Sandstone surface relaxivity determined by NMR T2 distribution and digital rock simulation for permeability evaluation

Lucas-Oliveira, Éverton; Araujo-Ferreira, A. G.; Trevizan, Willian Andrighetto; Santos, Bernardo Coutinho Camilo dos; Bonagamba, Tito J.

doi:10.1016/j.petrol.2020.107400

Cited by 40 publications

(21 citation statements)

References 21 publications

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“…All images have 1000 × 1000 × 1000 voxels, with isometric voxel size of 2.25 µm. It is worth mentioning that the segmented image includes isolated pores, unlike what is observed in the related work developed by Neumann [5] and Lucas-Oliveira [6] , in which computational physics analysis were applied to systems where all pores can be saturated through pore connections.…”

Section: Data Descriptionmentioning

confidence: 99%

Micro-computed tomography of sandstone rocks: Raw, filtered and segmented datasets

et al. 2022

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Section: Data Descriptionmentioning

confidence: 99%

Micro-computed tomography of sandstone rocks: Raw, filtered and segmented datasets

et al. 2022

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“…By analyzing the T 2 spectra of saturated and centrifuged samples, one can obtain information about the porosity, permeability, pore size distribution, and fluid saturation. 13 , 22 − 25 For example, Lucas-Oliveira et al 26 compared experimental and simulated NMR data with gas permeability through the combination of experiments and simulations and proved that the pore size distribution could be obtained using the T 2 relaxation spectrum. Zheng 20 and Liang et al 27 obtained accurate pore size distributions from NMR T 2 distributions by combining NMR and centrifugation experiments.…”

Section: Introductionmentioning

confidence: 99%

Study on the Quantitative Characterization and Seepage Evolution Characteristics of Pores of Loaded Coal Based on NMR

et al. 2021

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Quantitative characterization of the pore structure and gas seepage characteristics of loaded coal is of great significance to the study of high-efficiency gas drainage in coal seams. Aiming at the problem of imperfect characterizations of coal seepage characteristics based on nuclear magnetic resonance (NMR), a calculation method for the pore permeability of coal with different pore diameters is proposed. The pore structure and seepage characteristics of coal have been quantitatively studied using a nuclear magnetic resonance (NMR) system. The results show that with increasing external load, the proportion of the pore volume of the coal sample in the range of 0.01−0.52 μm gradually decreases, while that in the range of 5.11−352.97 μm increases. In this process, the porosity increases from 0.9967 to 1.0103%, the connectivity increases from 0.1718 to 0.2391, and the permeability increases from 2.64 × 10 −6 to 8.20 × 10 −6 μm 2 . The calculation of the coal sample connectivity and permeability using the improved NMR permeability component proves that 94.37−352.97 μm pores are the main channel of fluid flow. When the axial pressure increases, the coal body permeability in the aperture range of 94.37−352.97 μm rapidly increases. The improved permeability component calculation model can better reflect the variation law of pore permeability of the loaded coal body.

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“…Unfortunately, it is not a simple task to experimentally determine the parameter ρ, or to predict it theoretically, but it is usually taken in range 10-20 µm/s, sometimes higher. Recently, M. Nascimento et al developed a theoretical model which takes explicitly into account microscopic features of surface relaxivity [5], and E. Lucas-Oliveira and co-workers estimated ρ from T 2 distribution and digital rock simulations [6], reporting values of ρ as high as 50µm/s. One interesting statistical approach for relaxation taking into account paramagnetic impurities in the solid matrix has been reported by J.L.…”

Section: Introductionmentioning

confidence: 99%

NMR of Confined Fluids: a Numerical Study using COMSOL with application in Petrophysics

Oliveira

2021

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Nuclear Magnetic Resonance (NMR) is one of the main experimental tools to evaluate the production potential of porous rocks in oil wells. From the relative areas and mean values obtained from relaxation time distribution curves, information about fluid content, porosity and permeability can be obtained. In this report, a numerical study of pulsed NMR of confined fluids using the software COMSOL (license 9200972) is presented. This is done by solving the Bloch-Torrey equations considering surface relaxivity using the "flux/source" boundary conditions for different geometries, in the fast and slow diffusion regimes. The study is made for a single fluid and for a mixture of two coupled fluids (McConnell equations), first in isolated pores, and then in a "cylindrical porous plug" containing one single 20µm spherical pore surrounded by 800 × 2µm, unconnected, also spherical ones. NMR spectra and transverse relaxation are calculated as a function of pore sizes and coupling strength between fluids, for single π/2 pulses, followed by the FFT of the NMR signal (FID), and the echo amplitude after a spin-echo pulse sequence, respectively. The simulations show that, in the fast diffusion regime, pore sizes can be, 1 in principle, distinguished by transverse relaxation, but even in noiseless condition and full control of geometry, only a rough estimate of sizes can be obtained. A number of possible follow-up studies with COMSOL are discussed at the concluding remarks.

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Sandstone surface relaxivity determined by NMR T2 distribution and digital rock simulation for permeability evaluation

Cited by 40 publications

References 21 publications

Micro-computed tomography of sandstone rocks: Raw, filtered and segmented datasets

Micro-computed tomography of sandstone rocks: Raw, filtered and segmented datasets

Study on the Quantitative Characterization and Seepage Evolution Characteristics of Pores of Loaded Coal Based on NMR

NMR of Confined Fluids: a Numerical Study using COMSOL with application in Petrophysics

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