Viscoelastic relaxation attenuation property for saturated sandstones and corresponding investigation of micro-scale mechanism

Abstract

Attenuation experiments are performed by Metravib dynamic mechanical analyzer with sine wave loading style to study the viscoelastic relaxation property of pump-oil saturated and glycerol saturated Pengshan sandstone and Zigong arkoses with three kinds of porosities. Based on the thermal relaxation regularities, the activation energies and the atomic vibration frequencies of relaxation attenuation peaks for three kinds of saturated sandstones are evaluated. The results show that activation energies and atomic vibrations frequencies of sandstone samples are lower than those of interstitial atoms. The overall vibration behavior of atomic cluster with defects can be used to explain why vibration frequencies are low in samples. Besides the solid atoms, the gas and liquid atoms filled in defects contribute greatly to overall vibration of sample. Saturated sandstone, cemented by a combination of mineral crystals, is a polycrystalline, multiphase solid with internal complex structure and widespread defects, and it easily takes on thermal relaxation property under sine wave loading. Such flaws and defects as point defects, dislocation and grain boundary in samples and their interaction interaction can produce relaxation attenuation peak. To explain the relaxation mechanism by saturated liquid and internal structure of the sandstone, it is natural to relate the attenuation characteristics to its macro-meso-structure. It is notable that when taking the defects, multiple phase boundary into consideration, a new interesting phenomenon appears, there produces multi relaxation with broader peak and more widely distributed parameter. This investigation is helpful to study theoretical model and seismic data interpretation.