Abstract:Microscopic and meso-scopic structural characteristics of shale gas reservoir and carbonate reservoir rocks have significant impact on its macroscopic mechanical response characteristics. Throughout cyclic loading experiments under different stress levels, we analyze the stress and strain response, hysteresis curve, the instantaneous Young's modulus, dynamic Young's modulus, and Poisson's ratio under cyclic loading, and study the influence of stress on hysteresis loop at different strain amplitude. The following main observations are obtained: A. The meso-scopic heterogeneity of reservoir rocks in different scales cause the macroscopic nonlinear response characteristics; B. Based on the analysis of different modulus under different stress level conditions, the same state can have different elastic modulus value, and elastic modulus has the dependence of stress history; C. Rock particles contact and stick slip friction within the rock under cyclic loading is hysteresis, the relative proportion of adhesion and friction at different stages has different ratio; interface roughness has important effect on nonlinear response process.
Tang Jie,Guo Yuan,Sun Chengyu et al. Experiment study of wave velocity and elastic modules variation characteristics for carbonates. Journal of China University of Petroleum(Natural Science Edition),2012,36(5):62-66.
[2]
Behura J,Batzle M,Hofmann R et al. The shear properties of oil shales. The Leading Edge,2009,28(7):850-855.
[3]
Spencer J W. Stress relaxation at low frequencies in fluid saturated rocks:Attenuation and modulus dispersion. J Geophys Res,1981,86(B3):1803-1812.
[4]
Holcomb D J. Memory,relaxation,and microfracturing in dilatant rock. Journal of Geophysical Research:Solid Earth,1981,86(B7):6235-6248.
[5]
Tutuncu A N,Podio A L,Gregory A R et al. Nonlinear viscoelastic behavior of sedimentary rocks,Part Ⅰ:Effect of frequency and strain amplitude. Geophy-sics,1998,63(1):184-194.
[6]
Vernik L,Liu X. Velocity anisotropy in shales:A petrophysical study. Geophysics,1997,62(2):521-532.
Chen Yunping,Xi Daoying and Xue Yanwei. Hyste-resis and attenuation of saturated rocks under cyclic loading. Chinese Journal of Geophysics,2004,47(4):766-774.
Chen Yunping,Xi Daoying and Xue Yanwei. Dynamic stress-strain response in saturated rocks under cycling load. OGP,2003,38(4):409-413.
[9]
Xi D Y,Liu X Y,Zhang C Y. The corresponding relationship between time and temperature on relaxation attenuation of saturated rocks. Pure and Applied Geophysics,2007,164(11):2157-2173.
Tang Jie,Sun Chengyu,Zhou Jiahui et al. Study of nonlinear damping hysteresis response character for rock sample. Chinese Journal of Rock Mechanics and Engineering,2012,31(S 1):2948-2955.
Xi Daoying,Yi Liangkun,Xi Jun et al. Saturated sandstone viscoelastic behavior analysis by stress-strain approach. OGP,2012,47(4):619-623.
[12]
Tutuncu A N,Podio A L,Sharma M M. An experimental investigation of factors influencing compressional- and shear-wave velocities and attenuations in tight gas sandstones. Geophysics,1994,59(1):77-86.
[13]
Aleshin V,Van Den Abeele K. Micro-potential model for stress-strain hysteresis of micro-cracked materials. Journal of the Mechanics and Physics of Solids,2005,53(4):795-824.
[14]
Vakhnenko V O,Vakhnenko O O,TenCate J A et al. Modeling of stress-strain dependences for Berea sandstone under quasistatic loading. Physical Review B,2007,76(18):184108(8).
[15]
Aleshin V,Van Den Abeele K. Friction in uncon-forming grain contacts as a mechanism for tensorial stress-strain hysteresis. Journal of the Mechanics and Physics of Solids,2007,55(4):765-787.
[16]
Tutuncu A N,Podio A L,Gregory A R. Nonlinear viscoelastic behavior of sedimentary rock,Part Ⅱ:Hysteresis effects and influence of type of fluid on elastic moduli. Geophysics,1998,63(1):195-203.
[17]
Hornby B E. Experimental laboratory determination of the dynamic elastic properties of wet drained shales. J Geophys Res,1998,103(B12):29945-29964.
[18]
Yoshizawa H,Israelachvili J. Fundamental mecha-nisms of interfacial friction,2:Stick-slip friction of spherical and chain molecules. The Journal of Physical Chemistry,1993,97(43):11300-11313.
[19]
Guyer R A,Johnson P A. Nonlinear mesoscopic elasticity:evidence for a new class of materials. Physics Today,2008,52(4):30-36.