Experimental and Numerical Investigation of Hydraulic Fracturing in Dry Sandstone

This study investigates hydraulic fracturing in initially dry sandstone through laboratory experiments and coupled hydro-geomechanical modeling. Under a true-triaxial stress state, hydraulic fractures were induced in 250 mm cubic specimens of Molasse sandstone by injecting either glucose or glycerol solutions. These injections promote axisymmetric crack propagation in storage-viscosity- and leak-off-viscosity-dominated regimes for glucose and glycerol, respectively. Experimental measurements show that glycerol, the lower-viscosity fluid, leads to higher injection pressures and narrower fracture apertures. This behavior is attributed to poroelastic backstress caused by rapid fluid leak-off into the dry porous matrix. The backstress also partially arrests fracture growth, underscoring the critical role of the poroelastic effects under these conditions. A finite element-based model is developed using FEniCSx to interpret and replicate these findings. The implementation has been benchmarked against existing analytical and numerical solutions of hydraulic fracture growth. Preliminary simulations reproduce the observed experimental trends, confirming the importance of poroelastic effects during fracture propagation under these conditions.