Stress-intensity factor and fracture cross-sectional shape predictions from a three-dimensional model for hydraulically induced fractures

An efficient three-dimensional (3D) fracture model was developed that can be applied to arbitrary planar cracks with Mode 1 stress singularity at the fracture tip. Surface stress, thermally induced stress, and poroelasticity were included. In addition, the elasticity constants can be varied between elements. A parameter study was conducted with the model to evaluate the stress-intensity factor, the evolving shape of the fracture, and fracture width. The study includes the borehole effect, fracture migration, fracture barriers, fracture cross-sectional shape, fracture front shape and its stress-intensity factor, and evaulation of the validity of some simplified models. Further work on the details of the theory, algorithm, accuracy, and efficiency of the 3D fracture model is in progress.