As a common complex media in oil and gas reservoirs,the mechanical properties of mudstone in high depth environment are obviously different from those of shallow rocks.Based on the analysis of physical characteristics,the elastoplastic mechanical properties of mudstone with high buried depth in oil and gas reservoir engineering were studied.Firstly,triaxial conventional tests were conducted to characterize the mechanical behavior of mudstone under different confining pressures.The mudstone exhibited significant plastic compression and ductility dilation strain.Meanwhile,it also showed obvious strength hardening behavior and the failure exhibited ductile yielding platform.The peak strength increased with an increase in confining pressure.Secondly,the characteristics of yield failure,plastic hardening and volume dilation were discussed to study the elastoplastic mechanical properties of mudstone.The failure surface of mudstone performed a nonlinear yield behavior and the hardening characteristics could be described by power function.And the volume presented typical compression dilatancy transformation.Finally,an elastoplastic constitutive model was proposed with the use of non-associated flow rule under the framework of thermodynamics.The simulation was in good agreement with the experimental results,which confirmed the accuracy of the elastoplastic mechanical analysis.These results can provide reliable basis for engineering research and stability analysis of deep mudstone reservoir.
Chinese Journal of Underground Space and Engineering
high buried depth reservoir
non-associated flow rule
张玉( 1985-) ,男,山东青岛人,博士,副教授,主要从事岩石力学与工程等领域的教学与科研工作。E-mail: zhangyu@ upc.edu.cn