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Field-Deployable Solution for Nanoporosity Measurements in Mud Logging Operations and a Novel
Method for Fracability Analysis Using Mud Cuttings
• Field-Deployable FE-SEM for nanoporosity analysis
• Nanoindentation to investigate fracability
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Measurement Solutions for Mud Logging
Basic Requirements• Robust instruments Shock and vibration Extreme temperature and humidity swings Wider operating temperature and humidity swings than a typical lab
• Simple facilities 120/240V, single phase power No flammable gases No cylinder handling hazards
• Simple and repeatable workflow Automated data collection and simplest sample preparation
• Measurement throughput Must keep up with bit penetration rate
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Agilent’s Measurement Solutions for Mud Logging
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• Field Emission – Scanning Electron Microscope(FE-SEM) imaging of drill cuttings at 10nm resolution Determine total formation porosity including nanoporosity Take porosity measurements to the field; previously only
performed in central lab Near real-time porosity monitoring for improved perforation
planning
• Nanoindentation Testing (G200) for mechanical analysis Mechanical testing of mud cuttings possible Agreement with macro-scale mechanical testing of core
plugs appears to be excellent Possible direct mechanical measurement of fracture
probability
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Agilent 8500 FE-SEM Overview
• 8500 FE-SEM for Porosity Analysis
• 8500 FE-SEM Features & Benefits
• Technology
• Nanoporosity Imaging and Other Applications
• Summary
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Loucks et al., 2009
• Carbonate & shales have significant nanoporosity; comprising 50% of total porosity. • Classical porosity measurements miss the contribution of nanoporosity.• Nanoporosity analysis plays an important role for hydrocarbon estimations and future
hydrocarbon production. • Most nanopores are formed in grains of organic matter during thermal decomposition of
organic matter in hydrocarbon generation and therefore hold hydrocarbons.• Although organic-rich shale-gas formations may be hundreds of meters in gross thickness
(and may appear largely homogeneous), the vertical variability in the organic richness and mineralogy varies on relatively short vertical scales (e.g. 10’s cm - 1 meter).
• SEM-based characterization of mudrock nanopores is a critical first step in better understanding of the distribution and causes of pore development in shale-gas systems.
• 3D serial sectioning and imaging indicates that many of these organic pores are interconnected.
• Solution: The pore network can be characterized for nanoporosity at the well site by using Agilent’s low voltage field emission scanning electron microscopy with <10nm resolution.
Why Nano-Porosity Analysis?Improved perforation planning and recoverable reserve valuation
1000nm
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Limitations to Nanometer Porosity Analysis at Well SiteMud Cuttings and Core Samples
• Classical high resolution FE-SEM systems are difficult to deploy in a remote lab
environment as they require 3-phase power and cooling water.
– High cost, difficult facility requirements, and too sensitive to environmental vibrations.
• Smaller table-top SEM systems cannot achieve the required fidelity and resolution
for nanometer porosity analysis of cuttings and cores like FE-SEM systems.
– 50nm resolution is not enough for porosity analysis for most rock formation types
• There have been no solutions for high throughput sample preparation for mud
cuttings that would support field deployments of SEM systems.
– Sample prep needs to take a few minutes to providing real time porosity analysis on site
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The Solution for Nanometer Porosity Analysis at Well SiteMud Cuttings and Core Samples
• Agilent’s revolutionary miniaturized FE-SEM
achieves sub-10 nm resolution for mud
cutting imaging in a mobile package for
porosity analysis at the well site.
– A great solution for porosity analysis at the well
site requiring.
• Recent innovations in sample preparation
make it possible to take samples frequently
and prepare for imaging quickly.
– Allows for continuous real time monitoring of
nanometer porosity while drilling.
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Agilent 8500 FE-SEM Overview
• 8500 FE-SEM for Porosity Analysis
• 8500 FE-SEM Features & Benefits
• Technology
• Nanoporosity Imaging and Other Applications
• Summary
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8500 FESEM Key Features & Benefitsnano Porosity Applications in Petrology
• FE-SEM with performance required for nanoporosity measurements• Resolution comparable to conventional field emission microscopes• Consistent and long-lasting performance and high uptime
• Compact size for remote site applications• Fits on a bench-top in a remote lab space, no special facilities required• Better Cost of Ownership than conventional FE-SEM systems
• Variable low voltage imaging is best for porosity analysis of cuttings• Continuously variable voltage for optimizing image acquisition• Minimal sample charging and no coating required
• Programmable X,Y,Z stage supporting up to eight samples• Enables the high throughput imaging to support mud cutting monitoring
• Electrostatic Lens Design• Factory calibrated column for ease of use• Repeatable performance, no hysteresis, programmable imaging recipes
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Resolution Comparison Agilent 8500 versus a Conventional FE-SEM
• The 8500 compares well to conventional high-resolution FESEMs at 1kV
LEO 1525
8500 FE-SEM
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Low Voltage Imaging AdvantageSurface Fidelity is needed for Porosity Analysis
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Agilent 8500 FE-SEM Overview
• 8500 FE-SEM for Porosity Analysis
• 8500 FE-SEM Features & Benefits
• Technology
• Nanoporosity Imaging and Other Applications
• Summary
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Programmable XYZ Closed-Loop Piezo Stage
• 25x25x10mm travel
• Supports eight samples in a single
load with sample sizes < ½”
• 1um accuracy/0.1um read-back
• Set precise coordinates
• Store unlimited locations
• Automated sample exchange
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Kinematic Sample Mount
• Allows automated sample transfer
• Cross registration between imaging tools (e.g., optical, AFM, FIB)
• Re-registration between imaging sessions
• ±4um repeatability
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Miniature Electron Beam Column
Conventional SEM Column
500-
800m
m
9mm
85mm
38m
m
8500 Cartridge
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Miniature Electron Beam Column
11m
m1.
8mm
TFE source
Condenser
Deflectors
Objective lens
BlankerAperture
Normal incidence (±0.5°)~200pA beam current
1.8 steradian collection angleSE+BS, BS, Topo Modes
Operating Conditions
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Split Quadrant Detector Highlights Topography
Distinguishes backscattered electrons ejected from the sample at an angle
Normal Mode Topographic-X Mode Topographic-Y Mode
MCP Packagee‐
The detector is analogous to an illumination source
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Topographic Imaging
Reveals surface topography not evident in normal mode
12nm C film with 1.2um diameter holes suspended on a Cu grid
Secondary + Backscattered Electrons Topographic
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Intuitive User Interface• Straight-forward, easy to use• GUI designed for both novices and experts
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Low Cost of Ownership
• Electron source can be powered off and starts up quickly, extending the lifetime of source
• ECD Cartridge New electron source New pre-aligned electron beam column New MCP detector Field replaceable
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ConventionalFESEM
The Nanotechnology Sweet Spot
5nm 10nm 100nm1nm 1um 10um 100um 1000um500nm
Optical Microscope
Pric
e
Agilent 8500 FE-SEM
AffordabilityGap
# of
Nan
ocal
e ap
pica
tions
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PerformanceGap
$200K
$500K
$1,000K
$100K
$50K
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Agilent 8500 FE-SEM Overview
• 8500 FE-SEM for Porosity Analysis
• 8500 FE-SEM Features & Benefits
• Technology
• Nanoporosity Imaging and Other Applications
• Summary
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Sequence of Increasing Magnification SE images of Ion-Milled U.S. Gas Shale Sample – location 1
Images show pores only in the inter-granular clay-based matrix (cement)
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Sequence of Increasing Magnification SE images of Ion-Milled U.S. Gas Shale Sample – location 1 (con’t)
Images show pores only in the inter-granular clay-based matrix (cement)
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Sequence of Increasing Magnification SE images of Ion-Milled U.S. Gas Shale Sample – location 1 (con’t)
Images show pores only in the inter-granular clay-based matrix (cement)
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Sequence of Increasing Magnification SE images of Ion-Milled U.S. Gas Shale Sample – location 2
Images show pores only in the inter-granular clay-based matrix (cement)
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Page 27
Sequence of Increasing Magnification SE images of Ion-Milled U.S. Gas Shale Sample – location 2 (con’t)
Images show pores only in the inter-granular clay-based matrix (cement)
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Page 28
Sequence of Increasing Magnification SE images of Ion-Milled U.S. Gas Shale Sample – location 2 (con’t)
Images show pores only in the inter-granular clay-based matrix (cement)
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Page 29
Sequence of Increasing Magnification SE images of Ion-Milled U.S. Gas Shale Sample – location 3
Images show the rock to have a minimum of 3 different mineral phases. Only the inter-granular clay matrix (cement) has a significant amount of pores. The high-contrast grains (not determined) have inclusions that could be confused for pores in low resolution SEMs.
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Page 30
Sequence of Increasing Magnification SE images of Ion-Milled U.S. Gas Shale Sample – location 3 (con’t)
Images show the rock to have a minimum of 3 different mineral phases. Only the inter-granular clay matrix (cement) has a significant amount of pores. The high-contrast grains (not determined) have inclusions that could be confused for pores in low resolution SEMs.
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October 2013
Page 31
Sequence of Increasing Magnification SE images of Ion-Milled U.S. Gas Shale Sample – location 3 (con’t)
Images show the rock to have a minimum of 3 different mineral phases. Only the inter-granular clay matrix (cement) has a significant amount of pores. The high-contrast grains (not determined) have inclusions that could be confused for pores in low resolution SEMs.
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Wide Variety of Geologic Materials
Clays
DiatomSand
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Gypsum
NaCl Clay Mix
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Other 8500 FE-SEM Applications
• Polymers
• Thin Films
• MEMS & other devices
• Metals, Ceramics & Glass
• Bio Materials
• Non-conductive Samples
• Energy Sensitivity Samples
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Gulf Coast ConferenceAgilent Restricted
October 2013
Agilent 8500 FE-SEM Overview
• 8500 FE-SEM for Porosity Analysis
• 8500 FE-SEM Features & Benefits
• Technology
• Nanoporosity Imaging and Other Applications
• Summary
Page 34
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October 2013
8500 FESEM Summarynano Porosity Applications in Petrology
Page 35
• FE-SEM with performance required for nanoporosity measurements• Resolution comparable to conventional field emission microscopes• Consistent and long-lasting performance and high uptime
• Compact size for remote site applications• Fits on a bench-top in a remote lab space, no special facilities required• Better Cost of Ownership than conventional FE-SEM systems
• Variable low voltage imaging is best for porosity analysis of cuttings• Continuously variable voltage for optimizing image acquisition• Minimal sample charging and no coating required
• Programmable X,Y,Z stage supporting up to eight samples• Enables the high throughput imaging to support mud cutting monitoring
• Electrostatic Lens Design• Factory calibrated column for ease of use• Repeatable performance, no hysteresis, programmable imaging recipes
Gulf Coast ConferenceAgilent Restricted
October 2013
Agilent’s Measurement Solutions for Mud Logging
Page 36
• Field Emission – Scanning Electron Microscope(FE-SEM) imaging of drill cuttings at 10nm resolution Determine total formation porosity including nanoporosity Take porosity measurement to the field, previously only
performed in central lab Near real-time porosity monitoring for improved perforation
planning
• Nanoindentation Testing (G200) for mechanical analysis Mechanical testing of tailings possible Agreement with macro-scale mechanical testing of core
samples appears to be excellent Possible direct mechanical measurement of fracture
probability
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Nanomechanical Testing of Gas Shale
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Nanoindentation of mud cuttings
• Problem: Traditional macroscale mechanical testing of cores is costly, time-consuming, and often impractical
• Shale chips (3mm – 5mm) simulating mud cuttings were potted in epoxy for Nanoindentation
• Nanoindentation tests were performed parallel and perpendicular to bedding directions
• Agreement with macro-scale mechanical testing of core plugs appears to be excellent for initial studies
Kumar, Vikas. Geomechanical Characterization of Shale Using Nano-indentation. Diss. University of Oklahoma, 2012.
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What mechanical parameters are the most useful?
• Observed correlations have led researchers to conclude that shale is most likely to fracture easily and well if it has a high Young’s modulus and low Poisson’s ratio ()
• An alternative parameterization based on mineralogy suggests brittleness or fracability is dependent on quartz content
• A more conclusive parameterization is desirable
R.M. Bustin, A. Bustin, D. Ross, G. Chalmers, V. Murthy, C. Laxmi, and X. Cui, “Shale Gas Opportunities and Challenges,” Search and Discovery Articles, No. 40382, 2009. http://www.searchanddiscovery.com/documents/2009/40382bustin/ndx_bustin.pdf
B. Grieser and J.Bray, “Identification of Production in Unconventional Reservoirs,” SPE 106623 SPE Production and Operations Symposium, Oklahoma City, OK, 31 March–3 April, 2007
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Young’s modulus’ relation to Poisson’s ratio and Hardness
• Both Young’s modulus and Poisson’s ratio are elastic properties which are imprecisely related to fracability
• They predict the resulting strain (or vice versa) only up to the point of permanent deformation
• They contain no information about the threshold criteria for permanent deformation marked by the onset of fracture, plastic yield, or other mechanism
• The dimensionless parameter E/H may contain more information about the ability to generate and sustain cracks
• In fracture toughness measurements, the length of resulting cracks depends on the ratio E/H for a given load and fracture toughness constant
• Perhaps there is an even simpler and more relevant parameter at our disposal: W*p – Normalized Permanent Work
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Normalized Plastic Work – W*p
0
1
2
3
4
5
6
0 5 10 15 20
Displacement into Surface [microns]
Load
on
sam
ple
[N]
permanent work
elastic work
Force-displacement curve from a single high-force test in shale. Fracture causes the “step” at a force of 3N.
• Presumably, the dominant mechanisms for permanent damage in Shale are microfracturing and plastic yielding
• Nanoindentation tests can determine the amounts of plastic and elastic work performed for a given indentation (Wtotal = We + Wp)
• Normalizing Wp with respect to Wtotal reduces the dependence on indent size, thus creating W*p
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Comparing W*p vs. E/H over a large sample set
50
55
60
65
70
75
80
85
90
95
100
0 10 20 30 40 50 60
Young's modulus, normalized by hardness [-]
Perm
anen
t (un
reco
vere
d) w
ork,
no
rmal
ized
by
tota
l wor
k [%
]
• 100 indents at high force (5N) were performed on a Barnett shale core plug
• The high force, high displacement indents were large enough (>100um dia.) to sample relevant elements of this shale, including clay and mineral grains, within single indents
• At least for this material, W*p is linearly related to the E/H ratio mentioned previously
• So why not simply measure E and H instead?
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Young's modulusHardnessNormalized plastic work
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Novel Fracability Testing Using Mud Cuttings
• Roughness and heterogeneity at the surface cause a higher degree of scatter in the determination of the indenter tip contact area, A
• The calculation of E depends on A1/2, while the calculation of H depends directly on A
• Thus, it takes E about 25 tests to converge to within 2% of its final value. It takes H about 40 tests. In either case, it would require a sample larger than normal mud cuttings
• W*p is a dimensionless parameter that does not include A in its determination
• W*p converges to within 2% of final value in 2-3 measurements
• Further testing is ongoing to validate or invalidate this hypothesis
See: Mechanical Testing of Shale by Instrumented Indentation Jennifer Hay and Carl H. Sondergeld, AgilentTechnologiesAppNote 5990-5816EN (2010) http://cp.literature.agilent.com/litweb/pdf/5990-5816EN.pdf
Samples and SEM images courtesy of Carl H. Sondergeld, University of Oklahoma
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Questions?
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