scholarly journals Advanced NMR methodologies in rock core analysis

2021 ◽  
Author(s):  
◽  
Huabing Liu
Keyword(s):  
Pore Space ◽  
Network Models ◽  
2D Nmr ◽  
Immiscible Fluids ◽  
Surface Relaxation ◽  
Surface Relaxivity ◽  
Spatially Resolved ◽  
Pore Length ◽  
Heterogeneous Rocks ◽  
Nmr Methods

<p>¹H NMR techniques have gained extensive acceptance in petrophysics for the evaluation of fluid-saturating reservoir rocks. This thesis presents the development of new NMR methods regarding the reserves (determination of pore length scales and surface relaxivities), productivity (estimates of permeability) and recovery of fluids (resolves of saturation evolution) in rocks.  Traditionally, pore lengths are evaluated from the ground relaxation eigenmodes of spin-bearing molecules in pore space. This evaluation is not straightforward since it is affected by surface relaxivity. Here, we use an approach to determine pore length from detecting the high relaxation eigenmodes, in which way the eigenvalue spectrum directly scales to the pore size distribution. Based on this, we extend this approach for the use with low-field NMR spectrometers and 2D NMR eigenmode correlation methods. Surface relaxivity can be further extracted from these 2D correlation maps, which is in agreement with an independent NMR measurement.  Permeability is generally estimated from surface relaxation via empirical pore-network models. However, for heterogeneous rocks a single (or averaged) permeability value may not be adequate. Therefore, we measure surface relaxation in conjunction with MRI techniques. Permeability profiles can then be obtained from spatially resolved relaxation maps yielding local connectedness between adjacent slices. The results are confirmed by the comparison of brine-permeability measurements.  MRI experiments of fluids in rocks at reservoir-like conditions may yield optimized recovery strategies of reservoir fluids. In this context we combine MRI with diffusion-relaxation correlation measurements during flooding intervals. The results provide substantial information, such as flooding front and saturation profiles of immiscible fluids discriminated by fluid type.</p>

scholarly journals Advanced NMR methodologies in rock core analysis

2021 ◽  
Author(s):  
◽  
Huabing Liu
Keyword(s):  
Pore Space ◽  
Network Models ◽  
2D Nmr ◽  
Immiscible Fluids ◽  
Surface Relaxation ◽  
Surface Relaxivity ◽  
Spatially Resolved ◽  
Pore Length ◽  
Heterogeneous Rocks ◽  
Nmr Methods

<p>¹H NMR techniques have gained extensive acceptance in petrophysics for the evaluation of fluid-saturating reservoir rocks. This thesis presents the development of new NMR methods regarding the reserves (determination of pore length scales and surface relaxivities), productivity (estimates of permeability) and recovery of fluids (resolves of saturation evolution) in rocks.  Traditionally, pore lengths are evaluated from the ground relaxation eigenmodes of spin-bearing molecules in pore space. This evaluation is not straightforward since it is affected by surface relaxivity. Here, we use an approach to determine pore length from detecting the high relaxation eigenmodes, in which way the eigenvalue spectrum directly scales to the pore size distribution. Based on this, we extend this approach for the use with low-field NMR spectrometers and 2D NMR eigenmode correlation methods. Surface relaxivity can be further extracted from these 2D correlation maps, which is in agreement with an independent NMR measurement.  Permeability is generally estimated from surface relaxation via empirical pore-network models. However, for heterogeneous rocks a single (or averaged) permeability value may not be adequate. Therefore, we measure surface relaxation in conjunction with MRI techniques. Permeability profiles can then be obtained from spatially resolved relaxation maps yielding local connectedness between adjacent slices. The results are confirmed by the comparison of brine-permeability measurements.  MRI experiments of fluids in rocks at reservoir-like conditions may yield optimized recovery strategies of reservoir fluids. In this context we combine MRI with diffusion-relaxation correlation measurements during flooding intervals. The results provide substantial information, such as flooding front and saturation profiles of immiscible fluids discriminated by fluid type.</p>

Three Novel Friedelane Triterpenes with Antimicrobial Activity from the Stems of Celastrus Monospermus

2013 ◽  
Vol 37 (1) ◽  
pp. 14-18 ◽  
Author(s):  
Haiping Xie ◽  
Mingxiang Chen ◽  
Dingyong Wang ◽  
Runlin Xu
Keyword(s):  
Antimicrobial Activity ◽  
2D Nmr ◽  
Moderate Activity ◽  
Luminescent Bacterium ◽  
Fish Meat ◽  
Photobacterium Leiognathi ◽  
Nmr Methods ◽  
Oleanane Triterpenoid

Three novel friedelane triterpenes, monospermonal, monospermonol and monospermondiol, along with six known friedelanes, 3-oxofriedelane, 3-oxofriedelan-28-al, 3,12-dioxofriedelane, 3-oxo-28-hydroxyfriedelane, 3-oxo-11 β-hydroxyfriedelane, 3-oxo-12 α-hydroxyfriedelane and an oleanane triterpenoid, 3 β-hydroxyolean-12-ene, were isolated from the stems of Celastrus monospermus Roxb. The structures of novel compounds, monospermonal, monospermonol and monospermondiol, were identified as 3,12-dioxofriedelan-28-al, 3,12-dioxo-28-hydroxyfriedelane and 3-oxo-12 α,28-dihydroxyfriedelane, respectively by spectroscopies including 2D NMR methods. These nine friedelane-type triterpenes were tested for antimicrobial activity against luminescent bacterium Photobacterium leiognathi N1 that had been isolated from “glowing” fish meat. Monospermonal and monospermonol showed moderate activity.

ChemInform Abstract: Quantitative Investigations of Molecular Stereodynamics by 1D and 2D NMR Methods

ChemInform ◽  
2010 ◽  
Vol 22 (16) ◽  
pp. no-no
Author(s):  
K. G. ORRELL ◽  
V. SIK ◽  
D. STEPHENSON
Keyword(s):  
2D Nmr ◽  
Nmr Methods

Quantifying the Mechanisms Contributing to Nuclear-Magnetic-Resonance Surface Relaxation of Protons in Kerogen Pores of Organic-Rich Mudrocks

SPE Journal ◽  
2019 ◽  
Vol 24 (06) ◽  
pp. 2438-2457 ◽  
Author(s):  
Saurabh Tandon ◽  
Zoya Heidari
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Numerical Simulations ◽  
Dipolar Coupling ◽  
Surface Relaxation ◽  
Pore Scale ◽  
New Model ◽  
Surface Relaxivity ◽  
Coupling Mechanisms ◽  
Organic Pores

Summary The evaluation of nuclear–magnetic–resonance (NMR) measurements can be challenging in organic–rich mudrocks because of their heterogeneity, tight pores, presence of kerogen, and the lack of understanding regarding the relaxation mechanism on the kerogen surface. Numerical simulation of NMR responses in the pore–scale domain in such complex rocks is also not very useful because most of the inputs are derived from conventional surface–relaxivity models. The conventional grain/fluid–interaction models for quantifying surface relaxivity do not account for any dipolar coupling in kerogen pores. The objectives of this paper are to develop a new surface–relaxivity model that accurately accounts for homonuclear dipolar coupling in kerogen pores; to introduce a pore–scale simulation method for reliable modeling of NMR response; and to quantify the effects of applying the new relaxivity model on simulated NMR responses and phase saturations. We start by considering the generalized Langmuir adsorption (GLA) theory for the adsorption of hydrocarbons on the surfaces of organic pores in mudrock samples. We used this adsorption model and the anisotropic rotation of molecules to develop a new surface–relaxivity model that accurately quantifies both transverse (T2) and longitudinal (T1) relaxation of protons in kerogen pores. The new model was used to simulate NMR responses in ellipsoidal pores and segmented focused–ion–beam scanning–electron–microscope (FIB–SEM) images of organic–rich mudrock samples using a pore–scale finite–volume simulation technique. The inputs to the simulator are the previously discussed pore geometries and the bulk and surface properties of different fluids present in the pore space. The outputs from the simulator were T2 and T1 decay constants in the previously mentioned pore geometries. The results of NMR simulations are then used to quantify the sensitivity of NMR responses to surface relaxivities computed using different models and NMR–based estimates of adsorbed–hydrocarbon volume. The results obtained from the new model verified that intramolecular coupling dominates the T1 and T2 surface relaxivities at high correlation times (greater than 1×10–7 seconds), which are usually observed for hydrocarbons in kerogen pores. The new model also confirmed the observation that NMR responses in mudrocks are not a function of kerogen thermal maturity but strongly depend on kerogen type. The results of numerical simulations demonstrated that dominant T2 peaks, T1–T2 ratios, and estimated adsorbed fractions are functions of molecular correlation time. Numerical simulations of NMR responses in organic–rich mudrock demonstrated that misidentifying coupling mechanisms could cause errors of up to 40.9 and 57.3% in estimates of adsorbed–hydrocarbon volume calculated using T2 and T1–T2 measurements, respectively. The surface–relaxivity model developed in this paper is more reliable than the previously published relaxivity models because it includes the effects of different coupling mechanisms on surface relaxation in organic pores. The new model can be reliably extended for quantifying surface relaxivity at higher temperatures and for different fluids, which enables interpretation of NMR logs at in-situ conditions. Enhanced quantification of surface relaxivity also enhances NMR–based reservoir characterization and helps to improve the estimates of hydrocarbon reserves in organic–rich mudrocks.

A laboratory study to determine the effect of iron oxides on proton NMR measurements

Geophysics ◽  
2007 ◽  
Vol 72 (1) ◽  
pp. E27-E32 ◽  
Author(s):  
Kristina Keating ◽  
Rosemary Knight
Keyword(s):  
Iron Oxide ◽  
Relaxation Rate ◽  
Iron Oxides ◽  
Quartz Sand ◽  
Pore Space ◽  
Nmr Relaxation ◽  
Volume Ratio ◽  
Proton Nuclear Magnetic Resonance ◽  
Surface Relaxation ◽  
Relaxation Rates

Using laboratory methods, we investigate the effect of the presence and mineralogic form of iron on measured proton nuclear magnetic resonance (NMR) relaxation rates. Five samples of quartz sand were coated with ferrihydrite, goethite, hematite, lepidocrocite, and magnetite. The relaxation rates for these iron-oxide-coated sands saturated with water were measured and compared to the relaxation rate of quartz sand saturated with water. We found that the presence of the iron oxides led to increases in the relaxation rates by increasing the surface relaxation rate. The magnitude of the surface relaxation rate was different for the various iron-oxide minerals because of changes in both the surface-area-to-volume ratio of the pore space, and the surface relaxivity. The relaxation rate of the magnetite-coated sand was further increased because of internal magnetic field gradients caused by the presence of magnetite. We conclude that both the concentration and mineralogical form of iron can have a significant impact on NMR relaxation behavior.

Fast hybrid multi-dimensional NMR methods based on ultrafast 2D NMR

2015 ◽  
Vol 53 (11) ◽  
pp. 986-994 ◽  
Author(s):  
Serge Akoka ◽  
Patrick Giraudeau
Keyword(s):  
2D Nmr ◽  
Nmr Methods ◽  
Ultrafast 2D Nmr
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