Velocity of compressional waves in porous media at permafrost temperatures

Abstract Measurements of velocity of compressional waves in consolidated porous media, conducted within a temperature range of 26 degrees to -36 degrees C, indicate that: (1) compressional wave velocity in water-saturated rocks increases with decreasing temperature whereas it is nearly independent of temperature in dry rocks; (2) the shapes of the velocity versus temperature curves are functions of lithology, pore structure, and nature of interstitial fluids. As a saturated rock sample is cooled below O degrees C, the liquid in pore spaces with smaller surface-to-volume ratios (larger pores) begins to freeze and the liquid salinity controls the freezing process. As the temperature is decreased further, a point is reached where the surface-to-volume ratio in the remaining pore spaces is large enough to affect the freezing process, which is completed at the cryohydric temperature of the salts-water system.