Amplitude dependences of velocities and attenuation of P and S waves in the ultrasonic range in consolidated sandstones under pressure

摘要

Amplitude dependences of velocities and attenuation of P and S waves in dry consolidated sandstones under confining pressure are investigated experimentally. Anomalous behavior of kinematic and dynamic parameters of acoustic waves is discovered in the range of strain amplitudes epsilon(d) similar to (0.2-2.0) x 10(-6). With increasing amplitude, the wave velocity weakly rises (by 0.6%) or remains constant, whereas the attenuation coefficient drops significantly (by up to 18%). Hysteresis of the attenuation coefficient is observed in the first amplitude cycle (A(min) -> A(max) -> A(min)) and is absent in subsequent cycles. The attenuation coefficient is found to be more sensitive to amplitude variations than the wave velocity. The amplitude characteristics can be regarded as a promising prognostic criterion in problems of geological section prediction.