Numerical Simulation of Hydraulic Fracture Initiation From a Wellbore Considering Well Compliance

Abstract

Extensive experiment studies reveal that fracture initiation and growth is a complex behavior depending on the rock properties and injection conditions. Therefore, a reliable model is essential to interpret the fracture initiation and growth behavior. In this study, a fully coupled fracture model was proposed to analyze the behavior. The model considers wellbore compressibility, solid-fluid coupling, and multiscale propagation behavior. Explicit time marching is used to capture the fracture initiation process and implicit time stepping with the fracture tip asymptotic solution to solve fracture propagation. The model is validated against analytical solutions of the KGD model. Sensitivity analysis reveals that the initiation pressure is dependent on fracture toughness, while the peak pressure (breakdown pressure) is related to both rock properties and injection conditions. The peak pressure becomes larger as the increase of injection rate, fluid viscosity, Young’s modulus, and fracture toughness. Using a low injection rate and low-viscosity fluid favors capturing the fracture initiation pressure.