Nuclear Magnetic Resonance of Rocks: T1 vs. T2

Kleinberg, R.L.; Straley, Christian; Kenyon, W.E.; Akkurt, Ridvan; Farooqui, S.A.

doi:10.2118/26470-ms

Cited by 61 publications

(29 citation statements)

References 24 publications

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“…Another part of the water changed its state after addition to the peat sample as represented by larger T 1 /T 2 ratios, which were much larger than generally found in rock core samples [24]. These large T 1 /T 2 ratios of water in peat were in the same range as determined for agar gel or swollen sago beads (Fig.…”

Section: T1/t2supporting

confidence: 65%

“…However, many swellable materials, such as cellulose [21], hydrogels with different degrees of crosslinking [22], wheat starch [23] and maltodextrin [17] show strong differences between T 1 and T 2 . Their T 1 /T 2 ratios were found to be much larger than for free pure water (T 1 /T 2 ~ 1) or for rock core samples with T 1 /T 2 ratios generally between 2 to 3 [24]. The larger T 1 /T 2 ratios in those swellable materials were attributed to a water structuring caused by the polymer, which resulted in reduced rotational mobility of water molecules inside the structured water phase [17].…”

Section: Introductionmentioning

confidence: 91%

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Proton NMR Relaxometry as a Useful Tool to Evaluate Swelling Processes in Peat Soils~!2009-07-26~!2009-12-04~!2010-06-15~!

Jaeger¹,

Shchegolikhina²,

As³

et al. 2010

TOMRJ

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Dramatic physical and physico-chemical changes in soil properties may arise due to temperature and moisture variations as well as swelling of soil organic matter (SOM) under constant conditions. Soil property variations may influence sorption/desorption and transport processes of environmental contaminants and nutrients in natural-organic-matterrich soils. Notwithstanding the studies reported in literature, a mechanistic model for SOM swelling is unavailable yet. The objective of the present study was the evaluation of the swelling of peat soils, considered as SOM models, by 1 H NMR relaxometry and differential scanning calorimetry (DSC). Namely, information on the processes governing physical and physicochemical changes of peat during re-hydration were collected. The basic hypothesis of the present study was that the changes are slow and may affect water state as well as amounts of different water types into the peats. For this reason, such changes can be evidenced through the variations of mobility and thermal behaviour of the involved H 2 O molecules by using 1 H NMR relaxometry and DSC. According to the experimental results, a mechanistic model, describing the fundamental processes of peat swelling, was obtained. Two different peats re-wetted at three temperatures were used. The swelling process was monitored by measuring spin-spin relaxation time (T2) over a hydration time of several months. Moreover, DSC, T1 -T2 and T2 -D correlation measurements were done at the beginning and at the end of the hydration. Supplementary investigations were also done in order to discriminate between the swelling effects and the contributions from soil solution, internal magnetic field gradients and/or soil microorganisms to proton relaxation. All the results revealed peat swelling. It was evidenced by pore size distribution changes, volumetric expansion and redistribution of water, increasing amounts of nonfreezable and loosely bound water, as well as formation of gel phases and reduction of the translational and rotational mobility of H 2 O molecules. All the findings implied that changes of the physical and physicochemical properties of peats were obtained. In particular, three different processes having activation energies comprised in the interval 5 -50 kJ mol -1 were revealed. The mechanistic model which was, then, developed included water reorientation in bound water phases, water diffusion into the peat matrix and reorientation of SOM chains as fundamental processes governing SOM swelling. This study is of environmental significance in terms of re-naturation and re-watering of commercially applied peatlands and of sorption/desorption and transport processes of pollutants and nutrients in natural organic matter rich soils.

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Section: T1/t2supporting

confidence: 65%

Section: Introductionmentioning

confidence: 91%

Proton NMR Relaxometry as a Useful Tool to Evaluate Swelling Processes in Peat Soils~!2009-07-26~!2009-12-04~!2010-06-15~!

Jaeger¹,

Shchegolikhina²,

As³

et al. 2010

TOMRJ

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“…As shown in Fig. 1, these areas are often found using either sharp or tapered cut Heaviside functions in log(T 2 ) domain [1].…”

Section: Introductionmentioning

confidence: 90%

Computation of parameters in NMR using integral transforms: Tapered areas

Gruber

Venkataramanan

Freed

et al. 2013

2013 IEEE International Conference on Acoustics, Speech and Signal Processing

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This paper describes a method to compute tapered areas of a probability density function by means of integral transforms of its noisy Laplace transform. This problem is directly relevant to Nuclear Magnetic Resonance data for fluid and rock characterization. We describe integral transforms that are directly applicable to the measured magnetisation data, to estimate the tapered areas. In petrophysics, these tapered areas are useful in estimation of fluid saturations and bound and free fluid volumes. Since integral transforms are linear, uncertainty in the tapered areas can be computed as a function of signal-to-noise (SNR) in the data. Performance of these transforms is demonstrated on simulated data and compared to results from the traditional inverse Laplace transform.

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“…The dipole moment time evolution can be decomposed into a spectrum of attenuation times, i.e., the longitudinal (T 1 ) and transverse (T 2 ) relaxation time distributions. The measurement of T 2 relaxation is preferred as it is fast and usually provides similar distribution to T 1 (Kleinberg et al, 1993). Transverse (T 2 ) relaxation time includes three kinds of relaxation time: surface relaxation, volume relaxation and diffusion relaxation, which is suitable for different types of fluids.…”

Section: Nmr Relaxation Time Distributions Of Samplesmentioning

confidence: 99%

“…(1) The mean T 2 model (also called SDR model) can be formulated in several ways, which is a commonly used expression (Kleinberg et al, 1993;Skjetne et al, 1991;Westphal et al, 2005)…”

Section: The Free Fluid Modelsmentioning

confidence: 99%

New characterization on the petrophysical characteristics of tight sandstone reservoirs in Yanchang Formation Ordos Basin China

Zhi-qiang

Shi

2016

Energy Exploration & Exploitation

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New characterization on petrophysical characteristics of tight sandstone reservoirs is of an important value to exploration and exploitation of oil and gas. In this paper, low-field nuclear magnetic resonance, combined with casting thin sections, laser scanning confocal microscopy, scanning electron microscopy and pressure-controlled porosimetry were applied to investigate the pore structure characteristics of nine tight sandstone samples of Yanchang Formation in the Upper Triassic Ordos Basin China. And then, based on the nuclear magnetic resonance T 2 spectrum distribution and previous theoretical models, a new model is proposed to predict permeability of tight sandstone reservoirs. Petrophysical characteristics are qualitativelyquantificationally analyzed by a combination of various experiments, which is considered to be a new method that will be widely used in future research. Results indicate that nuclear magnetic resonance T 2 spectrum distribution has a close relationship with characteristics of pore types and pore radius distribution. Three T 2 spectrum peaks are identified by the relaxation time at 0.1-10 ms, 10-100 ms and >100 ms correspond to micropores (<0.2 mm), mesopores (0.2-4.9 mm) and macropores and fractures (>4.9 mm), respectively, which is well consistent with results from casting thin sections, laser scanning confocal microscopy, scanning electron microscopy and pressure-controlled porosimetry. Compared with the existing several classical models, the new permeability model can better estimate the permeability of tight sandstone samples. The new characterization method and new model can accurately evaluate petrophysical characteristics of typical tight sandstone samples, which have a great value for nuclear magnetic well logging in the exploration and exploitation of tight sandstone reservoirs in the Ordos basin.

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Nuclear Magnetic Resonance of Rocks: T1 vs. T2

Cited by 61 publications

References 24 publications

Proton NMR Relaxometry as a Useful Tool to Evaluate Swelling Processes in Peat Soils~!2009-07-26~!2009-12-04~!2010-06-15~!

Proton NMR Relaxometry as a Useful Tool to Evaluate Swelling Processes in Peat Soils~!2009-07-26~!2009-12-04~!2010-06-15~!

Computation of parameters in NMR using integral transforms: Tapered areas

New characterization on the petrophysical characteristics of tight sandstone reservoirs in Yanchang Formation Ordos Basin China

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