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运用?CT成像、X射线衍射等方法,构建了考虑砂砾矿物成分与分布特征的非均质砂砾岩的三维重构模型,采用基于连续介质的离散元程序(CDEM)模拟分析了不同水平地应力下砂砾岩水力压裂裂缝的起裂与扩展行为.通过与均质砂岩计算结果的对比,阐述了水平应力比变化和砾石颗粒对砂砾岩压裂裂缝起裂、扩展和空间展布的影响.同时,完成了非均质砂砾岩和均质砂岩物理模型的水力压裂试验,并与数值模拟结果进行了对比.研究表明,砂砾岩的非均质性显著影响压裂裂缝的起裂和扩展行为.相同应力条件下砂砾岩压裂裂缝的起裂压力小于均质砂岩起裂压力,随水平应力比增大两者起裂压力的差异逐渐减小,非均质性强的砂砾岩的起裂压力受水平应力比变化的影响较小.无论非均质砂砾岩或均质砂岩,水平应力比变化均影响压裂裂缝的空间展布和形态.
By using CT imaging and X-ray diffraction, a three-dimensional reconstruction model of heterogeneous glutenite that takes into account the composition and distribution of gravel minerals is constructed. Discrete elemental simulations based on continuous media (CDEM) The fracture initiation and propagation of the lower glutenite fractures were compared with those of the homogeneous sandstone. The effects of horizontal stress ratio change and the gravels on the initiation, propagation and spatial distribution of fractures in the conglomerate were expounded. At the same time, the hydraulic fracturing test of heterogeneous gritstone and homogeneous sandstone physical model was completed and compared with the numerical simulation results.The results show that the heterogeneity of gritstone significantly affects the initiation and propagation of fracturing fractures Behavior.The fracturing initiation pressure of glutenite fractures under the same stress is smaller than that of homogeneous sandstone, and the difference of initiation pressure decreases with the increase of horizontal stress ratio, and the heterogeneity of conglomerate The fracturing pressure is less affected by the change of horizontal stress than the change of horizontal stress ratio affects the spatial distribution and morphology of fracturing fractures, regardless of heterogeneous glutenite or homogeneous sandstone.