SCA 2017 Vienna, Austria - · PDF fileSCA 2017 –Vienna, Austria ... Attenuation...
Transcript of SCA 2017 Vienna, Austria - · PDF fileSCA 2017 –Vienna, Austria ... Attenuation...
![Page 1: SCA 2017 Vienna, Austria - · PDF fileSCA 2017 –Vienna, Austria ... Attenuation –Beer-Lambert Law ... • Recommend saturation verification via some second method,](https://reader031.fdocuments.us/reader031/viewer/2022030413/5a9f4d6c7f8b9a89178c94db/html5/thumbnails/1.jpg)
Working togetherfor a safer world
SCA 2017 – Vienna, Austria
Core Imaging - Short Course
Gamma, X-ray & CT imaging
![Page 2: SCA 2017 Vienna, Austria - · PDF fileSCA 2017 –Vienna, Austria ... Attenuation –Beer-Lambert Law ... • Recommend saturation verification via some second method,](https://reader031.fdocuments.us/reader031/viewer/2022030413/5a9f4d6c7f8b9a89178c94db/html5/thumbnails/2.jpg)
SCA 2017 – Core Imaging Short Course
1D to 3D Imaging Methods
• Gamma ray, x-ray and CT
• Gamma vs. x-ray
• Gamma log
• CT
• Note regarding grey-scale images
• Uses: description, analysis, assessment
• Beer-Lambert Law
• 1D + time
• Saturation determination
• Considerations
![Page 3: SCA 2017 Vienna, Austria - · PDF fileSCA 2017 –Vienna, Austria ... Attenuation –Beer-Lambert Law ... • Recommend saturation verification via some second method,](https://reader031.fdocuments.us/reader031/viewer/2022030413/5a9f4d6c7f8b9a89178c94db/html5/thumbnails/3.jpg)
SCA 2017 – Core Imaging Short Course
Gamma versus x-ray
• Gamma and x-ray are high energy electromagnetic rays
• No precise distinction between the two
• Gamma generally higher energy, generally more unique spectral signal
• Gamma usually from nuclear decay, x-ray from electron excitation
![Page 4: SCA 2017 Vienna, Austria - · PDF fileSCA 2017 –Vienna, Austria ... Attenuation –Beer-Lambert Law ... • Recommend saturation verification via some second method,](https://reader031.fdocuments.us/reader031/viewer/2022030413/5a9f4d6c7f8b9a89178c94db/html5/thumbnails/4.jpg)
SCA 2017 – Core Imaging Short Course
Attenuation
• Gamma / x-rays will be slowed (attenuated) as
they pass through and interact with a material
• Different materials exhibit different levels of
attenuation
• Materials exhibit lower attenuation coefficients
to higher energy rays
• Thicker material, will exponentially attenuate
(block) more rays and detected counts is
given by
𝐼 = 𝐼0 𝑒−µ𝑥
![Page 5: SCA 2017 Vienna, Austria - · PDF fileSCA 2017 –Vienna, Austria ... Attenuation –Beer-Lambert Law ... • Recommend saturation verification via some second method,](https://reader031.fdocuments.us/reader031/viewer/2022030413/5a9f4d6c7f8b9a89178c94db/html5/thumbnails/5.jpg)
SCA 2017 – Core Imaging Short Course
1D to 3D Imaging Methods
• Gamma ray, x-ray and CT
• Gamma vs. x-ray
• Gamma log
• CT
• Note regarding grey-scale images
• Uses: description, analysis, assessment
• Beer-Lambert Law
• 1D + time
• Saturation determination
• Considerations
![Page 6: SCA 2017 Vienna, Austria - · PDF fileSCA 2017 –Vienna, Austria ... Attenuation –Beer-Lambert Law ... • Recommend saturation verification via some second method,](https://reader031.fdocuments.us/reader031/viewer/2022030413/5a9f4d6c7f8b9a89178c94db/html5/thumbnails/6.jpg)
SCA 2017 – Core Imaging Short Course
Core Gamma Ray Logging
• Wellsite and/or Lab
• Mainly for core-log depth shifting
• Total and spectral gamma
• uranium/potassium/thorium ratios
• Equipment
• conveyor belt (1 ft/min, 18 m/h)
• NaI detector (shielded)
• analyser system
• computer
![Page 7: SCA 2017 Vienna, Austria - · PDF fileSCA 2017 –Vienna, Austria ... Attenuation –Beer-Lambert Law ... • Recommend saturation verification via some second method,](https://reader031.fdocuments.us/reader031/viewer/2022030413/5a9f4d6c7f8b9a89178c94db/html5/thumbnails/7.jpg)
SCA 2017 – Core Imaging Short Course
Core Gamma Example
![Page 8: SCA 2017 Vienna, Austria - · PDF fileSCA 2017 –Vienna, Austria ... Attenuation –Beer-Lambert Law ... • Recommend saturation verification via some second method,](https://reader031.fdocuments.us/reader031/viewer/2022030413/5a9f4d6c7f8b9a89178c94db/html5/thumbnails/8.jpg)
SCA 2017 – Core Imaging Short Course
1D to 3D Imaging Methods
• Gamma ray, x-ray and CT
• Gamma vs. x-ray
• Gamma log
• CT – spatially resolved x-ray measurements
• Note regarding grey-scale images
• Uses: description, analysis, assessment
• Beer-Lambert Law
• 1D + time
• Saturation determination
• Considerations
![Page 9: SCA 2017 Vienna, Austria - · PDF fileSCA 2017 –Vienna, Austria ... Attenuation –Beer-Lambert Law ... • Recommend saturation verification via some second method,](https://reader031.fdocuments.us/reader031/viewer/2022030413/5a9f4d6c7f8b9a89178c94db/html5/thumbnails/9.jpg)
SCA 2017 – Core Imaging Short Course
CT scanning – grey-scale image settings
• Hounsfield Unit = measures radiodensity
• function of attenuation coefficients
• Air: HU = -1000
• Water: HU = 0
WL(or WC) = Centre HU setting
WW = Width HU Setting
Standard CT setting
WC-1000, WW-4096
Core setting
WC-2000, WW-400
Range = -1048 to 3048 Range = 1800 to 2200
HU = 1000μ − μwμw − μa
![Page 10: SCA 2017 Vienna, Austria - · PDF fileSCA 2017 –Vienna, Austria ... Attenuation –Beer-Lambert Law ... • Recommend saturation verification via some second method,](https://reader031.fdocuments.us/reader031/viewer/2022030413/5a9f4d6c7f8b9a89178c94db/html5/thumbnails/10.jpg)
SCA 2017 – Core Imaging Short Course
CT scanning – grey-scale image settings
WC
WW
WC
WW
Different density profiles will require
different HU image settings
Standard
Equipment
Setting
Optimised
Core
Setting
![Page 11: SCA 2017 Vienna, Austria - · PDF fileSCA 2017 –Vienna, Austria ... Attenuation –Beer-Lambert Law ... • Recommend saturation verification via some second method,](https://reader031.fdocuments.us/reader031/viewer/2022030413/5a9f4d6c7f8b9a89178c94db/html5/thumbnails/11.jpg)
SCA 2017 – Core Imaging Short Course
CT scanning – grey-scale image settings
WC
WW
Standard CT equipment setting
WC = 1000
WW = 4096
Core density in the middle of the grey-scale
Small variance in observed image
![Page 12: SCA 2017 Vienna, Austria - · PDF fileSCA 2017 –Vienna, Austria ... Attenuation –Beer-Lambert Law ... • Recommend saturation verification via some second method,](https://reader031.fdocuments.us/reader031/viewer/2022030413/5a9f4d6c7f8b9a89178c94db/html5/thumbnails/12.jpg)
SCA 2017 – Core Imaging Short Course
CT scanning – grey-scale image settings
WC
WW
• SCA 2013-004 recommends initial assessment using WW=200Grey-scale optimised from lowest to highest density
Variance in observed image – white to black
Optimised settings
![Page 13: SCA 2017 Vienna, Austria - · PDF fileSCA 2017 –Vienna, Austria ... Attenuation –Beer-Lambert Law ... • Recommend saturation verification via some second method,](https://reader031.fdocuments.us/reader031/viewer/2022030413/5a9f4d6c7f8b9a89178c94db/html5/thumbnails/13.jpg)
SCA 2017 – Core Imaging Short Course
Helical CT scan – 3D
![Page 14: SCA 2017 Vienna, Austria - · PDF fileSCA 2017 –Vienna, Austria ... Attenuation –Beer-Lambert Law ... • Recommend saturation verification via some second method,](https://reader031.fdocuments.us/reader031/viewer/2022030413/5a9f4d6c7f8b9a89178c94db/html5/thumbnails/14.jpg)
SCA 2017 – Core Imaging Short Course
Helical CT scan – 3D analysis
• 3D scans allow various analytics
• Feature Identification Options
• Each feature is extracted, named,
and analyzed separately. For each
feature, you can specify name,
color, and visibility options.
![Page 15: SCA 2017 Vienna, Austria - · PDF fileSCA 2017 –Vienna, Austria ... Attenuation –Beer-Lambert Law ... • Recommend saturation verification via some second method,](https://reader031.fdocuments.us/reader031/viewer/2022030413/5a9f4d6c7f8b9a89178c94db/html5/thumbnails/15.jpg)
SCA 2017 – Core Imaging Short Course
Helical CT scan – 3D analysis
• Orientation
• Dip
• Strike
• Image log correlation
![Page 16: SCA 2017 Vienna, Austria - · PDF fileSCA 2017 –Vienna, Austria ... Attenuation –Beer-Lambert Law ... • Recommend saturation verification via some second method,](https://reader031.fdocuments.us/reader031/viewer/2022030413/5a9f4d6c7f8b9a89178c94db/html5/thumbnails/16.jpg)
SCA 2017 – Core Imaging Short Course
Helical CT scan – 3D analysis
• Virtual Plug Extraction
• Assess plug viability before
acquiring
![Page 17: SCA 2017 Vienna, Austria - · PDF fileSCA 2017 –Vienna, Austria ... Attenuation –Beer-Lambert Law ... • Recommend saturation verification via some second method,](https://reader031.fdocuments.us/reader031/viewer/2022030413/5a9f4d6c7f8b9a89178c94db/html5/thumbnails/17.jpg)
SCA 2017 – Core Imaging Short Course
1D to 3D Imaging Methods
• Gamma ray, x-ray and CT
• Gamma vs. x-ray
• Gamma log
• CT
• Note regarding grey-scale images
• Uses: description, analysis, assessment
• Beer-Lambert Law
• 1D + time (in situ saturation monitoring [ISSM])
• Saturation determination
• Considerations
![Page 18: SCA 2017 Vienna, Austria - · PDF fileSCA 2017 –Vienna, Austria ... Attenuation –Beer-Lambert Law ... • Recommend saturation verification via some second method,](https://reader031.fdocuments.us/reader031/viewer/2022030413/5a9f4d6c7f8b9a89178c94db/html5/thumbnails/18.jpg)
SCA 2017 – Core Imaging Short Course
Attenuation – Beer-Lambert Law
• Gamma / x-rays will be slowed (attenuated) as
they pass through and interact with a material
• Different materials exhibit different levels of
attenuation
• Materials exhibit lower attenuation coefficients
to higher energy rays
• Thicker material, will exponentially attenuate
(block) more rays and detected counts is
given by
𝐼 = 𝐼0 𝑒−µ𝑥
![Page 19: SCA 2017 Vienna, Austria - · PDF fileSCA 2017 –Vienna, Austria ... Attenuation –Beer-Lambert Law ... • Recommend saturation verification via some second method,](https://reader031.fdocuments.us/reader031/viewer/2022030413/5a9f4d6c7f8b9a89178c94db/html5/thumbnails/19.jpg)
SCA 2017 – Core Imaging Short Course
In situ saturation monitoring (ISSM)
• For a composite material, total attenuation is the sum of the individual
materials’ attenuation coefficients and the saturation of each material
• For core samples
• Core sample maintained in fixed position
• Assume the rock matrix is unchanging
• Changes in attenuation (detected counts) = change in fluid saturation
• Calibration performed Sw = 0, Sw =1 and intermediate values given by:
𝑆𝑤 =ln 𝐼 − ln(𝐼𝑆𝑜)
ln 𝐼𝑆𝑤 − ln(𝐼𝑆𝑜)=
ln ൗ𝐼 𝐼𝑆𝑜
ln ൗ𝐼𝑆𝑤
𝐼𝑆𝑜
• ISw is Sw=1, ISo is Sw = 0
![Page 20: SCA 2017 Vienna, Austria - · PDF fileSCA 2017 –Vienna, Austria ... Attenuation –Beer-Lambert Law ... • Recommend saturation verification via some second method,](https://reader031.fdocuments.us/reader031/viewer/2022030413/5a9f4d6c7f8b9a89178c94db/html5/thumbnails/20.jpg)
SCA 2017 – Core Imaging Short Course
In situ saturation monitoring (ISSM)
• Gamma usually exhibits higher energy than
x-rays
• Thus gamma requires longer scanning
times to acquire sufficient counts to
differentiate fluid (saturation) change
• Gamma usually requires ca. 2 - 10 mins per
location (2 mm slice, 1.5” diameter core)
• X-ray usually requires 1-10 s per location
(2 mm slice, 1.5” diameter core)
![Page 21: SCA 2017 Vienna, Austria - · PDF fileSCA 2017 –Vienna, Austria ... Attenuation –Beer-Lambert Law ... • Recommend saturation verification via some second method,](https://reader031.fdocuments.us/reader031/viewer/2022030413/5a9f4d6c7f8b9a89178c94db/html5/thumbnails/21.jpg)
SCA 2017 – Core Imaging Short Course
In situ saturation monitoring (ISSM)
• Method often requires one fluid phase to be
“doped” (x-ray blocker added)
• Iododecane
• IFT reduced (ambient & temperature)
• Problems at temperature
• NaI
• Light degradation
• Temperature degradation
• CsCl
• Can be problematic for clay-rich samples
• “Doping” cannot be used during most
chemical EOR processes
![Page 22: SCA 2017 Vienna, Austria - · PDF fileSCA 2017 –Vienna, Austria ... Attenuation –Beer-Lambert Law ... • Recommend saturation verification via some second method,](https://reader031.fdocuments.us/reader031/viewer/2022030413/5a9f4d6c7f8b9a89178c94db/html5/thumbnails/22.jpg)
SCA 2017 – Core Imaging Short Course
1D gamma / X-ray scanning
Attenuated
Radiation0
5
10
15
20
25
30
35
40
45
0 200 400 600 800
Sc
an
Lo
ca
tio
n
x-ray counts, I (thousands)
Sw = 0 Sw = 1
![Page 23: SCA 2017 Vienna, Austria - · PDF fileSCA 2017 –Vienna, Austria ... Attenuation –Beer-Lambert Law ... • Recommend saturation verification via some second method,](https://reader031.fdocuments.us/reader031/viewer/2022030413/5a9f4d6c7f8b9a89178c94db/html5/thumbnails/23.jpg)
SCA 2017 – Core Imaging Short Course
In situ saturation monitoring (ISSM)
• Saturation (for steady state relative permeability)
• ISSM is the only recommended method
• Alternatives (gravimetric and volumetric) incorporate large error
• E.g.
oil production = 1505 – 1500 = 5 ml
• Saturation dependent upon viable calibration
• Requires viable cleaning/displacement process
• Assumes core unchanged
• Assumes no significant movement of the scan location
• Heterogeneities can cause significant error with sub-millimetre shifts
![Page 24: SCA 2017 Vienna, Austria - · PDF fileSCA 2017 –Vienna, Austria ... Attenuation –Beer-Lambert Law ... • Recommend saturation verification via some second method,](https://reader031.fdocuments.us/reader031/viewer/2022030413/5a9f4d6c7f8b9a89178c94db/html5/thumbnails/24.jpg)
SCA 2017 – Core Imaging Short Course
In situ saturation monitoring (ISSM)
• Recommend saturation verification via some second method, e.g.
• Dean-Stark inadvisable due to positional shift
• Karl Fischer
• Must ensure all water is removed
• Possible errors for high water content
• Possible errors for high clay content
• tracer injection
• dispersion analysisSample must be homogeneous
![Page 25: SCA 2017 Vienna, Austria - · PDF fileSCA 2017 –Vienna, Austria ... Attenuation –Beer-Lambert Law ... • Recommend saturation verification via some second method,](https://reader031.fdocuments.us/reader031/viewer/2022030413/5a9f4d6c7f8b9a89178c94db/html5/thumbnails/25.jpg)
SCA 2017 – Core Imaging Short Course
In situ saturation monitoring (ISSM)
ISSM clearly shows capillary effects
![Page 26: SCA 2017 Vienna, Austria - · PDF fileSCA 2017 –Vienna, Austria ... Attenuation –Beer-Lambert Law ... • Recommend saturation verification via some second method,](https://reader031.fdocuments.us/reader031/viewer/2022030413/5a9f4d6c7f8b9a89178c94db/html5/thumbnails/26.jpg)
SCA 2017 – Core Imaging Short Course
In situ saturation monitoring (ISSM)
ISSM can show potential errors due to lab artefacts
Lab Average Sw
Waterflood-Sor = 0.72
EOR-Sor = 0.83
EOR potential = 11 s.u.
More realistic Sw
Waterflood Sor = 0.83
EOR-Sor = 0.87
EOR potential = 4 s.u.
![Page 27: SCA 2017 Vienna, Austria - · PDF fileSCA 2017 –Vienna, Austria ... Attenuation –Beer-Lambert Law ... • Recommend saturation verification via some second method,](https://reader031.fdocuments.us/reader031/viewer/2022030413/5a9f4d6c7f8b9a89178c94db/html5/thumbnails/27.jpg)
SCA 2017 – Core Imaging Short Course
Conclusions
• X-ray (or gamma) and x-ray computer tomography has been used for
many years and is a verified imaging method that can be used for:
• Reservoir characterisation, goniometry, fracture analysis, sample
assessment and evaluation, sample selection, digital rock properties,
saturation determination, etc.
• However, caution must be taken for the assumption that saturation
can be obtained from x-rays alone
• Due to doping requirements, it is probably not viable for chemical
EOR, except for very elongated scanning times