Full Length Research Paper
In order to establish the relationship existing between the seismic velocity and petrophysical properties of limestone, ultrasonic pulse transmission technique under simulated pressure of 2.5 to 10 Mpa and at a frequency of 300 to 800 kHz was used in the determination of both compressional-wave and shear- wave velocities. The measurements were carried out for both dry and fluid saturated limestone obtained from the Curfs quarry in Limburg, Southeastern Netherlands. Compressional wave velocities values range from 2218.2 to 3280 ms-1 for dry samples and 2448 to 3730 ms-1 for fluid saturated samples. While those for shear-wave velocities values range from 2024 to 2982 ms-1 for dry samples and 1568.2 to 2024 for fluid saturated samples.These velocities values were used to constrained limestone into two lithogic units- the compacted limestone units, also know as the hardgrounds (high velocity values) and undercompacted limestone units (low velocity values). The compressional wave velocities of fluid saturated limestone samples are relatively higher than those obtained for equivalent dry ones, while the shear wave velocities of the same fluid saturated limestone samples were lower than the dry ones. The degree of diagnesis in the weakly cement limestone is responsible for the high value of both compressional- wave and shear wave velocities obtained from the acoustic velocity measurement. The velocity obtained from the time average equation is much more than the velocity obtained from the laboratory measurement of velocity for the curfs quarry.
Key words: Acoustic, compressional and shear-wave velocity, cement, fluid saturation.
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