Shale fracturing for energy recovery: Current issues and review of available analytical and computational models

This paper reviews some of the major scientific challenges faced in the field of non-conventional energy production. Particular attention is given to shale rocks, in which the production of hydrocarbons involves hydraulic fracturing, fracture connectivity, multiphase flow, and reactive-transport. In regard to these problems, the paper describes a series of analytical and computational models to study fracturing in quasi-brittle solids and captures failure events in multi-phase geomaterials subjected to simultaneous changes in stress state, fluid pressure, moisture content, thermal and chemical conditions. Advantages and limitations of the different techniques are discussed, setting a vision for a new generation of multi-scale/multi-physical models for shale that can be used to support the optimization of the extraction processes, as well as to address industrial needs and mitigate the risks of environmental hazards, groundwater contamination and induced seismicity.