单轴加载条件下页岩层理角度对水力压裂缝扩展规律影响研究

发布时间：2019-05-25 04:39

【摘要】：水力压裂作为一种改造储层渗透性、压裂增产的技术,对页岩气开采具有重要意义。为研究射孔附近水力压裂过程中页岩各向异性特征对破裂压力及裂缝扩展的影响规律,开展了单轴试验条件下不同层理角度的页岩水力压裂试验。研究表明:页岩的破裂压力存在明显的各向异性,破裂压力随层理角度的分布曲线呈U型分布,其中0°和90°破裂压力最大,30°最小;页岩的破裂形态主要有两种,一种为沿着最大主应力方向即竖直方向起裂并延伸,另一种模式为裂缝先沿着最大主应力方向起裂并延伸,延伸过程中直接穿过层理面,随后渐渐转向为沿层理面方向扩展;破裂机制则包括拉张破坏和拉张剪切混合破坏。研究结果对于深入了解页岩裂缝起裂和延伸机理、水力压裂施工设计等具有重要的意义。
[Abstract]:Hydraulic fracturing, as a kind of technology to transform reservoir permeability and increase fracturing production, is of great significance to shale gas production. In order to study the influence of shale anisotropy on fracture pressure and fracture propagation during hydraulic fracturing near perforation, shale hydraulic fracturing tests with different bedding angles under uniaxial test conditions were carried out. The results show that the fracture pressure of shale has obvious anisotropy, and the distribution curve of fracture pressure with bedding angle is U-shaped, in which 0 掳and 90 掳fracture pressure is the largest and 30 掳is the smallest. There are two main fracture forms of shale, one is to crack and extend along the direction of maximum principal stress, the other is to crack and extend along the direction of maximum principal stress, and the other mode is to crack and extend along the direction of maximum principal stress, and through the bedding surface directly in the process of extension. Then gradually turn to expand along the direction of stratification surface; The fracture mechanism includes tensile failure and tensile shear mixed failure. The research results are of great significance for understanding the mechanism of shale fracture initiation and extension, hydraulic fracturing construction design and so on.
【作者单位】：中国科学院地质与地球物理研究所中国科学院页岩气与地质工程重点实验室;
【分类号】：TE377

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