Discretized Clay Shell Model (DCSM) of Clayey Sandstone: Evaluating the Effective Stress Coefficient of Permeability

2021 ◽  
Author(s):  
Pin-Lun Tai ◽  
Jia Jyun Dong
Keyword(s):  
Shell Model ◽  
Effective Stress ◽  
Coefficient Of Permeability ◽  
Stress Coefficient

Theoretical model of effective stress coefficient for rock/soil-like porous materials

2009 ◽  
Vol 22 (3) ◽  
pp. 251-260 ◽  
Author(s):  
Kai Zhang ◽  
Hui Zhou ◽  
Dawei Hu ◽  
Yang Zhao ◽  
Xiating Feng
Keyword(s):  
Theoretical Model ◽  
Porous Materials ◽  
Effective Stress ◽  
Stress Coefficient

Experimental Study of the Effective Stress Coefficient for Coal Anisotropic Permeability

2020 ◽  
Vol 34 (5) ◽  
pp. 5856-5867 ◽  
Author(s):  
Zhengshuai Liu ◽  
Dameng Liu ◽  
Yidong Cai ◽  
Zhejun Pan
Keyword(s):  
Experimental Study ◽  
Effective Stress ◽  
Anisotropic Permeability ◽  
Stress Coefficient

The influence of pore fluids and frequency on apparent effective stress behavior of seismic velocities

Geophysics ◽  
2010 ◽  
Vol 75 (1) ◽  
pp. N1-N7 ◽  
Author(s):  
Gary Mavko ◽  
Tiziana Vanorio
Keyword(s):  
Elastic Wave ◽  
Bulk Modulus ◽  
Effective Stress ◽  
High Frequency ◽  
Laboratory Data ◽  
Pore Fluids ◽  
Wave Velocities ◽  
Stress Behavior ◽  
Stress Coefficient ◽  
The Impact

Although poroelastic theory predicts that the effective stress coefficient equals unity for elastic moduli in monomineralic rocks, some rock elastic wave velocities measured at ultrasonic frequencies have effective stress coefficients less than one. Laboratory effective stress behavior for P-waves is often different than S-waves. Furthermore, laboratory ultrasonic velocities almost always reflect high-frequency artifacts associated with pore fluids, including an increase in velocities and flattening of velocity-versus-pressure curves. We have investigated the impact of pore fluids and frequency on the observed effective stress coefficient for elastic wave velocities by developing a model that calculates pore-fluid effects on velocity, including high-frequency squirt dispersion, and we have compared the model’s predictions with laboratory data. We modeled a rock frame with penny-shaped cracks for three situations: vacuum dry, saturated with helium, and saturated with brine. Even if the frame modulus depends only on the differential stress, the saturated-rock effective stress coefficient is predicted to be significantly less than one at ultrasonic frequencies because of two effects: an increase in the fluid bulk modulus with increasing pressure and the contribution of high-frequency squirt dispersion. The latter effect is most significant in soft fluids (helium in this experiment) in which the fluid-bulk modulus is less than or comparable to the thin-crack pore stiffness.

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