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

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 fracture orientation while possessing a nonlinear material response becomes more complex when the medium is subjected to anisotropic boundary stresses. Furthermore, the fracturing behaviour of geological porous media that exhibit high leak-off potential is not clearly understood. In this context, a novel testing technique is used to simulate in situ conditions in the laboratory and to study the instability characteristics of such geomaterials. 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 imaging instability/fracture propagation in a porous medium such as sand and bio-cemented sands. Pressure profiles and fracture propagation are simultaneously recorded during fluid injection into specimens subjected to different boundary stresses. Analysis of the images obtained during the fluid injection process provides information on the evolution of infiltration and fracture area during the injection event. The quantification of pressure and the corresponding fracture signature is, therefore, useful for a comprehensive understanding of the mechanics of fluid-induced fracture propagation.