Abstract Dynamic gas fracturing is a well stimulation technique that is able to create multiple fractures emanating from a wellbore. It operates by pressurizing at rise-times and peak pressures intermediate between conventional hydraulic fracturing and explosive fracturing. Two consecutive processes operate during this fracturing process: (i) generation and propagation of a dynamic stress wave that overpowers the static stress field and creates multiple radial fractures around borehole, followed by (ii) quasi-static pressurization and further extension of those starter-fractures by the expanding gas. Dynamic analysis is first performed to follow the evolution of the stress wave propagating from the borehole. The radial (r) distribution of peak tensile hoop-stress diminishes as 1 / r α with the power exponent ( α ) asymptoting to 2 as the loading rate decreases. This rapid attenuation generally limits the length of the body-wave-generated radial fractures to several borehole radii. The gas-loading of the borehole wall is followed by permeation of the gas pressure into the newly created radial fractures. Linear elastic fracture mechanics (LEFM) perturbation analysis shows that a regular distribution of multiple radial starter-cracks will preferentially propagate the longer cracks at the expense of the shorter cracks – that will arrest and snap-shut. This system naturally selects of the order of six dominant fractures that may grow in unison until the in situ stress field reasserts control as the fractures lengthen. This restricts the maximum number of the dominant fractures to of the order of six at the conclusion of treatment - a common observation in both in situ and laboratory experiments.

中文翻译：

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动态气体驱动裂缝的范围和几何形状

摘要 动态气体压裂是一种井增产技术，能够在井眼中形成多条裂缝。它通过在介于常规水力压裂和爆炸压裂之间的上升时间和峰值压力进行加压来运行。在这个压裂过程中，有两个连续的过程在运行：(i) 动态应力波的产生和传播，它压倒了静态应力场并在井眼周围产生了多个径向裂缝，然后是 (ii) 准静态加压和进一步扩展这些启动器-膨胀气体造成的裂缝。首先进行动态分析以跟踪从钻孔传播的应力波的演变。随着加载速率的降低，峰值拉伸环向应力的径向 (r) 分布以 1 / r α 的形式减小，而幂指数 ( α ) 渐近为 2。这种快速衰减通常将体波产生的径向裂缝的长度限制在几个钻孔半径内。钻孔壁的气体加载之后是气体压力渗透到新产生的径向裂缝中。线弹性断裂力学 (LEFM) 扰动分析表明，多个径向起始裂纹的规则分布将优先传播较长的裂纹，而较短的裂纹将被阻止和快速关闭。该系统自然地选择六个主要裂缝的顺序，这些裂缝可能会一致增长，直到随着裂缝的延长，原位应力场重新发挥控制作用。