室内水压致裂法测定岩石的断裂韧性

Experimental research on determination of rock fracture toughness with hydraulic fracturing method

水力压裂过程中,裂纹扩展准则至关重要。如果裂纹失稳扩展穿过隔层遇到水层或另一储层,将导致压裂失败。为了保证裂缝在施工设计范围内扩展,就要考虑裂缝尖端应力场的应力强度因子与隔层岩石断裂韧性的关系,进行相应施工设计。通过室内实验和测井资料分析,研究岩样断裂韧性与其相关变量的关系,得出岩样断裂韧性与其变量的关系是线性的。在压裂施工设计中,预测各个层段岩石的断裂韧性,比较目的层与隔层及其非目的层岩石断裂韧性,以便在水力压裂裂纹扩展过程中监测控制裂纹的横向扩展和纵向扩展,尤其是裂纹的纵向扩展,保证水力压裂质量。

The fracture propagation criteria are essentially impor-tant to hydraulic fracturing treatment. The fracturing treatment will fail if the hydraulically induced fractures extend to the water barri-ers or to other hydroearbon-contained layers. In order to guarantee the fracture propagating within the designed range of treatment, it is necessary to consider the relationship between stress intensity factor and barriers toughness to design the corresponding treatment when the fracture approaches to the barrier. Through indoor experi-ment and analysis of well logging data, the results of studying showed a linear relationship between the fracturing toughness of rock samples and the others correlative variable. During the fracture propagation, in order to inspect and control the transverse and longitudinal fracture propagation, especially the transverse propagation, and insure the hvdraulic, fracture' s quality, in the hydraulic fracturing treatment, it is very important to forecast the fracture toughness of the different layers, compare the fracture toughness between the destination layers and the inter-layers or non destina-tion layers.