Prof. Emmanuel Detournay

Biography

Emmanuel Detournay is currently the Theodore W. Bennett Chair Professor in Mining Engineering and Rock Mechanics in the Department of Civil, Environmental, and Geo- Engineering of the University of Minnesota (UMN). He holds a mining engineering degree from the University of Liège, Belgium and MSc and PhD degrees in Geoengineering from the UMN. Prior to joining the UMN faculty in 1993, he held various positions in consulting companies (Itasca, Minneapolis, MN; Agbabian Associates, El Segundo, CA) and in R&D (Dowell-Schlumberger, Tulsa, OK; Schlumberger, Cambridge, England). His expertise is in petroleum geomechanics, with two research focuses: drilling mechanics (bit/rock interaction, self-excited drilling vibrations, drillstring/borehole interaction, and directional drilling) and mechanics of fluid-driven fractures (asymptotic analysis, scaling, numerical modeling). He has co-authored about 160 papers in refereed publications. He has also been awarded 8 U.S. patents and has received several scientific awards for his work. In 2016, he was elected into the U.S. National Academy of Engineering. Since 2022, he has been serving as Director of the DOE sponsored Energy Frontier Research Center on Geo-Processes in Mineral Carbon Storage.

Introduction of the Lecture

Mechanics of Fluid-Driven Fracture: Recent Results

Over the past two decades, theoretical developments in hydraulic fracture modeling have led to new classes of solutions and computational algorithms that explicitly account for multiple time scales governing transitions between distinct propagation regimes. Following a brief review of these advances, this talk focuses on two topics that have received comparatively limited attention: (i) the deflation of a hydraulic fracture after shut-in due to fluid leak-off into the surrounding permeable formation, and (ii) the propagation of hydraulic fractures in poroelastic media.

Analysis of receding fractures after injection cessation reveals the emergence of the so-called Sunset Solution near the point of ultimate closure. In this asymptotic regime, the fracture radius recedes in a final stage of collapse, while the aperture scales linearly with the reverse time measured from closure. This behavior arises from a fundamental decoupling between kinematics and dynamics in the governing equations. Importantly, the robustness of the Sunset Solution provides a practical method to estimate the Carter leak-off coefficient directly from the temporal evolution of the fracture aperture at the wellbore.

A complementary model describing fracture propagation in highly permeable reservoir rocks is developed by coupling linear elastic fracture mechanics, poroelasticity, and lubrication theory. This formulation departs from conventional models in several key aspects: (i) it incorporates large-scale pore pressure perturbations and the resulting poroelastic effects; (ii) it accounts for the relatively small volume of fluid stored within the fracture compared to the total injected volume; and (iii) it includes fluid leak-off from both the borehole and the propagating fracture. The resulting solution predicts a non-monotonic evolution of injection pressure: pressure increases during the early-time radial flow regime, then decreases as the system transitions to a fracture-dominated flow regime. Consequently, the peak injection pressure does not signify formation breakdown but instead marks the transition between distinct porous flow regimes.