Development of a fracture capture simulator to quantify the instability evolution in porous medium

Abstract: Understanding and controlling fracture propagation is one of the most challenging engineering problems, especially in the oil and gas sector, groundwater hydrology and geothermal energy applications. Predicting the fracture orientation while also possessing a non-linear material response becomes more complex when the medium is non-homogeneous and anisotropic. Fracturing behaviour in geological porous media that exhibit high leak-off potential is not clearly understood. In this context, a novel testing technique is used to simulate the ground conditions in the laboratory and study the instability characteristics of such geo-materials. The bespoke apparatus designed and developed in this research programme is capable of applying true anisotropic boundary stresses, injecting fluid at a predefined flow rate and viscosity while also imaging the instability/ fracture propagation in a porous medium such as sand and weak rock. Pressure profiles and the progression of fracture are recorded simultaneously during the fluid injection process into specimens subjected to different boundary stresses. The fracture propagation data are analysed, which provides information on the evolution of fracture morphology and expansion velocity during the injection event.