Dr. Egor Dontsov, Chief Scientist at ResFrac gave a presentation to the ARMA HFC Warm-Up Series entitled “Morphology of Simultaneously Propagating Hydraulic Fractures.” Current hydraulic fracture designs rely heavily on inducing multiple cracks within each stage. Field-scale hydraulic fracture simulations for such scenarios demonstrate that there are situations, in which fractures develop complex shapes, whereby each individual fracture has its own unique geometry that is very different from its neighbors. At the same time, for some other parameters, fracture morphology tends to be more regular and less complex, so that all the generated fractures are similar to each other. Several groups of researchers have observed such behavior. The common finding is that high fluid viscosity and/or low fracture toughness lead to simpler morphology, while low viscosity and/or high toughness cause fractures to develop complex shapes. In this talk, the problem of fracture morphology is addressed from a somewhat simplified viewpoint, yet the one allowing to better understand the key parameters that affect the behavior.