Analysis and Modeling of Explosive Fracturing Process in a Transparent Surrogate of Jointed Rock

In traditional hydraulic fracturing stimulation, the effective conductivity of low permeability rock is increased by generating or activating fractures through injection of pressurized fluid. Methods that use dynamic loading from explosives and propellants potentially extend stimulation to previously unrealized geological resources. In contrast to traditional fracturing methods (e.g. hydraulic fracturing) the stresses in the source region may be significantly larger than the in-situ stress, which helps to create fractures not oriented with the maximum in-situ stress. Fractures initially are generated by the diverging stress wave propagating from the energy release zone. It has been shown in the past that the crack area and final extend depend on the ability of explosive products to flow into the cracks after the wave propagation. This mechanism has been confirmed utilizing high - speed schlieren imaging, and Photon Doppler Velocimety (PDV) in recent explosive fracturing experiments with 0.3-0.7 g of high explosive source detonated in prestressed 1-foot PMMA cubic blocks with and without articial joints. Modeling of these experiments is challenging, as various scales need to be resolved to address this problem. We present first analysis and 3D modelling attempts. The goal of this work is to study the main mechanisms of dynamic fracture in brittle materials validated against recent and ongoing small scale experiments in order to upscale the results to realistic scenarios for the purpose of subsurface dynamic stimulations of geothermal systems.