Permeability related question

[PratyushSwain101]

@jgostick

Can anybody kindly help me to understand where is the exact mistake? Why am I getting unusual permeability value?

Here is the pdf of the code DS - Copy.pdf

`Permeability Simulation Using PoreSpy and OpenPNM

import numpy as np
import pandas as pd
import openpnm as op
import porespy as ps
import seaborn as sns
import matplotlib.pyplot as plt

from skimage import io, color,img_as_ubyte, morphology
import imageio
np.set_printoptions(precision=4)
np.random.seed(10)
%matplotlib inline

Loading Binary Image

resolution = 0.711586e-6
name = 'DS'
im = io.imread("D:/DISSERTATION/CT Data/DS 25/DS_SST_Binary.tif")
Confirm image and check image porosity
io.imshow(im[:,:,100], cmap = 'gray')
<matplotlib.image.AxesImage at 0x28fd66dd990>

im = im == 0
io.imshow(im[:,:,1], cmap = 'gray')
<matplotlib.image.AxesImage at 0x28fcc952690>

Porosity, Shape and Dtype

print("Thotal porosity is ",ps.metrics.porosity(im)*100)
print(im.shape)
print(im.dtype)
Thotal porosity is 17.60148472222222
(600, 600, 600)
bool

Network Extraction PoreSpy Snow2

snow_output = ps.networks.snow2(im, voxel_size=resolution)
pn = op.io.network_from_porespy(snow_output.network)
geo = op.models.collections.geometry.spheres_and_cylinders
pn.add_model_collection(geo)
pn.regenerate_models()
print(pn)

══════════════════════════════════════════════════════════════════════════════
net : <openpnm.network.Network at 0x28fcfec7a10>
――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――

Properties Valid Values

――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――
2 throat.conns 27843 / 27843
3 pore.coords 17240 / 17240
4 pore.region_label 17240 / 17240
5 pore.phase 17240 / 17240
6 throat.phases 27843 / 27843
7 pore.region_volume 17240 / 17240
8 pore.equivalent_diameter 17240 / 17240
9 pore.local_peak 17240 / 17240
10 pore.global_peak 17240 / 17240
11 pore.geometric_centroid 17240 / 17240
12 throat.global_peak 27843 / 27843
13 pore.inscribed_diameter 17240 / 17240
14 pore.extended_diameter 17240 / 17240
15 throat.inscribed_diameter 27843 / 27843
16 throat.total_length 27843 / 27843
17 throat.direct_length 27843 / 27843
18 throat.perimeter 27843 / 27843
19 pore.volume 17240 / 17240
20 pore.surface_area 17240 / 17240
21 throat.cross_sectional_area 27843 / 27843
22 throat.equivalent_diameter 27843 / 27843
23 pore.coordination_number 17240 / 17240
24 pore.max_size 17240 / 17240
25 throat.spacing 27843 / 27843
26 pore.seed 17240 / 17240
27 pore.diameter 17240 / 17240
28 throat.max_size 27843 / 27843
29 throat.diameter 27843 / 27843
30 throat.hydraulic_size_factors 27843 / 27843
31 throat.diffusive_size_factors 27843 / 27843
32 throat.lens_volume 27843 / 27843
33 throat.length 27843 / 27843
34 throat.total_volume 27843 / 27843
35 throat.volume 27843 / 27843
――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――

Labels Assigned Locations

――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――
2 pore.all 17240
3 throat.all 27843
4 pore.boundary 1647
5 pore.xmin 263
6 pore.xmax 212
7 pore.ymin 253
8 pore.ymax 273
9 pore.zmin 392
10 pore.zmax 254
――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――
h = op.utils.check_network_health(pn)
op.topotools.trim(network=pn, pores=h['isolated_pores'])
op.topotools.trim(network=pn, pores=h['disconnected_pores'])
print(h)
――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――
Key Value
――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――
headless_throats []
looped_throats []
isolated_pores []
disconnected_pores []
duplicate_throats []
bidirectional_throats []
――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――
net = ps.networks.label_boundaries(network=pn)
print(net)

══════════════════════════════════════════════════════════════════════════════
net : <openpnm.network.Network at 0x28fcfec7a10>
――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――

Properties Valid Values

――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――
2 throat.conns 26312 / 26312
3 pore.coords 12706 / 12706
4 pore.region_label 12706 / 12706
5 pore.phase 12706 / 12706
6 throat.phases 26312 / 26312
7 pore.region_volume 12706 / 12706
8 pore.equivalent_diameter 12706 / 12706
9 pore.local_peak 12706 / 12706
10 pore.global_peak 12706 / 12706
11 pore.geometric_centroid 12706 / 12706
12 throat.global_peak 26312 / 26312
13 pore.inscribed_diameter 12706 / 12706
14 pore.extended_diameter 12706 / 12706
15 throat.inscribed_diameter 26312 / 26312
16 throat.total_length 26312 / 26312
17 throat.direct_length 26312 / 26312
18 throat.perimeter 26312 / 26312
19 pore.volume 12706 / 12706
20 pore.surface_area 12706 / 12706
21 throat.cross_sectional_area 26312 / 26312
22 throat.equivalent_diameter 26312 / 26312
23 pore.coordination_number 12706 / 12706
24 pore.max_size 12706 / 12706
25 throat.spacing 26312 / 26312
26 pore.seed 12706 / 12706
27 pore.diameter 12706 / 12706
28 throat.max_size 26312 / 26312
29 throat.diameter 26312 / 26312
30 throat.hydraulic_size_factors 26312 / 26312
31 throat.diffusive_size_factors 26312 / 26312
32 throat.lens_volume 26312 / 26312
33 throat.length 26312 / 26312
34 throat.total_volume 26312 / 26312
35 throat.volume 26312 / 26312
――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――

Labels Assigned Locations

――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――
2 pore.all 12706
3 throat.all 26312
4 pore.boundary 1358
5 pore.xmin 220
6 pore.xmax 160
7 pore.ymin 201
8 pore.ymax 236
9 pore.zmin 317
10 pore.zmax 224
11 pore.left 220
12 pore.right 160
13 pore.front 201
14 pore.back 236
15 pore.top 317
16 pore.bottom 224
――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――

Permeability

Defining Phase

phase = op.phase.Phase(network=pn)
phase['pore.viscosity']=1.0
phase.add_model_collection(op.models.collections.physics.basic)
phase.regenerate_models()
[14:07:23] WARNING throat.entry_pressure was not run since the following property is missing: _models.py:480
'throat.surface_tension'
WARNING throat.diffusive_conductance was not run since the following property is _models.py:480
missing: 'throat.diffusivity'

Apply Stokes flow

inlet = pn.pores('left')
outlet = pn.pores('right')
flow = op.algorithms.StokesFlow(network=pn, phase=phase)
flow.set_value_BC(pores=inlet, values=1)
flow.set_value_BC(pores=outlet, values=0)
flow.run()
phase.update(flow.soln)

Calculate permeability¶

NBVAL_IGNORE_OUTPUT

Q = flow.rate(pores=inlet, mode='group')[0]
A = 600600resolution**2
L = 600*resolution

mu and Delta_P were assumed to be 1.

K = Q * L / A
print(f'The value of K is: {K/0.98e-12*1000:.2f} mD')
The value of K is: 0.33 mD`

[jgostick]

And what value of K were you expecting?

[PratyushSwain101]

Thank you so much professor you your quick response.

This perticular simulation is performed on an unknown sample where I was expecting the permeability (K) of ≈ 400 mD.

Also for my own clarifaction I have performed the same on Berea Sandstone from DRP where I got the value of K : 5.28 mD, which is an incorrect value and which should be 121 mD ( According to this paper - )
High_accuracy_capillary_network_representation_in_.pdf

Here is the code -
Berea-Copy.pdf

Kindly, professor help in understading where I am exactly doing the mistake.

[jgostick]

The problem is almost always because of the hydraulic conductance values being influenced somehow. The three most common problems are:

1. Using inscribed diameters which can be too small (though this is a minor effect)
2. Having negative conductance values because pores overlap too much. You can check this by inspecting the conductance values (e.g. plt.hist(phase['throat.hydraulic_conductance'])
3. Boundary pores can be quite small since the boundary layer is only 3 voxels thick by default, meaning inscribed diameter will also be 3 voxels. You can try deleting the boundary pores, or putting the boundary conditions inside the network instead of on the boundary.