Modeling 3D Hydraulic Fracture Propagation and Thermal Fracturing Using Virtual Multidimensional Internal Bonds

Abstract

Fracture propagation, especially for fractures emanating from inclined wellbores and closed natural fracture often involves Mode I, Mode II, and at times Mode III fracture pattern simultaneously. In this paper a Virtual Multidimensional Internal Bond (VMIB) model is presented to simulate 3D mixed-mode fracture propagation. To represent the contact and friction between fracture surfaces, a three-dimensional element partition method is employed. The model is applied to simulate fracture propagation and coalescence in typical laboratory experiments, and is used to analyze the propagation of an embedded fracture. Simulation results for single and multiple fractures illustrate 3D features of the tensile and compressive fracture propagation, especially the propagation of a Mode III fracture. The results match well with the experimental observation suggesting that the presented method can capture the main features of 3D fracture propagation and coalescence. By developing an algorithm for applying pressure on the fracture surfaces, propagation of a natural fracture is also simulated. The result illustrates an interesting and important phenomenon of Mode III fracture propagation, namely the fracture front segmentation. Moreover, thermo-mechanical coupling has been introduced into the model. The results of thermal fracturing simulations are reasonable, which indicate that the present model provide a way to predict 3D thermal fracturing propagation.