A Sensitivity Study of the Effect of Image Resolution on Predicted Petrophysical Properties

Alyafei, Nayef; Raeini, Ali Q.; Paluszny, Adriana; Blunt, Martin J.

doi:10.1007/s11242-015-0563-0

Cited by 47 publications

(38 citation statements)

References 32 publications

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“…The upper part of image resolution line is not detectable in digital samples (modified from Alyafei et al . ).…”

Section: Real 3d Digital Samplesmentioning

confidence: 97%

“…A routine test for indicating heterogeneity of a rock sample is mercury injection capillary pressure (MICP) test (Thomeer 1960;Swanson 1981;Leal et al 2001;Kewen 2004;Pini, Krevor and Benson 2012;Al-Khidir et al 2013). MICP experiments of these samples were conducted by Alyafei et al (2015) and are presented in Fig. 2.…”

Section: R E a L 3 D D I G I T A L S A M P L E Smentioning

confidence: 99%

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3D multi‐fractal analysis of porous media using 3D digital images: considerations for heterogeneity evaluation

Karimpouli

Tahmasebi

2018

Geophysical Prospecting

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Pore structure heterogeneity is a critical parameter controlling mechanical, electrical and flow transport behaviour of rock. Multi‐fractal analysis method was used for a heterogeneity comparison of three‐dimensional rock samples with different lithology. Six real digital samples, containing three sandstones and three carbonates, were used. Based on the mercury injection capillary pressure test on these samples, we found that the carbonate samples are more heterogeneous than sandstones, but primary results of multi‐fractal behaviours for all samples were similar. We show that if multi‐fractal is used to evaluate and compare heterogeneity of different samples, one needs to follow some considerations such as (1) all samples must have the same size in pixel, (2) samples volume must be bigger than representative volume element, (3) multi‐fractal dimensions should be firstly normalized to a determined porosity value and (4) multi‐fractal results should be interpreted based on resolution of the imaging tool (effects of fine scale sub‐resolution pores are missed). Results revealed that using normalized fractal dimensions, the real samples were divided to less and high heterogeneous groups. Moreover, the study of scale effect also showed that porous structures of these samples are scale invariant in a wide range of scales (from one to eight times bigger).

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“…The upper part of image resolution line is not detectable in digital samples (modified from Alyafei et al . ).…”

Section: Real 3d Digital Samplesmentioning

confidence: 97%

Section: R E a L 3 D D I G I T A L S A M P L E Smentioning

confidence: 99%

3D multi‐fractal analysis of porous media using 3D digital images: considerations for heterogeneity evaluation

Karimpouli

Tahmasebi

2018

Geophysical Prospecting

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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%

“…Houben et al [22] scanned the clay with varying resolutions, however analysis was conducted on two-dimensional (2D) images and only qualitative influence of resolution on pore shape was reported. Alyafei et al [34] applied numerical approach to change the image resolution and no clear trend of permeability dependence on resolution was observed. Shah et al [35] studied function between permeability and voxel size and the result showed that permeability continued changing when approaching the smallest voxel size.…”

Section: Introductionmentioning

confidence: 99%

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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“…Similar research by Alyafei et al . () was conducted by computing the petrophysical properties of 3D images of sandstones (Berea and Doddington) and limestones (Estaillades and Ketton) at four different image resolutions (∼ 2.7, 5.4, 10.8 and 21.6

μ

m). The images with larger pixel sizes were obtained by resampling/the image with a pixel size of approximately 2.7

μ

m on to the

(x, y)

axis directly from the segmented images by factors of 2, 4 and 8 using the Lanczos resampling algorithm: a windowed interpolation method that performs a local average over specific finite window by averaging distance with the first oscillation of the sinc() function (Duchon, ).…”

Section: Introductionmentioning

confidence: 99%

The effect of X‐ray micro computed tomography image resolution on flow properties of porous rocks

Latief

Fauzi

Irayani

et al. 2017

Journal of Microscopy

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The study of digital rock physics has seen significant advances due to the development of X-ray micro computed tomography scanning devices. One of the advantages of using such a device is that the pore structure of rock can be mapped down to the micrometre level in three dimensions. However, in providing such high-resolution images (low voxel size), the resulting file sizes are necessarily large (of the order of gigabytes). Lower image resolution (high voxel size) produces smaller file sizes (of the order of hundreds of megabytes), but risks losing significant details. This study describes the effect of the image resolution obtained by means of hardware-based and software-based approach. Four samples of porous rock were scanned using a SkyScan 1173 High Energy Micro-CT. We found that acquisition using increased pixel binning of the camera (hardware-based resizing) significantly affects the calculated physical properties of the samples. By contrast, voxel resizing by means of a software-based approach during the reconstruction process yielded less effect on the porosity and specific surface area of the samples. However, the decreasing resolution of the image obtained by both the hardware-based and the software-based approaches affects the permeability significantly. We conclude that simulating fluid flow through the pore space using the Lattice Boltzmann method to calculate the permeability has a significant dependency on the image resolution.

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A Sensitivity Study of the Effect of Image Resolution on Predicted Petrophysical Properties

Cited by 47 publications

References 32 publications

3D multi‐fractal analysis of porous media using 3D digital images: considerations for heterogeneity evaluation

3D multi‐fractal analysis of porous media using 3D digital images: considerations for heterogeneity evaluation

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

The effect of X‐ray micro computed tomography image resolution on flow properties of porous rocks

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