ABSTRACT: The geometric evolution of a fracture set in a controlled laboratory experiment is accurately predicted using a physically-based network simulator (PBNS). The experimental fracture sets were produced by straining a brittle coating applied to an acrylic substrate. The physically-based fracture sets are generated using iterative solutions to the boundary value problem for multiple cracks in an otherwise homogeneous, isotropic, and linear elastic solid subject to uniform remote stress boundary conditions. A preliminary methodology for conditioning the PBNS networks to data from seismic surveys and well bore flow tests is also presented. The advantage of this methodology is that information concerning the elastic and fracture characteristics of the rocks and the mechanics of the rock fracture process can be combined with other well bore data to better estimate the geometry of a particular fractured formation.