Permeability of crystalline and argillaceous rocks

Brace, W. F.

doi:10.1016/0148-9062(80)90807-4

Cited by 614 publications

(332 citation statements)

References 27 publications

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“…The permeability ranges between aprroximately 0.1 and 0.5 Darcys. These values are consistent with other permeability calculations in fractured granite as compiled by Brace (1980). However, preliminary comparisons between the observed flow and the estimated flow (calculated from the theoretical permeability, an estimated fractured zone width and a pressure head) show that the the estimated flow is lower than the observed one.…”

Section: Pressure and Displacement Amplitude Ratiossupporting

confidence: 90%

Detection of open fractures with vertical seismic profiling

1986

International Journal of Rock Mechanics and Mining Sciences &am

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In Vertical Seismic Profiling surveys tube waves are generated by compressional waves impinging on subsurface fractures or permeable zones. The problem of generation of these waves by a non-normal incident P wave for an inclined borehole intersecting a tilted parallel wall fracture is formulated theoretically. The amplitude of tube waves depends on the permeability. the length of the fracture, and on the frequency. The relative effects of these parameters are studied individually. The problem is also formulated for a thin oblate ellipsoidal (penny-shaped) fracture. The results for the two fracture models are compared and contrasted.Field data from Tyngsboro, Massachusetts are shown for open fractures in granite. From tube wave amplitudes normalized to P wave amplitudes, calculated permeabilities are on the order of one hundred millidarcys.

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Section: Pressure and Displacement Amplitude Ratiossupporting

confidence: 90%

Detection of open fractures with vertical seismic profiling

1986

International Journal of Rock Mechanics and Mining Sciences &am

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“…Brace [1980] suggested that the predominant effect of plastic flow can eliminate all the interconnected porosity, ultimately leading to a percolation threshold. This would imply that in salt rocks due to a brittle/ductile transition in the deformation behavior at a confining pressure of-10 MPa no dilatancy induced permeability changes should occur, although the deformation proceeds in the dilatancy domain.…”

Section: Relationship Between the Geometry Of Effective Cracks And Thmentioning

confidence: 99%

Evolution of dilatancy and permeability in rock salt during hydrostatic compaction and triaxial deformation

Popp¹,

Kern²,

Schulze³

2001

J. Geophys. Res.

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Abstract. Combined gas permeability and P and $ wave velocity measurements were carried out on rock salt samples from the Gorleben salt dome and the Morsleben salt mine under hydrostatic and triaxial loading condions, mostly at room temperature. Permeabilities in the as-received samples vary between 10 46 and 2xl 0 '20 m 2. The initial permeability is primarily due to decompaction induced by drilling, core retrieval and sample preparation. Hydrostatic loading gives rise to a marked decrease of permeability and a coeval significant increase of P and $ wave velocities due to progressive closure of grain boundary cracks, tending to approach the in situ matrix permeability (< 10 '2ø m2). The pore space sensitivity of P and $ wave velocities is used to monitor the in situ state of the microstructure. Their reversals define the boundary in the state of stresses between dilatant and compactive domains (dilatancy boundary). Dilatancy during triaxial deformation of the compacted rock salt samples is found to evolve stress dependent in various stages. The crack initiation stress increases from -•18 MPa differential stress at 10 MPa confining pressure to -•30 MPa at confining pressures above-•70 MPa. Dilatancy is due to the opening of grain boundary and (100) cleavage cracks and depends on the applied confining pressure. The orientation of the open cracks is primarily controlled by the loading geometry system (compression, extension). As a consequence, permeability increases dramatically with progressive dilatancy, followed by a period of plus/minus constant permeability during strain hardening up to 10% axial strain or even more. This suggests that the evolution of permeability is not only a function of dilatancy but also of microcrack linkage. Importantly, the anisotropic crack array within the samples causes a strong directional dependence of permeability.

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“…direct means of assessing matrix permeability, as in situ permeability tests in low-porosity crystalline rocks are likely to be dominated by flow through macroscopic fractures [e.g., Brace, 1980]. Previous studies on the permeability of Kola core samples have produced a variety of results.…”

mentioning

confidence: 99%

Effects of lithology and depth on the permeability of core samples from the Kola and KTB drill holes

Morrow¹,

Lockner²,

Hickman³

et al. 1994

J. Geophys. Res.

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[1984] to the permeability data of the quartz-rich samples, we can estimate the closure pressure of the stress-relief cracks and thereby place bounds on the in situ effective pressure. This method may be useful for drill holes where the fluid pressure is not well constrained, such as at the Kola well. However, the use of crack closure to estimate in situ pressure was not appropriate for the basalt and amphibolite samples, because they are relatively crack-free in situ and remain so even after core retrieval. As a result, their permeability is near or below the measurable lower limit of our apparatus at the estimated in situ pressures of the rocks.

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Permeability of crystalline and argillaceous rocks

Cited by 614 publications

References 27 publications

Detection of open fractures with vertical seismic profiling

Detection of open fractures with vertical seismic profiling

Evolution of dilatancy and permeability in rock salt during hydrostatic compaction and triaxial deformation

Effects of lithology and depth on the permeability of core samples from the Kola and KTB drill holes

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