Pore pressure buildup coefficient in synthetic and natural sandstones

Berge, Patricia A.; Wang, H.F.; Bonner, B.P.

doi:10.1016/0148-9062(93)90083-p

Cited by 41 publications

(30 citation statements)

References 19 publications

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“…They range from 0.23 to 0.99 depending on the effective pressure. In a laboratory study of synthetic and natural sandstones, Berge et al [1993] obtained B near 0.7-0.8 for differential pressures of about 8 -21 MPa. For differential pressures below ϳ2 MPa, the measured values of B were approximately unity.…”

Section: Comparison Of Observed Hydraulic Properties In Shear Zone C mentioning

confidence: 99%

In situ measurements of hydraulic properties of a shear zone in northwestern South Carolina

Talwani¹,

Cobb²,

Schaeffer³

1999

J. Geophys. Res.

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Abstract. Subsequent to the initial impoundment of the Bad Creek Reservoir in northwest South Carolina in January 1991, lake level fluctuations (up to 33 m d Ϫ1 ) caused delayed (98 hours) correlative water level changes in an observation well (OW3) 250 m away. The bottom of the well is connected to the bottom of the reservoir by a shallowly dipping, 1 m wide shear zone. The amplitude of water level changes in OW3 was 0.19 of that in the reservoir. The amplitude ratio, R, of the water level changes in OW3 to those in the reservoir is a measure of the pore pressure transmitted through the shear zone. Assuming one-dimensional diffusion of pore pressure in the shear zone between the reservoir and OW3, these values of time lag and amplitude ratio of the water level fluctuations changes yield estimates of 0.05 m 2 s Ϫ1 for hydraulic diffusivity and 1.1 ϫ 10 Ϫ15 m 2 for permeability of the shear zone. In subsequent years the time lag decreased to 72 hours and R increased to 0.23, suggesting a nearly 60% increase in the two hydraulic parameters. We interpret the increase to be owing to flushing of fines in the shear zone due to the pumping action of lake level fluctuations or due to dissolution. After 1994, there were no further changes in these parameters suggesting steady state conditions. Our analysis demonstrated that the fluid pressure flow is restricted to the shear zone and the pore pressure transmitted through the shear zone showed a lognormal relationship with the frequency of lake level fluctuations, R ϭ 0.5 exp (Ϫ14.93/T), where T (days) is the period of lake level changes. Spectral analyses of the data were used to obtain a frequency independent hydraulic diffusivity (ϳ0.076 m 2 s Ϫ1 ) of the shear zone after it had reached steady state conditions. Using the undrained response of the reservoir, an in situ estimate value 0.66 was obtained for the Skempton's coefficient. The hydraulic diffusivity ϳ0.1 m 2 s Ϫ1 was found to be lower than that encountered at other locations of induced seismicity in the region.

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Section: Comparison Of Observed Hydraulic Properties In Shear Zone C mentioning

confidence: 99%

In situ measurements of hydraulic properties of a shear zone in northwestern South Carolina

Talwani¹,

Cobb²,

Schaeffer³

1999

J. Geophys. Res.

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“…The Biot-Willis constant a is entirely independent of the fluid in the pores even though B and K U both depend on the fluid bulk modulus [e.g., Berge et al, 1993]. The remaining material properties are the shear modulus G, the rock permeability k, the fluid viscosity h, the rock's electrical conductivity s, and the electrokinetic-coupling coefficient L. Models for these various coefficients/material-properties are given and discussed in Appendix A.…”

Section: Governing Equationsmentioning

confidence: 99%

Mechanical and electrical response due to fluid‐pressure equilibration following an earthquake

Pride¹

2004

J. Geophys. Res.

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[1] The mechanical and electrical response in a uniform porous crust are determined following a shear dislocation (earthquake) on an internal slip surface. A uniform crust is studied because many exact analytical relations hold between the various response fields in this case. The initial stress field that is created immediately following the earthquake subsequently relaxes through time as the fluid pressure equilibrates by fluid flow. Maps of the electric field generated due to the fluid flow (electrokinetic coupling) are presented. Using conservative estimates of the various parameters involved, electric fields significantly larger than the diurnal (magnetotelluric) fields are generated. Quantitative results for how various components of the stress tensor change due to the fluid equilibration are also presented. The Coulomb stress can easily change by 100% (and more) in the months following an earthquake due to the fluid-pressure equilibration.

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“…3. In fact, since it has often been reported that most rocks have similar mechanical properties, i.e., 0.6 ≤ µ ≤ 0.85 (Byerlee 1978) and 0.7 ≤ β ≤ 1.0 (Green and Wang 1986;Berge et al 1993), which correspond to the small rectangular area in Fig. 3, we can narrow down the feasible mechanical conditions for static stress to have been a trigger to the area where the small rectangular and the white areas intersect.…”

Section: Static Stress Changes On the Fault Plane Of The Chia-yi Eartmentioning

confidence: 99%

“…Changes in the Coulomb failure stress ( ) ∆CFS transferred from the ChiChi earthquake onto the hypocenter of the Chia-Yi earthquake with various friction ( µ ) and Skempton's coefficients ( β ). The white area indicates the region with positive ∆CFS values, while the rectangular area confined by the dashed lines defines µ and β for most rocks (Byerlee 1978;Green and Wang, 1986;Berge et al 1993). The optimal µ and β values at the site of the Chia-Yi event, therefore, fall in the region where the rectangular and the white areas intersect with an average ∆CFS value of about 0.1 bar.…”

Section: Static Stress Changes On the Fault Plane Of The Chia-yi Eartmentioning

confidence: 99%

Mechanical Properties, Slip and Nucleation of the 1999 Chia-Yi Earthquake: the Question of Static Stress Influence from the 1999 Chi-Chi Earthquake

Chang¹,

Wang²

2006

Terr. Atmos. Ocean. Sci.

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Pore pressure buildup coefficient in synthetic and natural sandstones

Cited by 41 publications

References 19 publications

In situ measurements of hydraulic properties of a shear zone in northwestern South Carolina

In situ measurements of hydraulic properties of a shear zone in northwestern South Carolina

Mechanical and electrical response due to fluid‐pressure equilibration following an earthquake

Mechanical Properties, Slip and Nucleation of the 1999 Chia-Yi Earthquake: the Question of Static Stress Influence from the 1999 Chi-Chi Earthquake

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