Computations of Absolute Permeability on Micro-CT Images

Mostaghimi, Peyman; Blunt, Martin J.; Bijeljic, Branko

doi:10.1007/s11004-012-9431-4

Cited by 395 publications

(283 citation statements)

References 40 publications

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“…Works have been done on the effect of sample size and resolution, however almost all of them are done separately [31][32][33][34][35][36][37]. The effect of sample size is well studied since Bear [38] brought up the idea of representative element volume (REV), which is the smallest volume over which the measurement result is representative of the macroscopic property.…”

Section: Introductionmentioning

confidence: 99%

“…The effect of sample size is well studied since Bear [38] brought up the idea of representative element volume (REV), which is the smallest volume over which the measurement result is representative of the macroscopic property. Many researchers checked the sample size to achieve REV [31,33,[39][40][41][42], but they ignored the influence of resolution. Though difference between experiment and DRA might be concluded to inadequate resolution [27,30,43], quantitative study of resolution effect is few [44].…”

Section: Introductionmentioning

confidence: 99%

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Critical Resolution and Sample Size of Digital Rock Analysis for Unconventional Reservoirs

Liu

Wang

2018

Energies

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Digital rock analysis (DRA) has exhibited strong ability and significant potential to help people to image geological microstructures and understand transport mechanisms in rocks underground, especially for unconventional reservoirs like tight sandstone and shale. More and more new technologies have been developed for higher resolutions, which always come with higher expense. However, the balance between cost (money and time) and benefit has never been figured out quantitatively for these studies. As the cost and benefit are directly related to image resolution and size, this work is focusing on whether there is a critical resolution and sample size when using DRA for accurate enough predictions of rock properties. By numerically changing the digital resolutions of the reconstructed structures from high-resolution micro-computed tomography (CT) scanned tight rock samples, it is found that the permeability predictions get stable when the resolution is higher than a cut-off resolution (COR). Different from physical rocks, the representative element volume (REV) of a digital rock is influenced by the digital resolution. The results of pore-scale modeling indicate that once sample size is larger than the critical sample size and the scan resolution higher than the critical resolution for a given rock, the predicted rock properties by DRA are accurate and representative.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Critical Resolution and Sample Size of Digital Rock Analysis for Unconventional Reservoirs

Liu

Wang

2018

Energies

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“…We provide in Table 3 the simulation results (Figure 6) of the absolute permeability along with the relative errors. For convenience the permeability is written in Darcy unit, 1 D = 9.869 233 × 10 −13 m 2 in line with the practice in the literature [4,5], the values in Table 3 are expressed in milliDarcy (mD), 1 mD = 10 −3 D. The difference is less than 2% suggesting that the implemented finite volume method (FVM) is capable to simulate accurately at the pore-scale. Unlike in the LBM, extension of our FVM model to non-Newtonian fluid can be handled without any numerical tuning parameters.…”

Section: Flow In Porous Mediamentioning

confidence: 95%

“…It is function of the complex microstructure of the rock, fluid properties (density, viscosity) and parameters (velocity). Since no simple universal correlation exists for the permeability, an accurate and efficient numerical tool to predict the permeability is highly desirable [2][3][4][5].…”

Section: Introductionmentioning

confidence: 99%

“…Using the 3D micro-CT images, numerical simulation has been applied to perform the pore-scale imaging modelling ranging from (i) the widely used lattice Boltzmann method [6,7]; (ii) the finite difference method [5]; (iii) finite element method [3]; and more recently (iv) finite volume method Polymers 2017, 9, 509 2 of 15 approach [4]. Most of the numerical simulation concerns with the modeling at pore-scale deals with Newtonian fluid or simplified pore network, which significantly alters the porous media geometry, assuming it consists of connected capillary tubes [8,9].…”

Section: Introductionmentioning

confidence: 99%

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The Effect of Heat Transfer and Polymer Concentration on Non-Newtonian Fluid from Pore-Scale Simulation of Rock X-ray Micro-CT

et al. 2017

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Most of the pore-scale imaging and simulations of non-Newtonian fluid are based on the simplifying geometry of network modeling and overlook the fluid rheology and heat transfer. In the present paper, we developed a non-isothermal and non-Newtonian numerical model of the flow properties at pore-scale by simulation of the 3D micro-CT images using a Finite Volume Method (FVM). The numerical model is based on the resolution of the momentum and energy conservation equations. Owing to an adaptive mesh generation technique and appropriate boundary conditions, rock permeability and mobility are accurately computed. A temperature and concentration-dependent power-law viscosity model in line with the experimental measurement of the fluid rheology is adopted. The model is first applied at isothermal condition to 2 benchmark samples, namely Fontainebleau sandstone and Grosmont carbonate, and is found to be in good agreement with the Lattice Boltzmann method (LBM). Finally, at non-isothermal conditions, an effective mobility is introduced that enables to perform a numerical sensitivity study to fluid rheology, heat transfer, and operating conditions. While the mobility seems to evolve linearly with polymer concentration in agreement with a derived theoretical model, the effect of the temperature seems negligible by comparison. However, a sharp contrast is found between carbonate and sandstone under the effect of a constant temperature gradient. Besides concerning the flow index and consistency factor, a master curve is derived when normalizing the mobility for both the carbonate and the sandstone.

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Effect of CT image size and resolution on the accuracy of rock property estimates

et al. 2017

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In order to study the effect of the micro‐CT scan resolution and size on the accuracy of upscaled digital rock property estimation of core samples Bentheimer sandstone images with the resolution varying from 0.9 μm to 24 μm are used. We statistically show that the correlation length of the pore‐to‐matrix distribution can be reliably determined for the images with the resolution finer than 9 voxels per correlation length and the representative volume for this property is about 153 correlation length. Similar resolution values for the statistically representative volume are also valid for the estimation of the total porosity, specific surface area, mean curvature, and topology of the pore space. Only the total porosity and the number of isolated pores are stably recovered, whereas geometry and the topological measures of the pore space are strongly affected by the resolution change. We also simulate fluid flow in the pore space and estimate permeability and tortuosity of the sample. The results demonstrate that the representative volume for the transport property calculation should be greater than 50 correlation lengths of pore‐to‐matrix distribution. On the other hand, permeability estimation based on the statistical analysis of equivalent realizations shows some weak influence of the resolution on the transport properties. The reason for this might be that the characteristic scale of the particular physical processes may affect the result stronger than the model (image) scale.

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Computations of Absolute Permeability on Micro-CT Images

Cited by 395 publications

References 40 publications

Critical Resolution and Sample Size of Digital Rock Analysis for Unconventional Reservoirs

Critical Resolution and Sample Size of Digital Rock Analysis for Unconventional Reservoirs

The Effect of Heat Transfer and Polymer Concentration on Non-Newtonian Fluid from Pore-Scale Simulation of Rock X-ray Micro-CT

Effect of CT image size and resolution on the accuracy of rock property estimates

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