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Scattering and intrinsic components of attenuation through the spectral ratio method in ultrasonic laboratory experiment TEXT SIZE: A A A
Elastic wave attenuation in the earth media is of great importance whether for the earth structure inversion, hydrocarbon reservoir characterization, or for fundamental studies on seismic rock physics. The laboratory measurement of attenuation is a basic means for rock physical studies while the spectral ratio method is a common approach. The spectral ratio attenuation, measured with the spectral ratio method, is determined jointly by scattering and intrinsic attenuation. Yet, these two effects are not taken into consideration in the theory on the spectral ratio method separately. Therefore, it is neither certain whether there is any scattering effect in the spectral ratio attenuation, nor clear if the underlying scattering effect might be ignorable. Based on the basic understanding of characteristics of laboratory waveform recordings, an energy flux theory is introduced to describe the scattering and intrinsic attenuation of elastic waves, and the corresponding coda excitation mechanism. Through the energy flux theory, the elastic wave attenuation, namely the energy flux attenuation, could also be measured. A good consistency between the energy flux attenuation and the spectral ratio attenuation is shown both in theory and in experiment. The consistency of these two direct wave attenuations implies the coexistence of intrinsic and scattering components in the spectral ratio attenuation. Besides, a comparison of experimental results of the spectral ratio attenuation against the squirt flow intrinsic attenuation is also analyzed, which also suggests the existence of scattering components. Through energy flux theory, the existence of scattering in the spectral ratio attenuation could be identified qualitatively based on the ultrasonic coda. In another word, an extremely significant coda may suggest the existence of intense scattering in the spectral ratio attenuation, also meaning that the scattering component in the spectral ratio attenuation might be unignorable.
 

Publication name

 CHINESE JOURNAL OF GEOPHYSICS-CHINESE EDITION, 61 (3):1083-1094; 10.6038/cjg2018L0359 MAR 2018

Author(s)

 Zhou Hao; Fu LiYun

Corresponding author(s) 

 ZHOU Hao 
 wlhlszh@foxmail.com  
 Chinese Acad Sci, Inst Geochem, State Key Lab Ore Deposit Geochem, Guiyang 550002, Guizhou, Peoples R China
 Univ Chinese Acad Sci, Beijing 100049, Peoples R China

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