Modeling Hydraulic Fracturing Initiation and Propagation in Porous Rock Formationsl

Abstract

Hydraulic fracturing has long been introduced to the oil and gas industry since the early nineteenth century for both reservoir characterization and reservoir stimulation. Despite the progress made in the last two decades, many challenges still have not been tackled regarding not only the propagation problem but also the initiation problem due to its complexity. The dissertation is divided into two stages, i.e., before and after fracture initiation. The first stage of the research aimed at improving the accuracy in solving the poro-mechanical response of wellbore during fluid injection before a tensile fracture occurs, which is crucial to determine the initiation of hydraulic fractures. The second stage focuses on the development of the numerical framework for hydraulic fracture propagation and its applications. The popular extended finite element method (XFEM) was adopted and a fully coupled poroelastic fracturing framework is programmed in Matlab using object-oriented programming paradigm. From the physics point of view, this framework managed to incorporate the coupled deformation and fluid flow in porous media, the fluid flow inside the fracture system, the fracture initiation, and evolution mechanics. From the numerical capability point of view, the framework was developed to be modular and extensible and multiple interacting fractures can be modeled. The poroelastic XFEM framework has been comprehensively verified against available solutions for several benchmark problems. With the adequate incorporation of devised modified traction-separation, the impacts of increased shale ductility on hydraulic fracturing have also been investigated for both the single-fracture scenario and multiple-fracture scenario.