POROELASTIC AND POROPLASTIC MODELING OF HYDRAULIC FRACTURING

It is essential to predict the behavior of hydraulic fractures accurately based on the understanding of fundamental mechanisms, governing process. The prevailing approach for hydraulic fracture modeling relies on Linear Elastic Fracture Mechanics (LEFM) that gives reasonable predictions for hard rock hydraulic fracturing, but often fails to give accurate predictions of fracture geometry and propagation pressure in soft/unconsolidated formation. The reasons are that the fracture process zone ahead of the crack tip, elasto-plastic material behavior and strong coupling between flow and stress cannot be neglected in these formations.

In this study, we developed a fully coupled poroelastic and poroplastic hydraulic fracturing model with cohesive zone method. The impact of formation plastic properties on fracture process is investigated. The results indicate that formation plastic behavior can have a great impact on fracture net pressure and geometry, especially when the plastic deformation area is large.