Instabilities and Loss of Symmetry of Hydraulically Stimulated Fractures

Tuesday, May 12, 2015 - 9:00am - 9:50am
Keller 3-180
Blaise Bourdin (Louisiana State University)
Empirical models for hydraulic fracturing rely heavily on uniqueness and symmetry assumptions. In this talk, I will start from a highly idealized case, the quasi-static stimulation of a single crack in a non-porous matrix. I will present a variational approach to brittle fracture generalizing Griffith criterion without the need for any a priori hypotheses on crack path. I will show numerical evidences that how even in this idealized case, loss of uniqueness and symmetry can arise. I will then focus on the case of interacting cracks, and show how commonly accepted solutions obtained through a local criterion may not be energetically stable. Finally, I will present recent work on a coupled hydro-mechanical model based on a regularization of the fracture energy, and accounting for fluid flow in the fracture system and the porous reservoir, during crack propagation.

This is a joint work with graduate students Chukwudi Chukwudozie (LSU Petroleum Engineering) and Erwan Tanné (LMS, Ecole Polytechnique, France).