract
Nowadays, a salt cavern, used as underground energy storage (e.g. natural gas, crude oil, hydrogen), is becoming more and more popular in China due to its many advantages, such as low permeability (≤10−21 m2), good water-soluble mining and the damage-healing characteristic of salt rocks. It not only solves the problem of energy resource supply-demand imbalance in China, but also provides a better, more secure and cost-effective way to store energy compared to aboveground energy storage systems. As for salt cavern storage, permeability is our primary concern in engineering, which is mainly influenced by damage and healing. In this work, some damaged salt specimens were prepared by uniaxial compression tests (the loading rate was 0.033 mm s−1). Then those specimens were immersed in either a saturated brine solution or oil at 50 °C for a few days. Microscopic investigations were carried out by X-ray Computed Tomography (CT), Scanning Electron Microscope (SEM) and Nuclear Magnetic Resonance (NMR) to investigate the change of salt microstructures after healing. Possible micro-healing mechanisms were discussed. It was found that fluids played an important role in the healing process of damaged salt. Healing effectiveness of micro-pores and -cracks with the brine solution was higher than that with oil mainly because of crystal recrystallization. The surface of the grains was smooth and had no visible microcracks after healing in brine, while there were many pits and micro-tunnels with oil. Oil could hinder the healing process by impeding the diffusion effect and restraining grain recrystallization. Meanwhile, intragranular and intergranular water could also work as a lubricant resulting in softening which made salt rock more deformable. NMR results confirmed that damaged salt had a better recovery with brine, displaying lower porosity and lower permeability compared to that with oil. This work provides preliminary microscopic investigations on the healing of damaged salt in order to reveal the salt healing mechanism. A systematic microscopic investigation by CT, SEM and NMR to study the effects of brine and oil on rock salt healing.![]()
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Affiliation(s)
- Jie Chen
- School of Resources and Safety Engineering
- State Key Laboratory of Coal Mine Disaster Dynamics and Control
- Chongqing University
- Chongqing 400044
- PR China
| | - Huihua Peng
- School of Resources and Safety Engineering
- State Key Laboratory of Coal Mine Disaster Dynamics and Control
- Chongqing University
- Chongqing 400044
- PR China
| | - Jinyang Fan
- School of Resources and Safety Engineering
- State Key Laboratory of Coal Mine Disaster Dynamics and Control
- Chongqing University
- Chongqing 400044
- PR China
| | - Xiong Zhang
- School of Resources and Safety Engineering
- State Key Laboratory of Coal Mine Disaster Dynamics and Control
- Chongqing University
- Chongqing 400044
- PR China
| | - Wei Liu
- School of Resources and Safety Engineering
- State Key Laboratory of Coal Mine Disaster Dynamics and Control
- Chongqing University
- Chongqing 400044
- PR China
| | - Deyi Jiang
- School of Resources and Safety Engineering
- State Key Laboratory of Coal Mine Disaster Dynamics and Control
- Chongqing University
- Chongqing 400044
- PR China
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6
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Experimental Investigation of Pore Structure and Movable Fluid Traits in Tight Sandstone. Processes (Basel) 2019. [DOI: 10.3390/pr7030149] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Whether the variation of pore structures and movable fluid characteristics enhance, deteriorate, or have no influence on reservoir quality has long been disputed, despite their considerable implications for hydrocarbon development in tight sandstone reservoirs. To elucidate these relationships, this study systematically analyzes pore structures qualitatively and quantitatively by various kinds of direct observations, indirect methods, and imaging simulations. We found that the uncertainty of porosity measurements, caused by the complex pore-throat structure, needs to be eliminated to accurately characterize reservoir quality. Bulk water was more easily removed, while surface water tended to be retained in the pores, and the heterogeneity of pore structures was caused by the abundance of tiny pores. The rates of water saturation reduction in macropores are faster than those for tiny pores, and sandstones with poor reservoir quality show no marked descending of lower limits of movable pore radius, indicating that the movable fluid would advance exempted from the larger pores. This study suggests that the deterioration of reservoir quality is strongly affected by the reduction of larger pores and the aqueous phases tended to remain in the tiny pores in the forms of surface water.
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Wang J, Xiao L, Liao G, Zhang Y, Cui Y, Sun Z, Dong Y, Hu L. NMR characterizing mixed wettability under intermediate-wet condition. Magn Reson Imaging 2019; 56:156-160. [DOI: 10.1016/j.mri.2018.09.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2018] [Revised: 09/21/2018] [Accepted: 09/22/2018] [Indexed: 10/28/2022]
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Yu Z, Zhang Y, Xiao L, Liao G. Characterization of porous media by T 2-T 2 correlation beyond fast diffusion limit. Magn Reson Imaging 2018; 56:19-23. [PMID: 30343123 DOI: 10.1016/j.mri.2018.10.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2018] [Revised: 10/07/2018] [Accepted: 10/18/2018] [Indexed: 10/28/2022]
Abstract
Pore size distribution and surface relaxivity are two important properties of porous media such as rock samples and can be obtained by NMR methods. However, it is difficult to obtain these information beyond the fast diffusion limit. Here we present a new method to directly characterize the averaged pore size of a porous sample with a narrow pore size distribution. This method is based on the parallel plates pore model and the T2-T2 correlation sequence. The pore size (a) - surface relaxivity (ρ) correlation maps were obtained using the non-negative least squares method. Three kinds of glass bead samples were measured and the averaged pore size and surface relaxivity were extracted.
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Affiliation(s)
- Zhou Yu
- State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China
| | - Yan Zhang
- State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China.
| | - Lizhi Xiao
- State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China; Harvard SEAS-CUPB Joint Laboratory on Petroleum Science, Cambridge, MA 02138, USA
| | - Guangzhi Liao
- State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China
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Ghomeshi S, Kryuchkov S, Kantzas A. An investigation into the effects of pore connectivity on T 2 NMR relaxation. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2018; 289:79-91. [PMID: 29476929 DOI: 10.1016/j.jmr.2018.02.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 02/09/2018] [Accepted: 02/10/2018] [Indexed: 06/08/2023]
Abstract
Nuclear Magnetic Resonance (NMR) is a powerful technique used to characterize fluids and flow in porous media. The NMR relaxation curves are closely related to pore geometry, and the inversion of the NMR relaxometry data is known to give useful information with regards to pore size distribution (PSD) through the relative amplitudes of the fluids stored in the small and large pores. While this information is crucial, the main challenge for the successful use of the NMR measurements is the proper interpretation of the measured signals. Natural porous media patterns consist of complex pore structures with many interconnected or "coupled" regions, as well as isolated pores. This connectivity along the throats changes the relaxation distribution and in order to properly interpret this data, a thorough understanding of the effects of pore connectivity on the NMR relaxation distribution is warranted. In this paper we address two main points. The first pertains to the fact that there is a discrepancy between the relaxation distribution obtained from experiments, and the ones obtained from solving the mathematical models of diffusion process in the digitized images of the pore space. There are several reasons that may attribute to this such as the lack of a proper incorporation of surface roughness into the model. However, here we are more interested in the effects of pore connectivity and to understand why the typical NMR relaxation distribution obtained from experiments are wider, while the numerical simulations predict that a wider NMR relaxation distribution may indicate poor connectivity. Secondly, by not taking into account the pore coupling effects, from our experience in interpreting the data, we tend to underestimate the pore volume of small pores and overestimate the amplitudes in the large pores. The role of pore coupling becomes even more prominent in rocks with small pore sizes such as for example in shales, clay in sandstones, and in the microstructures of carbonates.
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Affiliation(s)
- Shahin Ghomeshi
- University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada; Perm Inc., VP Technology, 3956 29 Street NE., Calgary, AB T1Y 6B6, Canada.
| | - Sergey Kryuchkov
- Perm Inc., VP Technology, 3956 29 Street NE., Calgary, AB T1Y 6B6, Canada.
| | - Apostolos Kantzas
- Room ES 902A, Chemical and Petroleum Engineering Department, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada.
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10
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Zhang Y, Xiao L, Liao G, Song YQ. Direct correlation of diffusion and pore size distributions with low field NMR. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 269:196-202. [PMID: 27371788 DOI: 10.1016/j.jmr.2016.06.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Revised: 06/17/2016] [Accepted: 06/17/2016] [Indexed: 06/06/2023]
Abstract
The time-dependent diffusion coefficient (D) is a powerful tool to probe microstructure in porous media, and can be obtained by the NMR method. In a real porous sample, molecular diffusion is very complex. Here we present a new method which directly measures the relationship between effective diffusion coefficients and pore size distributions without knowing surface relaxivity. This method is used to extract structural information and explore the relationship between D and a in porous media having broad pore size distributions. The diffusion information is encoded by the Pulsed Field Gradient (PFG) method and the pore size distributions are acquired by the Decay due to Diffusion in the Internal Field (DDIF) method. Two model samples were measured to verify this method. Restricted diffusion was analyzed, and shows that most fluid molecules experience pore wall. The D(a) curves obtained from correlation maps were fitted to the Padé approximant equation and a good agreement was found between the fitting lines and the measured data. Then a sandstone sample with unknown structure was measured. The state of confined fluids was analyzed and structural information, such as pore size distributions, were extracted. The D - T1 correlation maps were also obtained using the same method, which yielded surface relaxivities for different samples. All the experiments were conducted on 2MHz NMR equipment to obtain accurate diffusion information, where internal gradients can be neglected. This method is expected to have useful applications in the oil industry, particularly for NMR logging in the future.
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Affiliation(s)
- Yan Zhang
- State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China
| | - Lizhi Xiao
- State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China.
| | - Guangzhi Liao
- State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China
| | - Yi-Qiao Song
- Schlumberger-Doll Research, One Hampshire Street, Cambridge, MA 02139, United States
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11
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Silletta EV, Velasco MI, Gomez CG, Strumia MC, Stapf S, Mattea C, Monti GA, Acosta RH. Enhanced Surface Interaction of Water Confined in Hierarchical Porous Polymers Induced by Hydrogen Bonding. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:7427-7434. [PMID: 27341270 DOI: 10.1021/acs.langmuir.6b00824] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Hierarchical porous polymer systems are increasingly applied to catalysis, bioengineering, or separation technology because of the versatility provided by the connection of mesopores with percolating macroporous structures. Nuclear magnetic resonance (NMR) is a suitable technique for the study of such systems as it can detect signals stemming from the confined liquid and translate this information into pore size, molecular mobility, and liquid-surface interactions. We focus on the properties of water confined in macroporous polymers of ethylene glycol dimethacrylate and 2-hydroxyethyl methacrylate [poly(EGDMA-co-HEMA)] with different amounts of cross-linkers, in which a substantial variation of hydroxyl groups is achieved. As soft polymer scaffolds may swell upon saturation with determined liquids, the use of NMR is particularly important as it measures the system in its operational state. This study combines different NMR techniques to obtain information on surface interactions of water with hydrophilic polymer chains. A transition from a surface-induced relaxation in which relaxivity depends on the pore size to a regime where the organic pore surface strongly restricts water diffusion is observed. Surface affinities are defined through the molecular residence times near the network surface.
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Affiliation(s)
- Emilia V Silletta
- FaMAF-Universidad Nacional de Córdoba and IFEG-CONICET , 5016 Córdoba, Argentina
| | - Manuel I Velasco
- FaMAF-Universidad Nacional de Córdoba and IFEG-CONICET , 5016 Córdoba, Argentina
| | - Cesar G Gomez
- Departamento de Química Orgánica, Facultad de Ciencias Químicas (IMBIV-CONICET), Universidad Nacional de Córdoba , Haya de la Torre y Medina Allende, Edificio de Ciencias II-Ciudad Universitaria, 5000 Córdoba, Argentina
| | - Miriam C Strumia
- Departamento de Química Orgánica, Facultad de Ciencias Químicas (IMBIV-CONICET), Universidad Nacional de Córdoba , Haya de la Torre y Medina Allende, Edificio de Ciencias II-Ciudad Universitaria, 5000 Córdoba, Argentina
| | - Siegfried Stapf
- Fachgebiet Technische Physik II/Polymer Physik, Institute of Physics, Technische Universität Ilmenau , P.O. Box 100 565, 98684 Ilmenau, Germany
| | - Carlos Mattea
- Fachgebiet Technische Physik II/Polymer Physik, Institute of Physics, Technische Universität Ilmenau , P.O. Box 100 565, 98684 Ilmenau, Germany
| | - Gustavo A Monti
- FaMAF-Universidad Nacional de Córdoba and IFEG-CONICET , 5016 Córdoba, Argentina
| | - Rodolfo H Acosta
- FaMAF-Universidad Nacional de Córdoba and IFEG-CONICET , 5016 Córdoba, Argentina
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Zhang Y, Xiao L, Liao G, Blümich B. Direct correlation of internal gradients and pore size distributions with low field NMR. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 267:37-42. [PMID: 27111138 DOI: 10.1016/j.jmr.2016.04.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 04/13/2016] [Accepted: 04/18/2016] [Indexed: 06/05/2023]
Abstract
Internal magnetic field gradients Gint, which arise from the magnetic susceptibility difference Δχ between solid matrix and fluid in porous media relate to the pore geometry. However, this relationship is complex and not well understood. Here we correlate internal-gradient distributions to pore-size distributions directly to examine internal gradients in detail at low field NMR. The pore-size distributions were obtained by the method of Decay due to Diffusion in the Internal Field (DDIF), and the internal-gradient distributions were measured with the Carr-Purcell-Meiboom-Gill (CPMG) method. The internal-gradient-pore-size distributions correlation maps were obtained for water in packs of glass beads with different diameter and in a sandstone sample. The relationship between internal gradients and pore structure is analyzed in detail by considering the restricted diffusion of fluids in porous samples. For each case diffusion regimes are assigned by plotting normalized CPMG data and comparing the diffusion lengths, the dephasing lengths and pore diameters. In the free-diffusion limit, the correlation maps reveal the true relationship between pore structure and internal gradients so that Δχ can be approximated from the correlation maps. This limit is met most easily at low field. It provides information about porous media, which is expected to benefit the oil industry, in particular NMR well logging.
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Affiliation(s)
- Yan Zhang
- State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China
| | - Lizhi Xiao
- State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China.
| | - Guangzhi Liao
- State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China
| | - Bernhard Blümich
- Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Germany
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13
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Lewis RT, Seland JG. A multi-dimensional experiment for characterization of pore structure heterogeneity using NMR. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 263:19-32. [PMID: 26773523 DOI: 10.1016/j.jmr.2015.11.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 11/05/2015] [Accepted: 11/07/2015] [Indexed: 06/05/2023]
Abstract
In a liquid saturated porous sample the spatial inhomogeneous internal magnetic field in general depends on the strength of the static magnetic field, the differences in magnetic susceptibilities, but also on the geometry of the porous network. To thoroughly investigate how the internal field can be used to determine various properties of the porous structure, we present a novel multi-dimensional NMR experiment that enables us to measure several dynamic correlations in one experiment, and where all of the correlations involve the internal magnetic field and its dependence on the geometry of the porous network. (Correlations: internal gradient - pore size, internal gradient - magnetic susceptibility difference, internal gradient - longitudinal relaxation, longitudinal relaxation - magnetic susceptibility difference.) It is always a spatial average of the internal magnetic field, or one of the related properties, that is measured, which is important to take into consideration when analyzing the obtained results. We demonstrate how these correlations can be an indicator for pore structure heterogeneity, and focus in particular on how the effect from spatial averaging can be evaluated and taken into account in the different cases.
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Affiliation(s)
- Rhiannon T Lewis
- Department of Chemistry, University of Bergen, Allegaten 41, N-5007 Bergen, Norway
| | - John Georg Seland
- Department of Chemistry, University of Bergen, Allegaten 41, N-5007 Bergen, Norway.
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14
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Lewis RT, Djurhuus K, Seland JG. Characterising oil and water in porous media using decay due to diffusion in the internal field. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2015; 259:1-9. [PMID: 26254732 DOI: 10.1016/j.jmr.2015.07.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Revised: 07/08/2015] [Accepted: 07/09/2015] [Indexed: 06/04/2023]
Abstract
In the method Decay due to Diffusion in the Internal Field (DDIF), the diffusion behaviour of water molecules in the internal magnetic field makes it possible to determine a distribution of pore sizes in a sample. The DDIF experiment can also be extended to a DDIF-Carr-Purcell-Meiboom-Gill (DDIF-CPMG) experiment to measure correlations between the pore size and the transverse relaxation time, T2. In this study we have for the first time applied the DDIF experiment and the DDIF-CPMG experiment to porous materials saturated with both water and oil. Because of the large difference in diffusion rates between water and oil molecules, the DDIF experiment will act as a filter for the signal from oil, and we are left with the DDIF-signal from water only. This has been verified in model systems consisting of glass beads immersed in separate layers of water and oil, and in a sandstone sample saturated with water and oil. The results show that the DDIF and DDIF-CPMG experiments enable the determination of the confining geometry of the water phase, and how this geometry is correlated to T2. Data obtained in the sandstone sample saturated with water and oil also show that with the exception of the smallest pores there is no clear correlation between pore size and the relaxation time of water.
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Affiliation(s)
- Rhiannon T Lewis
- Department of Chemistry, University of Bergen, Allegaten 41, N-5007 Bergen, Norway
| | | | - John Georg Seland
- Department of Chemistry, University of Bergen, Allegaten 41, N-5007 Bergen, Norway.
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