Squirt flow in fully saturated rocks
- Stanford Univ., CA (United States). Dept. of Geophysics
The authors estimate velocity/frequency dispersion and attenuation in fully saturated rocks by employing the squirt-flow mechanism of solid-fluid interaction. In this model, pore fluid is squeezed from thin soft cracks into the surrounding large pores. Information about the compliance of these soft cracks at low confining pressures is extracted from high-pressure velocity data. The frequency dependence of squirt-induced pressure in the soft cracks is linked with the porosity and permeability of the soft pore space, and the characteristic squirt-flow length. These unknown parameters are combined into one expression that is assumed to be a fundamental rock property that does not depend on frequency. The appropriate value of this expression for a given rock can be found by matching the authors theoretical predictions with the experimental measurements of attenuation or velocity. The low-frequency velocity limits, as given by their model, are identical to those predicted by Gassmann`s formula. The high-frequency limits may significant exceed those given by the Biot theory: the high-frequency frame bulk modulus is close to that measured at high confining pressure. They have applied their model to D`Euville Limestone, Navajo Sandstone, and Westerly Granite. The model realistically predicts the observed velocity/frequency dispersion, and attenuation.
- OSTI ID:
- 37102
- Journal Information:
- Geophysics, Vol. 60, Issue 1; Other Information: PBD: Jan-Feb 1995
- Country of Publication:
- United States
- Language:
- English
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