Abstract
Compressional and shear wave velocities were measured in water-filled
Berea sandstone as a function of pore pressure, with a constant confining
pressure of 300 bars. The measurements were made at room temperature,
145C, and 198C. At 145C, compressional velocity increased from vapor-saturated
(low pore pressure) to liquid-saturated (high pore pressure) conditions,
whereas shear wave velocity decreased. For compressional waves there
was a velocity minimum and increased attenuation near the liquid-vapor
transition. The results at 198C show decreases of both compressional
and shear velocities and a small velocity minimum for compressional
velocity without marked attenuation. At both temperatures, Vp/Vs
and Poisson's ratios increased from steam- to water-saturated rock.
The results are compatible with the mechanical effects of mixing
steam and water in the pore space near the phase transition and may
be applicable to in situ geothermal field evaluation.
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