### Abstract

Mechanical and fluid transport properties of brine-saturated illite shale from the Wilcox Formation have been investigated to examine the effects of strain rate on fracture strength and to determine the conditions over which rates of deformation and internal fluid flow compete. Permeability (k) measurements predict time scales for fluid pressure equilibration mat are long relative to those of deformation experiments; values of k are small even at relatively low effective pressures P_{e} (assumed = P_{c} - Pf) and they drop below 10^{-20} m^{2} at pressures of ≥ 5 MPa. Failure strengths (σ_{1}-σ_{3}) of Wilcox shale specimens saturated (as nearly as can be achieved) with brine and shortened at strain rates of 2.8×l0^{-7} ϵ ≤8.2×10^{-3} s^{-1} fit an exponential law ϵ = A exp{α(σ_{1}-σ_{3})} of the same form as determined for Wilcox shale specimens deformed at much higher pressures in the absence of pore fluids. The positive slope and comparable value of a (= 0.29 MPa^{-1}) to that determined for specimens without pore fluids (α = 0.3 MPa^{-1}) suggest that Wilcox shale exhibits undrained behavior at strain rates > 10^{-7} s^{-1} and that strain rate effects associated with pore pressure perturbations and pore fluid transport occur at much lower strain rates.

Original language | English |
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Pages | 757-765 |

Number of pages | 9 |

Publication status | Published - 1994 Jan 1 |

Externally published | Yes |

Event | 1st North American Rock Mechanics Symposium, NARMS 1994 - Austin, United States Duration: 1994 Jun 1 → 1994 Jun 3 |

### Other

Other | 1st North American Rock Mechanics Symposium, NARMS 1994 |
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Country | United States |

City | Austin |

Period | 94/6/1 → 94/6/3 |

### Fingerprint

### ASJC Scopus subject areas

- Geochemistry and Petrology
- Geophysics

### Cite this

*Defomiation of Wilcox shale: Undrained strengths and effects of strain rate*. 757-765. Paper presented at 1st North American Rock Mechanics Symposium, NARMS 1994, Austin, United States.

**Defomiation of Wilcox shale : Undrained strengths and effects of strain rate.** / Kwon, Oh Myoung; Kronenberg, Andreas K.

Research output: Contribution to conference › Paper

}

TY - CONF

T1 - Defomiation of Wilcox shale

T2 - Undrained strengths and effects of strain rate

AU - Kwon, Oh Myoung

AU - Kronenberg, Andreas K.

PY - 1994/1/1

Y1 - 1994/1/1

N2 - Mechanical and fluid transport properties of brine-saturated illite shale from the Wilcox Formation have been investigated to examine the effects of strain rate on fracture strength and to determine the conditions over which rates of deformation and internal fluid flow compete. Permeability (k) measurements predict time scales for fluid pressure equilibration mat are long relative to those of deformation experiments; values of k are small even at relatively low effective pressures Pe (assumed = Pc - Pf) and they drop below 10-20 m2 at pressures of ≥ 5 MPa. Failure strengths (σ1-σ3) of Wilcox shale specimens saturated (as nearly as can be achieved) with brine and shortened at strain rates of 2.8×l0-7 ϵ ≤8.2×10-3 s-1 fit an exponential law ϵ = A exp{α(σ1-σ3)} of the same form as determined for Wilcox shale specimens deformed at much higher pressures in the absence of pore fluids. The positive slope and comparable value of a (= 0.29 MPa-1) to that determined for specimens without pore fluids (α = 0.3 MPa-1) suggest that Wilcox shale exhibits undrained behavior at strain rates > 10-7 s-1 and that strain rate effects associated with pore pressure perturbations and pore fluid transport occur at much lower strain rates.

AB - Mechanical and fluid transport properties of brine-saturated illite shale from the Wilcox Formation have been investigated to examine the effects of strain rate on fracture strength and to determine the conditions over which rates of deformation and internal fluid flow compete. Permeability (k) measurements predict time scales for fluid pressure equilibration mat are long relative to those of deformation experiments; values of k are small even at relatively low effective pressures Pe (assumed = Pc - Pf) and they drop below 10-20 m2 at pressures of ≥ 5 MPa. Failure strengths (σ1-σ3) of Wilcox shale specimens saturated (as nearly as can be achieved) with brine and shortened at strain rates of 2.8×l0-7 ϵ ≤8.2×10-3 s-1 fit an exponential law ϵ = A exp{α(σ1-σ3)} of the same form as determined for Wilcox shale specimens deformed at much higher pressures in the absence of pore fluids. The positive slope and comparable value of a (= 0.29 MPa-1) to that determined for specimens without pore fluids (α = 0.3 MPa-1) suggest that Wilcox shale exhibits undrained behavior at strain rates > 10-7 s-1 and that strain rate effects associated with pore pressure perturbations and pore fluid transport occur at much lower strain rates.

UR - http://www.scopus.com/inward/record.url?scp=85059217346&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85059217346&partnerID=8YFLogxK

M3 - Paper

AN - SCOPUS:85059217346

SP - 757

EP - 765

ER -