Coupled processes at fracture in geomaterials

Birth of a fault in a transversely isotropic rock under uni-axial compression
Birth of a fault in a transversely isotropic rock under uni-axial compression.

We are working on both theoretical and experimental developments in the area of fluid driven fracture propagation in porous rocks. Our aim is to better quantify the growth dynamics of fluid driven fractures occurring either naturally (magmatic dikes, fractures at glacier beds) or in relation to industrial injection.

  • Laboratory experiments

We have developed a unique experimental set-up to perform laboratory  experiments on cubic rock samples of 250mm*250mm*250mm size. The cubic blocks can be subjected to a true tria-axial state of stress (up to 20MPa) as well as pore-pressure. Fractures are driven by the injection of a fluid at a constant rate from a wellbore drilled in the specimen. 64 piezo-electric sensors are used to image the fracture growth via acoustic waves (akin to performing a 4D ‘seismic-like’ imaging at the lab-scale in the ultrasonic range). 16 additional piezo-electric sensors record passively acoustic emissions occurring during the failure process.

  • Theoretical developments

We have clarified the effect of turbulent flow on hydraulic fracture propagation, especially the effect of friction reducers added to the fracuring fluid during industrial stimulation of shale-gas wells.

We are also studying the impact of the complex rheology of most fracturing fluid on HF propagation (shear-thinning properties etc.).

We are also  actively working on the impact of rock anisotropy on fracture growth.

  • Numerical developments

We are developing a series of open-source codes for the modeling of  fracture propagation driven by coupled processes (fluid, solid loadings etc.) in both 2 and 3D.  Notably, we have recently released a python-based solver PyFrac for the simulation of planar 3D hydraulic fractures.

We are particularly interested in the proper verification of numerical codes, which is critical for such highly non-linear moving boundaries problems.