The use of multi-fracced horizontal well technology in unconventional gas and liquid rich reservoirs is one of the key reasons for the recent success in the exploitation of Unconventional Resources. These multiple fractures are placed in many stages along the horizontal well using diverse completion technologies. Yet, the understanding of fracture growth mechanics and the optimum fracture placement design methodology are still preliminary. Recent advances in computational mechanics and the development of appropriate stimulation modeling technology will further nurture innovation and press forward much needed optimization of the Completion and Stimulation technology in multi-fracced horizontal wells.

This paper contains two key components. Firstly, an analytical model is used to highlight some of the salient features of multiple hydraulic fractures interaction. The advantage of an analytical model is that it provides immediate insights into the controlling parameters and steer further numerical analysis on stimulation optimization. Secondly, an idealized 2D numerical model is employed to illustrate fracture interference and interaction – not just between fractures that are pumped simultaneously, but also multi-stage fractures interaction and even potentially well-to-well interaction. Most of this interaction can be attributed to the fact that we are placing fractures in extremely tight formation (shales) and most fracture stimulation operations are conducted and completed within a time frame that is shorter than the time needed for frac fluid to completely leak-off and the resultant in-situ stress perturbation to dissipate. The understanding of subsurface fractures interaction will impact on surface simultaneous operation planning and execution in full scale development of unconventional gas and oil.

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