页岩形变及破坏特征研究进展及展望

Research Progress and Prospect of Shale Deformation and Failure Characteristics

随着常规油气资源的减少,页岩油气等非常规资源的加速开发,如何获得准确的页岩力学参数为钻井与压裂提供指导是中外学者研究的方向。从页岩岩石力学的室内实验(如单轴、三轴、声波实验等)、理论研究、数值方法(如有限元、离散元等)三方面对页岩的应力-应变特性、岩石破裂模式、本构模型与强度理念等研究进展进行综述,得出如下结论:页岩的形变特征主要脆性为主,且峰值应力表现出明显层理相关性;页岩的破坏特征与层理方向、围压、裂缝特性、埋深、浸泡液体等具有密切联系;页岩内部具有大量微孔隙、微裂缝,其本构模型主要基于损伤理论建立;强度准则主要基于单一弱面准则与横观各向同性建立。展望了如3D打印技术与页岩模型相结合,打印出给定参数的类岩石样品;考虑多耦合因素控制及多弱面结构下的本构模型和岩石破裂准则等岩石力学研究前景。

With the reduction of conventional oil and gas resources and the accelerated development of unconventional resources such as shale oil and gas,how to obtain accurate shale mechanical parameters to provide guidance for drilling and fracturing was the research direction of scholars at home and abroad.The research progress of the stress-strain characteristics,rock failure mode,constitutive model and strength concept of shale from three aspects of laboratory experiments(such as uniaxial,triaxial,acoustic experiments),theoretical research and numerical methods(such as finite element,discrete element,etc.)of shale rock mechanics were reviewed.The deformation characteristics of shale have been mainly brittle,and the peak stress showes obvious bedding correlation.The failure characteristics of shale are closely related to bedding direction,confining pressure,fracture characteristics,burial depth and soaking liquid.The constitutive model is mainly based on damage theory because of a lot of micro pores and micro cracks in shale.The strength criterion has been established based on the single weak plane criterion and transverse isotropy.Prospects such as 3D printing technology combined with shale model to print out rock-like samples with given parameters.The research prospects of rock mechanics such as constitutive model and rock failure criterion under multi-coupling factor control and multi-weak surface structure are considered.