Abstract The carbonate reservoir contains numerous randomized natural fractures and cavities. Due to the stress concentration surrounding the cavity, the conventional hydraulic fracturing technique is very hard to connect the artificial fracture with the cavity. Under such situation, the pulsed fracturing (PF) technique should be an alternative stimulation approach. To investigate the PF process in the complex fracture-cavitied reservoir, a 3D modeling method for such reservoir is developed at first. The augmented virtual internal bond is adopted for rock matrix modeling, which is a micro–macro constitutive model that intrinsically contains the fracture mechanism at the micro level. The 3D element partition method (3D-EPM) is used to model the natural fractures, which allows the crack to cut through the element without any remeshing. A 3D modeling method for the natural cavity is developed. The PF behaviors in the fracture-cavitied reservoir are investigated. It is found that the natural fracture can strongly guide the PF path. The PF can break through the stress barrier surrounding a cavity and connect this cavity to great extent, which is very helpful to improve the reservoir stimulation. The findings provide valuable reference for the design and assessment of PF treatment in the fracture-cavitied reservoir.

中文翻译：

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复杂裂缝空洞储层脉冲裂缝三维数值模拟

摘要 碳酸盐岩储层包含大量随机的天然裂缝和空洞。由于空腔周围应力集中，传统的水力压裂技术很难将人工裂缝与空腔连接起来。在这种情况下，脉冲压裂（PF）技术应该是一种替代的增产方法。为了研究复杂缝洞型储层中的 PF 过程，首先开发了这种储层的 3D 建模方法。岩石基体建模采用增广虚拟内键，是一种本质上包含微观层面断裂机制的微观-宏观本构模型。3D 单元分割方法 (3D-EPM) 用于对天然裂缝进行建模，它允许裂缝穿过单元而无需任何重新划分网格。开发了一种用于自然腔体的 3D 建模方法。研究了裂缝空洞储层中的PF行为。发现天然裂缝可以强烈引导PF路径。PF可以突破空腔周围的应力屏障，并在很大程度上连接该空腔，这对提高储层改造非常有帮助。研究结果为缝洞型储层PF处理的设计和评价提供了有价值的参考。