基于离散元模拟的超声波振动作用下层理状页岩损伤分析

Damage Analysis of Bedding Shale under Ultrasonic Vibration Based on Discrete Element Simulation

为探究超声波振动辅助页岩储层改造的可行性,通过数值模拟方法建立层理状页岩的离散元模型,模拟不同层理倾角的层理状页岩在超声波振动下的损伤情况。结果表明:振动方向与层理面的夹角对超声波振动的传播有显著影响,振动方向与层理面夹角越小,生成微裂纹越多;裂纹主要集中在靠近振动源的地方,离振动源较远处生成的微裂纹数量较少;超声波振动对层理状页岩的强度影响明显,可在页岩内部诱生大量微裂纹,页岩微观结构和物理性质发生变化,单轴抗压强度和弹性模量会显著降低。该研究为利用超声波振动对层理状页岩进行储层改造提供了理论基础。

This study is to simulate the damage of layered shale under ultrasonic vibration with different bedding dip angles by establishing a discrete element model of layered shale with numerical simulation methods so as to explore the feasibility of ultrasonic vibration-assisted shale reservoir stimulation.The results show that the angle between the vibration direction and the bedding surface has a significant influence on the propagation of ultrasonic vibration.The smaller the angle,the more microcracks generated.The racks are mainly concentrated near the vibration stress,and fewer microcracks are generated in areas further away from the vibration source.Ultrasonic vibration has an obvious impact on the strength of layered shale,inducing a large number of microcracks inside the shale,and the change of microstructure and physical properties of the shale,also the uniaxial compressive strength and elastic modulus are significantly reduced.This study provides a theoretical basis for reservoir stimulation of layered shale using ultrasonic vibration.