UT-Austin’s Devine Fracture Pilot Site (DFPS), 50 miles southwest of San Antonio, Texas, has been targeted for a comprehensive, multidisciplinary development of fracture diagnostics techniques cross-validated by ground-truth data acquisition near a recently created, 175-ft-deep, horizontal hydraulic fracture. To evaluate the fracture-diagnostic techniques at this site, we attempted to develop hydrogeological and geomechanical models on the basis of bottomhole-pressure measurements during injection tests with a predefined volumetric flow-rate profile, resembling a diagnostic fracture injection test (DFIT). History-matching efforts using a simplified layer-cake hydrogeological model resulted in the field-scale formation permeability of 9.87×10^-15-m^2 (10-mD) and Darcy-scale fracture permeability. Analysis of bottomhole pressure and injection-rate history showed that (1) the preexisting horizontal fracture was closed adjacent to the injection well and (2) the initial pump-pressure increase at a negligible volumetric injection rate led to near-well fracture reopening, conductivity increase, and abrupt injection-rate increase. To overcome hydrogeological-model limitations of predicting fracture reopening throughout injection, we extended the modeling to a finite-element, poroelastic analysis of horizontal-fracture growth using a cohesive-zone model. Using this fracture-reopening model, we were able to match the transient-pressure response during the entire experiment by adjusting the hydromechanical properties. The current study lays the foundation for future work that our team will be performing at this well-characterized fracture site.