3D unrestricted fluid-driven fracture propagation based on coupled hydromechanical interface elements

Exploring unconventional reservoirs has raised several engineering challenges to improve oil/gas recovery. In the Brazilian pre-salt fields, highly heterogeneous carbonate formations compose these reservoirs containing fractures in multiple scales. The extracted carbon dioxide is reinjected in the reservoirs to increase oil recovery and reduce greenhouse gas emissions. For that reason, it is essential to develop robust numerical methods capable of simulating fracture propagation in naturally fractured porous media. This paper presents a new 3D mesh fragmentation technique to simulate non-planar hydraulic fracture propagation, considering its interaction with natural fractures. This method is based on discrete fracture representation through hydromechanical interface elements with a cohesive zone model to simulate fluid-driven fracture propagation. The proposed 3D mesh fragmentation algorithm inserts triple noded-interface elements into the continuum finite element faces, ensuring continuity of the fluid pressure field. The approach is successfully validated against experimental fracturing tests and analytical models. Also, by applying the proposed fragmentation technique, we study the influence of pre-existing oriented fractures on hydraulic fracture propagation in different scenarios. The results provide insight into the complex hydraulic fracturing process in naturally fractured formations. Finally, this approach is an attractive alternative to simulate multi-staged fracturing into 3D multilayered fractured rock formations.

Automated summary

This paper presents a new 3D mesh fragmentation technique to simulate non-planar hydraulic fracture propagation, considering its interaction with natural fractures. The approach is successfully validated against experimental fracturing tests and analytical models, providing insight into the complex hydraulic fracturing process in naturally fractured formations. This method is an attractive alternative to simulate multi-staged fracturing into 3D multilayered fractured rock formations.