Coupled modeling of complex fracture networks induced during hydraulic fracturing treatments

Hydraulic fracturing has been extensively utilized to stimulate production in low permeability naturally fractured reservoirs. There have been tremendous efforts to understand how hydraulic fracture develops in the presence of natural fractures to better describe complicated fracture network induced in the reservoirs. Hydraulic fracturing process in homogeneous reservoir is well represented by Linear Elastic Fracture Mechanics (LEFM) as fracture process zone is very small but in heterogeneous formations particularly in presence of microfractures, LEFM may not completely describe the rock failure behavior, hence more sophisticated models like cohesive models should be used. A cohesive zone model (CZM) is developed to couple fluid flow with elastic and plastic deformations of the rock. CZM approach is used to not only model propagation of the hydraulic fracture but also their interactions with natural fractures like crossing natural fractures. Additionally mechanical properties of digenetic cements inside natural fractures is also incorporated into this model. Pressure fluctuations before and after intersection of natural fractures is observed in the field and lab experiments, while this observation was not verified in two dimensional models, the presented model shows pressure fluctuations in non-planar hydraulic fractures due to slippage occurring before and after fracture intersections with the natural fracture.