The technique of multistage hydraulic fracturing from horizontal wells is universally credited with enabling the economical production of hydrocarbon resources from shale formations. The method almost always entails the injection of fluid through the wellbore with the potential to create hydraulic fractures from multiple reservoir entry points, typically clusters of wellbore perforations, that are spaced out along the wellbore within a section that is colloquially referred to as a "stage".

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... bly the most basic question about this situation is how many perforation clusters within a given fracturing stage can be expected to produce growing hydraulic fractures. This paper presents a numerical investigation of this issue that employs a newly-developed, fully coupled parallel planar 3D hydraulic fracturing simulator that features: implicit time stepping, an implicit level set scheme to locate the propagating hydraulic fracture fronts that respond to their regimes of propagation and enables highly accurate simulations using a very coarse mesh, and the capability to dynamically partition the fluid among multiple, simultaneously growing hydraulic fractures in parallel, overlapping planes. Our results demonstrate the dependence of the energetically preferred number of growing hydraulic fractures on the length of the isolated zone, the height of the reservoir, and the relative importance of the fluid viscosity. In particular, we show that reservoirs with effective height containment and injection strategies that ensure substantial viscous dissipation will promote growth of multiple simultaneous hydraulic fractures rather than localization to just one or two dominant fractures.