页岩局部脆性表征与压裂裂缝交互耦合演化机制研究

The efficient exploitation of shale gas has been an international hot topic. Its major mining technology is network fracturing, of which the scale and connected effect of fracture network is the core issue, and the formation mechanism of network and characterization of connectivity is the "bottleneck" content of study. For the formation and connectivity of fracture network the shale brittleness characteristics, development degree of natural fracture and stress conditions is a key factor to study. According to the shale mineral composition, distribution and characteristics of three-dimensional fracture, making the shale brittle as the starting point, the study on the fracture initiation behavior of shale fracturing and the evolutionary mechanisms and connected law of fracture are conducted. The multifractal description method on the shale mineral distribution and composition and the fracture development characteristics is established. Proposing the local brittleness views and establishing local brittle zone classification divides and quantitative characterization method of local brittle characteristics. Under the response of local brittleness, the rupture energy dissipation relationship of fracturing rock, and the interfusion and mergers mechanism of the fracture bifurcation mesoscopic damage and interactive-coupling evolution are analyzed. The formation dynamic process of fracture network system and the connected connotation mechanism are revealed. Through this topic, a new ideas and method can be provided for the study on the shale fracturing fracture behavior and the evolution connected characteristics of fracture network. It has an important significance and academic value to understand the formation mechanism of fracture network system clearly, and play a certain scientific guidance for the shale gas effective innovation and efficient development. Its research content is forward-looking, not reported at home and abroad, and the result is groundbreaking.

页岩气高效开采是国际上探讨的热点问题；缝网压裂是开采的主要技术手段；缝网规模与连通效果是研究的核心问题；缝网形成机制与连通性表征是研究的“瓶颈”问题；页岩脆性特征与天然裂隙发育程度及应力条件是关键因素。 课题从页岩矿物组成与三维裂隙分布特征入手，以页岩脆性为问题的切入点，研究页岩压裂造缝行为与裂缝演化机制及连通规律。建立页岩矿物分布组成与裂隙发育特征多重分形描述方法；提出了局部脆性观点，并建立局部脆性区域分级划分与局部脆性特征定量表征方法，研究局部脆性响应下页岩压裂破裂关系和裂缝分岔细观损伤与交互耦合演化缝网相融、兼并机制。揭示缝网体系形成动态过程与连通内涵机理特征。课题研究对页岩压裂破裂行为与缝网体系演化机制及连通特征开辟了新的研究思路与方法。对清晰认识页岩压裂缝网系统形成机理及页岩气有效改造与高效开发具有科学指导意义和学术价值。课题研究成果具有前瞻性，国内外未见报道，研究成果具有突破性

页岩气高效开采是国际上探讨的热点问题；缝网压裂是开采的主要技术手段；缝网规模与连通效果是研究的核心问题；缝网形成机制与连通性表征是研究的“瓶颈”问题；页岩脆性特征与天然裂隙发育程度及应力条件是关键因素。 课题从页岩矿物组成与三维裂隙分布特征入手，以页岩脆性为问题的切入点，研究页岩压裂造缝行为与裂缝演化机制及连通规律。建立页岩矿物分布组成与裂隙发育特征多重分形描述方法；提出了局部脆性观点，并建立局部脆性区域分级划分与局部脆性特征定量表征方法，研究局部脆性响应下页岩压裂破裂关系和裂缝分岔细观损伤与交互耦合演化缝网相融、兼并机制。揭示缝网体系形成动态过程与连通内涵机理特征。课题研究对页岩压裂破裂行为与缝网体系演化机制及连通特征开辟了新的研究思路与方法。对清晰认识页岩压裂缝网系统形成机理及页岩气有效改造与高效开发具有科学指导意义和学术价值。课题研究成果有18项，分别为13篇论文和5项实用性专利，均具有前瞻性，国内外未见报道，研究成果具有突破性，目前，多重分形理论在其它领域中有所应用，但基于多重分形理论研究不同页岩的矿物分布与三维裂隙发育特征方面的研究鲜有报道，本课题提出了运用多重分形理论研究页岩矿物组成分布与多级微尺度三维裂隙发育特征；国内外多数是对脆塑性的定性或是单因素的整体定量评价，尚未见局部脆性及其表征方法的相关研究与报道，课题研究内容具有前瞻性与挑战性。