Subcritical crack growth and other time‐ and environment‐dependent behavior in crustal rocks

Swanson, P. L.

doi:10.1029/jb089ib06p04137

Cited by 187 publications

(93 citation statements)

References 40 publications

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“…The author shows a photograph of a vein and alteration halo for a crack that apparently has slowed down and finally come to arrest, resulting in a continuously decreasing size of both the width of the alteration zone and the width of the vein itself. Furthermore, in laboratory acoustic emission measurements, Swanson (1984) found that the activity in the process zone occurred closer to the crack surfaces and at lower rates when the crack speed was reduced.…”

Section: A Mechanical Model For the Development Of The Damage Zone Anmentioning

confidence: 99%

Magma-driven hydraulic fracturing and infiltration of fluids into the damaged host rock, an example from Dronning Maud Land, Antarctica

Engvik

Bertram

Kalthoff

et al. 2005

Journal of Structural Geology

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Excellent outcrops in Dronning Maud Land, Antarctica, provide unique insight into the mode and extent of fluid infiltration into metamorphic and plutonic rocks in the middle crust. The fluids are liberated from pegmatitic veins and give rise to alteration halos. In the alteration halos, the conspicuous change in colour is correlated with (1) hydration mineral reactions, and (2) high density of microcracks in quartz and feldspar exceeding that observed in the unaltered host rock by an order of magnitude. The field relations indicate that the veins originated as melt-driven hydraulic fractures, sealed by pegmatite and aplite crystallising from volatile-rich melts, with the alteration halo being the wake of the process zone formed at the tip of the propagating fractures. It is proposed that (1) the size of the alteration zone and the width of the vein are correlated, resulting in higher values of both these quantities for cracks propagating at higher velocities and consequently higher crack propagation toughnesses; (2) the damage zone is characterised by a transient state of high permeability which was short-lived due to rapid healing and sealing of microcracks; (3) the infiltration and retrogression of the high-grade rocks can be considered as a quasi-instantaneous process on geologic time scales with a duration of hours to weeks. q

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Section: A Mechanical Model For the Development Of The Damage Zone Anmentioning

confidence: 99%

Magma-driven hydraulic fracturing and infiltration of fluids into the damaged host rock, an example from Dronning Maud Land, Antarctica

Engvik

Bertram

Kalthoff

et al. 2005

Journal of Structural Geology

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“…Brittle fracture strength is influenced by environmental factors such as relative humidity and chemical reactivity that can weaken the bonds between material grains Swanson, 1984). For instance, most rock and ceramic material exhibit maximum fracture resistance (termed critical fracture toughness) when tested in a vacuum, and that strength is significantly reduced in the presence of water or water vapor.…”

Section: Subcritical Crack Growthmentioning

confidence: 99%

“…Fracture propagation below the critical toughness, termed subcritical crack propagation, occurs at lower stress levels and much lower velocities. A useful attribute of subcritical crack growth is that propagation velocity, v, can be related to opening mode stress intensity at the crack tip, K I , with an empirically quantifiable, power-law relationship Swanson, 1984;Olson, 1993),…”

Section: Subcritical Crack Growthmentioning

confidence: 99%

Advanced Technology for Predicting the Fluid Flow Attributes of Naturally Fractured Reservoirs From Quantitative Geologic Data and Modeling

Olson

Lake

Laubach

2003

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Abstract:This report summarizes the work carried out during the period of September 29, 2000 to September 28, 2001. Our goal is to establish an integrated methodology of fractured reservoir characterization and show how that can be incorporated into fluid flow simulation. We have made progress in the characterization of mineral infilling of natural fractures. The main advancement in this regard was to recognize the strong interplay between diagenetic and mechanical processes. We accomplished several firsts in documenting and quantifying these processes, including documenting the range of emergent threshold in several formations and quantifying the internal structures of crack-seal bridges in fractures. These results will be the basis for an appreciation of fracture opening and filling rates that go well beyond our original goals. Looking at geochemical modeling of fracture infilling, our theoretical analysis addressed the problem of calcite precipitation in a fracture. We have built a model for the deposition of calcite within a fracture. The diagenetic processes of dissolution and partial cementation are key controls on the creation and distribution of natural fractures within hydrocarbon reservoirs. Even with extensive data collection, fracture permeability still creates uncertainty in reservoir description and the prediction of well performance. Data on the timing and stages of diagenetic events can provide explanation as to why, when and where natural fractures will be open and permeable. We have been pursuing the fracture mechanics testing of a wide range of rocks, particularly sandstone using a key rock property test that has hitherto not been widely applied to sedimentary rocks. A major accomplishment in this first year has been to identify sample suites available in the core repository at the University of Texas that represent a wide range of diagenetic alteration and to begin to test these samples. The basis for the fluid flow simulations to be carried out in this part of the project is the adequate spatial characterization of fracture networks. Our initial focus has been on the tendency of fracture sets to cluster into highly fracture zones that are often widely separated. Our preliminary modeling work shows the extent of this clustering to be controlled by the subcritical fracture index of the material. With continued progress, we move toward an integrated fracture characterization methodology that will ultimately be applied through detailed reservoir simulation.iv Fig. 3.1. Features associated with the crack-seal mechanism. Fig. 3.2. Evidence of fracture opening mechanics. Fig. 3.3. Demonstrations of how new imaging techniques reveal mechanically significant microstructures. Fig. 3.4. Internal structure of synkinematic cement bridges. Fig. 3.5. Complex crack-seal texture within an almost completely quartz-filled macrofracture. Fig. 3.6. Limited wavelength (UV-blue) gray-scale CL image showing crack-seal texture at the bases of euhedral quartz crystals growing into a macrofracture. Fig. 3.7. Compari...

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“…The factor c and the exponent /• are material dependent; for rocks • tends to be about 100 [Swanson 1984, Atkinson 1984]. …”

Section: Microcracksmentioning

confidence: 99%

A model for propagation and concentration of microcracks

Wackertapp

Hergarten

Neugebauer

2000

Geophysical Research Letters

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Abstract. We present a model for mode I propagation and concentration of microcracks in brittle solids driven by remote stresses or volumetric changes, e.g., due to thermal contraction or desiccation. Using a crack density integral, we obtain an effective elastic tensor; the dynamics of the crack density integral is described by an additional differential equation assuming subcritical microcrack growth. Numerical simulations allow the investigation of the physical background of pattern evolution and provide some hints that the pattern formed by the concentration of microcracks may have a significant influence on the macroscopic crack pattern which finally occurs.

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Subcritical crack growth and other time‐ and environment‐dependent behavior in crustal rocks

Cited by 187 publications

References 40 publications

Magma-driven hydraulic fracturing and infiltration of fluids into the damaged host rock, an example from Dronning Maud Land, Antarctica

Magma-driven hydraulic fracturing and infiltration of fluids into the damaged host rock, an example from Dronning Maud Land, Antarctica

Advanced Technology for Predicting the Fluid Flow Attributes of Naturally Fractured Reservoirs From Quantitative Geologic Data and Modeling

A model for propagation and concentration of microcracks

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