层理倾角对页岩三轴应力应变测试和纵横波速度的影响

Effect of bedding angle on shale triaxial stress,testing and velocity of P-wave and S-wave

针对页岩层理发育的特点,根据不同层理倾角条件下的三轴压缩实验和纵横波速度测试,获得层理倾角对页岩破坏形态、强度、弹性模量、泊松比和纵横波速的影响,明确轴向应力与纵横波速度变化关系,建立研究页岩储层的动、静态弹性模量与泊松比的相关因数,分析页岩的力学参数、纵横波速度的变异因数和各向异性因数。结果表明:页岩力学参数及纵横波速度受层理倾角线性变化,轴向应力与纵波速度正相关,动静态弹性模量和泊松比相关因数分别为1.39、1.18,力学参数的变异因数和各向异性因数均值较超声波速度大。该结果可以为页岩气测井解释、钻井设计和水力压裂改造提供基础参数。

In view of the characteristics of shale reservoir with significant bedding,tri-axial compression experiments and ultrasonic testing has been carried out in consideration of the bedding angle,the influence of failure pattern,strength,elastic modulus,Poisson's ratio and ultrasonic velocity at the bedding angle were obtained,the relationship between axial stress and velocity of longitudinal wave were defined,the relative coefficient between the dynamic and static elastic modulus and Poisson's ratio of shale reservoir is established,the coefficient of variation and anisotropy of mechanical parameters and ultrasonic velocity were analyzed.Results show that the mechanical parameters and velocity of longitudinal wave varied linearly by the bedding angle,the positive correlation between axial stress and velocity of longitudinal,the correlation coefficient of static elastic parameters and Poisson's ratio was 1.39and1.18,the mean value of variation coefficient of mechanical parameters and anisotropy coefficient was larger than ultrasonic velocity.The results can offer basic parameters for shale log interpretation,well drilling and hydraulic fracture.