Analysis of fracture propagation behavior and fracture geometry using a tri-axial fracturing system in naturally fractured reservoirs

Hydraulic fracture propagation behavior and fracture geometry in naturally fractured reservoirs are studied through a series of servo-controlled tri-axial fracturing experiments. Three interaction types between induced fractures with pre-fracture were observed. Difference of horizontal stress, angle of approach and shear strength of pre-fracture were considered to control the fracture propagation behavior. With increasing shear strength of these pre-fractures, the area of arrested behavior also increased. The geometry of hydraulic fracture is mainly controlled by in-situ stress and natural fractures in natural reservoir. Two hydraulic fracture patterns were observed in different stress regimes. In a normal stress regime, it was found to cause fractures, with interacting branches because of pre-existing fracture. Tortuous fractures were found along the direction of fracture height when one of the horizontal stresses is the maximum principle stress.