Kevin H. Searles

Fully Coupled 3-D Hydraulic Fracture Models—Development and Validation

Abstract This chapter discusses the development and validation of a 3-D finite element formulation for modeling fluid-driven hydraulic fractures propagating in a permeable poroelastic medium. It presents a fully coupled formulation for hydraulic fracture growth that is implemented in a finite element solver using both cohesive elements and the extended finite element method (XFEM). For the implementation based on cohesive elements, fracture trajectory remains constrained to a plane. However, for the XFEM implementation, fracture trajectory becomes entirely solution-dependent. In this chapter, it is shown that the fully coupled formulation for modeling hydraulic fractures accurately reproduces referenced asymptotic solutions for zero fluid lag, variable rock and fluid properties, and fluid loss (leak-off) conditions. It is further illustrated that, in addition to matching these asymptotic solutions pertaining to short time scales, the formulation is also suitable for considering laboratory and field-scale problems of greater time and length scales. This chapter concludes by showing simulation examples of such problems including (1) a model constructed to replicate conditions of a laboratory-scale fluid injection experiment and (2) a model constructed to replicate conditions of a field-scale fluid injection test.