Distributed fiber optic sensors installed in boreholes provide a new and data-rich perspective on the near-borehole environment. These sensors measure strain (or strain-rate) with high spatial resolution and can survive extreme conditions. These sensors should be capable of enduring the high temperatures that exist in Enhanced Geothermal System (EGS) boreholes. Here, we explore the information that these sensors may reveal in a EGS system. Potential EGS subsurface signals are simulated in two ways: 1) a massively parallel multi-physics code that is capable of modeling hydraulic stimulation of heterogeneous reservoir with a pre-existing discrete fracture network, and 2) a parallelized 3D finite difference code for high-frequency seismic signals. The approach matches both the low-frequency strain signals generated during the fracture process and higher-frequency signals from microseismic and perforation shots. Results indicate that quantitative interpretation of the fiber data provides valuable constraints on the fracture geometry and microseismic activity, both of which are key to understanding an EGS system. These sensors are subject to varying types of noise, both external and internal and we evaluate potential sources of noise such as the electronics, fiber/cable, and subsurface to improve interpretation of the signals and the characteristics of each noise type. In addition, we examine the likely failure mechanisms of fiber sensors in the typical EGS environment and provide suggestions on ways to improve performance and durability. Ultimately, a robust system understanding will allow identification of areas for future improvement and possible optimization in fiber and cable design.

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