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subcritical crack index

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<b>Subcritical</b> <b>crack</b> <b>index</b> measurements compiled for six shales. These are plo...
Published: 01 November 2014
Figure 8 Subcritical crack index measurements compiled for six shales. These are plotted by depth, although there is no depth correlation. New Albany Shale data from Fidler ( 2011 ); Barnett data from Gale and Holder ( 2008 , 2010 ).
Journal Article
Journal: AAPG Bulletin
Published: 01 April 2007
AAPG Bulletin (2007) 91 (4): 603-622.
... of orientation, size, and sealing properties. We measured a mechanical rock property, the subcritical crack index, which governs fracture pattern development. Natural fractures are common, narrow (<0.05 mm; <0.002 in.), sealed with calcite, and present in en echelon arrays. Individual fractures have high...
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Journal Article
Published: 01 May 2012
Journal of the Geological Society (2012) 169 (3): 297-310.
... modulus 2.3–17.0 GPa, most values <6.9 GPa) and moderate to high subcritical crack index (45–78), resulting from compacted soft lithic grains and clay-mineral cements. Low abundance contradicts models that postulate persistent incipient failure by subsurface fracture. The fracture sequence resembles...
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Series: Geological Society, London, Petroleum Geology Conference series
Published: 01 January 2010
DOI: 10.1144/0071131
EISBN: 9781862394131
... examined. ( a ) Texas locations; ( b ) New Albany Shale locations. Fig. 9. Plot of subcritical crack index measurements v. depth for samples from two Barnett Shale cores, the Mitchell Energy #2 T. P. Sims and a second core, labelled core A, from the FWB, north-central Texas. Fig. 10...
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Series: Geological Society, London, Special Publications
Published: 01 January 2004
DOI: 10.1144/GSL.SP.2004.231.01.05
EISBN: 9781862394797
...; and (2) the use of a subcritical crack-propagation rule, where propagation velocity during stable growth scales with the crack-tip stress intensity factor. Three regimes of fracture spacing are identified according to the magnitude of the subcritical index of the fracturing material. For low subcritical...
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Fracture patterns derived from geomechanical modeling, showing effects of d...
Published: 01 July 2000
Figure 4. Fracture patterns derived from geomechanical modeling, showing effects of differing subcritical crack index (n values) on resultant fracture spacing and clustering. Models show fracture traces (red lines) in map view and have identical boundary and initial conditions.
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Mechanical properties of Applecross sandstone samples at laboratory conditi...
Published: 01 May 2012
Fig. 6. Mechanical properties of Applecross sandstone samples at laboratory conditions ( T = 25 °C, P c = 1 atm). ( a ) Young’s modulus, E , for two specimens cut into 14 samples, each sample tested twice. ( b ) Subcritical crack index results for same two samples. Subcritical index
Series: Geological Society, London, Special Publications
Published: 01 January 2004
DOI: 10.1144/GSL.SP.2004.235.01.08
EISBN: 9781862394834
...) are a scanning artifact. Fracture characterization of Permian Clear Fork Formation dolostones was carried out in outcrops and core ( Moros Otero 1999 ; Gale et al. 2002 ). These results were used by Philip et al. (2002) , in conjunction with subcritical crack index measurements...
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Journal Article
Journal: The Leading Edge
Published: 01 July 2000
The Leading Edge (2000) 19 (7): 704-711.
...Figure 4. Fracture patterns derived from geomechanical modeling, showing effects of differing subcritical crack index (n values) on resultant fracture spacing and clustering. Models show fracture traces (red lines) in map view and have identical boundary and initial conditions. ...
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Journal Article
Published: 01 May 2012
Petroleum Geoscience (2012) 18 (2): 191-199.
...) Rock matrix E Young’s modulus 2.0 GPa ν Poison’s ratio 0.4 ρ s Average sediment density 2350 kg m −1 A Subcritical crack growth constant 10 7 m s −1 (MPa-m 1/2 ) −10 n Subcritical crack growth index 10 a 0 Initial microcrack radius 50 μm H 0 Initial...
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Series: Geological Society, London, Special Publications
Published: 01 January 2007
DOI: 10.1144/SP289.8
EISBN: 9781862395374
... of pattern geometry and fracture attribute distributions through time. The effects of mechanical layer thickness and subcritical index (stress corrosion cracking) are investigated. Natural, opening-mode fractures have been postulated to initiate from rock imperfections such as microcracks...
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Journal Article
Journal: GSA Bulletin
Published: 01 March 2005
GSA Bulletin (2005) 117 (3-4): 436-449.
... to induce process zone cracking. In brief, the distinction between rough surfaces in rocks and rough surfaces in glass is largely dependent on whether the onset of process zone cracking occurs in the subcritical or postcritical regimes. Although plumes are a record of the joint rupture from initiation...
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Journal Article
Journal: Interpretation
Published: 11 August 2016
Interpretation (2016) 4 (4): T485-T496.
... for the generation of potential fracture patterns based on the specific formation rock properties. Subcritical crack index (SCI) describes the velocity of fracture propagation as a function of stress intensity factor ( Lawn, 1974 ). With a higher subcritical fracture growth index, fracture lengths...
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Series: Geological Society, London, Special Publications
Published: 01 January 2006
DOI: 10.1144/GSL.SP.2006.261.01.02
EISBN: 9781862395091
... that the event rate N of the microcrack activity during the subcritical crack growth of a single tensile crack also exhibits a nonlinear dependence on the stress intensity, showing a form similar to Charles’s power law: Within this context, /' is referred to as the ‘effective’ stress corrosion index...
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Journal Article
Published: 01 February 1991
Quarterly Journal of Engineering Geology and Hydrogeology (1991) 24 (1): 123-134.
... Atkinson, B. K. 1979 . A fracture mechanics study of subcritical tensile cracking of quartz in wet environments. Pure and Applied Geophysics, 117 , 1011 – 1024 . Atkinson, B. K. 1984 . Subcritical crack growth in geological materials. Journal of Geophysics Research, 89...
Series: GCSSEPM
Published: 01 December 2009
DOI: 10.5724/gcs.09.29.0483
EISBN: 978-0-9836096-1-2
... impact was the loss of connectivity and percolation (Fig. 7) . Figure 7. Plot showing geomechanically generated fracture trace length and aperture patterns for a specified strain, mechanical layer thickness, and subcritical crack index. All segments having an aperture less than 0.6 mm...
Journal Article
Journal: The Leading Edge
Published: 01 March 2010
The Leading Edge (2010) 29 (3): 304-309.
... fluid pressure in such a reservoir causes pressure in the connected pore and fracture space of rocks to increase. Such an increase in the pore pressure consequently causes a decrease of the effective normal stress. This leads to sliding along pre-existing, favorably oriented, subcritical cracks. Figures...
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Journal Article
Published: 01 February 1998
Quarterly Journal of Engineering Geology and Hydrogeology (1998) 31 (1): 5-19.
... Geology, 19 , 364 – 371 . Anon 1990 . Methods of Test for Soils for Civil Engineering Purposes. Part 2. Classification Tests. British Standards Institution, London. Atkinson, B. K. 1984 . Subcritical crack growth in geological materials. Journal of Geophysical...
Journal Article
Journal: AAPG Bulletin
Published: 01 November 2009
AAPG Bulletin (2009) 93 (11): 1535-1549.
... × 7.2 m Fracture propagation area 6 × 6 m Layer thickness 1 m Fracture toughness, K Ic 1.5 MPa-√m Young's modulus 20 GPa Poisson's ratio 0.2 Friction coefficient 0.6 Subcritical index 50 Initial flaw length 0.1 m Number of flaws 100 Table 2 Predicted Failure Data...
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Journal Article
Journal: The Leading Edge
Published: 01 December 2010
The Leading Edge (2010) 29 (12): 1494-1499.
..., but lateral propagation occurs within the layer and can be nonplanar (Olson et al., 2007). Key input parameters required for fracture pattern generation are mechanical layer thickness ( Laubach et al. 2009 ), elastic moduli, subcritical index (a fracture propagation parameter for stress corrosion cracking...
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