scholarly journals Fluid Substitution and Shear Weakening in Clay‐Bearing Sandstone at Seismic Frequencies

2019 ◽  
Vol 124 (2) ◽  
pp. 1254-1272 ◽  
Author(s):  
Hanjun Yin ◽  
Jan V. M. Borgomano ◽  
Shangxu Wang ◽  
Mathilde Tiennot ◽  
Jérôme Fortin ◽  
...  
Keyword(s):  
Fluid Substitution ◽  
Seismic Frequencies

Fluid Substitution in Clay-Rich Sandstone at Seismic Frequencies

2020 ◽  
Author(s):  
H. Yin ◽  
J.V.M. Borgomano ◽  
S. Wang ◽  
M. Tiennot ◽  
J. Fortin ◽  
...  
Keyword(s):  
Fluid Substitution ◽  
Seismic Frequencies

Exact equations for fluid and solid substitution

Geophysics ◽  
2014 ◽  
Vol 79 (3) ◽  
pp. L21-L32 ◽  
Author(s):  
Nishank Saxena ◽  
Gary Mavko
Keyword(s):  
Shear Stress ◽  
Shear Modulus ◽  
Bulk Modulus ◽  
Fluid Substitution ◽  
Pore Shape ◽  
Effective Shear Modulus ◽  
Stiffness Measurement ◽  
Saturated Rock ◽  
Mean Stresses

We derived exact equations, elastic bulk and shear, for fluid and solid substitution in monomineralic isotropic rocks of arbitrary pore shape and suggested methods to obtain the required substitution parameters. We proved that the classical Gassmann’s bulk modulus equation for fluid-to-fluid substitution is exact for solid-to-solid substitution if compression-induced mean stresses (pressure) in initial and final pore solids are homogeneous and either the shear modulus of the substituted solid does not change or no shear stress is induced in pores. Moreover, when compression-induced mean stresses in initial and final pore solids are homogeneous, we evaluated exact generalizations of Gassmann’s bulk modulus equation, which depend on usually known parameters. For the effective shear modulus, we found general exactness conditions of Gassmann and other approximations. Using the new exact substitution equations, we interpreted that predicting solid-filled rock stiffness from a dry rock stiffness measurement requires more information (i.e., assumptions about the pore shape) compared to predicting the same from a fluid-saturated rock stiffness.

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