1 kHz elastic wave velocities in partially saturated limestones: Evidence of fluid distribution effect

1992 ◽  
Author(s):  
Thierry Cadoret ◽  
Dominique Marion ◽  
Bernard E. Zinszner
Keyword(s):  
Elastic Wave ◽  
Fluid Distribution ◽  
Partially Saturated ◽  
Wave Velocities ◽  
Distribution Effect

Fluid distribution effect on sonic attenuation in partially saturated limestones

Geophysics ◽  
1998 ◽  
Vol 63 (1) ◽  
pp. 154-160 ◽  
Author(s):  
Thierry Cadoret ◽  
Gary Mavko ◽  
Bernard Zinszner
Keyword(s):  
Wave Attenuation ◽  
Water Saturation ◽  
High Water ◽  
Fluid Distribution ◽  
Computer Assisted ◽  
Fluid Content ◽  
Partially Saturated ◽  
Fluid Saturation ◽  
Distribution Effect ◽  
Saturation Method

Extensional and torsional wave‐attenuation measurements are obtained at a sonic frequency around 1 kHz on partially saturated limestones using large resonant bars, 1 m long. To study the influence of the fluid distribution, we use two different saturation methods: drying and depressurization. When water saturation (Sw) is higher than 70%, the extensional wave attenuation is found to depend on whether the resonant bar is jacketed. This can be interpreted as the Biot‐Gardner‐White effect. The experimental results obtained on jacketed samples show that, during a drying experiment, extensional wave attenuation is influenced strongly by the fluid content when Sw is between approximately 60% and 100%. This sensitivity to fluid saturation vanishes when saturation is obtained through depressurization. Using a computer‐assisted tomographic (CT) scan, we found that, during depressurization, the fluid distribution is homogeneous at the millimetric scale at all saturations. In contrast, during drying, heterogeneous saturation was observed at high water‐saturation levels. Thus, we interpret the dependence of the extensional wave attenuation upon the saturation method as principally caused by a fluid distribution effect. Torsional attenuation shows no sensitivity to fluid saturation for Sw between 5% and 100%.

Elastic wave velocities during evaporative drying

Geophysics ◽  
1998 ◽  
Vol 63 (1) ◽  
pp. 171-183 ◽  
Author(s):  
David Goertz ◽  
Rosemary Knight
Keyword(s):  
Elastic Wave ◽  
Pore Space ◽  
Fluid Distribution ◽  
Drying Process ◽  
Shear Moduli ◽  
Velocity Saturation ◽  
Wave Velocities ◽  
Three Samples ◽  
Rate Period ◽  
Drying Rates

Laboratory measurements of drying rates and elastic wave velocities are made on limestone, dolomite, and sandstone samples during evaporative drying. The drying rate data are very similar in form. There is a constant rate period at higher saturations and a falling rate period below saturation levels of approximately 0.2. The falling rate period marks the transition in the sample from hydraulically connected to disconnected water. There is a strong link between elastic wave velocities and the drying process because different pore geometries drain at different stages in drying. The drainage of these different geometries results in specific changes in the moduli and velocities. Simple models of the pore geometries and the drying process are used to model the velocity data. The velocity‐saturation relationship for each of the three samples is very different in form because of differences in pore‐space microgeometry. Of particular interest is the velocity response during the falling rate period of drying. In the limestone and the sandstone, there is a significant decrease in bulk and shear moduli and elastic wave velocities because of the drainage of crack‐like pores and grain contacts. In contrast, the absence of these pore geometries in the dolomite results in essentially no changes in the moduli at low saturations. An understanding of the drying process and resulting pore‐scale fluid distribution provides useful insights into the observed form of the velocity‐saturation relationship.

Elastic Wave Velocities in Partially Saturated Ottawa Sand

2000 ◽  
Vol 64 (4) ◽  
pp. 1226-1234 ◽  
Author(s):  
Doru Velea ◽  
F.Douglas Shields ◽  
James M. Sabatier
Keyword(s):  
Elastic Wave ◽  
Ottawa Sand ◽  
Partially Saturated ◽  
Wave Velocities

Elastic wave velocities in partially saturated rocks: Saturation hysteresis

1996 ◽  
Vol 101 (B1) ◽  
pp. 837-844 ◽  
Author(s):  
Mickaële Le Ravalec ◽  
Yves Guéguen ◽  
Tamaz Chelidze
Keyword(s):  
Elastic Wave ◽  
Partially Saturated ◽  
Wave Velocities

Assessing rock brittleness and fracability from radial variation of elastic wave velocities from borehole acoustic logging

2016 ◽  
Vol 64 (4) ◽  
pp. 958-966 ◽  
Author(s):  
Xiao-Ming Tang ◽  
Song Xu ◽  
Chun-Xi Zhuang ◽  
Yuan-Da Su ◽  
Xue-Lian Chen
Keyword(s):  
Elastic Wave ◽  
Radial Variation ◽  
Acoustic Logging ◽  
Wave Velocities ◽  
Rock Brittleness
Sign in / Sign up

Export Citation Format

Share Document