• inform the design of the reservoir (conceptual geometry and fluid treatments) for enhanced permeability; and

  • simulate microseismic information to inform on the effected volume and magnitude range.

The response of the Fallon FORGE geothermal reservoir to hydraulic stimulation is modelled numerically to aid conceptual design of the well geometries and completions. The numerical modeling approach is based on: (a) full hydro-mechanical coupling; and (b) explicit representation of a Discrete Fracture Network (DFN). The reservoir-scale model in C has a core region of 1500 × 1200 × 1200 m volume around the positions of conceptual sub-horizontal well designs at the Fallon FORGE site. It contains relevant geological structure and a joint network constructed and simplified using borehole data. Stimulation has been performed in six stages/zones along the horizontal well using both openhole (low injection rate at 5 kg/s) and cased borehole (combination of high, 80 kg/s, and low injection rates) completions in order to test the role of hydraulic fracturing combined with hydro-shearing. The pattern of fracture stimulation in the two models has been analyzed and quantitatively assessed. Results indicate that the FORGE site is ideally suited for hydraulic stimulation of an EGS in sub-horizontal multistage wells due to orientations of the natural joint network in the regional principal stress field. Advantages and limitations of explicit representation of the DFN are presented and discussed.

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