复杂储层岩石脆性分析及应用研究

Brittleness Analysis of Rock and Its Application to Complex Reservoir

脆性指数(BI)是储层压裂评价的一个重要参数,复杂储层往往具有矿物成分多样、结构致密等特点,与页岩油气开采有一定的相似性,其脆性主要受矿物含量和含水饱和度等因素影响。脆性指数根据获取方式不同,定义也不同,有基于矿物组成的,也有基于弹性模量(E)和泊松比(ν)。从孔裂隙介质弹性波动理论出发,系统分析了各因素对岩石脆性指数影响,给出弹性模量和泊松比定义的脆性指数由页岩推广至致密砂砾岩的理论基础。通过对比致密砂砾岩储层压裂前后脆性指数特征,研究脆性指数对储层压裂的指导意义,为压裂效果的评价提供技术支持。

Brittleness Index （BI） is a key parameter of reservoir fracturing evaluation. Complex reservoir is characterized by various mineral composition and tight structure, it is similar with shale rock in some aspect and brittleness is mainly affected by mineral content and water saturation. For different purposes, the definition of BI is different. Some are defined based on the mineral content, and some are defined based on the elastic parameters （Young Modulus and Poisson ratio）. Based on the hole crack elastic wave theory, the effect of some factors on BI is analyzed systematically for tight glutenite reservoir. From the analysis, it is concluded that the brittleness index defined with Young Modulus and Poisson ratio can be generalized to tight glutenite reservoir. The BI is compared before and after the fracturing. The directive significance of BI for reservoir fracturing is researched, which provides the technology basis for reservoir fracturing.