During hydraulic stimulation treatment in an enhanced geothermal (EGS) reservoir, it has been suggested that new fractures are initiated from stimulated preexisting fractures and propagate through the reservoir. In this stimulation mechanism, a fracture propagation from a preexisting natural fracture and the interaction of newly formed fractures and preexisting natural fractures play an important role in the creation of a complex fracture network. In this study, we developed a physics-based numerical model that couples fluid flow between fracture surfaces, fracture deformation, and fracture propagation driven by fluid injection to better understand how a fracture network is created by a hydraulic stimulation treatment. The results showed that the created fracture network complexity is affected by the fracture intersection angle, stress state, and injection rates. Having flow path complexity is advantageous in EGS because it increases the heat exchange areas, the fracture surface to rock volume ratio, and the general reservoir permeability. Therefore, the implication from the results of this study to make a better EGS reservoir is to stimulate an EGS reservoir with 1) well-oriented fractures, 2) a high stress ratio, and 3) a low injection rate. These reservoir conditions and stimulation design will likely make more flow paths and create a more complex fracture network.

在增强的地热（EGS）储层中进行水力增产处理期间，已经有人提出，新的裂缝是从已增产的已有裂缝中引发的，并通过储层传播。在这种增产机制中，从先前存在的天然裂缝开始的裂缝扩展以及新形成的裂缝与先前存在的天然裂缝的相互作用在创建复杂的裂缝网络中起着重要的作用。在这项研究中，我们开发了基于物理的数值模型，该模型将裂缝表面之间的流体流动，裂缝变形耦合在一起。以及由流体注入驱动的裂缝扩展，以更好地了解如何通过水力增产措施创建裂缝网络。结果表明，所产生的裂缝网络复杂度受裂缝相交角，应力状态和注入速率的影响。具有流道复杂性在EGS中是有利的，因为它会增加热交换面积，裂缝表面与岩石的体积比以及总的储层渗透率。因此，从这项研究结果中得出一个更好的EGS储层的含意是增产一个具有1）定向良好的裂缝，2）高应力比和3）低注入速率的EGS储层。这些储层条件和增产设计可能会产生更多的流动路径，并形成更复杂的裂缝网络。