Hydro-shearing using low injection rates to stimulate the fractured geothermal reservoir for permeability enhancement. In this work, a series of 3D thermo-hydro-mechanical (THM) coupled simulations were run to investigate the hydro-shearing processes in enhanced geothermal system (EGS). In our model, natural fractures were considered according to the borehole televiewer image results. The enhancement of reservoir permeability was calculated using an empirical model derived from the hydro-mechanical coupling experiments. The THM coupled model was calibrated by reproducing the field monitoring data at the Utah FORGE site. The artificial reservoir volume and its permeability enhancement were investigated during injection test on well 58–32. The modelling results proved that hydro-shearing stimulation does not require the injection pressure to exceed the in-situ minimum principal stress. The hydro-shearing stimulation mechanism is controlled by the water injection induced reservoir cooling and pore pressure increase. For the given injection conditions at well 58–32, the artificial reservoir volume was estimated at about 67,000 m3. The maximum enhancement of reservoir permeability occurs in the vertical direction, thus using horizontal wells is beneficial for geothermal development at this site. The results presented in this work were beneficial for engineers to understand the hydro-shearing stimulation method.

中文翻译：

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犹他州 FORGE 现场增强型地热系统中水切变增产的数值模拟


使用低注入速率的水力剪切来刺激裂缝性地热储层以提高渗透率。在这项工作中，运行了一系列 3D 热-水-机械 （THM） 耦合模拟，以研究增强型地热系统 （EGS） 中的水剪过程。在我们的模型中，根据钻孔电视图像结果考虑了自然裂缝。使用从水力学耦合实验中得出的经验模型计算储层渗透率的增强。THM 耦合模型是通过复制犹他州 FORGE 站点的现场监测数据来校准的。在 58-32 井的注入试验期间研究了人工储层体积及其渗透率增强。建模结果证明，水剪增产不需要注入压力超过原位最小主应力。水剪增产机理受注水诱导储层冷却和孔隙压力增加控制。对于 58-32 井的给定注入条件，人工储层体积估计约为 67,000 m3。储层渗透性的最大增强发生在垂直方向，因此使用水平井有利于该地点的地热开发。这项工作中呈现的结果有利于工程师理解水力剪切增产方法。