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Application of Mechanical and Mineralogical Rock Properties to Identify Fracture Fabrics in the
Devonian Duvernay Formation in Alberta
Presented by
Mehrdad Soltanzadeh, Ph.D., P.Eng.
Duvernay Project,Study Area and Geology
Study Area
(Source: Switzer et al., 1994)
Study
Area
Geology
900 m of Detailed Core Description for 29 Wells
(Source: Switzer et al., 1994)
Core-based Stratigraphy
(Source: Switzer et al., 1994)
Idealized Core-based Parasequence/TR Cycle in the Upper Duvernay Shale
Stratigraphic Depositional Model
Observed Fractures in Duvernay
(a) (b) (d)
(h)(e) (f) (g)
(c)
Examples of fracture fabrics observed in the Duvernay Formation cores: (a) subvertical fracture, (b) parallel set of subvertical fractures, (c) conjugate set of sub-vertical planar fractures (arrows) on bedding plane, (d) hackle plume on fracture surface, (e) polished slip faces (PSF), (f) bedding–plane fragments of core in Figure 4e showing indistinct PSF surfaces with striae, (g) cleavage lineation on bedding-parallel core surface with oblique calcite-cemented microfracture (arrow), (h) bed-parallel parting (BPP) or core disking.
Fractures and Geomechanics
Mechanical Rock PropertiesLab Tests• Uniaxial/Triaxial• Hardness• Multi-stage• Multi-stress• Ultrasonic• Brazilian
Mechanical Properties• Static/Dynamic
Properties• Strength
Properties• Anisotropy• Tensile Strength
Logs
• Sonic/Dipole Sonic
• Cross-dipole Sonic
• Density
Mechanical Properties
• Dynamic Elastic Properties
• Strength Properties
• Anisotropy
Log-based Elastic Properties
Dynamic Poisson’s Ratio Dynamic Young’s Modulus (GPa)
Ireton F
Ireton F
Ireton D
Ireton C
Ireton B
Ireton A
Duvernay C5
Duvernay C4
Duvernay C3
Duvernay C2
Duvernay C1
Duvernay B
Duvernay A
0.10 0.15 0.20 0.25 0.30 0.35 0.40 20 30 40 50 60 70 80
(a) (b)
Lab-based Elastic Properties
Static Poisson’s Ratio Dynamic Poisson’s Ratio
Effect of Fluid Type and Pressure?
Duvernay
Ireton
Poisson’s Ratio
Fre
qu
en
cy
Static vs. DynamicDepth
(m)
Petrophysics
Calculated Quartz Volume (V/V)
Qu
artz
Vo
lum
e fr
om
XR
D (%
)
(a)
Calculated TOC (%)
TOC
from
SR
A (%
)
(b)
Mineralogy and Mechanical Properties
Data from a key wellData from 16 wells
Investigating Brittleness• So-called ‘Brittleness Index’ suppose to help with
identifying brittle rock from ductile rock. This is anambiguous definition with different interpretations.
• Both science and experience confirm that fracturingbehaviour cannot be limited to a small number ofattributes such as elastic properties.
• However, it may be possible to integrate these datawith other information and come up with some‘locally-defined’ parameters that act as proxies foridentifying the ‘fraccability’ of the rock.
Trying Different Indices• Mineralogical Brittleness Indices:
• Mechanical Brittleness Indices:
𝐵𝑅𝐷𝑜𝑙𝑜𝑚𝑖𝑡𝑒 =𝐷𝑜𝑙𝑜𝑚𝑖𝑡𝑒[+𝑄𝑢𝑎𝑟𝑡𝑧]
𝐴𝑙𝑙 𝑀𝑖𝑛𝑒𝑟𝑎𝑙𝑠× 100 Commonly-used Parameter
𝐵𝑅𝐶𝑙𝑎𝑦 = 1 −𝐶𝑙𝑎𝑦 [+𝑇𝑂𝐶]
𝐴𝑙𝑙 𝑀𝑖𝑛𝑒𝑟𝑎𝑙𝑠 × 100 Used in This Study
𝐵𝑅𝑅𝑖𝑐𝑘𝑚𝑎𝑛 =1
2
𝐸 − 𝐸𝑚𝑖𝑛
𝐸𝑚𝑎𝑥 − 𝐸𝑚𝑖𝑛+
𝜈𝑚𝑎𝑥 − 𝜈
𝜈𝑚𝑎𝑥 − 𝜈𝑚𝑖𝑛 × 100
𝐸𝑝𝑠 =𝐸
1 − 𝜈2=
2𝐺
1 − 𝜈 Used in This Study
Commonly-used Parameter
Eps Comes from Fracture Mechanics
• Fracture Geometry
• Stress Profile
PKN Fracture Model
Comparison of Different Indices
Rickman’s Brittleness Index (%)
80 10 20 30 40 50 60 70
(c)Ireton F
Ireton F
Ireton D
Ireton C
Ireton B
Ireton A
Duvernay C5
Duvernay C4
Duvernay C3
Duvernay C2
Duvernay C1
Duvernay B
Duvernay A
(a)
Plane-strain Young’s Modulus (GPa)
20 30 40 50 60 70 80
(d)Ireton F
Ireton F
Ireton D
Ireton C
Ireton B
Ireton A
Duvernay C5
Duvernay C4
Duvernay C3
Duvernay C2
Duvernay C1
Duvernay B
Duvernay A
(b)Ireton F
Ireton F
Ireton D
Ireton C
Ireton B
Ireton A
Duvernay C5
Duvernay C4
Duvernay C3
Duvernay C2
Duvernay C1
Duvernay B
Duvernay A
0 20 40 60 80 100
Brittleness Index based on Dolomite and Quartz (%)
(c) (d)
Brittleness Index based on Clay (%)
30 40 50 60 70 80 90 100
El Diablo
The best correlation exists between these
two parameters.
Eps vs. BRClay
Effective Porosity
Fractures on Cores and Image LogsPS-YM
BRClay
BRRickman
YM
PRGamma
Logs Image Log Graphic Core Description
Fractures and Rock Properties
Fraccablity
Range
Fracture Types and Rock Properties
Sonic PR YM BR SP. GR Hardness
Rock Properties Core Description
Identifying Fracture Types
(a) (b)
Hardness vs. Log-based Properties
Conclusions• Shale behaviour in the field is strongly affected by in-situ
conditions, so, integrating field and lab measurements needs to be performed with extreme caution.
• Different plays may need to be treated differently as shown for the brittleness index.
• Observed fractures on the core and image logs are probably one of the most trustworthy criteria to determine rock’s fraccability.
• Rock properties, along with stresses, have identifiable effects on the formation of different fracture fabrics.
• Data integration in unconventional plays can help with more precise characterization of the play behaviour and provides opportunities for application of more efficient approaches for development of these plays.
Acknowledgments
Co-authors:• Graham David, Graham Davies Geological Consulting Ltd.
• Amy Fox, Canadian Discovery Ltd.
• David Hum, Core Laboratories LP
• Nasir Rahim, Canadian Discovery Ltd.
Trican Geological Solutions Ltd.• Albert Cui, Ken Glover.
Canadian Discovery Ltd.• Sarah Hawkes, Ching Zhu, Leydy Garcia, Susan Wang, Suzie Jia.
Seven Generations Energy Ltd.